Thickness measurement on a sled - Drawing a blank

[keninar]

Once again I comeback to the mountain for guidance. I am drawing a blank on what I am missing.

Have a very basic adjustable sled of 3/4 Baltic Birch with 4" end pieces of .5, .625, and .75 thickness for the workpiece in use.

Sled is 24 long by 12 wide. shown here with a 6" long by 5.5 in wide workpiece, 0.5 in thickness.

MPC configured with a .5" thickness

Sled seems to have worked well on a variety of workpiece sizes, but none of the previous pieces had a cutpath or thru drilled hole.
This workpiece has 3 holes to be drilled through the workpiece.

Initial loadup went well. Found the bit, Found the surface.
When the machine went through its "finding thickness" routine, it homed on the side nearest the keypad, then moved just past the workpiece to home again.
A Z-stall error was returned as the bit dropped and touched the sled.

I sure thought I had done this type of sled arrangement ( with thru cutpaths) and got the notification along the lines of "Cut thru project or board?"

Thoughts on what I am missing? Or am I trying to do something I cannot - only thought I had done so?

Thanks!

keninar

Just reread the post title. Appears that I cannot remember how to spell, either. Apologies!

[Capt Bruce]

I believe the problem is that the CW expects to be able to probe down past your virtual board's width on the side away from the keyboard and enter the cut out U shape in the sliding guide bar and then on the top surface of the bar. Instead it is encountering your sled top and causing the Z-stall. It will normally do this when you are doing a cut through or drill operation to check actual thickness.

I use sleds the same width as my actual workpiece so I can't advise you how to compensate using your 12" wide sled. Other better informed users will chime in now and suggest a solution I'm sure.


Edit: Just reread the post title. Appears that I cannot remember how to spell, either. Apologies!

Got you covered!

[fwharris]

Bruce is right, the machine is looking to go below the bottom surface of the board to find the board thickness. If it stops to soon it will give you the stall error.

If you want to use your sled, center your work piece on the sled and add two side rails on the edges of the sled. You might also have to add either some filler pieces on each side of your work piece or run two strips of masking tape so that the Y truck rides over them for the board sensor.

[FWMiller]

You can also use jog to center and leave the workpiece on the side of the sled. But the key is to get the machine to see the full width of the sled instead of the edge of your workpiece. The board sensor is detecting the difference in contrast between your workpiece and the sled. If you have an extra piece to use as a blank to fill the width of the sled then it would measure across the sled. Masking tape as suggested above can also do the trick.

[keninar]

Thanks. Makes perfect sense. I must have been dreaming.

keninar

[FWMiller]

It may have worked before. If the color of the wood matched the sled it might have not seen a board edge until it measured all the way across the sled.

[bergerud]

If I remember correctly, the bob at the sliding plate to check board thickness will not occur if the carving/cutting operations are less than 1/2" deep. Maybe the earlier carves you remember were not so deep.

[keninar]

You are correct, Sir. Previous use of the sled did not incorporate and thru actions (drill and/or cutpath).

It wasn't until app 0300 this morning that I realized that point.

Again, Thanks for the input!!

keninar

[cnsranch]

I have that problem with 1.187.....fix is to not use the drill tool.....draw a circle the appropriate width, select your bit and give it a depth that will cut through the board, not the sled.