z-stage losing steps

[Owen M Collins]

I am on a 2009 Cupcake and I keep having my z-stage lose steps. It doesn't always happen, and it doesn't always happen at the same time in a build. I have tried different models, rebuilding G-code, Printing from SD card and USB. Sometimes the z-stage craps out and goes only a partial amount of what it should.

I am using Giseburt's PSMD board and the 3G5D shield. Based on a thread in the Makerbot Google group, I feel it could be a Power supply issue, but it could be something else.

Any advice?

Owen

[Aaron Double]

Is this the original configuration? as in all of the pulleys and the big belt? If so, see if the set screws on the pulleys are aligned. If not, they can wobble and change the tension on the belt which can make in skip.

Aaron Double

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[Matthew Wilson]

Indeed, I would look for mechanical faults first. The z-stepper has
it the hardest on the makerbot. I replaced my Z-stage with this:
http://www.thingiverse.com/thing:14492 which let me turn down the
z-motor current. (said design isn't perfect, but it works)

> --
>
>

[Matthew Wilson]

Indeed, I would look for mechanical faults first. The z-stepper has
it the hardest on the makerbot. I replaced my Z-stage with this:
http://www.thingiverse.com/thing:14492 which let me turn down the
z-motor current. (said design isn't perfect, but it works)


On Mon, Nov 26, 2012 at 10:31 AM, Aaron Double <aad...@gmail.com> wrote:

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[Owen M Collins]

Yes original belt and pulleys. Good call everyone, I will check mechanical gremlins first.

THanks everyone,
O.

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[Owen M Collins]

Hmm, I didn't see any skips. I checked all the set screws and they are all snug and lined up. But there were some z-height moves that were just less than others.

O.

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[Dan Laskowski]

Regarding aligning the set screws to avoid wobble / extra stress in the z-axis -- I took a couple of inches of copper wire and wrapped the threads of the rod to form a slightly larger, fairly smooth surface on the rod in the place were the pulleys with set screws would be.  Then the pulleys were pretty much centered on the rods and it reduced the wobble in the z-axis system.

To say it again: The wire was wound around the rod in the direction of the threads and actually laid in the thread grooves so that the diameter of the threaded rod with copper wire was slightly larger than the threaded rod by itself.  That way, the pulley fit snug over the rod with wire and was more or less exactly centered over the rod.  Without the extra wire, the pulleys were always off center a bit and you had to align the set screws or you would have other problems.

[Owen M Collins]

Well,

When I jog the z-stage in the control panel it moves 10mm.

O tried to build a single wall calibration piece, but instead of the 10mm height of the model, it was overall 6.81mm tall and RepG thought it had gone up 11.18mm (including the raft I guess).

It is not overheating, or at least the stepper does not even feel warm. One LED is on on the z-stage stepper for PSMD board.

I don't see the gear attached z-stepper missing steps.

I have loaded Sailfish firmware onto the Motherboard and am using RepG 40 for Sailfish. It is still Extruder controller firmware version 3.0.

Ugh.

On Nov 30, 2012, at 9:10 AM, Dan Laskowski wrote:

> Regarding aligning the set screws to avoid wobble / extra stress in the z-axis -- I took a couple of inches of copper wire and wrapped the threads of the rod to form a slightly larger, fairly smooth surface on the rod in the place were the pulleys with set screws would be. Then the pulleys were pretty much centered on the rods and it reduced the wobble in the z-axis system.
>
> To say it again: The wire was wound around the rod in the direction of the threads and actually laid in the thread grooves so that the diameter of the threaded rod with copper wire was slightly larger than the threaded rod by itself. That way, the pulley fit snug over the rod with wire and was more or less exactly centered over the rod. Without the extra wire, the pulleys were always off center a bit and you had to align the set screws or you would have other problems.
>

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[makerman]

If the motor is not warm you can turn the little pot on the pololu board a bit to the right.
This will increase the motor current and hence the force of the motor.
The Z motor can be driven with half step, this will increase the motor force too.

[sirir...@hotmail.com]

I too had major issues with my z stage. what was going on with mine was the vibration of it moving was tightening the nuts on the shafts and changing the tension.

i got around it by removing the lower nuts and over tightning the top ones and basicly hanging the z stage.

 

after i changed my z stage, which i highly recomend, it made my printer so much better. im even still using the DC gearmotor extruder.

the only parts you need to buy are 3 linear bearings and 2x 8mm smooth shafts. everything else can be printed. either by you or im sure you can find a person here to help you out if needed.

( http://www.thingiverse.com/thing:10478) is what im using.

[Owen M Collins]

I'll look into the tightening of the nuts and such. I don't know if that is it. 

the new z-stage you put in looks interesting though. Once i get it working I will be able to finish the low-rider and then maybe I will get rid of the wobbling in the z-stage. But first Printing!

THanks,

O.

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[Dan Laskowski]

My rods are just hanging -- no bottom nuts at all.  To be specific from the top: Pulley, nut [as a spacer] and top bearing.  Then it fits through the bottom bearing and that is it.  They stay in place with gravity and have been working that way just fine for three years.

[sirir...@hotmail.com]

thats simmiler to what i did. mine was: pully, top nut, bearing, inside nut tightned against bearing, and bearing hold down plate on the inside. bottom bearing was there only as a spacer, no nuts.

[Aaron Eiche]

Can you provide a picture of this? (I know this is several months back) I'm trying to temporarily resolve my z-stage problems so I can print out some things to move away from the cupcake z-stage design. Right now my z-stage can barely move 2mm without horrible grinding/binding. It was working earlier today, but I must've gotten something messed up in my fiddling that fouled it up.

[Dan Laskowski]

Not much to show, really.  You can see the copper wire wrapped in the threads -- it goes all the way through the pulley to "center" the pulley on the rod.  My rods are not "synced" and work fine.

The order of parts on my rod are like this: pully with copper wire wrap, a nut, a bearing and another nut tightened against the first nut and bearing.  This whole assembly is dropped into the top hole on the Makerbot and the rod goes through the bottom hole with bearing.  It is a loose fit in the bottom hole -- no nuts.  The whole assembly just hangs there.  Gravity is enough to keep everything in place.

Note: The copper wire I used was left over solid telephone wire.

For me, the old system works reasonably well and I with these changes, I haven't had a real need to change in three years of printing.

[Dan Laskowski]

By the way -- there was one more thing I did for my machines: I bought 2 meters of aftermarket threaded rod of good quality, cut it to length and then sorted the cut pieces to find the straightest ones to put in my Cupcakes. I have 2 wobble arresters on each of my machines too.  I put them on the rods that wobbled the most so basically, each machine has two rods that are running pretty straight without wobble arresters and with the free hanging assembly, it works pretty good!

[Jetguy]

Or, just do this
http://www.flickr.com/photos/90025904@N04/8683803660/
http://www.flickr.com/photos/90025904@N04/8683804874/

[Jetguy]

BTW, those are oldschool parts by member "Twotimes" Aaron Double
He was a major influence on my early days of 3D printing and made some
amazing upgrades such as the X-Y lowrider and the awsome Z rider. I'm
trying to find the Z rider posting and links but until then I found
the X-Y. If you have a Cupcake, I cannot tell you enough how much you
need to print and use this upgrade. It turns your machine in a
something you could never imagine.
Again, I have huge respect Aaron, he helped a lot of people.


Thought about putting them on Github but i have not used it
personally. Was planning on bothering people who I know who use it to
give me a demo at Makerfaire. Whosawatsis or Rob Giseburt, you game?


Lowrider info:


Files:
http://www.google.com/url?sa=D&q=https://dl.dropbox.com/u/31642495/lowrider%2520gen%25208%2520mech%2520endstops.zip&usg=AFQjCNHy9kuJ-CND8vS6q3h8YLPTficb4w


Instructions: (little out of date) http://www.flickr.com/photos/48982649@N07/sets/72157624995806009/


And parts:


Shout if you need anything else,


Aaron Double
twotimes


On Jun 2, 10:46 am, Jetguy <vernonbar...@gmail.com> wrote:
> Or, just do thishttp://www.flickr.com/photos/90025904@N04/8683803660/http://www.flickr.com/photos/90025904@N04/8683804874/

[Jetguy]

Ah, it was before they split off and made the Vintage group.
http://groups.google.com/group/makerbot/browse_thread/thread/813e3891f009798a/bf5b6a0b5b605322?lnk=gst&q=twotimes+z+rider+files#bf5b6a0b5b605322
Here is links to files in my dropbox. Email me directly if you want
wobble
arrester files although there are some derivatives that work better
than
mine.


Best,


Aaron Double


Hello there,


Here are dropbox links to the files and links to the instructions.
One
question, your cupcake is higher than 100 right? If not there is a
different lowrider for that.


Lowrider:


https://dl.dropbox.com/u/31642495/lowrider%20gen%208%20mech%20endstop...


http://www.flickr.com/photos/48982649@N07/sets/72157624995806009/


https://dl.dropbox.com/u/31642495/Lowrider%20parts.png


Z rider:


https://dl.dropbox.com/u/31642495/Z-rider8.zip


http://www.flickr.com/photos/48982649@N07/sets/72157626095454522/


Word of warning, the instructions are a bit outdated and use linear
bearings now so you should get 2 8mm rods 10in long and 4 lm8uu
linear
bearings.


Best,


Aaron Double

On Jun 2, 10:57 am, Jetguy <vernonbar...@gmail.com> wrote:
> BTW, those are oldschool parts by member "Twotimes" Aaron Double
> He was a major influence on my early days of 3D printing and made some
> amazing upgrades such as the X-Y lowrider and the awsome Z rider. I'm
> trying to find the Z rider posting and links but until then I found
> the X-Y. If you have a Cupcake, I cannot tell you enough how much you
> need to print and use this upgrade. It turns your machine in a
> something you could never imagine.
> Again, I have huge respect Aaron, he helped a lot of people.
>
> Thought about putting them on Github but i have not used it
> personally. Was planning on bothering people who I know who use it to
> give me a demo at Makerfaire. Whosawatsis or Rob Giseburt, you game?
>
> Lowrider info:
>

> Files:http://www.google.com/url?sa=D&q=https://dl.dropbox.com/u/31642495/lo...
>
> Instructions: (little out of date)http://www.flickr.com/photos/48982649@N07/sets/72157624995806009/

>
> And parts:
>
> Shout if you need anything else,
>
> Aaron Double
> twotimes
>
> On Jun 2, 10:46 am, Jetguy <vernonbar...@gmail.com> wrote:
>
>
>

> > Or, just do thishttp://www.flickr.com/photos/90025904@N04/8683803660/http://www.flick...

[Jetguy]

Opps, sorry if that looked like I said email me for the arrestor
files, no, I don't have any of those, I just quoted Aaron's entire
post and the way I pasted it in it wasn't clear ,
Contact him for any questions.

On Jun 2, 11:05 am, Jetguy <vernonbar...@gmail.com> wrote:
> Ah, it was before they split off and made the Vintage group.http://groups.google.com/group/makerbot/browse_thread/thread/813e3891...

[Aaron Eiche]

That replacement Z-rider looks like a lot of printing. my initial goal was to print out some wobble arrestors and some couplings for linear bearings and smooth rods (incidentally, also Aaron Double). Something to improve reliability enough to get this thing printing for long runs. 

I did buy myself some threaded rod for my printer but the pieces I cut off didn't seem to help (I think they made things worse, but I really don't know. I'm not sure where I ended up placing my original rods. Maybe I should do some testing...

[Aaron Eiche]

Hey Aaron, 

Do you still have the wobble arrestor for Z-Screws on the cupcake? I would like that object so I can get a few more printed.

-Aaron E.

[Aaron Eiche]

I followed your advice yesterday - pulled out all my rods, cleaned them, checked for straightness (swapped out a couple), and replaced them leaving them hanging. One thing that I noticed while trying to implement your solution is that your bearing brackets on top are screwed into the underside of the 'roof' rather than on top in the original design. This is (obviously) what the rods are hanging on.

Anyway, with all that my Z-stage moved up and down without incident. Naturally I'm delighted.. I'm inclined to believe it's a few things: 

1) Clean rods - I would be surprised if something in the nut's threads or the threads of the rods was largely responsible for the binding

2) The rods hanging rather than sitting -  I think the freedom for the rod to move a bit more allows for the rod to take the position change rather than the whole structure.

3) Straight(er) rods. I didn't really want to do this, but I think going out the garage and trying to find ways to check the rods gave me the opportunity to inspect them. I ended up going with 3/4 original rods and using one of my self-made ones. I'm interested in your method (if you have one) for finding 'straight' rods. I tried putting mine in a corner of right-angle aluminum and rotating it to see if shifted at any point. I had limited success.

I didn't have any wire that matched up to what you had - I had some solid core ~26awg, but it didn't fill the threads fully. I ended up just aligning my pulleys.

I put some oil on the screws last night to reduce any opportunity for seizing . I'm going to try and print and see what I get over the next few days. I'll post here how it goes (for potentially anyone else who has this problem.)

Thanks again Dan for your examples and suggestions.

[Dan Laskowski]

Glad things are working better!

Regarding selecting straight rods: I just rolled mine on something flat [a piece of glass] and picked the ones that rolled the best.

Everything else sounds like you are on the right track.

Enjoy!