inside cuts coming out too small.

[knight_toolworks]

I have always had this al little bit on my prt/alpha but I noticed I was getting .03 smaller and the outside sometimes larger or smaller depending on the sharpness of the bit and some other slop. I realized I had not changed the pinions for about 3 years and cut more now. so I replaced them all and now the cuts are better but insides are still the .03 and the outside is perfect. this has been on several materials and different types of cuts. even a climb and a cleanup cut at 1ips.
I also see this slight bevel in this flat cut the top should be flat but you see the little bit of a dip maybe a few thousands but it needs flat. this is with a conventional cut with a 1/4" bit downcut at 1ips and 10k. it seems a bit worse when the cut is going in the y then the x.
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/C78ACF3B-8D85-4925-ADE3-1DF596B15FFC_zpskvayhxhi.jpg (http://s154.photobucket.com/user/knighttoolworks/media/posting/C78ACF3B-8D85-4925-ADE3-1DF596B15FFC_zpskvayhxhi.jpg.html)

[knight_toolworks]

no help at all?

[Kyle Stapleton]

Are you doing one toolpath and leting the software figure out that there is an inside profile and an outside profile or two One inside and one outside?

[knight_toolworks]

usually selecting all the cuts and letting the software figure it out. I have not tested it just on a inside cut.

[dlcw]

Steve,

Could the path with the down spiral be compressing the material into the board a little bit. I found this on a project I was doing. The down cut spiral pushed chips down into the pocket it was clearing because there was no room for chips to escape and it did push the material down just a hair. I ended up with two toolpaths. I did a down spiral to clear most of the pocket, then an upcut to finish it. No chips to compress into the pocket when cutting.

Just a thought.

[knight_toolworks]

Steve,

Could the path with the down spiral be compressing the material into the board a little bit. I found this on a project I was doing. The down cut spiral pushed chips down into the pocket it was clearing because there was no room for chips to escape and it did push the material down just a hair. I ended up with two toolpaths. I did a down spiral to clear most of the pocket, then an upcut to finish it. No chips to compress into the pocket when cutting.

Just a thought.
no it seems to do it with all material and bits. even if I did a separate cleanup pass it will do it if I remember right. I will test it a bit more.
the slop is a bigger worry for me I have noticed it on other parts. always when coning from a 90 degree cut. wonder if the racks are wearing I have almost 3000 hours on the machine.