Undersize Parts

[44-henry]

This is probably a simple problem with a simple solution, but I'm stuck. I've been working with my Tormach and have been getting test parts coming out consistently .010 undersize. I've checked the cutter diameter and it seems ok, my program works for parts in my Shopbot router, but apparently not so good in the Tormach. Thanks.

[Mooser]

Is the problem the same on inside as well as outside measurements?
ie: If you make a pocket is it oversize .010 when outside dims are undersize .010? Then it's a cutter comp. related problem. If the pocket is undersize .010 it's probably a drive or steps/unit problem

I'm sure you checked this first but is there a value in the wear column in the mach tool table?
Mooser

[44-henry]

Mooser, thanks for the reply. I tried a couple things and here is what I have found to date. I checked all three axis with a dial indicator and found that the indicated travels all match the computer. I replaced my cutting tool with a 2 flute 3/16 endmill that miked out right at .187. I setup a test cut including a 1" pocket, a 1" square, and a .5" circle. After the cuts I checked the measurements and the pocket measured .990 square, the square measured .990 and the circle measured .490. I checked the wear values in the tool table and everything is at 0. Is there anything obvious I'm missing here? Thanks.

[Mooser]

If the outside is small and the insides are also small then it doesn't sound like a compensation issue, (inside error should be opposite of the outside error)
Can you post your code?

Actually, are you writing the code manually or is it generated? (ie mastercam)

if you tried something like and make sure the G40 (cancel any cutter comp) is there

SPINDLE START, ETC
G40
G0 X-.09375 Y-.09375 Z.1
G1 Z-.05 F5
G1 X1.09375
G1 Y1.09375
G1 X-.09375
G1 Y-.09375
G1 Z.1
SPINDLE STOP ETC

with a .1875 dia cutter this should result in a 1" sqr. if not it would appear that the steps per movement on mach is wrong (it's not in sync with the pitch of the ballscrews)
please lets have a look at the code
Mooser

[benji2505]

Where I would look first:

1. Is the cutter radius comp the right one for the tool? or do you comp for another tool?

2. Program a G50 G64 G52x0y0 at the beginning of the code. Make sure there is no code for G51, G61 or G52 after this in the program

It does not sound like a machine related issue to me since it consistent in all directions.

Good luck. I know these things are totally annoying.

Benji

[44-henry]

I'll post the code I'm using when I'm back in the lab tomorrow. I have Mastercam, but have not had much chance to work with it yet. Currently I am drawing my parts in AutoCAD saving them to DXF format and than importing them into PartWizard. This is the same program I use on our ShopBot router and is what I have been using for the last couple years; however, I know Mastercam would be way better. I'll try the file you sent and see what happens. Thanks.