sled tracking away from the brass roller plate

[myshop1044]

After an 1hr and 45 min I notice the sled would not move to the right to begin the trim groove around the project. It just sat there and would not give any error message. I then notice that the sled was about 1/4" away from the brass roller plate guide.
I did the roller pressure test and it was 99.2
I did the compression test on the rollers and they checked out ok. The released ok.
I did the paper test under rollers in a compressed state and could not remove the paper srtips on either side of the machine.
I did a measure length test on the sled and on the last pass to the right, it started to walk off to the right away from the brass roller guide plate.
I tried the measure test on 2 other boards 1/2 and 3/4" X 24" and it walked away again about a 1/16" away from the guide plate.
The sandpaper belts look good, not much movement left or right.

what do I look for now ?
Myshop

[CarverJerry]

Is the head level? Just a thought.

CJ

[Deolman]

How clean do the upper rollers look?

[myshop1044]

I greassed the four post and the head pressure is now 88.6.
the rollers seems to up and down very easy. How do you check to see if they are dirty
and how do you check to see if the head is level.
Myshop

[AskBud]

I greassed the four post and the head pressure is now 88.6.
the rollers seems to up and down very easy. How do you check to see if they are dirty
and how do you check to see if the head is level.
Myshop
Quick and dirty head level check!
1) Get a 4 foot board (with parallel sides and edges).
2) Cut the board in to two 2 foot pieces.
3) Place each board on the belts (on its edge), one on the keyboard side and the other opposite.
4) Tear 4 half inch strips from a sheet of paper.
5) Lay each strip on top of the wood, so each will be under a roller point. Leave the longest portion toward the outside of the machine.
6) Lower your machine head so the rollers just touch the paper.
7) You will now tug on each piece of paper, and feel the resistance. Each should have the same feel (these papers are your feeler gages to assure a level head).

Each time you adjust the head, the above steps will help assure a level head (I'm writing about the machine head).
AskBud

[myshop1044]

Thanks AB, I did do that test but it was on the sled and the paper was very tight, now I will try your way and see what happens

Thanks again.
Myshop
Hope to see you at the conference.

[Deolman]

To inspect the rollers, just raise the head and look at them while turning them. The rollers I am referring to are the ones that come down and contact your board on the top. Unless you have a lot of buildup on them, I doubt that's the problem. Possibly one is binding?

When doing the above paper test, be sure the board is exactly the same thickness on each side of the machine.

[AskBud]

You may, also, want to check your sled to make sure it is not the problem (since you did not mention problems without it). Just turn your sled around (end for end) and run the measurement tests from the keypad.

Thinking about the "walking" problem.
Lots of things could come into play other than just an un-level head.
True, it's un-even pressure from something, however, the list could include many things. It could even be a combination!
Here are some that come to mind, dirty traction belts (they can be cleaned), warped board/sled, dull bit and heavy cut, Aux rollers un-even (causing a warp-like condition), bottom of board/sled slick (more so on one portion of the length).
Other may add to the list, but I've drawn a blank for now.

Here is a link to one "Abrasive Belt Cleaner" for your belts. sometimes called a Sandpaper eraser.
http://www.woodcraft.com/Product/2000271/9/Abrasive-Belt-Cleaner-112-x-112-x-812.aspx
AskBud

[myshop1044]

Thanks for all the suggestions fellows.
Bud I did the vertical board/paper test and the grip on the papper was good. I always wipe down the rollers down each morning before I start carving.
I just clean the sandpaper belts with a belt cleaner stick that I use on my belt sander just to make sure.
I too though about my sled, I have used that same sled about 20 times already. It has a 3/8" ply bottom and a 7/8" cedar
top to match the wood I'm carving.
I checked the flatness on the length and the width in multiple places and it is still flat. I too thought about turning the sled around
and replaced the tape on he bottom, just to make sure.
I went ahead and tried a carving watching for the travling and it did not appear to move very much. I checked it every 15 min or so while it was carving.
So we will see what happens today. I am thinking of going to the rubber belts. do they really do that good of a job?
later
another day of carvings

Myshop

[AskBud]

I do not have the new belts, so someone else will need to jump in.
I'm not sure they would be the solution to a walking/drifting problem, but they would seem to have a better grip.
AskBud

[Oldtrainerguy]

Check the screws on the slide plate. Mine was doing that and I found that the screws were loose on the slide plate to the point they almost fell out.

[Digitalwoodshop]

Thinking like a machine..... all the suggestions above are really great and would all be on my list.... I see 2 are missing and will cause this....

1. A Rolled Under forward belt, very hard to see... It will raise the board slightly at the brass roller and cause the board to track away from the brass roller... If you cannot see the roller edge near the keyboard side then you will more than likely find a rolled under belt. You can cut the belt 1/2 inch back and rip it, like I do....

2. The Screws under the machine that go into the smooth rails are loose... More than likely the one on the far side of the keyboard making the board walk toward that side...

Before you start install a wide board and with a bit installed using Z Data touch the board and record the numbers....

Just a few WAG's or Wild AL Guesses....

AL

[myshop1044]

Al, I have my machine torn down and I'm not sure what screws you talking about
" The Screws under the machine that go into the smooth rails are loose... More than likely the one on the far side of the keyboard making the board walk toward that side..."
What and where are the smooth rails and where are the screws?
Do you have s pic or diagraim that would show these screws.
I checked everything under and all screws are tight.
Thanks again

Myshop

[fwharris]

Perry,

Al is talking about the 4 corner posts.....

[Digitalwoodshop]

Yes, 4 Corner Post Screws.....

AL