I think I have a board thickness problem

[mijoda52]

Hey Everybody. Hope you are all well and feeling good. I think I may have a board thickness issue. My problem is that when I start a carve, the cutting head makes 10 to 15 passes before it comes into contact with the board. This makes the carve shallower than it should be. The carve looks good but it is a little bit too shallow. Everything seems to be working ok during the pre-carve sensing process. The contact during the jog looks right on the money. Anybody have any ideas? Thanks.

[bergerud]

Is this a single bit project? If not, try a single carving bit project.

If the bit that does the touch is the same as the bit which carves too shallow, you may have a problem with the z encoder.

[SteveNelson46]

Is this a single bit project? If not, try a single carving bit project.

If the bit that does the touch is the same as the bit which carves too shallow, you may have a problem with the z encoder.

Does the bit touch the swing out bit plate during the initial board measurement?
Does the bit touch the board during the initial board measurement?

If the answer is no to either one of these questions you may have the bit pushed up too far into the collet. Using a stop collar will help to position it in the same place each time the bit is inserted.

[bergerud]

My understanding is that the touch on the board surface is the only thing that determines the depth that that bit will cut. The depth that other bits will cut is not determined so exactly. Instead, their depths are adjusted using the difference of the touches at the bit plate. For example, if the board touch is done with the 1/8" cutting bit, the depth of the carving bit will depend on the accuracy of touches at the bit plate.

In trouble shooting this depth problem, I think it is important to know whether the problem bit was also the bit which touched the board.

[Digitalwoodshop]

My first thought is that the "Bit Plate" is BENT up or down and not level... Causing the length of bit issue causing the air carve for the first few passes.

[mijoda52]

Hey Everybody. Thanks for the replies. This is a single bit cut and I inspected the touch plate and it does not appear to be bent. The bit is contacting the plate on the initial reading. So does the machine read the final board thickness as it jogs the bit into position? Thanks

[fwharris]

This is not a board thickness problem. The carving depth is based on what it sees as the top board surface when it does the "finding surface" step before the carve. Is the bit touching on the board surface or maybe the rail surface if you are using a sled?

If this is a pattern carve with a feather around the pattern the bit will ease down to the surface before it actually starts carving.