Replies

1. 
   MBL | Jul 15, 2004 07:34am | #1

   Friend,

   What do you mean by blade drift?

   Also, the wheels are coplanar with no tension or only a little bit. But as they reach proper tension, they wouldn't necessarily be.

   Duginski's book appears to show to check for coplanar by one check of the stick. However, the complete test needs to be done not just close to the center, but also at the left and right edges of the wheels.

   If you check only at the center for linearity, as shown in his book, the wheels may stil not be coplanar.

   In the Delta clone here, they could never be coplanar until the alignment pin at the base of the upright arm was relocated.

   That was verified by removing the pin, loosening the large nut that holds the arm to the base, and rotating the arm from its original position which then allowed making the wheels coplanar. Then used a self-tapping bolt at a new location as alignment pin.

   Good luck.

   -mbl-

   
   

   ---

   Edited 7/15/2004 12:38 am ET by mbl

2. 
   djcolorado | Jul 15, 2004 09:12am | #2

   If the problem you are talking about is drift consistantly in one direction and assuming you have done the obvious adjustments of the blade guides, it could be the nature of the beast you have.  On my Jet 18",  I have no blade which will cut perfectly parallel to the mitre slot, and each blade drifts a different amount.  When everything is adjusted well, the amount of drift is completely repeatable and I just adjust the fence/mitre to be parallel/perpendicular to where the blade wants to go.   I did have one blade that drifted in one direction so badly that I couldn't use it because there was not enough adjustment in the fence.  I got a blade from a different supplier that had the same tooth design and pitch and thickness and had no problems setting it up,  so subtle difference in blade manufacturing can make a difference. 

1. 
   Curtis | Jul 15, 2004 12:24pm | #3

   Hello

   Ive had a Rockwell 14" band saw for years, Its a good saw, although I had the same problem with the blade drift, after going through all the different ways to fix the problems of blade drift , I figured Why fight this machine, instead of fighting it I started working with it.

   I cut freehand a piece of scrap (with straight edges) I first draw a straight line parallel to the edge, then I cut the board freehand, somewhere in the middle of the cut I stop the saw,and clamp the wood in place, the edge of the wood will show you the drift, next I use that wood to set my fence to the proper angle.

   Ive had no problems cutting straight since I started using this method,Although I do need to cut and check  the drift each time before starting a new blade.

   My fence is never straight but at least my cuts are.

   thats my two cents, I hope it may help you.

   sincerely.   C.A.G.

   C.A.G.

   Edited 7/15/2004 9:14 pm ET by curtis

1. 
   Michmesquite | Jul 15, 2004 09:21pm | #5

   This is excellent advice and should be done each time a blade is installed/re0installed. _________________________________

   Michael in San Jose

   "In all affairs it's a healthy thing now and then to hang a question mark on the things you have long taken for granted." Bertrand Russell 

2. 
   RDc | Jul 16, 2004 04:37am | #6

   My problem is that when I think the wheels are coplanar and the blade is on, as I rotate the top wheel by hand, the blade comes off the wheels.  I adjust the tilt of the top wheel very slowly and then the blade goes off in the other direction.  I can not find a happy medium.  The motor and the table are not on the machine yet.  I use a straight edge to check the bottom and top wheel alignment and they seem coplanar.  When I rotate the top wheel, the blade comes off again.  This is my problem. 

   Thanks for the help, rod

1. 
   MBL | Jul 16, 2004 05:15am | #7

   Dear rod,

   Have been through what you are describing.

   Re-check for coplanar not only at just point with the straight edge but also at the left-edge and right edge of the wheels.

   For coplanar, the wheels have to align in at all places of the wheels, but checking on 3 or minimum 2 would do.

   You need to check very very carefully and make sure the stick edge is good. Just eye-sight is fine. No need for more accuracy. The stick needs to have also just about the correct length so as to place it without hitting at the ends.

   Also, although you say that you adjust the tilt (tracking) very slowly, but actually it should be 'very minutely' because that adjustment is quite sensitive. Just make a small adjustment and turn SEVERAL times, it's not a continuous adjusting. It'd be too much.

   If you rotate the wheel by hand, you will note that in the forward direction the blade tracks one way, and rotating by hand the opposite direction, it will track the other way. So make sure you rotate only in the forward direction.

   Also, you will NEED to instal the motor to actually adjust the tracking because the motor torque will add additional stress to the blade (at the speed) and actually help the band go towards the center due to centrifugal force and the fact that the rubber tire is crowned (is humped towards the center).

   For tracking when you have the motor installed, you 'bump' the motor with the switch on/off quickly and check where the blade moves to, and then make MINUTE tilting. Just the shortest bump of the switch will relate to quite a few turns, enough to verify the tracking and not too many for the blade to rail off or over-climb.

   You adjust the tilt by adjusting so that the band 'climbs' towards the crown, from usually being near the edge. Sometimes you overshoot in the tilt, so go back again minutely is so. Make sure you keep in mind which way to turn the knob to move the blade towards the crown. Would say that on the Delta or clones, the right tracking is within 1/8 of a turn of the knob, or so. It's not much. However, as the tension is increased, the tracking needs to be re-adjusted, again, minutely. All is done 'bumping' the on/off switch. Don't shoot for maximum tension initially. Leave that for much later. Sometimes it might be next day or so, specially since you are doing a major overhaul. Do some test-cuts at medium speed and keep learning its adjustments. It's mostly observation.

   When the blade runs and tracks well, that's it. The wheels will not be coplanar when actually tensioned. There's a nut for locking the track adjustment. Make it tight and even mark it with some paint so you can go back to it if needed. It's valid only for that blade.

   Good luck.

   -mbl-

3. 
   forestgirl | Jul 15, 2004 07:07pm | #4

   Rod, I'll reiterate mbl's question about blade drift.  Are you asking about the blade "drifting" on the upper wheel, or about its tendency to cut at an angle?

   Cutting at an angle is what most of us mean when discussing blade drift, and if your saw is tuned well and tensioned properly, then it's time to look to the blade for answers.  You may not be able to totally eliminate blade drift, but I've found that a quality blade makes all the difference in the world.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
   Another proud member of the  "I Rocked With ToolDoc Club" .... :>)