adjust accuracy

[bobmoore]

I have a prs standard with SB control version 3.8.4 .When I program it to cut at 72.3605 inches I get 72.312 actual inches. Can someone remind me how/where to go in and change those values.

[Gary Campbell]

Bob..
Are you checking this distance against a tape with a vbit or is your results number the result of a cut? If its a cut the follow this:

1) Lay a tape from one end of the table to the other, parallel with the X travel. Tape in place
2) With a sharp Vbit move the cutter exactly over the 2" mark. type in ZX
3) Type in MX,90 Is the bit exactly over the 92" mark? If so, you don't need any adjustment. If not, use the keypad to get the bit exactly over the 92" mark
4) The adjustment formula is: {(Screen position) / Tape (90") * (existing unit value)} = {new Unit Value}

I'm going to assume your tape check was OK. If not your pinions are most likely worn. If it is, then the most likely cause is that the bit diameter is different than you have it defined as in the tool database. Cut a slow feedrate slot 1/8" deep and read the slot width with your calipers. Use that dimension as your bit diameter.

[bobmoore]

Thanks Gary but awhile back shopbot tech support had me go in and change some unit values and I think the new ones may be off slightly. The unit values are what I was looking to fine tune. Machine sounds good and pinions feel /look good. I will try your vbit with tape routine as that will cancel any bit inaccuracy and post asap.

[bobmoore]

Well that is embarrassing. Checked with vbit Gary and everything is fine. I must have changed the drawing and forgot to save the changes. Thanks for the help.

[srwtlc]

If that was a measured cut part, bit deflection could be within that range.