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Author Topic: New Problem, Machine Not Cutting Square  (Read 2148 times)

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New Problem, Machine Not Cutting Square
« on: March 29, 2009, 08:27:55 PM »
 ???Hey Guys,

Everything has been going well until the other day.  I was cutting curved stair tread parts for a friend from a set of CAD drawings he imported to me.  The machine ran great and the parts came out OK.  Then I cut a 12” circle out of solid Walnut, again everything seemed to be OK.

A little later he brought the 12” circle back with one he had cut on another machine.  Everything matched perfectly except a portion that was about 1/32 larger.  Then we rechecked the curved stair tread parts.  They also measured about 1/32 longer then the dimensions from the CAD drawing and that was on a 9’ part.

I decided to cut out some 4” squares to see what was happening.  The first couple of squares showed the “X” axis as cutting bigger then the “Y”.  I adjusted the motor tuning a little for the “X” and cut some more blocks.  The blocks are now cutting within .001 to .002 from side to side which I consider every good and within the manufacturers specifications, but the problem comes when I check the block for squareness.   The block measures 5.639 in one direction and 5.659 in the other direction.  That’s a total of .020 or .010 out of square.

I’m not sure what to do now.  I haven’t cut anymore parts yet or any parts larger then 4” to see if this problem grows bigger with bigger parts or stays like it is.

Does anyone have any suggestions?

Chuck
Coeur d’ Alene Cabinetry

Offline lemo

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Re: New Problem, Machine Not Cutting Square
« Reply #1 on: March 29, 2009, 10:15:37 PM »
Do not adjust the tuning unless you are running the FULL travel. Go get a long ruler. I got a 72 inch starret aluminum straight edge with numbers for about $25.
Then chuck a needle or a pointy thing into the spindle and go to zero, then to the extreme other edge, then tune till you hit that far end. The remaining error is the maximum error you will have. Which means that if you only travel 1 inch that it's 1/72 of that error.

Then route a large square/angle into mdf. If that 's not straight, then your gantry is not aligned properly (left right side). Or something is loose and introduces backlash. One of the machines I build had backlash because a screw hit the and of the thread and did not clamp down fully. So... with larger forces in curves, that darn thing slipped back and force 0.01- .03..... Backlash where there should never be any. So don't take things for granted. Check the mechanics and tune with the largest moved you can make. You can verify with a dial, but do not think that you will be achieving the best precision only running short distances.

Mach3 does cut straight lines and round circles. I had to make that painful experience as well 8).
Lemo
Cut five times and still to short...