W-T 16" blade tension

[Ron Kellison]

I just acquired an old WT BN1135 bandsaw. The blade on the saw looks like it's a 6 TPI and I'll probably change it out. I'm curious to know if the beautiful old beast will be able to properly tension a 3/4" blade for resawing hardwood. I'm thinking of getting a Lenox Woodmaster CT or a Lenox Bi-metal.

Thanks for any knowledge you can share.

[Jeff Heath]

The simple answer is, Yes, it will be able tension any blade you want to use on it, assuming the saw is complete with nothing broken.

The old cast iron machines are fantastic, and much more rigid than the sheet metal stuff sold today. Once you go through it and get it set up properly, you'll have a saw that will last a lifetime.

Choose your blade based on the type of work you do. You can't go wrong with Lenox bi-metal blades. They wear well, and are excellent quality, assuming whomever welds the blade is having a good day. If it comes from Lenox, you're all set. Lots of places sell Lenox blades by having large coiled rolls that they weld themselves. Some don't have a clue what they're doing. I had one clown weld 4 Lenox blades for me, and each one was 4" too long for a 36" saw. I had to send them back and get them re-done.

[David Kumm]

Ron, if unsure you could first try the Laguna Resaw King. The band is .024 rather than .035 of the CT so it will flex around the wheel and tension much easier. I've not used the WT so I'm not doubting Jeff's word here, just giving you another option for a carbide blade. The 1/2" Trimaster runs the thinner band too. My Y20 has the strength to tension a carbide blade but not with the old stock spring. It needed an upgrade to deliver with carbide. Dave

[Jim Wheeler]

I just acquired an old WT BN1135 bandsaw. The blade on the saw looks like it's a 6 TPI and I'll probably change it out. I'm curious to know if the beautiful old beast will be able to properly tension a 3/4" blade for resawing hardwood. I'm thinking of getting a Lenox Woodmaster CT or a Lenox Bi-metal.

Thanks for any knowledge you can share.


It's going to depend on what is meant by properly tension. There are those who say the proper tension is anywhere from 15,000 to 25,000 psi of blade cross sectional area. I have read claims by various manufacturers that their blades can be strained to as much as 30,000 psi and even more, and I have no doubt of that. Keep in mind, however, that such values are commonly used on large saws for cutting metals, where great beam strength is required. I have seen only one company that specifically recommends a tension of at least 15,000 psi for wood-cutting machines; most don't seem to make any recommendation at all except not to over tension on a light machine. No elucidation as to what constitutes a light machine either.

For a 3/4 inch wide blade, 0.035 inches thick, it would require a little over 700 pounds of spring force or wheel load to achieve 15,000 psi. That's about the same as suspending a 700 pound weight from the upper shaft. To achieve 25,000 psi on such a blade would require at least 1,175 pounds of force - probably closer to 1,200 after losses to friction in the adjustment mechanism. That's over half a ton.

Will a 16 inch Walker/Turner tension a 3/4 inch blade to 15,000 psi? Maybe, but probably not without upgrading the stock spring. Can the frame, shafting, and wheels withstand the 1,200 pounds of force needed to tension that same blade to 25,000 psi? I don't know, but I wouldn't care to find out using my saw - if I owned a WT. I rather doubt that it could - not without the frame deforming a bit and throwing things out of alignment at the very least. However, such a high figure should not at all be necessary on that small a machine.

I am one of those who is of the opinion that the proper tension for any blade is the least amount which produces acceptable results. I know for a fact that I can get acceptable results sawing 10 to 12 inches thick, with a 3/4 inch blade tensioned to only about 10,000 psi (about 450 lbs. of wheel load.) I know, because I've done it - and done so on an 18 inch, shop-built saw with a wooden frame. Now if I was attempting to saw that thick with a 1/4 inch or 3/8 inch wide blade, I've no doubt that I would need something close to 25,000 psi of tension. That's because such blades do not have as much inherent beam strength as the wider blades. The wider the blade, the less tension it will require to achieve the necessary beam strength for the job being done - all other things being equal.

If I recall correctly, a 16 inch W/T has a resaw capacity of 11 or 12 inches. So if it has a decent spring in the tensioning mechanism, it should be able to "properly" tension a 3/4 inch blade for that kind of cut - ie., to 10,000 psi at a wheel load of approx. 450 pounds. Others may disagree. In any event try a bimetal blade first - they are much less expensive if it should prove beyond your saw's capacity.

Regards,

Jim

He who welds steel with flaming pine cones may accomplish anything!​

[Ron Kellison]

Jim, The old saw has been unused for over 20 years, all that time under tension. When I finally get my hands on it next week I suspect I will find that the tires are flat-spotted and the spring will have been compressed for so long it's lost some of the original strength. I've read some interesting threads about how hard it is to find the proper spring for this particular bandsaw but there are work-arounds. Thanks for the advice about the bi-metal blades. I will certainly be giving it a lot of thought before I start spending more money! Getting blades directly from Lenox up here in Canada may be difficult but I'm sure I can find a good source close to me in Ottawa.