Fwd: Delta Bot Meeting Notes

[Jeff Hutchison]

Ladies and Laddies, the Delta-Bot team intends to scale up... the plan is for something like a ~12ft tall Delta.  Minutes of our meeting from last night can be found below.

---------- Forwarded message ----------
From: Jeff Hutchison <jhutc...@gmail.com>
Date: Wed, Feb 3, 2016 at 1:56 PM
Subject: Delta Bot Meeting Notes
To: Mark Sullivan <msul...@cyclotronics.com>, Chris Kelley (Google+), shane hooper <shane...@gmail.com>, greg southerland <greg...@hotmail.com>, Jennifer Evans <jcev...@gmail.com>, Alberto Bertolin <albertol...@yahoo.com>
Cc: 1ron...@gmail.com, "Roland T. von Kurnatowski III" <roland...@txrxlabs.org>

Delta-Bot meeting was held Tuesday, 2nd Feb, 2016 at El Tiempo.  In attendance were Mark Sullivan, Chris Kelley, Shane Hooper, Greg Southerland, Jenn Evans, Alberto Bertolin, and Jeff Hutchison.  Meeting took place (nominally) between 7:00PM and 8:00PM.

The re-establishment of a regular [productive] meeting

- It was resolved that the Delta-Bot meeting would be reinstated as a productive TXRX Labs event

- Meeting is still listed on calendar from 6:30 to 8:00 on Tuesday nights

- Activities carried out for the greater glory of TX/RX labs will be viewed favorably by the organisation and volunteer hours will be granted.

The location of said meeting

- It was discussed that the meeting should be held at El Tiempo as the regular location

- An alternate location of Batanga for 9 Feb was proposed and accepted by the group

The 12 foot tall delta

- The team has been challenged by Roland to design and produce a truly badass monster delta bot

- Framing of the bot was discussed.  Either HAM radio tower or stage lighting framework were both deemed appropriate (WASP uses some sort of stage lighting framework for their monster delta).

- Mark has HAM tower in Joplin... Jeff has a truck in KS.... Jeff also has three Fanuc 3hp DC servos with drivers (currently installed in the Shoda router in KS).

- Media selection was discussed.  ABS, PLA, Concrete and expanding foam were all discussed.

- Pellet based plastic printing was discussed... in order to ensure proper extrusion of filament from pellets, a steady state operation is preferred/required.  This might be achievable through a take-up system.

- Expanding foam was explored.  Expansion coefficients vary between products.  Pumping could be peristaltic or gear pump.  Both are subject to pulsation, which will create variability in the amount extruded.  Multistage pumps would reduce this pulsation.  Hoses will likely be disposable.

Action items from the meeting:

- Document meeting (Jeff H.)

- Update TXRX calendar entry to reflect meeting location change (and relevant group topic change)

- Design frame

- http://victoriatx.craigslist.org/for/5379308893.html

- Design drive system

- Evaluate options regarding media

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 9thFeb, 2016 at El Tiempo.  In attendance were Mark Sullivan, Shane Hooper, Greg Southerland, and Jeff Hutchison.  Meeting took place (nominally) between 7:30PM and 8:30PM.

The location of said meeting

- It was decided that the meeting should be held at El Tiempo instead of Batanga as previously agreed.  El Tiempo will remain the default location for the meeting.

The 12 foot tall delta:

Frame

- Design of the frame is progressing

- Mark has proposed a collapsible design, Greg will CAD it up and see what it looks like

- Greg expressed concern of frame buckling under load from the wheels... clamping around the tube was discussed.

- A counterweight will be incorporated to offset the mass of the arms and end device

Wheels

- Greg proposed a urethane rollerskate wheel with a groove carved to match the frame.  The idea was met with universal approval.

Motors

- Expected ideal motors will be ~1hp AC servos (motor and driver cost ~200 per set)

Drive

- Chain drive was discussed, roller chain connecting links were identified as an available solution to attachment http://www.rollerchain4less.com/C2080H--K1-Attachment-Connecting-Link_p_2211.html?gclid=CjwKEAiA3Ou1BRDso5XyhduuwFASJABP3PEDwnAMxmqMlSNFPC6KS6lbaVqF0a8RLRka6VfEOA4FUhoCbOjw_wcB

- Gear ratios and speed were briefly discussed

U-Joints

- Greg has a plan for the design of the U-joints, will design and present to the group

Base

- Materials selection for base was discussed.  MDF, melamine, or sheet metal would all be viable, and should be selected based on print media

- Expected print area will be circular with ~50" diameter

Print Media

- Further discussion into extrusion of plastic was held... pellets need not be melted, solidified as filament, melted again and extruded... direct pellet to melt to extrude would be the expected operation.  Local Motors 3D printer was referenced - https://localmotors.com/3d-printed-car/

Action items from the meeting:

- Document meeting (Jeff H.)

- Take to-go order to Jenn (Jeff H.)

- Update TXRX calendar entry to reflect meeting location change (and relevant group topic change)

- Design frame

- Design arms/joints

- Design drive system

- Evaluate options regarding media

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 23rd Feb, 2016 at El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Alberto Bertolin, Jenn Evans and Jeff Hutchison.  Meeting took place (nominally) between 7:00PM and 8:00PM.

The 12 foot tall delta:

Frame

- Greg has modeled multiple options for a triangular design with special attention to transport

- Discussions regarding transport led to a discussion re-opened regarding geometry.  A planar arrangement of the columns will work, and will be looked at further.

- Scissor-lift type sections between columns will allow the system to collapse

- Column motors and trucks can be connected by machine pins to the scissor mechanism to expand and collapse.

Print Media

- Selected media will significantly impact the amount of time required for a print.  expanding foam should allow for a high build rate, and low object mass.

Action items from the meeting:

- Document meeting (Jeff H.)

- Research foam options (Jeff H.)

- Redesign frame with new geometry (Greg)

- Design arms/joints

[Greg Southerland]

Great job Jeff 

I feel this captured the meeting very well 

Work has been started in the planer configuration 

Let's post to txrx

Sent from my iPhone

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[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 15 Mar, 2016 at El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Shane Hooper, Carol Schmidt, Alberto Bertolin, Jenn Evans and Jeff Hutchison.  Meeting took place (nominally) between 7:30PM and 8:30PM.

The 12 foot tall delta:

Frame

- Discussions regarding mounting and deployment of the "rig".

- A tilt-up design (a la drilling rig) was proposed, carries the penalty of being fixed to the vehicle and cannot be easily brought into smaller venues

- The best of both worlds - a tilt up design that can be removed for smaller venues was proposed and agreed by the group.

Bed

- Assuming foam as the print media, a roll of plastic sheet can be pulled out for the print bed... cut off with each print.

Print Media

- Expanding foam was further researched by Mark S. and found to be economically sensible

 - BASF urethane at $2700 for a 55 gal drum of each component (110 gal total).  They also have 2x15 gallon kits for about $900.

 - 2x55 gallons makes 70 cubic meters of foam

 - PLA has a density of 1250 kg/m³

 - ABS has a density of 1040 kg/m³

 - ABS and PLA pellet bulk pricing on Alibaba $3-5K per ton

 - The foam takes 30s to rise and set, which should work

 - Pneumatic drum pumps can be used to dispense

Static Mixer nozzle

 - Modeled and 3D printed (good idea)

 - Ordered in packs of 10 for 22 bucks (better idea)

Action items from the meeting:

- Document meeting (Jeff H.)

- Redesign frame with new geometry (Greg)

- Design arms/joints

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 22 Mar, 2016 at El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Jenn Evans and Jeff Hutchison.  Meeting took place (nominally) between 7:00PM and 8:00PM.

The 12 foot tall delta:

Frame

- Geometry continues to vex... Jeff promised to have a physical model built for next meeting

- Transition from planar legs to equilateral triangle planchette will take place in the arms

- Any forces from the planchette will be substantial at the legs (or vise versa)... on account of the tremendous moment arm

Solidworks server

- Greg will install Solidworks server on his laptop in order to overcome the issues being experienced with the license server currently in use.

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 29 Mar, 2016 at El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Shane Hooper, Alberto Bertolin, Jenn Evans and Jeff Hutchison.  Meeting took place (nominally) between 7:00PM and 8:00PM.

The 12 foot tall delta:

Frame

- Jeff presented a physical model

- As predicted, there was a substantial spreading force in the outer arms when actuated.

- Mark has proposed an alternate design which he will present next week

Solidworks server

- Greg and Mark installed Solidworks server on Greg's laptop

Info - the physical model was built using makerbeam, bamboo skewers, and 3D printed parts.

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 26 Apr, 2016 at El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Jenn Evans and Jeff Hutchison.  Meeting took place (nominally) between 7:00PM and 8:00PM.

The 12 foot tall delta:

Mark presented his alternate design

- Legs were planar

- Trucks were low profile

- Arms will need to be carefully designed in order to ensure that they are light weight and rigid

- Planchette was angled to constrain geometry

   - if all three sets of arms were connected to a flat side of the planchette, it would gain an unintentional 4th axis (without control)

- Greg will work to detail the alternate design

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 3 May, 2016 at El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Jenn Evans, Jeff Hutchison, Shane Hooper, Lajos Garmati, Chris Kelley, Wanjun Zhang, and Andrew Siverly.  Meeting took place (nominally) between 7:00PM and 8:00PM.

The 12 foot tall delta:

Frame Geometry:

The planar delta design was challenged... defended... reconsidered.  A triangular arrangement has regained support

A collapsible base was reiterated for this concept

Consideration for a stadium-cam style geometry did not gain traction (for full stability, down-wires would be needed, would interfere with build volume)

Whatever the geometry, it'll need to be deploy-able within a 10'x10' booth space... something like a 5' square in the back middle might be perfect

Securing it to the floor or hang from the ceiling... the space will dictate what is possible

Print Media

No matter what media is used, high-build is critical, light weight is critical

Expanding foam may have unwanted off-gassing, might be difficult to work with

Perhaps we could invent a filament that contains a blowing agent and it would expand as it prints

Polystyrene beads would be an excellent aggregate for printing

Hot-melt glue could coat the beads and be activated on printing

The polystyrene beads could also be expanded in the printing process... the hopper would be much smaller for it

Laser metal deposition is awesome, and we should do it, but with polystyrene

https://www.youtube.com/watch?v=yKnlmfuMSgo

Powder printer?

Too boring to watch print... and then so. much. material. handling..

Wait, material handling, how do you convey PS pellets?

Pneumatic conveyance of PS pellets would be suuuuper easy

not pneumatic, but hilarious, and sorta humane: https://www.youtube.com/watch?v=lO5TikjZU3c

Legs:

Still radio tower sections, trucks still based on roller skate wheels

Arms:

Still need to be light weight and rigid... carbon fiber triangles are the leading concept here

Servos:

Aside from Jeff's Fanuc kit up in KS, we have several 1-off servos available, and one matched trio

Mitsubishi Melservo set from the tree mill

Need the serial protocol to make them work

A tape encoder was discussed

Software

Roland has volunteered to be responsible for the LinuxCNC work

Actions:

Minutes of mtg - Jeff

Frame - Greg

Print Head - Shane

[Greg Southerland]

Excellent job once again Jeff

Sent from my iPhone

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 10 May, 2016 at El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Jeff Hutchison, Shane Hooper, and Alberto Bertolin.  Meeting took place (nominally) between 7:00PM and 8:00PM.

The 12 foot tall delta:

Corrections:

Although Roland Von Kurnatowski was mentioned in the minutes... I forgot to include him in the attendance list.  I deeply regret any harm this may have caused.

Frame Geometry:

The collapsible base was discussed.  Greg suggested that the base should break into 3 parts with the connectors folding against the leg as shown (poorly) in the (crudely MSPaint'd) sketch below:

Print surface:

The folding base discussion led to a discussion about the print surface.  A giant embroidery hoop was suggested:

Servos:

There was a discussion regarding stepper motors.  Servos remain in favor

Actions:

Minutes of mtg - Jeff

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 10 May, 2016 at El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Carol Schmidt, Jenn Evans, Chris Kelley, Jeff Hutchison, Wanjun Zhang, and Roland Von Kurnatowski.  Meeting took place (nominally) between 7:00PM and 8:00PM.

The 12 foot tall delta:

Position feedback

DRO tape, ultrasonic, laser interferometers, various different systems were discussed.

Print media

various media were discussed.

Decision making

Unless we can consider items decided, we'll never move forward

Target deadline

A working printer by December

Actions:

Minutes of mtg - Jeff

[Mark Sullivan]

I'd add that we decided we needed a common file share and this has been set up.

- Mark Sullivan -

(713)823-9938

Fax (281)946-5978

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 24 May, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Shane Hooper, Jenn Evans, Chris Kelley, Larry (?), Jeff Hutchison,and Roland Von Kurnatowski made an appearance.  Meeting took place between 7:00PM and 8:00PM at TXRX, followed by continued discussion at El Tiempo

The 12 foot tall delta:

Presentation of model:

Greg presented his model on the overhead projector and the team discussed the design elements.

Team has returned to a traditional delta arrangement to solve the myriad problems brought about by "creative" geometry

Drive sprocket location was discussed, the position should be optimized

A vote was taken with regards to the number of pieces into which the delta would be disassembled.  

The option to have one single collapsible printer was rejected on the basis that it would potentially be too heavy and unwieldy.  

The option to separate the lower base independent of the legs was accepted 

Provision of hinges didn't offer substantial benefit over simply breaking the thing down into component parts.  

Dimensional variations between components drive the request to use different bolt patterns so that the fit up is the same each time.

The top connections were not solved in the meeting

A poorly described and poorly defended concept (by a cold and cold medicine addled member) for "two sets of trucks" was shot down.. but now that said member has a clear head, the proper description is drawn (poorly) here:

The pulleys at the top stay at the top, the additional trucks become the top support and are engaged on the chain (with the normal trucks disengaged) for lifting and then locked to the frame at the top.  The assembly takes place on the ground, is lifted into position, and then minimal (if any) ladder work for the assembler.  

Continuation at El Tiempo:

Various points were discussed... the extrusion media came up, and the previous problems of outgassing of noxious foams was reiterated.  The concept of starch foam (like the cornstarch packing peanuts) was brought up, followed by the question of how they're made.  The simplest answer is that a paste is cooked and extruded.

http://cdn.intechopen.com/pdfs-wm/34062.pdf

http://www.google.com/patents/US20090170971

http://www.sciencedirect.com/science/article/pii/S0032386102004974

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 7 June, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Shane Hooper +1, Larry (?), and Jeff Hutchison  Meeting took place between 6:00PM and 7:00PM at TXRX, followed by continued discussion at El Tiempo

An unminuted meeting took place 31 May...

The 12 foot tall delta:

Updated model.

Greg has made substantial progress in the model

Gear ratio for drives has been confirmed to give appropriate truck speed

Timing belts to be used with a 2 stage reduction

Bicycle chain (for reduction section) was suggested, decided against - it's cheaper, but not as good.

Truck guide wheels were modeled with pillow block bearings as well as the internal bearings... this is excessive

The counterweight is not expected to need any guidance... however, if necessary, a ring and rod can be added to keep it centered in the tower.

Carbon steel base pieces are proposed - the additional weight will keep the CoG for the unit low... this may not be necessary.

Aluminum will be used for the trucks

Print Media

Further discussion regarding starch foam was punctuated with hyperlinks from 24 May meeting.

Actions

Minutes - Jeff

Add tolerances to drawings - Greg

Release to Manufacture - Greg

Waterjet parts - Roland

Assembly - Team

Starch/Polymer foam experimentation - Jeff

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 14 June, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Mark Sullivan, Greg Southerland, Chris Kelley, Shane Hooper +1, Elijah (?), and Jeff Hutchison  Meeting took place between 6:30PM and 7:30PM at TXRX, followed by continued discussion at El Tiempo (where Jenn Evans and Suzie re-joined the group)

The 12 foot tall delta:

Arms

Will be constructed from 1" 80/20

A stiffener plate was detailed, proposed, decided against

If additional stiffness is needed, a different profile of aluminum extrusion may be used.

The arms are removable and securable for shipping (spring hasps are used in both positions)

The spring hasp design was challenged, but will certainly be robust enough for the application

Base

The thickness of plates/sheet in the base was reconsidered.
1/2" plate is excessive, provides for drilling/tapping ends for bolting, but not needed
Through bolting can be acheived with nut plates, tacking nuts to the sheet metal, or other methods
Field-bolting will be with captive bolts to minimize chance of losing them

Print Media

Churros are extruded, deep fried, relatively low density, and delicious
Oil-less fryers are really just convection ovens
https://www.amazon.com/BIG-BOSS-1300-Watt-Oil-Less-16-Quart/dp/B007P6SAZ4
A convection-section in the hot-end could be used to set cookable foam
Wave-guiding microwaves might be beyond the scope of the project.
Can PLA be foamed?  Yes... it is an alternative to EPS, and used similarly.
http://www.sciencedirect.com/science/article/pii/S0079670014000392
If a source for foam PLA can be found, it might be a preferable alternative to foamed starch

Actions

Minutes - Jeff

Starch/Polymer foam experimentation - Jeff

[Jeff Hutchison]

file:///C:/Users/d57301/Downloads/ijms-10-05381.pdf

CO2 can be used to induce foaming in PLA

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 5 July, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Lajos Gyarmati, Elijah (?), and Jeff Hutchison  Meeting took place between 6:30PM and 7:30PM at TXRX, followed by continued discussion at El Tiempo 

The 12 foot tall delta:

Arms

Square tubing fits the 80/20 perfectly (a little tight)

Design discussion

With Lajos available, Greg went through the design and discussed design decisions

Planchette

The arm looks as if it might bind when the planchette is in the extreme outer position.
Greg continues to work to shrink the planchette and u-joints
Greg presented his u-joint design

Actions

Minutes - Jeff

Starch/Polymer foam experimentation - Jeff

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 12 July, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Lajos Gyarmati, Elijah (?), and Jeff Hutchison  Meeting took place between 6:00PM and 7:00PM at TXRX, followed by continued discussion at El Tiempo 

The 12 foot tall delta:

Planchette

Further discussion regarding the potential for binding when the planchette is in the extreme outer position.

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 19 July, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Roland, Chris Kelley, Shane Hooper +1, Elijah, and Jeff Hutchison  Meeting took place between 6:00PM and 7:00PM at TXRX, followed by continued discussion at El Tiempo 

The 12 foot tall delta:

Greg presented the 3D model updates

Accuracy / Repeatability / Tolerence

Accuracy of one tenth of an inch was suggested and there were no objections heard.

Chain Take up

Greg presented an elegant tensioning screw design

Linear rail 

As shown (Torchmate style plate rail) was rejected by the team

Important to note that the rail only needs to extend through the motion range of the trucks (top of legs)

With limited length ~6ft, the price of "proper" rails might not be prohibitive

Trucks

Truck design is dependent upon linear rail (or tower w/ skateboard wheels) design

Arms and U-joints can be mounted to either trucks or rails as design evolves

Arms and U-Joints

Overall design is excellent - some debate about bushings vs bearings, no clear winner/loser in this design.  

Speed holes in the arms will require substantial machining... unless they're available like that - think stop sign posts, but aluminum

Speed holes in the u-joints are not necessary

Path forward (action)

The straightness of radio towers is unknown (they're straight, but /how/ straight?) Mark will order the towers and we'll get started with them

The arms, planchette, and u-joint are in good enough shape design-wise to get started, we will proceed

Drive system may require subtle adjustment depending on whether skateboard wheel trucks or linear rail is selected

No meeting next week as Greg and Jeff will be catching fish in Puerto Rico

[Greg Southerland]

Thanks Jeff well written as usual and really captured the meeting 

Sent from my iPhone

<image.png>

The pulleys at the top stay at the top, the additional trucks become the top support and are engaged on the chain (with the normal trucks disengaged) for lifting and then locked to the frame at the top.  The assembly takes place on the ground, is lifted into position, and then minimal (if any) ladder work for the assembler.  

Continuation at El Tiempo:

Various points were discussed... the extrusion media came up, and the previous problems of outgassing of noxious foams was reiterated.  The concept of starch foam (like the cornstarch packing peanuts) was brought up, followed by the question of how they're made.  The simplest answer is that a paste is cooked and extruded.

http://cdn.intechopen.com/pdfs-wm/34062.pdf

http://www.google.com/patents/US20090170971

http://www.sciencedirect.com/science/article/pii/S0032386102004974

[Jeff Hutchison]

Greg called and won't be able to make it to the space tonight... I'm bailing as well.  See you next week.

[Mark Sullivan]

Although our Fearless Leader and our Scribe were absent, some of use got together for dinner and to talk about the project.

- Mark Sullivan reports that the tower sections have been ordered

- Chris Kelley filled in recent newcomer Alijah Ballard and guest Anirban Joy on the project and brought them up to speed.

- Both had some good suggestions

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 9 Aug, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Chris Kelley, Alijah Ballard, and Jeff Hutchison  Meeting took place between 6:00PM and 7:00PM at TXRX, followed by continued discussion at El Tiempo, where we were joined by Shane Hooper and Suzy

Puerto Rico

Exactly zero fish were caught.. but a good time was had by all

The 12 foot tall delta:

Cross Brace

During the week, Greg modeled a cross-brace for mounting linear rails to the legs.  The first pass at this design involved multiple pieces to be integrated. 

Mark's response: Instead of a separate saddle, the saddle could be cut into side walls of the channel.  This would actually be easier to machine since it would mean cutting square stair-steps instead of an angle oblique to the Z axis.

The modified design offers multiple benefits over the original... it reduces part count and machining operations... the part would be machined in a single setup, with the stair steps cut as shown here: http://web.mit.edu/hyperbook/Patrikalakis-Maekawa-Cho/node213.html - work could be completed (if desired) with a tool change to ball end mill.

However, the stair steps appeared to be rather coarse, and there was concern regarding stresses on the tubes of the legs.  There was also concern related to the CAM work required to define the cuts.

Depth of the groove was discussed and Greg pointed out that a shallower groove would require a longer (non-standard) U-bolt... therefore the depth is perfect as designed.

The number of cross braces was discussed.  The legs have zig-zag bracing at a regular frequency, and the linear shaft rail guides have bolt holes at a regular frequency... there may be interference between the bracing and the bolt holes.

The linear shaft rail guides are designed to be supported at every bolt hole - for a given deflection under a given load.  The loads on this machine will be VERY small, and 100% support is not necessary - especially with the position tolerances that have been discussed.

Print Media

Jeff has researched and ordered various substances to experiment with.  The objective is to come up with a stable foam that can be fixed either with heat or chemically.  A whip-cream'er and a soap foamer (to be used with an air-compressor) have been purchased for experimentation, along with a small inductive heater.

http://green-plastics.net/posts/76/qaa-help-with-cornstarch-pla-plastic-project/

As the components arrive over the course of the week, I'll mix, spray, curse, and document the results... I hope that next tuesday I'll have a demonstration ready (instead of just a big mess).

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Fax (281)946-5978

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[Mark Sullivan]

And, guess what just arrived ..

.

[Greg Southerland]

Can you see if they are 11-1/4 center to center 

Sent from my iPhone

On Aug 10, 2016, at 12:59 PM, Mark Sullivan <msul...@cyclotronics.com> wrote:

And, guess what just arrived ..

.

<IMG_20160810_124845168.jpg>

On Wed, Aug 10, 2016 at 11:38 AM, Jeff Hutchison <jhutc...@gmail.com> wrote:

Delta-Bot meeting was held Tuesday, 9 Aug, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Chris Kelley, Alijah Ballard, and Jeff Hutchison  Meeting took place between 6:00PM and 7:00PM at TXRX, followed by continued discussion at El Tiempo, where we were joined by Shane Hooper and Suzy

Puerto Rico

Exactly zero fish were caught.. but a good time was had by all

The 12 foot tall delta:

Cross Brace

During the week, Greg modeled a cross-brace for mounting linear rails to the legs.  The first pass at this design involved multiple pieces to be integrated. 

<image.png>

Mark's response: Instead of a separate saddle, the saddle could be cut into side walls of the channel.  This would actually be easier to machine since it would mean cutting square stair-steps instead of an angle oblique to the Z axis.

<image.png>

The modified design offers multiple benefits over the original... it reduces part count and machining operations... the part would be machined in a single setup, with the stair steps cut as shown here: http://web.mit.edu/hyperbook/Patrikalakis-Maekawa-Cho/node213.html - work could be completed (if desired) with a tool change to ball end mill.

However, the stair steps appeared to be rather coarse, and there was concern regarding stresses on the tubes of the legs.  There was also concern related to the CAM work required to define the cuts.

Depth of the groove was discussed and Greg pointed out that a shallower groove would require a longer (non-standard) U-bolt... therefore the depth is perfect as designed.

The number of cross braces was discussed.  The legs have zig-zag bracing at a regular frequency, and the linear shaft rail guides have bolt holes at a regular frequency... there may be interference between the bracing and the bolt holes.

<image.png><image.png>

The linear shaft rail guides are designed to be supported at every bolt hole - for a given deflection under a given load.  The loads on this machine will be VERY small, and 100% support is not necessary - especially with the position tolerances that have been discussed.

Print Media

Jeff has researched and ordered various substances to experiment with.  The objective is to come up with a stable foam that can be fixed either with heat or chemically.  A whip-cream'er and a soap foamer (to be used with an air-compressor) have been purchased for experimentation, along with a small inductive heater.

<image.png>

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[Mark Sullivan]

Yes.  11.25

[Greg Southerland]

Thanks 

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[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 23 Aug, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Mark Sullivan, Chris Kelley, Roland Von Kurnatowski, Lajos Gyarmati and Jeff Hutchison  Meeting took place between 6:00PM and 7:00PM at TXRX, followed by continued discussion at El Tiempo.

The 12 foot tall delta:

Legs

Radio towers are in, and they appear to be "in spec".  It was noted that the cross bracing appears to be hand welded, and Greg expressed some small degree of concern about potential interference with the rollers on the trucks.  Straightness can potentially be "measured" using a gun-barrel checking method described here

Trucks

Chris has been modelling and has come up with an excellent solution. 

Model shows T-Nut tab and slot construction, but team discussed welding after fitup as the machine will be mobile and subject to loosening forces.

​

Wheels

Roller skate wheels, machined groove to match radio tower tube.  Use 6 per truck.  Mounted on economically priced pillow block bearings from eBay.

Extruder

Jeff has done exactly zero experiments with the foam components ordered... these activities should ramp up in September

Chris has downloaded part models for a large format pellet extruder.  Making the auger will pose the greatest challenge.

[greg southerland]

the  target speed for the truck is  2500"/min

I really feel that Chris's truck design was excellent the only issue I have as seen is that I would like see the 4 of the wheel pillow block bearings in fixed holes  and not mounted in slots. This will allow the truck position  in relation to the rails to be  fixed measurement.  The other 2 wheels opposite if the arm mounts should be adjustable with slotted holes to allow tension to the rails. I love the truck design and it gets my vote. I hope the rest of you chimes in with yay or nay so we can advance the project further. the larger chain is the right way to go if off the shelf pulleys and sprockets  can be sourced economically to obtain the 250'/min  truck speed. 

---

From: txrx...@googlegroups.com <txrx...@googlegroups.com> on behalf of Jeff Hutchison <jhutc...@gmail.com>
Sent: Wednesday, August 24, 2016 8:59 AM
To: txrxlabs
Subject: Re: [TX/RX Labs] Re: Delta Bot Meeting Notes

 

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[greg southerland]

sorry the last sentence should read 2500"/min.

the larger chain is the right way to go if off the shelf pulleys and sprockets  can be sourced economically to obtain the 2500"/min  truck speed. 

---

From: txrx...@googlegroups.com <txrx...@googlegroups.com> on behalf of greg southerland <greg...@hotmail.com>
Sent: Wednesday, August 24, 2016 10:29 AM
To: txrx...@googlegroups.com

Subject: Re: [TX/RX Labs] Re: Delta Bot Meeting Notes

 

the  target speed for the truck is  2500"/min

I really feel that Chris's truck design was excellent the only issue I have as seen is that I would like see the 4 of the wheel pillow block bearings in fixed holes  and not mounted in slots. This will allow the truck position  in relation to the rails to be  fixed measurement.  The other 2 wheels opposite if the arm mounts should be adjustable with slotted holes to allow tension to the rails. I love the truck design and it gets my vote. I hope the rest of you chimes in with yay or nay so we can advance the project further. the larger chain is the right way to go if off the shelf pulleys and sprockets  can be sourced economically to obtain the 2500'/min  truck speed. 

[Jeff Hutchison]

Agreed.... and for reference:

​

[Chris K.]

The reason for having all the pillow block holes slotted was two fold:

1) Radial symmetry - Without it, a 2.5D trilateral shape has 2 wrong orientations for every correct one, whereas with it, all orientations are correct. This eliminates the possibility of getting half-way through assembly and realizing that one part is on the wrong way.

2) Preload of the wheels/bearings should allow the truck to remain in location relative to the ideal central axis of the towers, not the actual plane of any side of the tower. Otherwise, adjustments over time from wear will cause the position of the arm pivot points to move which will require adjustment of the kinematics parameters.


As for speed, I think 2500 IPM is unnecessarily fast. Our big router table's rapids are capped at less than half that speed and it is still our fastest machine. Also, I don't think any form of extruder we are likely to use will be able to keep up with a travel speed of much more than 100-150 IPM. The problem with needlessly high speeds is that they tend to require hard accelerations and decelerations which, given how many will be in a given print, will be much harder on the structure of the machine than transporting it.


Greg: Have you looked into the economics of using (#25) chain and sprockets for the reduction instead of timing belts?

[greg southerland]

I wanted to use the timing belts to minimize backlash 

and chain stretch. The reason for chain was the extreme distance. The reason for a separate encoder run by cable  is because we are using chain for the long distance. 

   

Sent from my iPhone

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[greg southerland]

The 25 chain will not take the hp at the speed Mark requested. That was the reason for the double chain 

Sent from my iPhone

On Aug 26, 2016, at 1:27 PM, Chris K. <tensa...@gmail.com> wrote:

[Chris K.]

I was not talking about #25 chain for the chain running up the tower, just for the short loops in the speed reduction stages.

On the final shaft, the one the tower chain and the second stage speed reduction is on, the hypothetical #25 chain would be under far less load than the tower chain due to the smaller chain being wrapped around a much larger diameter sprocket. If the radius of the larger #25 sprocket is more than about 3.5 times greater than the smaller #35 tower chain sprocket, then the tower-chain will fail before the smaller chain.

The chain/belt on the final speed reduction stage will see the highest load but the chain/belt on the first speed reduction stage will see the highest speeds.

My concern with the belt system is that they have problems when you get to the higher reduction ratios. When you have a small pulley coupled with a much larger one and you are trying to minimize the distance between shafts, you run in to the problem of not have enough teeth in engagement on the smaller one.

I was thinking that roller chain is less likely to skip on smaller sprockets (due to much deeper "teeth") than belts. Also, if necessary, we can manufacture larger roller chain sprockets much easier than timing belt pulleys to save costs and achieve higher reductions.

Another possibility is to use belts on a lower cost and lower-ratio first stage where the belt will see the highest speeds and use chain on the second stage with a higher ratio where the chain will see lower speeds but we can manufacture the larger sprocket at any size we want.


Finally, a properly tensioned chain drive won't have any more backlash than a belt drive. It will may be a bit noisier and less efficient, but I believe we have power to spare.

[greg southerland]

Let's discuss it Tuesday 

Sent from my iPhone

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 30 Aug, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Mark Sullivan, Chris Kelley, Alijah Ballard, Roland Von Kurnatowski, Anirban Joy, Shane Hooper, Suzie, and Jeff Hutchison  Meeting took place between 6:30PM and 7:30PM at TXRX, followed by continued discussion at El Tiempo, 

With a substantial turn-out, the contributions were excellent.  Many discussions were held.

The 12 foot tall delta:

Truck Speed

2500 in/min has been challenged for two primary reasons... it may be faster than is reasonable, and it increases the gear reduction required

Chris cited multiple examples of large machines (router and plasma tables) running far below this rate, and still being "fast"

Off-the-shelf (or easily waterjetted) components should govern the actual speed

Gear Reduction

Chris proposes chain and sprocket for the gear reduction

Sprockets can be water-jet cut cheaper than they can be purchased

Chain does not necessarily increase the backlash (at the penalty of efficiency and lifespan)

Timing cogs get very expensive in large sizes (needed for high reduction ratio)

Timing belts are more susceptible to slipping than a chain drive would be

If a two stage gear reduction is used, timing belts might be the better choice for the high-speed / low-torque stage, and then chain would be more suitable for the opposite.

This problem is best solved mechanically (not on the electrical side)

Dimensional governance

Column tops and bottoms need to have the same dimensions so that when the bot is lying down, it's not slanted or tipping

Trucks need to have a smaller dimension so as not to touch the ground 

Counterweights

The need for a counterweight was debated

Provision for a counterweight must be provided, even if no weight is added

The counterweight system does not need to be on the chain, can be separate

Extruder

The planchette has a mounting pattern that should accommodate all manner of extruders - and support experimentation

The connector for the extruder (or other end effector) will need to provide power and bi-directional signals.  USB was proposed, networking and serial protocols were also proposed.

Some extruders may have a substantial weight, which exacerbates the issue of rapid movement and also the counterweights (which add inertia to the system)

Dynamics

Moving the weight of the extruder to a neutral point, or reducing its movement a-la the WASP 3D printer design (below) was discussed

The option to do this is highly dependent upon what type of extruder is installed... and the type that was under consideration (auger/pellet design) will not work in this arrangement.  The WASP has a flexible short bowden tube between the floating extruder motor and the fixed hot end.  In the auger/pellet design, the pellets are melted in the auger section, and a rigid, heated tube would be needed between the planchette and the floating extruder.

Motion Sensing and Control

Alijah informed the group that the HTC Vive's motion sensing system was open sourced recently
The refresh rate may be too slow for direct closed loop control, the information can be used for correcting the machine movement

Room for everything to ride on the thing

Motion sensing, and other instrumentation don't have to be rigidly designed in - but provision for adding things should be a governing design concept

Modularity is the key to a platform that can be optimized iteratively.

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[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 6 Sept, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Chris Kelley, Alijah Ballard, Shane Hooper, and Jeff Hutchison  Meeting took place between 6:30PM and 7:30PM at TXRX, followed by continued discussion at El Tiempo, 

The 12 foot tall delta:

Extruder

Pellet extruders have ooze issues... an "unloading piston" was discussed as a potential remedy.  Part finishing was also discussed.

Food for thought:

https://all3dp.com/3d-print-chairs-furniture-pellet-filament/

[Mark Sullivan]

When you said, "food for thought," I was hoping we were back to Churros!

[Jeff Hutchison]

https://www.youtube.com/watch?v=GWqXL4ruWI0

[Jeff Hutchison]

https://www.youtube.com/watch?v=WRTTXSbeTJc

[Mark Sullivan]

LOVE the fritter mode (corador)

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 13 Sept, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Mark Sullivan, Chris Kelley, Alijah Ballard, Shane Hooper, Suzie, and Jeff Hutchison  Meeting took place between 6:30PM and 7:30PM at TXRX, followed by continued discussion at El Tiempo, 

The 12 foot tall delta:

Optimization

With the arrival of a new 3D printer (under evaluation for purchase), the team observed the design and discussed elements of overdesign

The overall build was incredibly (perhaps insanely) stout

The carriage was bizarrely large and looked heavy, with substantially more wire than needed

^ The WASP printer runs a hot-end with an RJ-45.  Anything more than this is overkill (as evidenced by the fact that the WASP works beautifully)

Shane pointed out that it looked like a design that "grew" as they worked on it.

Other printers with plugs to the hot-ends use molex connectors - they work, but they are bulky and excessive

Further points of discussion - "closing the loop" on control... will not improve quality in these small and medium size FDM printers.

Stepper motors are more than sufficient to provide amazing accuracy and repeatability in a well designed (smaller) FDM printer (whether cartesian or delta)

The overall take-away is that as we design (and over design) our 3D printer, we should be mindful of the propensity towards over-design where it does not yield better output

Wheels

Skateboard wheels have arrived, but the CNC lathe is down

Wheels are Shore A 99 hardness 

Regarding their maintainability: http://www.sdplastics.com/polyurethane_machining.html

 

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 18 Oct, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Mark Sullivan, Chris Kelley, Alijah Ballard, Shane Hooper, Suzie, Lajos Gyarmati, Roland Von Kurnatowski, Mike Reynolds, and Jeff Hutchison  Meeting took place between 6:00PM and 7:00PM at TXRX, followed by continued discussion at El Tiempo, 

The 12 foot tall delta:

Trucks

Chris Kelley has completed a prototype truck in wood.  The results proved what was expected - the rails are built to a level of tolerance that permits smooth movement without binding or loss of contact.  Wheels will all be on slotted holes (as designed) to allow for tightening to the tower.  Misalignment is not a concern due to the geometry of the design.

A taller truck will be made for the purpose of increasing stability.  Note that this does not reduce the build area, as the length is added to the bottom of the truck.

Trucks will be aluminum and can be cut as soon as the model is updated for added length.

Base

Bases were proposed to be made from 10ga steel... a counter proposal of 3/8 Aluminum was made by Roland.

Steel powdercoats nicely... aluminum may get banged up

Funding

Lab will reimburse members for their outlay - upon completion of working bot

Mark volunteered to take care of the servo's and drivers

Schedule

A working robot (exclusive of extruder) to be completed by the end of the year

Portability

Roland reminded the group that this must be deployable with minimal effort.

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 20 Dec, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Mark Sullivan, Alijah Ballard (and his dad),  and Jeff Hutchison  Meeting took place between 6:00PM and 6:30PM at TXRX, followed by continued discussion at El Tiempo, 

The 12 foot tall delta:

Top frame

Mark presented a simplified design for the top frame - something akin to the connector below:

Bottom gear box

Greg has revised the model to include a motor with a brake and was able to keep the gearbox removable.  

There was also a discussion regarding the guide pins and assembly sequence

On Wed, Dec 14, 2016 at 5:52 PM, Jeff Hutchison <jhutc...@gmail.com> wrote:

Delta-Bot meeting was held Tuesday, 13 Dec, 2016 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Mark Sullivan, Chris Kelley, Alijah Ballard, Shane Hooper, Suzie, Roland Von Kurnatowski, Mike Reynolds, Jennifer Evans, and Jeff Hutchison  Meeting took place between 6:00PM and 7:00PM at TXRX, followed by continued discussion at El Tiempo, 

The 12 foot tall delta:

Motors

Motors must have brakes.  This will add ~40mm to the length of the units, and will require some adjustment to the gearbox design.

Gearbox

The gearbox may remain removable - and possibly should remain removable to facilitate servicing
Many options for reorientation were discussed

Top and bottom boxes (what are we calling these?)

A lower-profile top was presented.. but lost favor after a discussion of fabrication impacts.  One single alignment jig can be used for all six pieces if they are identical.
Another benefit of the full-height top box is that the struts will be identical to the bottom, and more stout than the presented alternative.
A drawback to the reversion is that there will be slightly more weight in the pod <- pods?? is that what we were calling them?

Arms

Arm design was brought up... a good modular design will allow for an interface point on the trucks that will permit arm design changes without impacting truck design

Design concepts

Slots were determined unfavorable where they are not absolutely necessary (e.g. for tensioning)  Less error is expected in fabrication than in assembly.

Portability

Roland reminded the group (again) that this must be deployable with minimal effort.

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 3 Jan, 2017 at TXRX Labs, followed by El Tiempo.  In attendance were Roland, Greg Southerland, Mark Sullivan, Chris Kelley,  and Jeff Hutchison  Meeting took place between 6:00PM and 8:30PM at TXRX, followed by continued discussion at El Tiempo, 

The 12 foot tall delta:

Material of construction

Make it out of Aluminum - unanimous

Cost of 5051 sheet not excessive compared to steel - much stiffer

Some scrap in shop - not enough, will need to order more

Greg has been doing layouts for cuts and material estimating

Portability

The unit (in whole or in part) must be deployable through a standard size door

A collapsing unit would be very cool, but will be all the mass, and pretty large

More pieces isn't ideal, but is better for the installers if they are easier to handle - and fit through a door.

Top frame

Further refinement of Mark's top frame 

Connectors can be attached to 3 tower uprights (in-plane) or 4 (out of plane)

Connectors do not need to be above top plate

Plate can be installed permanently - with connectors add/remove for (dis)assembly

Methods of connection between connectors and top plate discussed

Magic magnets

https://en.wikipedia.org/wiki/Electropermanent_magnet

https://www.youtube.com/watch?v=Pkj6ILblIyg

Guides (cone and hole) can be used to ensure alignment

Long wrench

http://www.amscousa.com/Window_Hardware/Operators/Clerestory_Extension_Poles_and_Adapters.htm

Push-push

http://www.saintlouisdesigns.com/touchlatches.html

Roland suggested U-bolts instead of splitting the connectors

Arm Joint

Greg presented his design for the arm joint

Chris reminded the team that he had already designed a joint

Both designs were similar

Chris used a shoulder bolt in his design

Greg had installed his bearings on the bar instead of the yokes

Both designs involved a fair bit of machining and setups

Both are good

Trucks

Discussion revolved around chain connection - master link will be attached to truck.. will be sufficiently strong for service

Connectors

As the design is to be disassembled, connectors will be needed

https://www.amazon.com/gp/product/B00IJ6756O/

6 bucks for a five pack - (6 pin ea)

http://www.ebay.com/itm/Pair-Waterproof-Aviation-Cable-Connector-Plug-Socket-SD20-12-12-Pins-IP68-/231464989843?hash=item35e4637493:g:WL8AAOSwDNdV2-jh

15 bucks ea - but they're IP-68 and 12 pins...

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 17 Jan, 2017 at TXRX Labs, followed by El Tiempo.  In attendance were Roland, Greg Southerland, Mark Sullivan, Shane Hooper, Alijah Ballard, and Jeff Hutchison, followed by continued discussion at El Tiempo, 

The 12 foot tall delta:

Material of construction

Aluminum was questioned... refer to previous minutes for details.

Portability and top pod design

Greg had shared a design idea for a folding upper brace, to be deployed on the ground before erecting the tower leg.

​This design was further refined from a 270° fold to a 90° fold

​effectively flipping the pivot point from being on top of the plate to being under the plate.  In order to ensure adequate stiffness, the upper plate will be backed by a section of aluminum square/rectangle tubing (as shown in the crude sketch above)


​Pins a-la McMaster Carr will ensure alignment

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 13 Jun, 2017 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, his friend Daniel, Mark Sullivan, Shane Hooper, Alijah Ballard, and Jeff Hutchison, followed by continued discussion at El Tiempo, 

It's been a while since I last posted an update of our progress... we've been meeting most Tuesdays, and we completed the design some time ago.  In summary, after the design was completed, it was checked for fit, and the flat file was prepped for cutting on the waterjet (out of aluminum)

A single "pod" has been cut out, and it fits together nicely - although there's a little bit too much slop in the slots for the carriage bolts.

Although the most interesting part of a build, is the build... the most minute-able part of a build is the design part.  Next week I'll take some pictures of the parts that have been cut so that I have more to share.

Shane proposed using 3mm filament through a 2.85mm nozzle and printing in vase mode... for reference, a 20lb spool of PLA 3mm filament can be bought off Amazon for 236 bucks, making it about 12 bucks a pound for the filament... for pellets, we can get 10lb for 37.60... or ~1/3 the price.  Other sources exist

[Jeff Hutchison]

Delta-Bot meeting was held Tuesday, 13 Jun, 2017 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Daniel, Mark Sullivan, Alijah Ballard, and Jeff Hutchison, followed by continued discussion at El Tiempo, 

More waterjet cutting after tolerances were revised - the carriage bolts now fit perfectly in the slots.  Photos of the wooden prototype carriage and aluminum components are attached.

During the meeting, a Gantt chart was developed to detail all remaining activities (attached).

In the chart, the current week is 9, based on the work that has been ongoing (for much more than 9 weeks, haha).

Many of the activities are "roll-ups" of multiple activities, but the resolution of the chart is 1 week.

We intend to schedule assembly sessions in addition to our regular meetings so that the entire team can work together to complete activities.

Greg proposed that we change venue for next week's meeting - Laurenzo's will be the place.

On Wed, Jul 12, 2017 at 10:01 AM, Jeff Hutchison <jhutc...@gmail.com> wrote:

Delta-Bot meeting was held Tuesday, 13 Jun, 2017 at TXRX Labs, followed by El Tiempo.  In attendance were Greg Southerland, Daniel, Mark Sullivan, Alijah Ballard, and Jeff Hutchison, followed by continued discussion at El Tiempo, 

More waterjet cutting after tolerances were revised - the carriage bolts now fit perfectly in the slots.  Photos of the wooden prototype carriage and aluminum components are attached.

During the meeting, a Gantt chart was developed to detail all remaining activities (attached).

In the chart, the current week is 9, based on the work that has been ongoing (for much more than 9 weeks, haha).

Many of the activities are "roll-ups" of multiple activities, but the resolution of the chart is 1 week.

We intend to schedule assembly sessions in addition to our regular meetings so that the entire team can work together to complete activities.

Greg proposed that we change venue for next week's meeting - Laurenzo's will be the place.

[Jeff Hutchison]

Several parts of this video show polyurethane being used as print media:

https://www.youtube.com/watch?v=IRBQv2TJFX4

Readily available on Amazon:

https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=dow+froth+pak&rh=i%3Aaps%2Ck%3Adow+froth+pak