Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: SScnc on July 09, 2009, 09:25:12 AM

Title: Smoother Radi's
Post by: SScnc on July 09, 2009, 09:25:12 AM

I built my own CNC mill which works great. My only concern is that when i cut a radius, it leaves a "choppy" finish on the material. Is there any way i can smooth this out? Possibly something i can set with Mach3. Thanks

My setup is Gecko G540, Keling 48v PS, Keling 270oz motors, etc..

Title: Re: Smoother Radi's
Post by: Jeff_Birt on July 09, 2009, 09:37:52 AM

Sounds like you have a lot of backlash/slop in your drive system. Have you measured your backlash.

Title: Re: Smoother Radi's
Post by: RICH on July 09, 2009, 10:46:19 AM

You could make a rough and then do a finish cut. Experiment with your particular machine a little to see what works best.
RICH

Title: Re: Smoother Radi's
Post by: Hood on July 09, 2009, 10:57:21 AM

Is the code an arc or many short lines?
Hood

Title: Re: Smoother Radi's
Post by: RICH on July 09, 2009, 11:03:28 AM

What program are you using to generate the code?
RICH

Title: Re: Smoother Radi's
Post by: SScnc on July 09, 2009, 12:55:17 PM

-No Backlash
- I do rough then finish
-Code is an Arc
-I use CamBam Plus

Title: Re: Smoother Radi's
Post by: Jeff_Birt on July 09, 2009, 02:55:51 PM

Quote

-No Backlash

Impossible, every thing has some amount of backlash! Have you actually measured it with a good dial indicator??

CamBam produces good Gcode. Your fixture/part/machine has to have some excessive sort of slop or backlash OR you are taking way to aggressive a cut.

Title: Re: Smoother Radi's
Post by: SScnc on July 09, 2009, 03:34:44 PM

well obviously it has backlash but i have backlash comp on. Its less then .0002 on each axis.

.010 finish cut, climb milling.

Title: Re: Smoother Radi's
Post by: Hood on July 09, 2009, 05:14:56 PM

What is your step per unit?
Hood

Title: Re: Smoother Radi's
Post by: SScnc on July 09, 2009, 08:13:38 PM

not sure of exact numbers but it is around 10k

Title: Re: Smoother Radi's
Post by: Hood on July 10, 2009, 02:48:09 AM

That should be fine to give you smooth enough arcs so it would seem it must be mechanical if your code is a true arc, it could I suppose be you need a wider pulse but unlikely as you would notice this all the time.
 Can you post a pic of the rough arcs?
Hood

Title: Re: Smoother Radi's
Post by: SScnc on July 11, 2009, 06:04:43 AM

Well i have the G540 and like many others, I was having problems losing steps in the Z axis. I've read that using sherline mode fixes this, which it did. Now from my understanding all sherline mode does is increase the pulse width to 40micro.

Anyway, as for the rough radius, I think it was just the material i was cutting (cast tool and jig plate) because i ran some normal 6061 Aluminum last night and the radi's look fine.  Its a mystery ???

Title: Re: Smoother Radi's
Post by: docltf on July 11, 2009, 12:26:10 PM

SScnc

 to jump your thread for a moment. do you have a good source for your cast tool and jig plate material . is their a chance for your supplier info.

thanks bill

Title: Re: Smoother Radi's
Post by: SScnc on July 11, 2009, 04:33:44 PM

check out www.speedymetals.com

It is kind of hard to find within the site, so click on aluminum then plate, and its under there.