Plotting on a cylinder

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nathan

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May 5, 2011, 8:42:10 PM5/5/11
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I made an egg-bot inspired coil winder and I thought it would be fun
to try and plot on a cylinder using the pen-holder from my egg-bot and
the egg-bot control software in Inkscape.

You can see a video here:

http://www.guitar-list.com/make-cnc-pickup-winder/control-system


Nathan

Brian Schmalz

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May 5, 2011, 9:48:14 PM5/5/11
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Nathan,

As far as getting your motors to spin fast enough using the EiBotBoard, did you try the EM command to set the motors in full step mode? For the same step rate, they'd go 16 times faster . . .

*Brian
 
Home www.schmalzhaus.com
Work www.logicpd.com



From: nathan <guitarlist...@googlemail.com>
To: EggBotUser <eggbo...@googlegroups.com>
Sent: Thu, May 5, 2011 7:42:10 PM
Subject: [EggBot] Plotting on a cylinder
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Shab Levy

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May 5, 2011, 10:09:15 PM5/5/11
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Why go to all this trouble if you want to draw on cylindrical object? It's much easier to send the design directly to your regular printer and wrap the paper around the cylinder!
 
Shab

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bruce shapiro

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May 5, 2011, 10:32:59 PM5/5/11
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Well, Nathan may have a completely different answer-- but at least one reason for all the "trouble" is, it teaches valuable lessons.  Being able to modify and customize your own NC machines can be a quite useful thing.  For instance, you may want to engrave (or cut) cylinders.  One example (though perhaps a tad large for Eggbot's motors ;-)) is the rig I made for cutting metal pipes, circa 1995:
http://www.taomc.com/the_process/studio_machines/plasma_cutter.html   (bottom)

Though the images are terrible, hopefully you can make out the rotational axis, and the long linear axis running well below the cylinder. This machine traces its roots directly to the original Eggbot.


bruce

len...@oskay.net

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May 5, 2011, 10:36:46 PM5/5/11
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The ability to print on cylindrical objects is a request we get on a regular basis, and we are considering offering something like that in the future. We've also been looking at phenolic as a possible material for the upcoming extra large chassis. Nathan, it looks great!

Lenore

nathan

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May 6, 2011, 3:26:34 AM5/6/11
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Thanks Brian.

I want to use the machine as a fine wire coil winder (to make guitar
pickups). I need high resolution on the traverse (pen) motor but speed
on the other motor. I believe the latest version of the EiBotBoard
uses the same microstepping setting on both motors. For my applicaton
microstepping for the pen motor has to be at least 8X (without having
to gear the motor down), but full step for the other motor would be
ideal and speed things up greatly. That is the reason I decided to try
the EasyDrivers for the time being.

With the EiBotBoard I tried increasing the speed until I reached a
point where the motors stalled at around 5 rotations per second, I
wonder if I was hitting a limit with the power supply (I was using the
original Egg-Bot for these tests)? Perhaps I should go back and
experiment some more.

Another issue I found was the limit of 32,000 steps per move. For my
application I need to wind around 8,000 turns of wire (diameter around
0.063mm) across a 12mm wide bobbin - so to just to wind a single layer
across the bobbin requires lots of separate moves.

There are much simpler ways of winding guitar pickups, but they
wouldn't be half as fun or educational!

Nathan


On May 6, 2:48 am, Brian Schmalz <brian_schm...@yahoo.com> wrote:
> Nathan,
>
> As far as getting your motors to spin fast enough using the EiBotBoard, did you
> try the EM command to set the motors in full step mode? For the same step rate,
> they'd go 16 times faster . . .
>
> *Brian
>
>  Homewww.schmalzhaus.com
> Workwww.logicpd.com
>
> ________________________________
> From: nathan <guitarlist.enquir...@googlemail.com>
> To: EggBotUser <eggbo...@googlegroups.com>
> Sent: Thu, May 5, 2011 7:42:10 PM
> Subject: [EggBot] Plotting on a cylinder
>
> I made an egg-bot inspired coil winder and I thought it would be fun
> to try and plot on a cylinder using the pen-holder from my egg-bot and
> the egg-bot control software in Inkscape.
>
> You can see a video here:
>
> http://www.guitar-list.com/make-cnc-pickup-winder/control-system
>
> Nathan
>
> --
> You received this message because you are subscribed to the Google Groups
> "EggBotUser" group.
> To post to this group, send email to eggbo...@googlegroups.com.
> To unsubscribe from this group, send email to
> eggbotuser+...@googlegroups.com.

Joel Genaw

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Dec 6, 2016, 4:55:17 PM12/6/16
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Hey Lenore,

I came across your post from 2011 saying that printing on cylindrical objects was something you were looking into for the future. I was wondering if anything has come of this? Is there now an option for this? is it still in the works?

thanks,

Joel 

Lenore M. Edman

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Dec 6, 2016, 5:09:58 PM12/6/16
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Not yet! We’re still considering the idea, but don’t have a definite design yet. 
Cheers,
Lenore

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Scott VanRavenswaay

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Dec 6, 2016, 6:12:23 PM12/6/16
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I have done this by simple physical means. My requirements did not need servo up/down because my nib was fine enough and the dither done in such a way that the resultant TSP looked quite good without it. Obviously this won't work for other cases. 

What I did was use a marker and a makeshift "slip tube" that provided enough room for the pen to travel up and down, letting gravity keep it in contact with the surface so that when the motor arm rotates, it takes advantage of only the horizontal movement of the arc. DId I describe this in a way that makes sense? Additionally, I attached extra weight on the pen and had to slow the motor rotation down to match the speed at which the pen could travel up and down in the tube. A looser pen/tube fit would mean you could plot faster, but at the expensive of slop from friction.

A similar skew issue applies as does for an oblate spheroid that you account for when creating a design for an egg, but was easily ignored, at least for the orientation and content of my drawings.

//VR 

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Joel Genaw

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Dec 30, 2016, 4:49:37 PM12/30/16
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If I were to build the hardware, how would I go about making the software work? Can the settings of the pens stepper motor be adjusted in the software? I m thinking about putting a gear and pulley on the pen stepper motor with a belt that would move a carriage similar to the x axis on 3d printers. But I m guessing currently the software translates the design for the movement on the pen on an arc rather than a linear rail and so the steps on the stepper would need to be increased. I m not a software guy more of a builder so I don't know where or how to go about adjusting the software, is this a simple adjustment to the software?

Windell H. Oskay

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Dec 30, 2016, 5:51:42 PM12/30/16
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> On Dec 30, 2016, at 1:39 PM, Joel Genaw <joel...@gmail.com> wrote:
>
> If I were to build the hardware, how would I go about making the software work? Can the settings of the pens stepper motor be adjusted in the software? I m thinking about putting a gear and pulley on the pen stepper motor with a belt that would move a carriage similar to the x axis on 3d printers. But I m guessing currently the software translates the design for the movement on the pen on an arc rather than a linear rail and so the steps on the stepper would need to be increased. I m not a software guy more of a builder so I don't know where or how to go about adjusting the software, is this a simple adjustment to the software?

As long as you use the same motor to drive the pen back and forth-- you move the stepper that used to turn the pen, to now move axially up and down the cylinder --you won't need any adjustments to the software. The only difference is that you might want a taller template within Inkscape.

Windell H. Oskay, Ph.D.
Co-Founder and Chief Scientist
Evil Mad Scientist Laboratories
175 San Lazaro Ave, STE 150
Sunnyvale CA 94086
http://www.evilmadscientist.com/

Bruce Shapiro

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Dec 30, 2016, 6:28:54 PM12/30/16
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In addition to Windell's response, not only do you not need to change
the software, but you will not see any of the distortion (squishing)
which is inherent when plotting with Eggbot on an egg (or sphere), more
pronounced the farther you plot from its equator. You will, however,
need to scale your drawings in both dimensions with an appropriate
aspect ratio for them to plot accurately - accounting for whatever
belt/pulley (or other) assembly you use to translate the pen axis'
rotation to linear movement and its resulting steps/inch (pen axis), and
the diameter of your cylinder (steps/inch on the cylinder in the "egg"
axis).

Bruce - (Eggbot's dad)

Joel Genaw

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Jan 4, 2017, 12:04:17 AM1/4/17
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Thanks for the info guys, it's very helpful and much appreciated.

Scott VanRavenswaay

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Jan 4, 2017, 2:18:16 AM1/4/17
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I realize I worded it poorly, but what I was trying to say is that a similar "close enough" stretch can be done when plotting on a cylinder as is done for an egg shape; I should have said "stretch" and not "skew". And I suppose I was not clear at all about the "slip tube" I implemented, and maybe what I did was silly but rather than alter the frame of the eggbot, I was able to put the pen arm to the highest position (as if for the largest egg) to get the widest arc (as close to "flat" as could get) but couldn't leave everything as is, due to the arc the pen tip makes as the pen arm wants to follow the arc (as it's motor shaft rotates) but meets resistance forcing it to stay in the plan of the long axis of the cylinder. 

If this doesn't make sense, I can post pictures. Sorry, but it seems to be taking me many words to express a simple idea.

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