Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Pico on February 27, 2011, 11:28:44 AM

Title: Cuts much too large
Post by: Pico on February 27, 2011, 11:28:44 AM

I'm probably making a really stupid basic mistake, but I've been playing around with this thing for the last two days and can't understand what's wrong. My router (rockcliff with cnchobby controller) makes cuts about 5 to 6 times larger than it should. I have checked the motor tuning settings which have not changed so that doesn't appear to be the problem. Help!

Title: Re: Cuts much too large
Post by: Hood on February 27, 2011, 04:50:48 PM

Is this with any move, eg Jogging, MDI, Code?
Is it possible the microstepping of your drives has been switched? Not sure if they are variable though.
Is there a scale set at the side of each axis DRO?
Hood

Title: Re: Cuts much too large
Post by: Pico on March 02, 2011, 03:48:07 PM

This does not happen with jogging. It happens with code - and is driving me further crazy as I was just fiddling with it and it is now cutting  small, maybe 1/10th the size it's suppose to. I can't use the MDI command as a small blank box tops up above the "Input" and I type a command in and hit "Input" and the command cancels. The scale set by the DROs says +1.00. Thanks for your help.

Title: Re: Cuts much too large
Post by: Hood on March 02, 2011, 04:42:19 PM

To use MDI you click on it, type what you want, example G0X10 then press the enter key on your keyboard.
If you attach your xml and your code I will have a look and see if I can find an issue
Hood

Title: Re: Cuts much too large
Post by: Pico on March 02, 2011, 05:01:00 PM

I do type in G0 X10 but when I click enter, it cancels. What is xml? Thanks.

Title: Re: Cuts much too large
Post by: Hood on March 02, 2011, 05:02:21 PM

The xml is your config file and will be in the Mach3 folder, it will have the mname of the profile you use and will have a xml extension.
Hood

Title: Re: Cuts much too large
Post by: ger21 on March 02, 2011, 05:02:21 PM

Sounds like your setup in metric, and the g-code is inches? Or the opposite?

Title: Re: Cuts much too large
Post by: Pico on March 03, 2011, 09:46:38 AM

The native units is in English Gcode, as is my gcode. So that is correct. I have attempted to find the config file. I  went to: my computer - local disc (C) - Mach3 and there is no config file. I also went to program files and there is no Mach3 there. Where do I go to now? Thanks for the help.

Title: Re: Cuts much too large
Post by: Hood on March 03, 2011, 09:57:18 AM

It should be in C:\Mach3 unless you installed Mach to a different location. However the sure fire way to find where it  is is right click on the shortcut you use to start Mach then look at the properties then target and that will show you exactly where it is.
Hood

Title: Re: Cuts much too large
Post by: Pico on March 03, 2011, 11:49:23 AM

Does it have a different name than config? I went through properties - target and ended at the same place as before. No config folder there. Thanks.

Title: Re: Cuts much too large
Post by: Hood on March 03, 2011, 01:12:40 PM

It has the name of the profile you are using. If you start  Mach you will see at the lower right part of the main page the name of the profile.
Hood

Title: Re: Cuts much too large
Post by: Pico on March 03, 2011, 03:14:32 PM

Here it is.

Title: Re: Cuts much too large
Post by: Hood on March 03, 2011, 04:06:41 PM

Are your steps per unit set correctly? 2000 per inch doesnt seem like much.
Hood

Title: Re: Cuts much too large
Post by: Pico on March 03, 2011, 04:21:11 PM

Don't know. I set this thing up over two years ago and don't remember what I set it at. I think I lost some settings in a computer problem and I've been having  difficulties ever since. What do you suggest? I'll run down and try 10,000 to see if it works better. I tried the automatic set several days ago and that cranked it up waaaay too much.

Title: Re: Cuts much too large
Post by: Pico on March 03, 2011, 04:34:13 PM

10000 is too much. The motors whine and make funny noises.

Title: Re: Cuts much too large
Post by: Hood on March 03, 2011, 04:35:02 PM

Well its easily calculated if you know a few things
Stepper or servo? If stepper it will normally be 200 steps per rev
Drive microstepping, for example Geckos will be 10
Any gearing between motors and screws
Pitch of screws

So as an example
200 steps per rev x 10 micro step = 2000 steps per motor rev
Screw 10TPI  and no gearing between motor and screw so it would need 10 turns for 1 inch so 2000 x 10 = 20000 steps per unit.
As said thats just an example, it will depend on your actual setup.
Hood

Title: Re: Cuts much too large
Post by: Hood on March 03, 2011, 04:35:55 PM

10,000 may still not be too much, it may be your velocity and acceleration are too high. Work out the correct steps per unit via the method above.
Hood

Title: Re: Cuts much too large
Post by: Pico on March 03, 2011, 04:56:14 PM

Thanks for the info, I'll dig into my instructions and see what I can find. Will report back.

Title: Re: Cuts much too large
Post by: Hood on March 03, 2011, 05:25:44 PM

Ok.
Hood

Title: Re: Cuts much too large
Post by: Pico on March 03, 2011, 06:57:17 PM

Motors are 200 steps/rev, set at 1/2 microsteps = 400steps per rev, with threaded rod at 20 TPI = 8000 steps per unit. I've set the motor tuning at that and the motors seems to work best with the accel and velocity at 5 to 10 %. Best of all, no more crazy cuts, I haven't measured down to the nearest hundred but the movement appears to be correct. Thanks for the help, this was driving me nutzo.

Title: Re: Cuts much too large
Post by: Hood on March 03, 2011, 07:06:05 PM

Good to hear you are up and running again :)
Hood

Title: Re: Cuts much too large
Post by: Pico on March 03, 2011, 07:30:28 PM

Thanks again!