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Bad cuts
« on: April 07, 2012, 11:29:51 PM »
I just got a Romaxx and have had no success getting a good face on my cuts.

I'm using Vcarve and Mach3, a bosch colt and onsrud bits.
I'm getting chatter marks and can also clearly see each depth of cut.
I've adjusted the velocity in Mach 3 from 160 down to 60 and that helped a little. I've tried running the router from 15k-36k rpm and the result are the same.

I'm a newbie and a bit confused at what to adjust first as there are so many options.
I'm cutting profiles and pockets in 3/8" Baltic Birch ply with 1/4" compression bits and 3/4" maple with a 3/4" bit. I'm using bits that Onsrud recommended.

Help is greatly appreciated!

Offline Tweakie.CNC

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Re: Bad cuts
« Reply #1 on: April 08, 2012, 03:46:35 AM »
Hi Dminnery,

My fist action would be to reduce the step-over size associated with the selected tool in the VCarve tool table and see if that improved the situation (obviously you would need to create a new tool-path at the new settings).

Just a thought.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Bad cuts
« Reply #2 on: April 08, 2012, 10:00:39 AM »
Chattering usually means you're cutting too much too fast.  Reduce your depth of cut per pass and as Tweakie suggested, reduce the step over distance.  The rigidity of the machine has a lot to do with how much you can cut in a pass and how fast.  Also, 3/4" is a lot of bit for the Bosch Colt router...especially working with hardwoods.
Re: Bad cuts
« Reply #3 on: April 08, 2012, 10:23:51 AM »
I'll adjust the step-over, currently set at .1, thanks.

I'll try cutting at a shallower depth as well. sorry mis-typed, I'm using a 1/4" bit in 3/4" maple-will edit post.

Offline Tweakie.CNC

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Re: Bad cuts
« Reply #4 on: April 08, 2012, 10:39:30 AM »
Hi Dminnery,

Thinking more about this.....

As the Romaxx is a pretty robust machine and 0.1" step-over is not an unrealistic figure it may be worth checking your machine for tightness of all parts and perhaps also the front bearings of the Bosch Colt.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Bad cuts
« Reply #5 on: April 08, 2012, 10:41:51 AM »
Tweakie,
that exactly what I was thinking. Will check all screws first and check run-out on the router.
I'll be ditching the colt for a Porter Cable 892 in the next week or two anyway.
Re: Bad cuts
« Reply #6 on: April 08, 2012, 06:23:09 PM »
I slowed down the velocity in Mach3 to 60ipm and in VCarve I adjusted the step-over to .05 from 1.0

The chatter is better but not perfect, and I can still see tool markings between the .1" depth of the passes. Either way I should be able to cut a .1" depth  with a 1/4" bit at around 100ipm and still get good results.
These adjustments helped a bit, but did not solve the problem.

The Router looks good and all the bolts are tight, so not sure that's the problem.
What other adjustments should I look into?
Re: Bad cuts
« Reply #7 on: April 08, 2012, 06:27:21 PM »
Velocity in Mach3 has no effect during a program run...other than possibly limiting your feedrate to the velocity setting.  With velocity set to 60IPM, your machine will rapid at 60IPM.  Feedrate during a program run is set by the gcode program.  F30 would set the feedrate to 30IPM.