UCB and "Finding board thickness"

So I split a two-sided cave into separate MPN files. Carved the back using the UCB earlier without a problem.

Flipped the board over to run the second MPN (the front of the carve) on the back of the same board. I had a series of strange errors and weird things (including being unable to get the board to jog to the left after a certain point). Took the board out, checked all the connectors, re-set the 1/8th inch clearance. Swept out machine. Put board in different places on the UCB.

I keep getting the error where after I jog to the forward-most hole on the UCB, the machine can't find the board thickness. The bit goes into the forward-most hole away from the keyboard and touches the outside thing (the part that you glue the dowel into). I sometimes get the error about the sliding plate but it's on the inside of the UCB against the rail closest to the keyboard per the instructions (I believe this is correct---this is what I've been doing all along). Mostly I get caught in a Re-try/Abort loop because the machine can't find the board thickness.

I'm puzzled because I can see the bit touching the dowel-piece. And I just did this the other day, so I can't figure out what I'm doing wrong.

Any assistance is appreciated.

Are you sure you have the right touch blocks on the right sides? The touch blocks are supposed to fool the machine into thinking the board is down on the belts. The lower block is supposed to be on the keypad side.

You can also operate without the touch blocks. The machine will bob three times looking for the sliding plate, give up and ask if the sliding plate is in position. Say YES and it will prompt for you to key in the board thickness. (You must, however, take off both blocks.)

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Originally Posted by bergerud

Are you sure you have the right touch blocks on the right sides? The touch blocks are supposed to fool the machine into thinking the board is down on the belts. The lower block is supposed to be on the keypad side.

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Yes, I understand and I have the touch blocks on the right sides (just like the picture in the instructions). As noted above, I just used the UCB to carve the back of this piece using a separate MPN file.

I have used the sled successfully on other single-sided carves (using similar material), so it isn't clear to me why this suddenly stopped working.

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Originally Posted by bergerud

You can also operate without the touch blocks. The machine will bob three times looking for the sliding plate, give up and ask if the sliding plate is in position. Say YES and it will prompt for you to key in the board thickness. (You must, however, take off both blocks.)

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Yes, I will sometimes get prompted to check the sliding plate, which is already in position. However, I think the options I'm given are 1)RETRY or 2)ABORT. I have been prompted for the board thickness, but I think that's when I'm in the JOG sequence. As I recall, if I accidentally hit ENTER (Finding SURFACE...Press STOP to jog > STOP > 3) JOG) I'll be prompted to key in numbers. Something like that. But I don't recall this prompt happening with the sliding plate thing.

Regardless, if I'm understanding you, I should remove both touch blocks and get to the board thickness keying step to key in the board thickness, skipping the touch blocks all together.

I previously keyed in the thickness with .5 MDF to see what happens and it worked well enough but I haven't done this with the kiln-dried maple that I've been working with. I've planed the maple is a nominal .6 inches, though it's actually a little bit thicker than that, say .655.

So may I ask how exact this dimension needs to be to use the key in method? IOW, is "board thickness" in reference to the board within the project (the MPN file) or the actual board?

Could I be causing myself problems because I don't use the exact dimension of the board in the project file? I measure the boards using the Carvewright before I start anything---in fact, it's something I do when I'm waiting for glue to dry or something else to cool. I have a stack of prepped boards in the shop and I write the dimensions using a Sharpie on a piece of blue tape and stack the boards on edge so I can find a piece quickly (pretty handy and not just for the Carvewright). I pull a board and take the blue tape with the dims into my studio to use for my board settings values. But I usually round the numbers down since I use CENTER ON BOARD, so a board that measure 43.4 x 6.53 x .671 I will round down to 43 x 6 x .6. This has worked fine for the carves I've done, including the two-sided, but I wasn't using the UCB for those.

Thanks for your help. I really appreictae it.

So many questions! Let me explain how the machine measures board thickness for a board on the belts. After touching on the board, the bit touches at the brass roller. Then it moves to the other side of the board and bobs in the hole of the sliding plate. Then it tries to touch on the sliding plate (it has an idea where it is from the brass roller touch.) The difference between the touch on the board and the touch on the sliding plate determines the board thickness.

If the machine touches at the brass roller and then cannot touch at the sliding plate, you get the 1)RETRY or 2)ABORT and it is a no go (unless you give it something to touch).

If the machine does not touch at the brass roller, it still tries to touch at the sliding plate (who knows why!). This time, when it fails to touch after three bobs, you answer yes that the sliding plate it there and then it will ask for the board thickness.

If the touch at the sliding plate determines a board thickness much different than the project thickness, it will ask which you want.

I think the board thickness is important only for cut throughs and piercing. The wrong board thickness could leave small or no tabs.

Note that if the project cutting depth is 1/2" or less, the machine will not bother at all with the thickness measurement. No bobs at the sliding plate.

I hope this helps. The machine behavior is different in the many different situations.

Thanks for your response.

So I remove the touch blocks from the sled and use .6 as the thickness even though the board is a wee bit thicker than that because I can deal with any small tabs. I'll go try that.