Hi everyone. I have a (used) Shopsmith band saw where the drift is so extreme that no matter how much I angle the infeed it still just keeps drifting. Eventually I am feeding the stock at such an extreme angle (about 30 degrees from centerline) that the blade binds and the saw trips a circuit breaker.
I have checked and double-checked everything I can think of: I adjusted the upper and lower guide blocks and rollers, checked the squareness of table to blade, and increased blade tension. [I kept cranking up the tension on the blade-a 1/2" 3 TPI re-saw blade-and it didn't solve the problem. Eventually I cranked it up all the way and all it did was throw the blade off the wheels.] I have tried three different blade widths/types. I have tried raising and lowering the blade guard height. I checked the wheels and both rotate true without wobble.
There are two things I haven't tried: replacing the tires and putting in new guide blocks. Could worn tires or guide blocks be causing this kind of problem?
Thanks for any ideas or suggestions you might have.
A sharp well made blade will still cut stock easily with the blocks completely removed. I don't know, I have set a fence at pretty decent angles to account for drift, 35 degrees does sound like a lot.
Are you feeding to fast? Is your blade upside down, when unwinding that rolled blade was it turned inside out? Are the blades resharpened and done incorrectly? Are you cutting wood, not ply or Mdf?
Second the motion to ensure proper tracking of blade on wheel. Another thought was whether the blade-tensioning spring might be worn out, but obviously it was tensioning (having come off the wheel). Although….the fact that it came off wheel may hint at improper tracking?
Thanks for your helpful questions and comments. I'll try to address these below.
1. Blade tracking
The Shopsmith bandsaw is unusual because it does not have a blade tracking adjustment. There is an "auto-track roller bearing" mounted just below the spot where the blade contacts the idler wheel-but it has no front-back adjustability. You can only move it side to side-so that it is centered behind the blade. You can't use it to adjust where the blade rides on the wheels/tires.
2. infeed speed
Very slow: cutting 4" thick hardwood stock, I am moving at a pace of about 30 seconds per inch.
3. blade quality and sharpness
Have tried three different blades, one (used) 1/4 general purpose, one 3/8" 4 tpi (new), and one 1/2" 3 tpi (new). Blades were sharp enough that I needed band aids after blade installation. All 3 mistrack.
4. blade orientation
It's a valid question-especially for a beginner like myself-but the blade is correctly oriented with the munchy-munchy teeth point downward.
5. material being cut
Blade drifts on both hardwoods and softwoods of all types I have tried (maple, oak, crab-apple, pine).
6. Worn blade tensioning spring
Not sure how to tell if it is worn, but I did follow the procedures in the manual for re-aligning the blade tension scale.
At this point the guide blocks are looking more and more like the culprit: they are very worn down and don't seat themselves perfectly parallel to the blade (bottom edges of the blocks are nearly touching the blade, but upper edges ride about 1/32 away from blade).
I'll probably get new blocks soon. May be I should order new tires at the same time, but I don't know how to tell a worn band saw tire from a non-worn one…
Thanks again for your help. I'll re-post if I make any progress.
I had similar problems until I went to carbide blades. Fixed the issue. No more drift until I finally dulled that blade. I get 105" carbide blades 1/2" for re-sawing for $25 from "Supercut"
The blade should be riding the crown of the tires. The tires should fit tightly, with no play. Insure that your tracking is true. Do this by hand for a few revolutions.
From you description, it sounds like the blade has a lot of play, and that may be under tensioned. Try the tension'ing spring adjustment you mentioned above.
A few degrees either way is acceptable, not 30 deg.
as many have said - obviously the blade needs to track the center of the upper tire. it is 'nice' to be reasonably centered on the bottom - but really the bottom wheel is to complete the blade circuit. The tracking is controlled from the top tire throught the guide blocks… then through your workpiece.
What happens below the table is pretty irrelevant (within reason)
The obligatory video from Mr. Unix is truly the best IMHO… but not applicable to a shopsmith.
I cannot imagine a way to even intentionally make a blade track 30 degrees from true.
I took a look at the Shopsmith forum thread a while back before setting up the bandsaw, and thought that I followed all of these procedures, but mabe I got lazy somewhere. Since tires are firmly seated to wheel rims and since blade appears to be tracking correctly as it contacts and exits the idler wheel, I'll try replacing the guide blocks. When I do, I'll probably start from square one and recheck all adjustments discussed on the Shopsmith forum thread. I'll report back this weekend.
Hello Museum, do yourself a favor and call ShopSmith, they are more than willing to walk you through a fix. More than likely it is something simple and after awhile you just can't see it. I've had an abundance of really helpful conversations with the help at ShopSmith, they are more than willing to help.
Hey MG,
My Shopsmith band saw is a 1975 vintage and I'm the original owner.
Drift was always a problem for me, too. Last year I bought the Carter system and haven't had a problem since. I've been running a 5/8 Shopsmith blade through 5 3/4" white oak and have been getting perfect cuts.
I don't know how old your saw is or if the previous owner abused it, but my experience is that the tension spring doesn't get weak.
EDIT: Chrisstef's suggestion is an excellent one, also.
Your blade had no teeth set on the one side making it always wanting to turn. With the saw off run your finger down the side of the blade that it is turning away from and then compare that to the side it is turning towards. Some how there is no set to the one side causing your problem
I had the MAGNA forerunner to Shopsmith for years. Never had such an issue. Used the phenolic "Cool Blocks" just kissing the blades, tensioned to the indicator.
I did put on new tires considering the age of the saw when I got it.
Try starting over with the set up. Rubber tires? Glued to wheels?
Keep us posted.
Bill
It sounds like the wheels are out of plane with each other. use a straight edge set even with the bottom wheel and see where the top wheel is. my guess is it needs to be pushed back on the arbor a bit.
The Carter system looks beautiful (for when my ship comes in), and seems like it would help.
I will double-check the set of the teeth tonight, but I believe both of the re-saw blades had alternate-set teeth.
The "auto-track" bearing-which the back of the blade rides against as it goes onto the idler wheel-seems to be at least part of the problem. That bearing cannot be adjusted to allow the gullets of the teeth to ride on the crown of the tire. It is fixed so that the back edge of the blade always rides at the same position on the tire. Result: if you use a 1/4" blade, the teeth will be centered on the tire. If you use a 3/8" blade, the teeth will ride a little closer to the edge of the tire. If you use a 1/2" blade, the teeth will be almost at the edge of the tire (the edge closest to the operator while running wood through). Unfortunately, I don't have a photograph of the saw from above (plan view), but here's what it looks like from the side:
If you can see them, the red arrows in "JPG"'s inset photo show that you can only adjust the bearing to make it parallel to the blade path, and centered on the back of the blade.
Thanks to DrDirt for providing the link to the Shopsmith forum discussion http://www.shopsmith.com/ss_forum/viewtopic.php?t=8542 that the inset photo is taken from, and thanks to JPG on the Shopsmith forum for the outstanding overview of setting blade alignment on the Shopsmith band saw.
My plan of attack this weekend will be to install the new guide blocks and start over with the entire alignment procedure from square one.
Thank you to everyone who has given their time to help me with this problem.
Following up on my Shopsmith bandsaw that had extreme blade drift. Here's what I did:
1. Removed blade and cleaned it (removing pitch/gum/deposits)
2. Reinstalled blade and properly tensioned it
3. Checked for co-planar alignment of drive and idler wheels
4. Started from square one with all alignment/adjustment procedures outlined in the manual (as well as those covered in the Shopsmith forum post) and re-set everything
5. Installed and adjusted a set of the "Cool Blocks" (phenolic resin) guide blocks.
There was an overall improvement in the situation:
- the drift angle was less extreme- down to maybe 10 - 12 degrees off of parallel
- the blade did not get jammed in the wood as much as before (tripping circuit breaker)
- cutting through thinner or softer wood I'm now able to cut along a pencil line (e.g, I can rip a board, sort of).
But it still seems that something just is not right:
- as mentioned before, the fixed position of the "auto-track" bearing prevents moving where the blade rides on the tire: it remains impossible to center the teeth gullets of a 1/2" blade on the tire. Doing so would require grinding into the metal of the saw's frame.
- when re-sawing hard hardwoods (such as crabapple), the cut is still very wavy and curved. In some instances, the cut looks almost acceptable on the top edge of the wood, but when I look at the side that was riding on the table the cut can arc nearly 1/2" off of the intended cut line.
- while cutting I can see that sometimes the blade is angling (from top to bottom) through the wood. Sighting along the work piece, the point where it enters the wood (on the top) is about 1/4" to the right of the point where it exits the wood (on the bottom).
Some of these problems are probably caused by my lack of skill.
- I realized, for example, some of my worst results came from chunks of wood that were not sufficiently flattened on the bottom (side facing the table).
- I'm learning that I can get better results by cutting extremely slowly through difficult woods
- I discovered that, in some instances, the blade-binding that I thought was a result of the blade twisting in the wood was actually caused by something else: the wood had so much internal tension that it was pinching the blade. After ripping about a six-inch cut through a piece of wood, the kerf would close up completely at the front end. I have never heard of needing a riving knife on a bandsaw, and don't know how I would install one. But maybe…?
For now, I'll continue to practice, and see how much I can improve my results through better technique. If I have any "Aha"/ "Glory Hallelujah" moments I'll let you all know. Thanks again for all of your help.
- I realized, for example, some of my worst results came from chunks of wood that were not sufficiently flattened on the bottom (side facing the table).
Yes, very important (even though it's tempting to thing that flatness doesn't really matter on a band saw). The blade will pull the stock down toward the table, and at an angle depending on geometry.
- I m learning that I can get better results by cutting extremely slowly through difficult woods
Yes, again. You can't hurry a band saw, and more to the point, you don't want to-pushing really hard sets you up for having your hand(s) slip off the stock into amputation-land. In some instances, could also badly bend or break a blade.
- I discovered that, in some instances, the blade-binding that I thought was a result of the blade twisting in the wood was actually caused by something else: the wood had so much internal tension that it was pinching the blade. After ripping about a six-inch cut through a piece of wood, the kerf would close up completely at the front end. I have never heard of needing a riving knife on a bandsaw, and don t know how I would install one. But maybe…?
Case-hardening. Wedges will work, just add them in as the stock passes the blade aways.
For now, I ll continue to practice, and see how much I can improve my results through better technique. If I have any "Aha"/ "Glory Hallelujah" moments I ll let you all know. Thanks again for all of your help.
Congrats onthe thoughtful and successful troubleshooting!
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