Shopsmith Forums

My understanding of "blade drift" problems when resawing on a bandsaw has just been greatly enhanced.

Check out this video from Stockroom Supply. I've seen mixed reviews on their "Little Ripper" ripping-sled product, but this video was certainly an eye-opener for me.

I agree, very interesting!

I've seen other info about the problems that a fence causes as the stress in the wood is relieved. Using an old style SS bandsaw table with a miter gauge in the cross slot makes a short fence that doesn't extend past the blade leaving the wood free to move after it's cut. So far this has worked out pretty well for me. My past experience with other bandsaws taught me that tension was critical but I think the Shopsmith alignment system on the 11" bandsaw works very well for fine blades.

Another thread mentioned using a simple pin as a guide and adjusting for drift as you go, but I'd guess having drift when the wood is unrestricted sort of points to other problems. A dull blade is often a problem, and I think mainly because it doesn't go dull evenly on both sides. Whenever one side of the blade cuts better than the other the it will want to turn as it cuts. I've seen the suggestion to even out blades by holding a whetstone up against one side of the blade as it runs, but that just seems like an easy way to wreck a blade to me so never tried it.

edma194 wrote: ↑Sun Nov 22, 2020 2:24 pm I've seen other info about the problems that a fence causes as the stress in the wood is relieved. Using an old style SS bandsaw table with a miter gauge in the cross slot makes a short fence that doesn't extend past the blade leaving the wood free to move after it's cut. So far this has worked out pretty well for me. My past experience with other bandsaws taught me that tension was critical but I think the Shopsmith alignment system on the 11" bandsaw works very well for fine blades.

Another thread mentioned using a simple pin as a guide and adjusting for drift as you go, but I'd guess having drift when the wood is unrestricted sort of points to other problems. A dull blade is often a problem, and I think mainly because it doesn't go dull evenly on both sides. Whenever one side of the blade cuts better than the other the it will want to turn as it cuts. I've seen the suggestion to even out blades by holding a whetstone up against one side of the blade as it runs, but that just seems like an easy way to wreck a blade to me so never tried it.

That's a good point about using the miter gauge as a short fence. I have the old-style table, but when ripping I invariably mount a full-length auxiliary fence to the miter gauge. I like the added height of my auxiliary fence, but now I'm thinking that I should make a shorter one.

On further reflection, I'm not sure this stands up. When I put a new blade on and set up to rip, I always adjust the rip fence for the drift. I usually take a length of 1/2" plywood 2-3 wide, draw a line down the center and rip it by eye about half way. Clamp to the table and then set the fence to it. Plywood is not tension wood. So that type of drift is real.

Now, could tension wood cause additional issues, certainly.

algale wrote: ↑Sun Nov 22, 2020 3:22 pm On further reflection, I'm not sure this stands up. When I put a new blade on and set up to rip, I always adjust the rip fence for the drift. I usually take a length of 1/2" plywood 2-3 wide, draw a line down the center and rip it by eye about half way. Clamp to the table and then set the fence to it. Plywood is not tension wood. So that type of drift is real.

Now, could tension wood cause additional issues, certainly.

I totally agree Al. That is the way I have done it for years and it works perfectly. Also, the way the video describes it the drift should be wood dependent when using a fence. When I set my fence as you describe the drift never changes. I can detension the blade and retension it and saw different pieces of stock and the fence does not need to be readjusted.

Thanks. This thread really helped. The Little Ripper seemed too good to be true, and it didn't make sense to me that a wood tension problem would not be different with different woods. Y'all saved me a pile of $$$ that is far better spent on wood.

Both Doug Reid and Scott M. have discussed this on Youtube, here are links to those videos.

https://www.youtube.com/watch?v=19KUOXatLPY
https://www.youtube.com/watch?v=5lqzmibP3vg

I guess I'm not much qualified to input on this because I don't use bandsaw extensively, but I have never seen any drift either on rip or crosscut and I cannot see how a symmetrically-set blade running between properly set guide blocks would drift EXCEPT if the material were binding against the blade due to the fence as described in the OP's Stockroom Supply video above.

Nor would it drift due to where the blade tracks on the wheels. Doug Reid just says it's there and that I need to correct for it. I am not comfortable with skewing the fence to fix the "problem".

The Stockroom Supply theory makes sense, and also using the miter gauge as a short fence. Maybe something like a bandsaw version of a riving knife would remedy as well.

Re-watching this Stockroom Supply video, I think I figured it out why he seems to magically get no drift. It is because the first thing he does on his lumber with the Little Ripper it to "square it up". He actually takes two cuts to square up that face because the first cut wasn't enough. Well, guess what: when he is squaring up his lumber, what he is really doing is cutting the blade drift line through his lumber. The blade of course cuts a face exactly parallel to the drift -- not parallel to the direction he is pushing the lumber through the blade. But once that first face is cut parallel to the drift, the next slice will, of course, also be exactly parallel to the first cut. So while he doesn't set the fence or the Little Ripper to the drift, he cuts the wood to the drift by wasting some material each time he starts cutting a new log or rough piece of lumber. With a log you are sawing into a board, maybe not a big deal if the first few cuts are waste. But if you've already milled up a nice milled (S4S) board you want to cut into strips or resaw, it makes sense to set the fence one time with a hunk of plywood scrap and be done with it rather than always wasting your good wood.

The issue I'm describing would be much more obvious if he started with a piece of milled wood (S4S), used the Little Ripper to try to cut it. I'm certain that first cut wouldn't be a nice even thickness. But the next cut would would be.

The easiest way to debunk his tension wood explanation for blade drift is to put a brand new blade on your band saw, set it up and tension it perfectly. Now take a piece of straight edged piece of plywood about 2 inches wide and 2 feet long, draw a line down the center and try to rip it down the center by hand with no fence. Remember there's no tension wood in plywood. Chances are you are going to have to push that plywood through the blade at an angle to keep that blade cutting down the center line you marked on the plywood. Stop when you are about halfway through the board. Voila, that angle the plywood is sitting at on the table is your blade drift.

Using a piece of plywood with a 'new' blade is a good way to make whatever contribution a dull blade contributes greater by the time the center is reached.
As for plywood having no tension wood, it has multiple contributers to that(each layer does it's own thing).

I agree a new blade(if near perfect) should not have significant drift. But how often does that occur - I use used blades almost all the time.

JMO