Replies

1. 
   jackiechan | May 12, 2002 07:59am | #1

   Lefty,

   A moderate amount of blade drift is expected on most blades.  If you're finding an excessive amount of drift, the blade is trying to compensate for one or more inconsistancies.  The first thing you should check is that both of the blade wheels are in alignment with each other.  Unplug the machine, back off all of the guide blocks and thrust bearings, and load up the widest blade that you've got, cranking up the tension to the appropriate mark on the scale.  (You'll want to remove the table for all of this.) With the blade under tension, hold a reliable straight edge against both the blade wheels.  If everything is kosher, the top and bottom of each wheel will be touching the straight edge.  The Jet band saw has a top wheel tilt/lock mechanism used to track the blade.  You may have to adjust the tilt of the top wheel to make it coplanar with the bottom one.  (If that doesn't work, untension the blade, remove it, and then remove the wheels.  There are washers behind them that you can either add to to take away from to make the proper adjustment.)  With the blade on and under correct tension, you need to track the blade. Keep the machine unplugged.  Slowly spin the top wheel by hand, and check how the blade is riding on it.  You want it to be tracking in the middle, or ever so slightly forward, depending on the width of the blade.  Slowly turn the top wheel tilt mechanism to achieve blade on wheel center.  If it's not working, take a look at the condition of the rubber tires on the wheels.  These could be worn or damaged from previous use, but they're an easy replacement.  You're half way home.  Now you have to align all four guide blocks, and both thrust bearings.  You may want to use a set of feeler gages for this (cheap sets at auto parts stores), or alternatively, you can use a new dollar bill folded in half.  Loosen and remove the guide blocks from the saw, you want to make sure that the ends are squared off.  If they've been worn ragged, either turn them around and use the good end, or carefully touch them up on a disc sander.  (Or toss them and pick up a new set of Cool Blocks for about $15.)  Put them back in the saw and place a .004" feeler gage (or dollar) between it and the blade.  Line it up, and lock it down.  (Repeat for the other three guide blocks.) Now back off the guide block holder until the blocks are .015" (1/64") behind the gullets of the blade.  Back the thrust bearing so it's .015" behind the spine of the blade.  Close the covers, replace the table, making sure its square to the blade, and fire up the saw.  If you're still getting an excessive drift, try a brand new blade.  (I highly recommend the Timberwolf blades - they usually have an ad in Fine Woodworking).

   I hope this helps.

   -JC

1. 
   wrongway | May 13, 2002 02:25am | #2

   Thanks for the information Jackie. What would you consider as an excessive amount of drift. I ask this question because i do not want to do the alignment you described to me unless the drift angle is excessive and it is necessary to make these adjustments.  I would guess that it is about 6 to 8 degrees. What do you think? Also the rip fence on the saw does not seem to have any adjustments for the drift angle unless I am missing something. I do not have any instructions for it. It may be an aftermarket because the at the top of the fence on either side are bolts holding it together and they are metric,10mm. I may need to use my own rip fence when the time comes. Thanks again for your help....Lefty

1. 
   Andrew | May 13, 2002 04:47am | #3

   Lefty, don't tear your saw apart yet, first try a new blade, as a dull blade will wander all over the place.

2. 
   jackiechan | May 13, 2002 06:44am | #4

   Lefty,

   6 - 8 degrees is about right (depending on the width of the blade).  The Jet 14" Band Saw's stock fence is an aluminum box construction with a 2" slot in its face where a resaw guide would be attached.  The fence is attached to the lock/slide mechanism via (4) 10mm hex head bolts, through the top - all four are in the (black metal) locking end of the fence.  The Jet logo would have been on a sticker just above the locking handle.  If this describes your fence, it's most likely the stock unit.  The non-locking end of the fence has a hook with a height adjustable knob in side.  Make sure that all four corners of the fence are the same height from the table top.  This fence can be adjusted - slightly - to accommodate drift by loosening the bolts and shifting the fence.  If you know which direction you'd like to move the fence, loosen one of the bolts closest to the locking handle just slightly, and the other three a little more than that.  This way, you can use the first bolt like a pivot.  Be sure not to overtighten the bolts.

   Here's a link to an online manual for a Jet 20" band saw.  Check out the fence setup section.  Even though it's the 20" model, the fence is the same as the 14", just bigger.

   http://www.jettools.com/HelpCenter/Manuals/Woodworking/Manuals/JWBS-20.pdf

   - JC

2. 
   gerry001 | May 13, 2002 03:59pm | #5

   Lefty,

   I'll agree with Jackie and add a bit. With an unknown machine you should first check the wheels at several points. Remember they can be out in any of three dimensions. Use the straight edge near the hub to adjust it. Then check about 1-2 inches in from the edge. If the table's off, do this also on the other side. My Jet showed both an offset and a twist. You can use a single point after the first time, unless you overtighten wide blades.

   Still, it's most likely the blade. All my blades are Timberwolf (as Jackie recommends), and I only had to adjust the fence the first time, and I cut 8-12" veneer with a nice uniform thickness.

   Gerry