Losing tracking, bad mpc, possesed machine....Help!

[chevytrucking]

Could one of you pros look at this mpc and see if there's any reason I can't get this to carve? I've tried it twice, both times with very similar results. I seems to go fine until about 30 minutes into a 1hr carve, then it gets off track. I stopped it once I noticed it was off track, no sense dulling my bit any further.

Oak board, planed and jointed nicely, qc chuck, shop temp 65, no constraints on the mpc, stayed under rollers, tape on tracking side (second time through) roller left trail down entire length.

Is there anyway to influence the cutpath of a CW? It jumps from end to end so many times on this mpc, it seems like its just asking for a tracking error. I cut a sign out yesterday with a raster carve and it was perfect, but that didn't require so much x travel.

Shouldn't it be able to cut this many vector lines accurately? I need this project by Sunday, or someone is going to very disappointed in me.

500625006450061

[atauer]

There are a few different variables that come into play on this.

First off, what type of traction belts are you using? Sand or rubber?

Checked your head pressure lately? Could be a low head pressure causing the board to slip.

[bergerud]

It sure looks like a board tracking problem. I would first check your front belt to see if it is rolled under and hitting the brass roller. See if there is a lump at the belt edge and how close the belt is to the O ring on the brass roller. If the belt is rolled under, it can be easily fixed.

[chevytrucking]

I have the sand paper belts, in fact I just replaced the one that is to the right, facing the keyboard. The other one does have a worn area about a quarter of an inch wide on the tracking roller side, but it's not rolled over as far as I can tell. I'm not in the shop now, but I'll look at it closer in the morning.
I

[Digitalwoodshop]

My vote is for a rolled under belt at the brass roller like said above, the belt under the muffler... The "Rascal is hard to SEE"..... and Second... Get a New V90 Bit...

AL

[mtylerfl]

I have the sand paper belts, in fact I just replaced the one that is to the right, facing the keyboard. The other one does have a worn area about a quarter of an inch wide on the tracking roller side, but it's not rolled over as far as I can tell. I'm not in the shop now, but I'll look at it closer in the morning.
I

Hello,

How's your shop temperature? Run the machine at 55 degrees or above. Might not be the problem, but this time of year tracking errors go way up, due to the cold...very common indeed.

Also, take a read of the following Tips & Tricks. It may help you during troubleshooting...
http://www.carvewright.com/downloads/tips/CarveWrightTips&Tricks_Jan_Feb10.pdf

[chevytrucking]

Well, I went out to the shop and looked a little closer at my machine. I had mentioned that the back belt had about a quarter inch wear area on the squaring plate edge. The more I looked at it and rotated it, the worse it looked. I didn't have a spare belt, so I took this one off and turned it around. Re-ran the mpc, and it came out much better, but still not perfect. What's weird is that it overshot a couple of the X direction grid lines during the carve, but seemed to be back on track a couple minutes later. The errors were minor enough that I fixed them with a dremel and a tiny dab of wood putty. I'm kind of a perfectionist and I can still see the errors, but the family I made it for didn't even notice. However, I still don't trust my machine to carve this mpc accurately.

[bergerud]

The fact that it "corrects" makes me think the tracking roller is working ok. I think you should next check the x gears. You may have a broken tooth.

[mtylerfl]

Also, you never mentioned your shop temp...low temp can cause uneven head pressure...which can lead to belt rollover and belt shifting...which leads to bad tracking. Even without a belt rollover, uneven head pressure on your board can affect tracking adversly (i.e., more pressure on one side of the board than the other...goofs up the data from the brass roller). Of course, if your shop is already warm enough, it can still possibly be traced to head pressure/uneven head. Keep checking and you'll find the problem.

[chevytrucking]

I had my shop temp in the first post, it was 65 the first couple of times, than Saturday when I tried it again it was about 60. I've used my machine with no problems at 40 a few times, so I've never been really concerned if its over 60. I don't have a bathroom scale to check head pressure, but I'll try and find somewhere and check it.

[mtylerfl]

I had my shop temp in the first post, it was 65 the first couple of times, than Saturday when I tried it again it was about 60. I've used my machine with no problems at 40 a few times, so I've never been really concerned if its over 60. I don't have a bathroom scale to check head pressure, but I'll try and find somewhere and check it.

Hello,

I'm sorry...you certainly DID mention your shop temp and I completely missed that. I apologize and will try to be more careful in the future.

Good idea to check the head pressure with a scale (I've seen them before at WalMart for about $10 if you don't have one handy already). Also check the head alignment to verify that the head is level and applying even pressure over the surface of the board.

Hopefully the problem can found be resolved soon so you can get back to confident carving.