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Re: Cut parts are wonrg size
« Reply #10 on: July 20, 2012, 11:37:56 AM »
Rich and everyone,

Sorry for the delay in posting the dfx and the code. Take a look and let me know if there is something amiss.

Thanks

Dave

Offline Tweakie.CNC

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Re: Cut parts are wonrg size
« Reply #11 on: July 20, 2012, 01:08:03 PM »
Hi Dave,

If it's any help to you - providing you are using a 0.25" diameter cutter that GCode produces a part exactly 6" wide.

I have a sneaky feeling you may have your axis calibration set incorrectly.  ???

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Cut parts are wonrg size
« Reply #12 on: July 20, 2012, 01:41:43 PM »
Ok...

so I have set the calibration for the tool to move 1". Measuring with a digital caliper, it sure seems to move 1".

Is there a better way to do this?

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Re: Cut parts are wonrg size
« Reply #13 on: July 20, 2012, 05:02:22 PM »
The dxf is no good that you posted. Base on the posted code, the pathing of the file is as shown.So if you cut on the line with a .25" dia cutter
the outside diameter should measure 6". Note that the start point is very far away from drawing 0,0,0,.

You can calculate the steps per unit for each axis or use the axis calibration feature of Mach.
You may want to calibrate based on the longest axis move possible thus inaccuracy wil be less at shorter distances.
Seeming to move without measuring is of no value in CNC work.

RICH

« Last Edit: July 20, 2012, 05:06:17 PM by RICH »
Re: Cut parts are wonrg size
« Reply #14 on: July 20, 2012, 08:59:43 PM »
Hi Dave,
I am with Tweakie and Rich.
To me it llooks as if the settings are not very accurate. Only a slight lack. But the origin of the part is far away about 1100"
You said accuracy is within 0.001 , but multiply it with 1100 that's the problem. about 1"
Always try to set the origin at a corner or within the part. ( middle) test code by hand the origin is in X = middle Y = lower side

G17G20G0X0Y0
G0Z1
G1Z0.2
G1X1.125F50
Y0.75
X3.125
G3X-3.125Y0.75I-3.125J0
G1X-1.125
Y0
X0
G0Z1
G0X2.2913Y1.5098
G1Z0.2
G3X-2.2913Y1.5098I-2.2913J-0.7598
G1X2.2913
G0Z1
m30
%

Just a thought
Alex

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Re: Cut parts are wonrg size
« Reply #15 on: July 21, 2012, 05:34:32 AM »
Just another thought on this one….

If a 1/16” diameter cutter had been used for this particular toolpath that could explain why the parts are coming out at 6 3/16” wide.

So, with a 1/16” diameter cutter and this toolpath, changing the X & Y Scale DRO’s to 0.9700 should bring the part back to 6” wide.

Just a silly thought.

Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Cut parts are wonrg size
« Reply #16 on: July 22, 2012, 11:22:15 AM »
OOps ... mistake :o
in my last post here.
When the origin is far away like in this case, the size of the part is not affected, only the position is out.
(when she settings are not very accurate)

Alex
Re: Cut parts are wonrg size
« Reply #17 on: July 22, 2012, 08:06:11 PM »
Fenix....I am also new and learning.  When I first started, using a router, my parts were also sized different than programmed. I had not set up the steps of the motors.  I am using BobCad and Mach 3.

I used a tape measure, set the move to be 20" and measured the actual move. I then entered the actual move and the program calibrated the adjustment.  I had to do this with the X,Y and Z axis.

Good luck.
Only one way to Get-er-Done......Do-er-Right!