my circles arent circles

Re: my circles arent circles

Postby thephridge » Fri Apr 06, 2018 4:01 pm

Why is it only happening on the nodes?
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Re: my circles arent circles

Postby IslaWW » Fri Apr 06, 2018 4:18 pm

This is without a doubt a deflection issue. You are cutting faster and/or deeper that your machine and/or bit can contain the force.

It is happening on the tabs for sure. It will only happen on the nodes, if your machines setting allow it to stop on the nodes. What control software are you using? You should not be stopping or slowing on those node points unless you have an antiquated controller or your settings are messed up.
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Re: my circles arent circles

Postby thephridge » Fri Apr 06, 2018 4:27 pm

See attached. This is the same machine and material using other software and Linux CNC. No Issues.
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20180406_111907_resized_1.jpg
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Re: my circles arent circles

Postby IslaWW » Fri Apr 06, 2018 4:31 pm

post the 2 files, the differences will be obvious
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Re: my circles arent circles

Postby joeporter » Fri Apr 06, 2018 4:32 pm

What kind of material is this? It looks soft, is it flexing when the cutter pulls up for the tab?....joe
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Re: my circles arent circles

Postby thephridge » Fri Apr 06, 2018 4:33 pm

Okay. May take a few minutes to figure out how to get it from linux to where we can upload but stand by...

Thank you.
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Re: my circles arent circles

Postby thephridge » Fri Apr 06, 2018 4:36 pm

Its pvc foam.
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Re: my circles arent circles

Postby joeporter » Fri Apr 06, 2018 4:38 pm

thephridge wrote:Its pvc foam.
Try the same cut in a piece of 1/4" plywood or MDF and compare results...joe
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Re: my circles arent circles

Postby LittleGreyMan » Fri Apr 06, 2018 4:40 pm

On one side, Aspire + Mach 4
On the other side, other cad software + Linux CNC

Cut the file you generated with Aspire with Linux CNC.

Did the other software generate tabs?
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Re: my circles arent circles

Postby thephridge » Fri Apr 06, 2018 4:44 pm

We are using V Carve and M4. Other cad and Linux CNC control software did tabs perfectly.
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Re: my circles arent circles

Postby martin54 » Fri Apr 06, 2018 4:48 pm

If it cuts fine using linux then I would have a look at your mach4 configuration & settings
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Re: my circles arent circles

Postby thephridge » Fri Apr 06, 2018 5:34 pm

This one we did in other CAD software and Linux CNC with no issues. Same machine. Same material. About the same feed rate.
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Re: my circles arent circles

Postby martin54 » Fri Apr 06, 2018 5:46 pm

Have you tried cutting the Aspire file using linux cnc as LGM suggested ??

As a signmaker I have cut quite a lot of foamex & never had any issues using either Aspire or VCP :lol: :lol:
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Re: my circles arent circles

Postby TReischl » Fri Apr 06, 2018 8:58 pm

A very simple method to eliminate any software questions is to program a circle manually, then run it.

In Mach you would:

Position the spindle in the center of a piece of material.
Set both X and Y to zero at that position
Zero Z axis to the surface of the material
Enter the following sequence:

My comments are in parenthesis and should not be added.

M3 (spindle on)
G0X4Y0 (rapid to X4 Y0)
G1Z.1F25 (feed to .1 inch above work at 25 IPM)
G1Z-.1 (cut .1 inch into material at 25 IPM)
G3X4Y0I-2J0 (cut full circle with the center -2 inches in X from current location)
G0Z1 (rapid to 1 inch above material)
M5 (turn spindle off)

Unless you changed a bunch of stuff in Mach, your machine will power up in absolute mode which the above code uses. A lot of the stuff in the beginning of a program is to make sure things are set properly in case they were changed. That is why this code seems so short, no need for it. Of course, a good thing to do to make sure you do not have problems is set the Z zero a few inches up in the air and set zero to do a test run, or you can use the dry run function. I prefer the sky cutting method myself.

That G3 line instructs the machine to cut a full circle in one go. Knowing a little bit of G code goes a long way in solving lots of "issues". Instead of sitting around having no clue whether it is mechanical or software, you can eliminate the software portion of the issue very quickly.

If your machine still cuts a crummy circle, you have machine issues. BTW, you list your machine as homebuilt. Did you design it yourself or follow some of the plans available on line?

But, all that said, it is your machine. You just need to verify that for yourself. Then you can get on with fixing the real issue. Like Martin said above, I have been cutting circles on my homebuilt machine for over 10 years now. They are all round and do not look like yours, even when I use tabs.

Edit: I just saw your post about having cut good circles with Linux CNC. Sooo, thousands of users are using Vectric to program circles everyday, so you can be pretty sure it is not the software. That leaves one thing, the way your Mach 4 is set up. I would jump on a control forum to figure it out.
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Re: my circles arent circles

Postby martin54 » Sat Apr 07, 2018 2:33 pm

What post processor are you using for your gcode ? Just had a quick look & can't see one for mach4
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