Traction Belt Trick

[bergerud]

According to the laws of physics, sandpaper belts must drift sideways and roll up! Carvewright says that the belts roll up if the head pressure drops below 80 lb. We all know from observing band saw blades and belt sanders that the blade or sand paper moves in the direction which makes it tighter. This is why band saw wheels and flat belt pulleys are domed. Sander rollers are not domed and so they easily drift. On the Carvewright machine, the belts depend on the wood to stop the drift. In theory, this could work if

1. The wood is always under the 80 lb force of both top rollers.

2. The wood (left squaring plate) is exactly perpendicular to the sand paper rollers. (Otherwise the board could push the belts to the right.)

3. The sand paper rollers are all parallel to each other and the springs spreading the rollers are the same strength.

4. The sand paper itself is of uniform width.

5. There is no sawdust in the belt rollers!

Since none of these conditions is realized, the sand paper (or rubber) belts WILL drift. Some machines will drift faster than others, but all will drift. We all have too keep an eye on these belts and periodically re-center them before they roll up on one side or the other.

TIP: The sand paper rollers (X drive conveyor assemblies) need not be removed and put in a vise to re-center the belts. Cut two 3/8" diameter approximately 0.8" long pieces of metal (from old bolts). These two pieces can be wedged between the spring shafts and the edges of the outfeed table (see pictures below). The cam action of lifting the outfeed table pushes on the spring shafts and releases the tension on the sand paper belt. The belt can easily be slid back to center. (Make sure you unroll the edge of the belt if if has rolled up.) The same procedure works on the front and rear belts.

[JOHNB]

seems like an excellent tip. i haven't used it yet(hope i don't have to), but i sure could've a few times in the past. also try cutting a .5" or so off of each belt.

[Kenm810]

Looks like a little more info., we can add to our
growing bag of "Tips" :cool:

[Pratyeka]

I have a question about those traction belts. Is it absolutely necessary to have the supporting plate between the rollers? If not, then two hard rubber rollers on each side could do the job instead of traction belts... Unless it's critical that the wood piece rests on something absolutely rigid as far as height is concerned?

[Rick P]

Interesting question Pratyeka...I'm guessing the "current" rubber rollers will not deliver enough frictional drive to move the wood accurately or enough support...but there might be a roll cover material that could ??

[Digitalwoodshop]

I believe that Belt roll over is caused by the user. If you don't insure you place the board in the machine square every time it will cause the belt to drift. A board not placed in the machine up against the left guide will act like your wheels turned on your car.

Just my opinion.... You can re engineer the thing all day but put a board in at a angle and something will need to give. Now it is the sand paper belts. 800 and 500 cutting hours on my 2 main machines and I have never had a belt roll. I have replaced them when they are limp and don't have enough grip, but not that I can remember for a rolled belt.

Or.... Belts move because of Sawdust inside the belt area? I have dual dust collection so dust is limited.

Anyone else with a down draft get belt roll?

AL

Sorry, I am a little Testy.... It's 4:30 AM and I just finished working as I have a small show today....Sunday.

[mtylerfl]

Hello,

I have never had a traction belt problem of any kind whatsoever on either one of my machines either. No rollover - no rips - nothing. They still look new after I vacuum the sawdust off.

Checking to be sure the head pressure is good, keeping the four posts cleaned and lubed, making sure the boards have no defects, are square and inserted into the machine properly, and assuring the sliding plate is not too tight against the board are what I do. Either I am defying the "laws of physics" or I'm just careful. I think being careful is why I've not had any issues with the traction belts. (knocking on wood now!);)

[Jeff_Birt]

If not, then two hard rubber rollers on each side could do the job instead of traction belts...


Greater surface area = greater static friction = no slipping = better tracking.

[TerryT]

I replaced my traction belts at about 450 hours of carve time. I probably could have gotten a hundred or so more out of them. I never had any problem with them other than a broken bit putting an eighth inch wide by 2 inch cut in one of them at about 300 hours or so. I never had to adjust or align them at all.

[ChrisAlb]

Since none of these conditions is realized, the sand paper (or rubber) belts WILL drift. Some machines will drift faster than others, but all will drift.

I could not disagree more with this. 2 years, over 450 hours and I never once had a belt roll up or drift at all.

At 420 hours I had to replace my original belts because I was doing that mirror for Alex and I had a very heavy sled/wood combination in the machine. Not paying close enough attention, I didn't have the head down tight enough and when it measured the project, it tipped a lot after coming out from under the right roller and the left belt tore. COMPLETELY MY FAULT. I'm sure I would have gotten many many more hours from the originals had "I" not screwed up.

The new belts? Tracking perfectly as always. So I agree completely with AL. If your belts are rolling up, it's a 99% chance you've overlooked something in the set up.

I leave the 1% there because as with anything, there is always the SLIGHT possibility of a defect in the belt manufacturing.

[Kenm810]

Even though I have an extra set of belts, and have completed hundreds of hours of carvings,
I still have the original traction belts on my one and only CC Machine. It just might be luck,
but I do try to take care of them.
I have been doing a few things that I feel have helped a little.
First I scuff or sand the bottom of all my project boards, Carrier Boards, and Sleds,
also I lightly sand and round all the edges and corners of them, so they won’t dig into the belts anywhere.
Also Thanks to AL (Digitalwoodshop) I learned to use strips of 1” masking tape on the bottom of every project I put into my Machine.
It costs only Pennies and It’s never gummed up my traction belts, and always gives the Belts Traction Sensor something to bite into.
That’s Just the way I do it and it’s worked for me so far.

[swhitney]

With two machines, I have had to replace only one set of belts, and it was due to a user error!! I do keep an extra set in case "idiot alzhiemers" strikes again......

[bergerud]

From reading the many forum entries about traction belts, it is clear that many people do have problems with the belts. Talk about cutting them down and so on. My belts both drifted and the front one started to roll up after 80 hours. The point of my original post was to show the people who have trouble with the belts, an easy trick to re-center them. If you have no trouble with your belts - great. Maybe someday you will and can use the trick.

Foolishly, I expounded all the reasons I could think of why belts would drift and offended some of you by stating that they must drift. 450 hours with no drift certainly seems contrary to this! The system is dynamically unstable like a belt sander, but unlike a belt sander, the belts travel in both directions. If the travel in each direction is on the average almost equal, I concede, belts may drift very very slowly.

(The reason I say they must drift as a law of physics is because there is no restoring force. Systems are unstable if a movement from equilibrium does not cause a force to return the system to equilibrium.)

[swhitney]

If I may speak for those of us who have yet to have belt traction problems....

No ill will was directed and none taken... Just sharing experiences.

The tip, indeed may come in handy one day. Thank you

Scott

[mtylerfl]

Agreed - nice tip!

[elfritzer]

Just a note about replacing traction belts. Yesterday I replaced mine while following the instructions given with the belts, modified by the post about using two bar clamps. After the clamps had slipped off about five times, I ploughed out a U-shaped piece of wood about the length of the rollers. This piece of wood held the roller captive, and would not allow the clamp to slip off the roller. It made all the difference in the world. It turned a frustrating experience into a piece of cake. Back to my projects!

[Kenm810]

Good one to make in advance
and store in my tricks box
for my machine. :wink:
Thanks for Sharing it with us

[dbfletcher]

I also have suffered from belt drift. I have read this thread very very carfully, and now i am convinced I possible could have another defect with my machine. So far i Have sent it back to carvewright twice, replaced the z-truck, replaced powersupply, and have replaced belts twice. I dont even have 50 hrs on this machine. Howerver,, the belt roll i expereince is only one one side. If you are facing the keypad, the blet on the right will roll towards the side of the keypad after a very short time. Today I took the belt out again... and this time after centering the belt I just rotated the belt by hand. After a few revolutions going conuterclockwise I could see the belt has shifted toward the keypad side. Rotate the belt in the opposite direction... and sure enough it drifted the other direction. Is there any type of adjustment on the belt carrier? Unfortuantely after the belt does roll... going the opposite direction does not "unroll" it. It just move the entire belt.


Open to any and all suggestions.

Thanks,

Doug Fletcher

[bergerud]

I do not see is any way to adjust the belts like on a belt sander. If your belt drifts really fast, something must far from parallel. Check that the springs on each side are pushing equally (not binding) or that the the belt has not stretched on one side. If you flip the belt over and it goes the other way, it must be the belt. If it goes the same way, it must be the rollers. Let us know when you discover the cause.

[bergerud]

On reading your post again, I was struck by the fact that the belt went the other way when you changed the rotation. I think of belts drifting in the direction that makes them tighter, but this is a screw type behavior. Flipping the belt over might not change the direction if it is the belt "screwing" along the rollers. I cannot imagine how the rollers could cause this, so I think it must be the belt. Have you experienced the same behavior with the other belts? Could dampness in your shop be causing the belts to distort? Any body else have any ideas?

[Wilbur]

Some way the belt is tighter on that side. I have not had any experience with this but some way the tension is not the same all the way across.
Either the belt or the roller is out of line.

Wilbur

[dbfletcher]

On reading your post again, I was struck by the fact that the belt went the other way when you changed the rotation. I think of belts drifting in the direction that makes them tighter, but this is a screw type behavior. Flipping the belt over might not change the direction if it is the belt "screwing" along the rollers. I cannot imagine how the rollers could cause this, so I think it must be the belt. Have you experienced the same behavior with the other belts? Could dampness in your shop be causing the belts to distort? Any body else have any ideas?

Yes.. i have had this problem with 3 sets of belts. I did buy the new heavy duty belts but didnt not put them on yet. and like i said... it only seems to be the one roller. I kep having hope that someday i might have a machine that works like some of the member s on this list. I was still just exicited that I got a full project out with out any errors (1.5 hrs carve time). It just amazes me that there are machines out there that have worked well since day one.

[pkunk]

On my first Beta machine, I had a problem with belt tracking on just the right hand belt. CW decided it was the roller assy and sent me a replacement. It worked perfectly from then on. There is no adjustment on the assy., but it could be the belt. Try reversing the belt to see if it tracks in the other direction.

[Jeff_Birt]

Look around for the instructions for installing the new heavy duty rubber belts. They have you check a few things that could come loose and cause the belts to not track properly. It would be worth checking.

[AskBud]

See if this is what you need.
AskBud
http://www.carvewright.com/images/service/Service_instructions/CarveWright_service_replace_rubber_drive_belt.pdf

[Azbear]

Yes.. i have had this problem with 3 sets of belts. I did buy the new heavy duty belts but didnt not put them on yet. and like i said... it only seems to be the one roller. I kep having hope that someday i might have a machine that works like some of the member s on this list. I was still just exicited that I got a full project out with out any errors (1.5 hrs carve time). It just amazes me that there are machines out there that have worked well since day one.

Did you find the reason for your belt drift?

I am on my 3rd or 4th machine. Can't keep track any more. Sears replaced the 1st two after too many trips to the Texas repair place. On my 1st machine I was bad at cleaing out the dust. At the time, back then, CW had told me that they tested many machines and had a 6 hour carve without cleaning anything during the carve. They just let it carve. So I followed their lead. That 1st machine never had a belt drift of any kind. Ever. It died of power supply, broken z truck, truck rails working loose, many other issues.

My 2nd and 3rd machine had belt drift towards the squaring plate right out of the box on the left from key board side (rear?).

On the 3rd machine, I saw the belt drift and checked what was reccomended. Didn't notice an obvious cause. I did a few small carves, to check things out. During the board measurment in one direction, I notice a bit of drift, then then measuring direction the opposite way, the belt went back to center direction on the roller.

I saw the belt starting to drift again and stopped the carve of a 40 inch board during measuring. I checked ALL of the posts here and checked the machine again.
All head support posts are tight and lubed.
Squaring plate is tight and square as I can get it. Right angle to the rollers, right?
I never found much dust under the belts or rollers.
I always set the sliding plate to the board so it just slightly touches.
All of my boards are squared up. I do understand I'm working with wood and wood is not as stable as metal. I use a caliper and square to double check my boards after coming out of the board prep area. All is great.
If I pull out the belt assembly again, should something be a bit more lubed so the any moving parts can move more easily?
Not sure what to check next. Frustrated. YUP!

Sure wish CW didn't make these machines so fussy. I noticed the new chuck they now offer. Looks like Ron's chuck. Maybe Ron can come up with a more stout belt assembly that would keep belts from becoming an issue. With all of the suggestions and fixes here on the forum, we might see them on the next generation of machines from CW. I too would like to do long time carves as others here on the forum do. I know this post is long winded, but I really don't want to have to send it to Texas if I can get it going. Can't afford the down time. I also don't want to hear the Mrs. tell me "I told you so" again.

To all, I now am wondering if an adjustment screw could be installed and used to make a very slight adjustment to line up the belt/rollers? My belt sander has adjustments for belt tracking. This might keep things a bit easier and faster to get back to carving.

[dbfletcher]

Did you find the reason for your belt drift?


Unfortunately no... I have just learned to live with it. Using the belt trick in this thread I just center the belts before each project. Like others have said... cutting 1/2 inch off the side of the belt also seems to help.

Doug Fletcher

[mtylerfl]

Hi Azbear,

Belt drift is usually an indication of some other underlying problem - particularly on boards longer than about 3 feet. Besides the obvious cause of placing a board 'badly' (which I ruled out from your description of the care you are taking), I am guessing that the head may be slightly uneven and/or that there is a head pressure issue going on there, or if it occurs only on longer boards, the extra outfeed rollers you may be using are interfering with 'straight/even passage' through the machine.

I suppose (just guessing again) that possibly the belts themselves have been stressed and maybe have uneven tension which could lead to belt drift...total guess, but maybe belt replacement could solve if you can confirm the head is level and the head pressure is good.

Seems to me I read about someone saying they had uneven spring pressure (inside the belt plate assembly) that was causing drift, but can't find the post so maybe my memory is faulty on that. (EDIT: just noticed Pkunk's post above, sounds like that could have been the issue he experienced?)

In any case, I'm sorry you have had to deal with the problem - seems like it could be remedied somehow - and hopefully, soon!

[Digitalwoodshop]

Check your head level too.

AL

[Azbear]

The belt issue will be something I'll live with too. Now I have a length measuring issue.

My head pressure is about 80. That's ok right?

Head level? How do I check that? The way I checked it is I raised the head up and took measurements from the solid metal part that holds the out feed board supports up to the ridge on the head on the four corners. I got 5-1/4" on all 4.

My board is 40" on the nose. The machine is now telling me it's only 32+". I know it is not the brass roller encoder, (I think) as I can see the knurl marks on the board the whole length. I did not use any tape. I tried another prepped board and got close to the same results. I adjusted the length of my board in designer as my design was only on one part of the board to get the carve completed. It carved just fine.

I am looking for a "calibrating for dummies" version of the written procedure in the manual for adjust for incorrect length measurements. I do just not understand it.


Is there someone who might be able to get the machine to measure correctly?

[mtylerfl]

...I am looking for a "calibrating for dummies" version of the written procedure in the manual for adjust for incorrect length measurements. I do just not understand it...

Hello Azbear,

Here is a link to the Tips & Tricks that describes the new calibration procedure: ISSUE 27 January – February 2010 – Maintaining Accurate Board Tracking (http://www.carvewright.com/downloads/tips/CarveWrightTips&Tricks_Jan_Feb_2010.pdf)

Hope that helps get you "on track"!

[AskBud]

The belt issue will be something I'll live with too. Now I have a length measuring issue.

My head pressure is about 80. That's ok right?

Head level? How do I check that? The way I checked it is I raised the head up and took measurements from the solid metal part that holds the out feed board supports up to the ridge on the head on the four corners. I got 5-1/4" on all 4.
Take some 3/4" stock and make 2 pieces about 16" long and 2" or 3" wide. Run them through your table saw, or planer (so the edges are truly parallel). Place them in the unit (on edge) just inside the 2 squaring plates on both sides of the machine. Place small pieces of paper on the top of each board (where the roller will touch). Lower the head using/moving one of the papers as a "Feeler Gauge", to the point that the roller just touches, but the paper can be removed with slight pressure (but does not tear). Now, without changing the head, check the other three papers.

My board is 40" on the nose. The machine is now telling me it's only 32+". I know it is not the brass roller encoder, (I think) as I can see the knurl marks on the board the whole length. I did not use any tape. I tried another prepped board and got close to the same results. I adjusted the length of my board in designer as my design was only on one part of the board to get the carve completed. It carved just fine.
I think you may be just a tad too long to not be using external/added roller supports. Without the extra rollers, the stock will extend too far past the roller tables, and the board will begin to tilt/lever as soon as it leaves the head rollers. As soon as it begins to tilt, it has a good chance of loosing contact with the brass roller (and will also begin carving deeper in that area).
I'll bet your measurements are more accurate on boards less than 30"!
PS: I am away from my machines, but during your measurement, are you asked if you are going to "Stay under rollers"? I think, that a YES answer will alter your measurement by subtracting the 7" extra board required (show just the allowable carve length).


I am looking for a "calibrating for dummies" version of the written procedure in the manual for adjust for incorrect length measurements. I do just not understand it.
I, nor Sear's, have never had to recalibrate my units, as long as they use sandpaper belts. Recalibration is usually done when placing rubber belts (which I do not have).

PS: There is a "Damper" under the brass roller that, if missing or out of place, will cause false measurements and error messages.


Is there someone who might be able to get the machine to measure correctly?
See relpies above, after each section.
AskBud

[Azbear]

See relpies above, after each section.
AskBud

My head pressure is about 80. That's ok right?

Head level? How do I check that? The way I checked it is I raised the head up and took measurements from the solid metal part that holds the out feed board supports up to the ridge on the head on the four corners. I got 5-1/4" on all 4.
Take some 3/4" stock and make 2 pieces about 16" long and 2" or 3" wide. Run them through your table saw, or planer (so the edges are truly parallel). Place them in the unit (on edge) just inside the 2 squaring plates on both sides of the machine. Place small pieces of paper on the top of each board (where the roller will touch). Lower the head using/moving one of the papers as a "Feeler Gauge", to the point that the roller just touches, but the paper can be removed with slight pressure (but does not tear). Now, without changing the head, check the other three papers.

I did not check it this way, but I will.

My board is 40" on the nose. The machine is now telling me it's only 32+". I know it is not the brass roller encoder, (I think) as I can see the knurl marks on the board the whole length. I did not use any tape. I tried another prepped board and got close to the same results. I adjusted the length of my board in designer as my design was only on one part of the board to get the carve completed. It carved just fine.
I think you may be just a tad too long to not be using external/added roller supports. Without the extra rollers, the stock will extend too far past the roller tables, and the board will begin to tilt/lever as soon as it leaves the head rollers. As soon as it begins to tilt, it has a good chance of loosing contact with the brass roller (and will also begin carving deeper in that area).

I can see the marks left on the bottom of my board from the brass roller the entire length of the boards. This means the board is staying in contact with the roller while measuring, right?

I'll bet your measurements are more accurate on boards less than 30"!

Yes it is more acuarate under 30". I am using the support rollers on the machine and I am also using external support roller on stands. I lined them up with a level with the belts. CW says the max board length to be carved is 12' long. As mine is only 40", I should be ok with acurate measuring, but it's not.

PS: I am away from my machines, but during your measurement, are you asked if you are going to "Stay under rollers"? I think, that a YES answer will alter your measurement by subtracting the 7" extra board required (show just the allowable carve length).

In this long board carve, I did say YES to the question.

I'm thinking all is ok and just need to recalibrate the board length measuring?

Can someone who has been through this, please contact me to help me understand the "add" or "subtract" units part of the procedure? This is the part that confuses me.

[Azbear]

Anyone?

I'm asking for help. Pm me if you think you might be able to help. I did the + and the - with no luck. Now I'm getting out of range error. Was at 890.000, and 18.4". Now I'm at 874.250 and the measurment is getting closer, 18.7" but still measuring short. Need 19".

[dcalvin4]

damper on brass roller missing or out of place cause missmesure ...this is damper a small ruber hose about 1/8 dia by 1/4 long that sits upright on the head of the screw that holds the brass counter roller in place the damper is like an aid to keep the brass counter pushed up against the wood so the brass counter will not slip when measureing the wood (aids the spring} ..also put a strip of masking tape along the bottom of the wood as this also helps with the traction of thebrass counter roller
i had this miss measure prob. an drove me nuts before i fixed it..i looked at this damper an looked at the brass counter forever till i finally found where it went then i said that is as really odd way to increase the pressure on the wood and thought why didnt cw just put a stronger spring an it instead ..
if you cant figure it out email me an we will set a phone call
denny

[Azbear]

dcalvin, check your pm.

To all, I'm trying everything suggested here and still can't get the board measurment of length corrected. I can see the knurl marks under the board. The entire length. I see this on 3 different boards. With and without tape.

I'm still stuck on the x calibration. I do not understand the 4 and 1/32 with adding or subtracting. As stated above. I'm getting close I think, just subtracting a number thats close to displayed number. But now against the out of range message.

(p.s.-my neighbors are learning new cuss words coming from my shop. The dogs are hiding in the back yard.)