Z creep down, cutting too deep.

[grt520]

OK... I'm new with this. I've carved 5 boards approximately 7 5/8" X 20" on .8" think African Mohogany. The first 4 were practice to see what the machine would do. The 5th was for real. A grandfather/grandson project that he dreamed up for his mother. All went pretty much as expected until the last cherry pattern that was carved. I had it set for 1/16" deep and the last few of the letters in it started going deeper. The last cherry pattern got deeper as it progressed to the right.....Reason unknown.

Now, I'm back to the first sign, have improved it a bit and tried it on the back of the original. This one has a desert scene on it and was consistent on the first test cut but deeper than I wanted. Now, on the back of the original, I'm testing to see if I like the new improved version before I cut into my last $6.00 20" board. (I know....I need to find a better source of less expensive wood). The desert scene starts out just fine but within about 2 inches the depth changes from 1/8" down to 1/4". The Letter depth also set for 1/8" started at about 1/3". At that rate, a few more inches of cutting, I'll be cutting through the board and into the machine.

I've checked the head tension and it's correct. I've checked the bit (using the 1/8" carving bit) and it's properly seated and the set screws have not moved. The bit is the same length as the 1/8" cutting bit, so I'm confident that the bit hasn't slipped. I checked the Z-Axis belt...don't find any missing teeth but the Z-Truck seems not to move real smoothly. No binds really, but it's not as smooth as I would think it should be from bottom to top (with power off of course). It's as if the Z-Axis is losing it's "top surface" location and it's drifting down.

Help!! And only one project turned out ..... and it is flawed because of this but my grandson was pleased. I'm glad he's young and not as particular as me ..... yet!!

: (

[rjustice]

A couple possibilities that I am aware of... It sounds like you have checked one of them, but it is worth checking anyway. You stated that the set screws havent moved... The ones from the factory are supposed to have loctite on them. They could feel tight, because of the loctite, but not actually be holding the bit. I also assume you are talking about the 1/16 tapered carving bit, even though you stated the 1/8 cutting bit...
The simplest thing to try would be to heat up the bit adapter and loosen up the set screws, apply new BLUE locktite to the threads, and re-tighten up. then re try a carve on a scrap piece.
The other possibility that is the more likely one would be the "Z axis encoder"... You will need to contact LHR and they will help you with that one.

I wish you luck...

Ron

[grt520]

Thanks Ron. It is the carving bit that I'm using and I checked it against the 1/8" cutting bit for the correct length setting. They are the same. So... sounds like it may be the encoder.... bummer. I'll see if I can contact LHR Monday. Thanks for the reply.

Gary (in Tucson)

[liquidguitars]

Under options on the keypad hit "07" page down to the "z" location and move the truck up and down to get a readout. Note the numbers as you move the truck up and down, if the number are way off could be you need a new Z pack replacement to fix it.

LG

[rjustice]

Thanks Ron. It is the carving bit that I'm using and I checked it against the 1/8" cutting bit for the correct length setting. They are the same. So... sounds like it may be the encoder.... bummer. I'll see if I can contact LHR Monday. Thanks for the reply.

Gary (in Tucson)

The lengths are arbitrary, and really dont mean anything. It could be coincidence that they are the same. Each time the machine carves a new part it touches the tool off on the bit plate to calibrate the length of the tool, and then touches the workpiece to find the top of stock.

Good luck

Ron