Newbie question

[liblakelady]

I'm trying to create a sled. I found a great Mpc on another thread. It calls for a 14.5 x 44" board. I cut a a piece of 3/4 ply to use and started my process. I loaded the board and when it ask to stay under the rollers, yes and then it says "load board". But the board is loaded. So I pull it out and find it has a slight warp. Go cut another board, this time a nice straight flat mdf. I load and the same error. So I throw a small 4x14 in and run a quick keyhole to make sure the machine is running. No problems there. I also vacuumed and blew out the machine taking extra care to clean the rollers and then lube everything up. I also checked the pressure and it reads 80lbs. I Reload the nice flat mdf board and no go. I pull it and run another smaller carve with no problems and load that big honker board again and no go. Now, I'm thinking I don't want this problem every time I use a sled. I went over the board with a fine tooth comb. It is flat, the edge is clean. I can't find a thing wrong. Any suggestions before I cut up yet another cabinet grade sheet of plywood

[fwharris]

What is the thickness of the sheet your using? OOPs see you stated 3/4" plywood...

Do you have the sliding plate moved all of the way over to the far edge?

With your trouble board in and head cranked down do a sensor check (0,7) and arrow down to the compression roller readings. Both should say compressed.

[dbfletcher]

Im asuming your mdf is .5" thick.... it might be just a hair under that, so what I think is happening is the rollers (front and or rear) are not being compressed, so the machine doesn't believe a board is loaded. The specs for the Carvewright state board must be .5" thick, but it seems some machines need a slightly thicker board.

[bergerud]

Your head my not be level. As fwharris said, do the sensor check with the wide board in. If a roller says open then it means the roller is not being pushed up enough to trip the switch. Then crank the head to almost the top and look at the gaps at the tops of the posts. If the gaps are not the same on both sides (ie. the right side is lower) then the head is not level. If it is level, we will have to think some more.

[liblakelady]

Im asuming your mdf is .5" thick.... it might be just a hair under that, so what I think is happening is the rollers (front and or rear) are not being compressed, so the machine doesn't believe a board is loaded. The specs for the Carvewright state board must be .5" thick, but it seems some machines need a slightly thicker board.

The mdf is from a cabinet shop and .75" thick

[bergerud]

The problem is not the board thickness. The problem is that one of the switches on top of the rollers is not clicking closed to tell the machine that the board is loaded. As you crank down on the wide board, listen for the clicks of the switches. You should hear two clicks but I bet you only hear one. The switches are on the keypad side of the rollers.

The fact that the behavior is different for narrow boards as for wide boards makes me think that the rollers (or whole head) are not level.

[liblakelady]

Thank you all for the quick and accurate responses. I think I have it under control today. I cleaned and lubed the posts and screws again and did a head pressure test and it comes in just over 75. Seems like with the wide board I have to crank down several loud clicks to get the rollers compressed.