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Issue cutting circular profile path

Posted by HSU-JSMC-COBB 
Issue cutting circular profile path
February 02, 2018 09:47PM
Hello everyone,

Ran my first cut on my Handibot large sheet tool today. The first tool path went great- except the image I cut with the 90 Degree V-Bit was mirrored. I'm sure that is a setting I missed somewhere...so that's not really what my main concern is right now.

My main question/concern, is about my failed profile path cuts. I am trying to cut a circle around the image I am engraving so it is shaped like a coaster.

However, when I run the tool path, the router begins to cut the circle, then randomly cuts across the circle and makes a D shape. I thought maybe it was because I had 'ramps' on my tool path, so I turned them off and it worked great!!!

But THEN, I went to make the same cut again and ran the 'fixed' tool path again, and it went back to making the D cross-cut across the circle.

Is this a blip in the code? system? human error? Image attached of a few of the failed cuts for reference.

Thanks for your thoughts and time for this newbie,

open | download - IMG_6164.JPG (40.9 KB)
open | download - IMG_6162.JPG (39.4 KB)
Re: Issue cutting circular profile path
February 03, 2018 11:45AM
I looks like your cuts are exceeding the X-axis travel of the tool. If the tool tries to travel past 6" in the X axis, it will collide with the hard stop on the axis and "lose steps" meaning the X axis will continue trying to move (and thinking that it is moving) while the tool is actually stuck on the hard stop. The rest of the moves continue as normal and you get a flat line where there should have been a curve.

If you want to cut something larger than 6" in the X axis you can tile the job and cut it in sections. Check out the two docs I've attached to this post for more info on tiling.
open | download - 3Toolpath Tiling for Handibot.pdf (445.9 KB)
open | download - 4Tiling with Large Sheet Tool.pdf (248.3 KB)
Re: Issue cutting circular profile path
February 05, 2018 11:20PM
Hi Brian,

Thank you, the 6" rule is great to know.

But in this case, my design was only 4" in diameter along the X and Y axis.

The multiple circles you see in the pictures are a result of multiple attempts at the same cut, with just moving the material back and forth to an un-cut section.


Re: Issue cutting circular profile path
February 07, 2018 01:55AM
in your second photo, it sure looks like the X gantry is against the right-hand stop.

Since the machine is brand new to you I'd suggest doing what we call air cuts to get to know the machine without wasting a lot of wood. Set the Z up high so that when a file runs it won't contact wood and turn off the router so you can play in relative quiet. Now you can drive the x and Y around and get to know where the limits are, mark them with a sharpy, run the circle again being sure X and Y are zeroed.

Hope this helps.

Re: Issue cutting circular profile path
February 12, 2018 10:29AM

Sorry for being away for a while--I've been on the road and the forum has been a little glitchy...but I think we're all good now, and I'm home!

Have you updated FabMo recently? There's a new feature in the 1.6.0 version that lets you select a tool profile. The "default" profile has some kinda wacky speed settings...so it is good to make sure you're on the handibot profile.

I also agree with Mark about test-cutting. Try turning the router off and "cutting" high up off the surface of your material. You'll be able to listen to the motion of the motors and if a motor is stalling or otherwise unable to complete a move, it should become obvious and we can work from there.

Re: Issue cutting circular profile path
December 20, 2018 11:27AM
Hi Everyone,

Its been a while! Thank you all for your insight. I finally had a few days to really sit down again with the machine (and some cuts I want done to motivate me even more) and I think I figured out what the main issue has been all along.

Deep in these forms, I found someone with a somewhat similar problem to what I was experiencing. And in fact, it was the mirrored image issue that revealed it...

My Y-Axis motor on the machine needed to have its direction reversed. Ever since assembling the Handibot, the Y-Axis was never correctly oriented. X was fine...but the Y kept trying to home on the opposite end than I'd expect, and any cuts I tried to make were mirrored on that Axis. It also may explain why my design, which was well within the cutting area, was acting strange- if the Y-Axis was trying to move in the opposite direction that it should have been- it was indeed trying to move beyond the cut area.

So I went into FabMo and under the 'channels' tab changed my Y-Axis direction from CW to CCW (Y Axis is Channel 2). Problem solved.

Writing this to thank you and to also just have it out there in case someone else runs into this issue.

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