Sled question

[tackytim]

Hello,

I have a pattern that I am carving that I built a sled for. The sled is 3/4 thick and the board I am carving is 3/4, so 1 1/2" thick total. I used the outline feature in designer and selected the pattern to be cut out. I loaded the board and the machine touched off with the 1/8 cutting bit and the machine gave the message "board too thick to cut through: 1) Abort 2) Continue" I chose continue and it is currently carving. When it completes the pattern with the cutting bit, will it treat the cut path as if it was cutting through only 3/4 and leave tabs like it normally would and just cut a little into my sled (as i was intending), or will it not perform the cut path at all? I realize the 1/8" bit only cuts 1" deep, I was thinking the machine would just use the thickness of the programmed board and perform the cut path just over 3/4 deep and leave the tabs.

This is my first project with a sled.

Thanks,

Tim

[fwharris]

Did you get any message asking to cut through the project or the board? Did you set your board size in designer as 3/4 or 1 1/2?

[tackytim]

No, the machine did not ask to cut through project or board. The board in designer was set to 3/4. From some searching on the forum, it seems it should have asked project or board. If it asks me to load the 1/8 bit after the carving bit has finished, I may just see what happens and have my finger on the stop button. I did set the max cut depth to .260 so it should take it in small cuts.

[bergerud]

I believe that after the machine gives the board too thick message and you press continue, it will cut to the maximum depth possible. Be ready for the bit to cut into the sled. Tabs may be cut.

[tackytim]

Well, it seems it wasn't a problem. The machine finished the carve, asked for the 1/8" bit, and started routing. It left the tabs and went into the sled only .075" (measured with dial caliper). *phew*

[bergerud]

Did the machine ask for the board thickness before it continued?

[tackytim]

No, it just asked to load 1/8 cutting bit, it touched off on the swing out plate and went to work. I'm almost positive it did not ask for cut through project/board at the beginning. I plan on making a 2nd identical project in a day or two, so when I start that one I'll make sure to note any prompts from the machine.

[bergerud]

Let me explain how I think things work. Just before the machine tries to determine the board thickness by touching the sliding plate, it bobs at the brass roller. This bob is not really a measurement; it does it only to get an estimate as to where the sliding plate will be.

Normally, with a board thickness of 1" or less, it touches at the brass roller and then goes for the sliding plate. If there is no touch at the sliding plate, it asks only retry or abort because it knows it should be able to touch it.

If it cannot touch at the brass roller, it still goes for the touch at the sliding plate (who knows why!). But, this time when it cannot touch, it asks retry or continue and lets you input the board thickness.

(There is another case where it measures the board thickness and finds it far off. In this case it asks which thickness to use - project or board.)

In your case, it seems that it thinks it is touching at the brass roller when it is not. The truck is bottoming out and the machine is mistaking that for a touch. Then, when it cannot touch the sliding plate, you only get retry or abort.

I think something is wrong here with the firmware or the z truck encoder. Reformat and reflash the card to first eliminate the firmware.

[fwharris]

Would it be worth doing a Z calibration?

[Cgav34]

formatted card, but did the same thing again. I have some 1/2" MDF that I'm going to cut tomorrow for the base of a new sled, see if that works.

Still don't know why 3/4" wont work though.