What in the name of Saint Carvewright caused this?

[dehrlich]

Well the machine is singing along, carving out a lid for a small blanket chest out of a nicely figured piece of quartersawn white oak, when it started sounding different. For some reason it decided that the carve region wasn't deep enough I guess (see photo). At first I thought I would let it go and see if I could just blend it and make it work, then it started getting deeper and I had to stop it. What would cause this? I am attaching a copy of the mpc, although I don't see how that could be the problem. The bit didn't slip, neither did the board. Any ideas? I hate to ruin any more good lumber. Even though I am a dealer, it still isn't cheap. Any help is appreciated.

63740

63741

[TerryT]

The first two things that come to mind are
1. Slipping or loose bit if you have a carvetight chuck.
2. Bad or dirty Z encoder.

From there you have to go down the list of other possibilites.

[lynnfrwd]

I agree with Terry. My first thought was dirty z-encoder.

[Digitalwoodshop]

Like above,

Dirty Encoder

Clear Disk on the Encoder has vibrated loose and can spin free.

A Copper Solder Joint on the Encoder has Fractured and is causing the lost pulses.

Z Belt has become loose in the back of the truck. not likely but holding the belt and trying to move the head is the test.

A Z roller Bearing has frozen and on the UP stroke it is providing resistance and it does not retract enough and the computer does not catch it...

FSC Cable... This should have been my first reason.... Remember the test... Move the head to to top pin. Then call up the Z Data and it will start out as 0000.
First Test... Move the head up and down 6 times and back to the top... Should be 0000.

Second Test... Move the head up and down AND Left and Right or even just gently MOVE the Flex... You are looking for a Broken wire in the Flex that disconnects SOMETIMES most likely on the Down Stroke and 20 pulses becomes 25 because 5 are being missed by the broken wire...

And last but NOT least.. I had this happen... A Broken TOOTH on the Z Gear Box... I actually caused it JERKING out the Flex Cable... Broke about 3 teeth... BUT it is possible to DAMAGE a tooth and during a carve have it finally fall off.... Remove Motor and Gearbox and Inspect....

NICE DESIGN....

Good Luck,

AL

[dehrlich]

Must have been the encoder. I took the cover off and checked everything, then gently blew it out. Cleaned everything else good and lubed while I had access. Did two carves and everything ok.

One thing though, I don't know what that little blower scoop thing is for other than being in the way when you don't remember to put it back when you put the cover back on... but I ended up breaking it. Machine runs fine without it, will replace next time I order parts but it's annoying. Perhaps i'll just super glue it on next time. Anyway, thanks for the help everyone.

[chief2007]

I glued a scoop on one of my machines works just fine.