My smooth isnt soo smooth..

[Keith Oates]

Hey guys i am having issues with my prs alpha. while cutting a smooth pocket. It seems that i am losing zero. like if i cut around a letter, you can see the cut marks where the end mill has ran, it seems to be raising very slightly. but only at certain times or in certain areas. The rest of the pocket will be smooth. I have resurfaced our table and the problem is still there. any clues or help ???. Thx!!

[bleeth]

It sounds like you could be very slightly loosing steps. You're z may be a bit to tight. Follow the SB doc on adjusting your z slide and this may solve your issue. Also make sure your pinion gears are in good shape and motor is engaging properly.

Also note that depending on the length of the program you could be seeing a bit of tolerance accumulation that is pretty much impossible to eliminate. Smooth backgrounds around a bunch of raised letters is actually one of the toughest things to do. One work around, depending on the design, is to cut a pocket for the letters and cut the letters separate and pop them in with some adhesive. This method is heavily used by signmakers as it makes finishing easier as well. If your software has the inlay feature this is really easy to program.

[dana_swift]

Is the bit slipping in the collet? Collet not tight enough? Have you cut things successfully before, is the problem new, or have you never gotten reliable flat bottoms on the pockets?

Be sure your bit is the correct size for the collet. The shank for a 1/4" collet must be 0.250 not some nearby size. Mic it or use a good caliper.

Check the collet for dust and debris. Be sure it is clean, dust in the slots will prevent correct tightening.

The alpha should not lose steps, thats the reason you paid the extra money for the alpha. So its the bit-collet or possibly backlash somewhere, start with the bit-collet.

D