What Would Cause Improperly Positioned Drilled Holes?

[ridgecrest]

I've been trying to make a couple cribbage boards and I have been unsuccessful as the holes are not properly positioned. I have a purchased pattern that I tried carving as well as a cribbage board that I downloaded from this forum. Both are doing the same thing. The holes looks to be perfectly positioned in Designer 1.187.

I took the machine apart as I assumed that the X-Drive gear may have broken teeth. After inspecting the gears, I found no issues.

Here are pictures of my carving attempts. The first board I let carve to completion where as the second (oval) carve I terminated before completion.

Any help will be greatly appreciated.

6552865529

[fwharris]

I would check your head pressure first. Are you using any masking tape on the bottom edge that rides on the brass roller?

[lynnfrwd]

Board popping out from rollers? 7" inch rule. Board loosing traction? Slippage?

[bergerud]

My guess would be as Lynnfrwd says. The 7 inch rule. If the board comes out from under the rollers during the hole drilling process, two bad things can happen. When the front roller drops, the brass roller stops keeping track of the board position and the position becomes dependent on the x gear system. Backlash in the gears can introduce error. The second thing is that the board can slip on the sandpaper as it pushes the rollers back up. This is worse with low head pressure. You need to use a longer board (7 inches longer) to make sure you stay under the rollers during the whole operation. You can also tape small extensions onto your board if it is not long enough.

[ridgecrest]

fwharris and lynnfrwd, I have not checked the head pressure but I will do so tomorrow and post my findings. The first carve was on a new sled that I made today. The board to be carved is 16x6 and the sled is 23x6. The second carve is 16x91/4 and I used 24" rails with masking tape running the length of the rail. My machine has the heavy duty belts.

The improperly placed holes are throughout the entire carve not just on the ends.

[bergerud]

It may be a problem with the brass roller. Do you see roller tracks on the sled? Is the rubber belt too close to the brass roller? A common problem is the rubber belt interfering with O ring on the brass roller. You may have to move the brass roller further away from the belt.

Edit: push the brass roller down by hand like the board would and see if it touches the rubber belt.

[TerryT]

Are you using an "A" model machine by any chance?

[Digitalwoodshop]

Once the brass roller looses contact is all over... No hole will be in the proper place.. I see the Cut Path started in the correct place in Y so that is good... But if you have over 250 cut hours I would replace the Y gear box bearings if you already have not.

With Rails, that puts extra pressure on the brass roller edge of the belt making it bulge more... That could be the source of the problem... Rubber Belt Bulging and touching the brass roller. I would remove the brass roller and make the holes oval and center the roller between the belts.

It's all about the brass roller... And check EVERY hole and be sure that the numbers are GREEN... Any YELLOW numbers are restrained and can cause the hole to be FORCED to be drilled in a location OTHER than where the mpc want it... Right click and remove Attachment to go from yellow to green. It FORCES due to the physical board might be different and by making it yelllow you tell the computer... This measurement from this point is MORE important than placing the hole in the right place...


AL

[TerryT]

Two more questions besides the model of the machine....
Did you resize the mpc's or allow the machine to scale them?