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Is there any benefit to variable TPI hacksaw blades where there the TPI varies from one end to the other?

I only see potential caveats:

  • it might cause problems or how inconvenient it is to have only a few inches of the same TPI on a blade
  • the quality and ease of cut with full strokes
  • how severe issues are when cutting thin stock and you run into the coarse TPI section of the blade

One vendor's website claims:

... Tri-Cut Hacksaw Blades ... have a unique design with 3 teeth sizes on 1 blade. They feature 32 teeth/inch up front for quick starts, 24 teeth/inch in the middle and 18 teeth/inch on the end for fast and smooth conventional cutting. These hacksaw blades are ideal for general-purpose cutting.

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    1) Could you point to a specific brand/model? My search for "variable TPI hacksaw blade" turned up this question and a bunch of blades for sale, each of which seems to have a fixed TPI over the whole length. 2) What is the purpose for making/having/using such a blade? 3) This, sadly, is going to be off-topic because each of the things you're asking about are opinion based, but I'm curious to know the answers to the first 2 questions anyway - this isn't something I'd ever heard of before.
    – FreeMan
    Nov 23, 2020 at 12:34
  • @FreeMan kleintools.com/catalog/hacksaw-blades/… I wonder about the purpose of the blade too.
    – DKNguyen
    Nov 23, 2020 at 14:03
  • Wow, weird. It is a good question, however, it's still off-topic because you're asking for opinions and, I think, opinions is all we could provide in the way of answers. I'd suggest buying one and trying it out, but it seems they sell 'em in 100-packs which likely makes that less economically feaseable.
    – FreeMan
    Nov 23, 2020 at 14:19
  • @FreeMan Would asking for caveats make it less opinion based?
    – DKNguyen
    Nov 23, 2020 at 14:20
  • You could try. There are only 2 close votes right now, but it's still early in the day. My impression (having never used one) is that you'd end up with the benefits and drawbacks of all 3 TPI on each stroke because most of us would end up taking fairly full-length strokes. I suppose if you were cutting smaller diameter/thickness, it would be easier to focus the stroke on the "proper" portion of the blade. Your best bet would be to try to find user reviews at various tool review and/or retailer sites.
    – FreeMan
    Nov 23, 2020 at 14:23

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It's a gimmick.

Since proper tooth size on a hacksaw is directly related to the thickness of the metal you are cutting, you are guaranteed to have 2/3 of the blade be the wrong toothing for whatever you are cutting.

Save your money to buy a better quality hacksaw frame that you can easily and quickly switch blades on, or get additional hacksaw frames and keep different toothed blades mounted in each one.

There is a different product of the same name that has some benefits in some situations - a "Variable Tooth" which is more of a slight variation (like 17-18-19-18-17-18 instead of 18) to reduce problems of harmonic vibrations from an interaction of tooth size and sawing speed. This is not the product you asked about, and it's of limited benefit for hand hack sawing where the user will simply adjust speed to avoid the vibrations.

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