one wavy line of text on 3 line carve

[bergerud]

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1) Put same board in fixture- tested for tight by lifting fixture by holding board. Pic "fixture hold".

Do you mean that you tighten the wingnuts until the board is pinched between the sides of the carrier? If so, that is not the way I intended it.

The sides would not stay parallel as the bottom would squeeze in. The sides are supposed to stay parallel; it is the sandpaper and roller pressure which supposed to hold the board. I do not know if this could have anything to do with it, but, check that the bottom of the carrier is flat on the belt near the brass roller.

[Wood Art 1]

Dan, my apologies for hijacking your fixture. Have used this fixture for about two years. Replaced the bottom rails once and sanded them smooth to eliminate tracking roller groove a couple of times. Always use masking tape. ALWAYS tighten side to prevent slippage. Only use the end stop when board length gets close to 19" max fixture length. If the 8" plaques are all cut from the same board - I set the board into both ends of the fixture to set the base fixture width to match board width. Then I set the top of the board slightly less than 1/8" proud into the fixture, using a handmade gauge - setting the board at both ends to tighten the rails. Move the board to the center - approx - and squeeze the board into the fixture.
The wingnuts at the bottom of the fixture prevent the bottom from squeezing in. Only the wing nut in the rails is used to tighten the piece into the fixture. Approximately one turn tightens the board.
Therefore every board that goes into the CW gets measured by the CW.

[bergerud]

Oh sorry, I did not know you added the extra tightening clamp in the middle. Ok, so... still no reason for the weird tracking.

[DickB]

I wonder if the carrier is slipping. The drift in the letters seems to coincide with the order of carving, suggesting that something is slipping. Because the board is proud of the carrier, one roller is going to be contacting the board and one contacting only the sides of the carrier. The latter roller will be exerting less pressure because the carrier is lower. I wonder if this is causing the carrier to slip. If you measure 65 lbs with a board contacting both rollers, the actual pressure with one roller contacting the board and one contacting the carrier is going to be less, is it not?

[Wood Art 1]

Dick, I lubed the guides and got the pressure to 75-77 lbs. the fixture will not move in the CW until I crank up the head when removing the fixture after carving. I will do another test and hold my hands on the fixture and belts to determine if there is any slippage. The Plaque does not come out of the fixture until I loosen the side clamp. I will try some more tests with the attachment @ .51, .52 etc to see if it continues. I will try another font at .5 attachment and etc. to see if it continues. I have about ten examples of the same font at .7 attachment that all came out straight, between the United States and the May 3 examples.

[bergerud]

I do not think the board is moving in the carrier. With the sandpaper and the side clamping, it does not seem likely to me. Easy to test though. Just mark the carrier rail and see if the board moves.

[DickB]

I will do another test and hold my hands on the fixture and belts to determine if there is any slippage.

Even if the carrier is not slipping on the belts, it could be slipping on the roller. That is what matters.

With a board under both rollers, pressure should be exerted equally onto each belt. If one roller drops off the board onto the carrier, there will be less pressure of the carrier against that belt. It seems to me that the carrier could lift slightly on that belt, also lifting slightly from the roller. The carrier may still move in sync with both belts but not the roller.

I have had roller contact issues with slightly warped boards when the board contacts the outfeed roller, which were properly adjusted in height for a perfectly straight board, but lifted the warped board ever so slightly. It doesn't take much moment to cause the roller to lose contact and slip.

[bergerud]

If the side of the carrier is straight, I do not think it is slipping on the belts or roller. If the carrier was going to slip, it would do it while measuring the board. There is very little head pressure during board measurement stage. After that, the head is cranked down. I am thinking more like something is messing with the brass roller. (Press down the brass roller to see how close it comes to the front belt.)

[Wood Art 1]

Dan, I just checked the roller clearance to the belt. Pushed down to move the roller to max and with a mirror inside the CW to observe, still have about 1/16" clearance.
Ran a bunch of tests with various attachment figures. Using the same MPC but adjusting the attachment from .5 to top of board to ? Marked the fixture and the belt to see if there was slippage.
Test 3) Result OK, .5 Attach , no slippage
4) OK, .2 attach, (M36y120a,), no slippage
5) Wavy, .52 attach, (M36y210a,), no slip
6) Wavy, .55 attach, (M36y120a,), no slip
7) OK, .57 attach, (M36y120a,), no slip
OK, .6 attach, (M36y120a,), no slip
9) OK, .65 attach,

[bergerud]

Could it be that the backlash in the x gear system is getting too large? With vector stuff, where the x drive has to go back and forth, the x backlash can be problem. Could the belt system have too much drag? Has a belt shifted?

Sorry, I am out of ideas!