2D parts tracer

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AussieBoy

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Hi, I would like to make a 2D parts tracer. A bit like Arcroid.
Only just the tracer part.
What is the best way to go about this.
I think using a robot would be difficult as it would be stiff to move the arm to trace the part.
It would have to trace coordinates, may be GCode and then convert to dwg / dxf somehow.
Thanks,
 
If you made a fairly lightweight arm using two suitable resolution optical encoders, there would be no stiffness at all - the encoder bearings would act as the joints.
If it were very large, it may need triangulation with a support bearing directly above the shoulder joint.

Or you could use a bearing for a joint plus a parallel arm or timing belt link so the elbow encoder was not at the joint, to reduce the moving weight even more.

How accurate do you need it to be, positionally, and over what size or area range?

What's possible or practical very much depends on the accuracy required and how much you are willing to pay for the parts.

eg. With encoders such as these, programmed for the maximum line count:

You could get resolution around 25uM with a 1m (total length) arm.
 
In order to design this you need to define all assumptions for size in XYZ, resolution , error tolerance , input method and trace method.

e.g. Perimeter limits, OD, ID, centres, straight edges? point to point line drawing merged to nearest grid size. From a video image, flat screen or 3D model? Don't worry about how yet, just what.
 
Hi, I know I said I wasn't interested in the cutting part. But I am intrigued.
1.
I am guessing that for the cutting mode there are motors to provide the driving force. As Encoders only return feedback for the position to be determined?
2.
With this line of the quote below.
"If you made a fairly lightweight arm using two suitable resolution optical encoders, there would be no stiffness at all - the encoder bearings would act as the joints".
Are you suggesting a robot could be built for this purpose if using the optical encoders. Only a robot would be good, to use for other tasks such as welding may be.
3.
You could get resolution around 25uM with a 1m (total length) arm.
700 x 400 mm area would be more than adequate.
4.
I guess this could all be connected to an Arduino for the control side and the data pushed out via usb.
Thanks,


 
Back in the late 70's we used to design a 4 or 6 layer board with colored pencils on mylar grid in less than a week. We'd send it for digitizing to gerber code to Toronto which took less than a day. They used an xy pointer to capture the start/stop end-points on a 0.1" grid then send the Gerber code files to our board shop and we'd get the boards back.

I don't know what you are digitizing in 2D but G-code is very similar to Gerber code which has different syntax and added features for trace width and drill size.
 
Hi, I know I said I wasn't interested in the cutting part. But I am intrigued.
1.
I am guessing that for the cutting mode there are motors to provide the driving force. As Encoders only return feedback for the position to be determined?
??
That setup is only for a precision 2D measuring arm, not a robot...
 
Could I buy cheaper encoders for initial testing?
Yes, something like these from ebay should work, but they have only about 1/100th the resolution.
 
From the answers above I ended up looking at these pages
Really please and hope to give it a go.
Also found these
 
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