Z-Axis Stalls

[SAA3840]

OK, I've had z-stalls before and they were generally caused by worn-out QCs letting the bit wobble. Well I've been getting them again but they have nothing to do with the bit, the carve never started. As soon as the machine finished measuring the board and the bits it started the carve but the bit never touched wood. The z-stall shut it down. And no, there is/was no bit wobble, I grasped the bit and tried to wiggle it and it wouldn't move.

I removed the z-truck and replaced three of the bearings and that didn't cure it. I removed the plastic cover from the back of the z-motor, emptied out the sawdust, cleaned the plastic rotating disc with alcahol and a q-tip. Reassembled it all and the stall still comes in, before the bit touches the wood.

I've attached the mpc I was trying to do but I don't really think there's anything wrong with it that would or could cause a z-stall. I removed the carving that was to be done on the "top" of the board to make the upload smaller. The only thing on the mpc is the "reverse" side of the board.
Any ideas?? I'm stumped.

7/28 Edit: I started the carve again but before the bit tried to touch the wood and carve, I stopped it and removed the bit. I then let "carve" with no bit. I still got the error, so I'm thinking that the ribbon cable (as suggested above) might just be the problem. I'll check that tomorrow.

Thank You to Nighthawk & Icutone.

[Nighthawk12]

A few weeks ago got a Z Axis stall It would go through it's checking but before it would carve it would stall. to make a long story short the ribbon cable that goes in the Z truck was broke across 4 of the wires inside where it entered the z truck. Replaced the ribbon cable and I was back to carving.



Jim

[Icutone2]

Check the flat ribbon pluged in all the way also it canot touch the cooling fins on the touch pad side.

[SAA3840]

Well I checked the flat cable and it 'looked' ok but I had a replacement so I installed it and guess what, the Z-stalls quit. The project fired up, right at the begining point and went great. Had to stop it as it was getting late. I'll restart it in the morning.

[Digitalwoodshop]

I believe you have a motion mechanical problem... The Z goes down to touch the bit plate looking for resistance or a increase in Z Motor current. When it senses the increase in current it knows it touched the bit plate and reverses direction. YOU MUST get in the habit of ALWAYS watching the bit touch the bit plate. Even I get a problem here from time to time, on the last bit of a 3 bit carve I saw the bit stop 1/2 inch above the bit plate.
Reacting quickly on the next time down I pushed the head down into the bit plate causing a Refind. That let me clean the rails, bearings and Z Belt of wood chips. The next Refind worked fine and I saved the project.

So I believe you have CRUD on the bearing wheels, Crud on the Rails, or Crud in the teeth of the Z Belt or pulley.

It's a MECHANICAL Problem.... A Air carve is all about never touching the bit plate.

SO if you check and clean everything you should be fine.

In the past this was normally a OLD Z Problem..... I am assuming you have the NEW Z Bundle with the heavier 14 pin cable rather than the older 16 pin thinner wires.

AL