New Bandsaw Blade for Thin Metal

MTBob

MTBob

Well-Known Member
I typically use a 14 tooth bandsaw blade for general metal cutting (and most anything else). But, a 14 TPI blade is not designed to cut .080" steel knife blanks. It'll cut OK, for a while, until the teeth begin to disintegrate. I've always used the general rule that there needs to be a minimum of 3 teeth contacting the work (I often violate that rule). But, cutting thin material with too low a tooth count will wreck the blade and is hard to control the cut.
So, I tried out this 24 TPI bimetallic blade on some .080 26C3 and first impressions are that it works well. It's kind a like a hacksaw blade, including a wavy edge for added kerf clearance. It sure beats using a 14 TPI blade.
We'll see how long this lasts.
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I ordered some of those from Amazon as they were a little cheaper.

I won't waste my money again. Teeth tore off almost instantly and blade was shot after half an hour.

I used 4 blades and same thing happened on all of them. Mine were 14-18 TPI variable. But my regular blades are always 14 TPI and I can usually stretch those a couple months even cutting titanium and thin steel.

Hopefully you'll have better luck.
 
I tend to back the cut with wood to give the teeth some extra support when cutting thin steel. Not a sure-fire fix but I think it helps.
 
I don't pay much mind to the "3 tooth engagement" rule.

I cut 1" or bigger solid bar with a 14/18 or a 14TPI blade pretty regularly. At the same time, I'll cut 24 gauge sheet with the same blades. On my current vertical metal bandsaw it's a pain in the but to swap blades (my fault, made it with a couple hard to get to screws)

The main thing I pay attention to is feed rate and feed pressure.

One trick I have for getting more life out of a blade is once the teeth at the weld joint crap out, take a stone or a grinder and taper them back so they don't catch and stall the saw (or throw the blade off). I'm only giving up something like an extra 1/4" of blade (plus the teeth that were annealed after welding). Doesn't do much for cheap blades, since the rest of the blade gets dull quick, anyway, but for expensive blades, I think it's worth the 30 second time investment.
 
I have been using these M42 blades from Amazon on G10, Micarta, my home made laminates, etc on a wood bandsaw with good success in the 14 and 14/18 TPI. I tried putting my 14" bandsaw down to it's slowest speed to cut blade blanks and it didn't work well at all! Even at it's slowest speed, I think the HF 14" I have is still too fast for metal blank cutting. Cutting stainless, brass, etc, it is fine, but it didn't do well even with mild steel bars or Nitro V/AEB-L barstock or 440C or 1095.

I have a PortaBand and when using 14/18 TPI blades on 1/16" thick knife blade steels, the teeth get knocked off very quickly due to the thinness of the metal. I may have to try putting wood under it! I gotta get some 24 TPI blades for my Portaband since I do a lot of fillet knives. The Dewalt blades and Morse seem pretty good for 3/32" and thicker steels, but 1/16" blade steel kills my blades in 14/18.
 
For sure, how well this 24 TPI blade holds up is yet to be discovered.
Most often (but not always) a bandsaw blade will fail due to running the saw at too high a speed. More specifically, the blade must run at a Surface Feed Per Minute (SFM) suitable for the given metal (think of this as "blade speed"). Too high a feed rate can also contribute to failure.
Typically the blade speed recommended for general metal cutting is ranges from about 150-250 SFM. 250 for low carbon steel (1018) to 150 (say 52100), even lower for Ti. I generally set my speed at about 175 SFM for general metal cutting. While cutting some more .080" 26C3 I even used a coolant mister to lubricate and cool the blade while running at about 125 SFM.
For reference this is the bandsaw I use, Circa 1960'ish 14" Delta. It has a very old, and still very workable, variable speed/constant torque belt drive (the round thing below the bandsaw) that then drives a step-down pulley to power the bandsaw wheel. This results very low speeds, much like a KBAC controller would provide.
To calculate the SFM of your blade speed use this formula. First measure the bandsaw wheel diameter and the RPM of the wheel - and, then use this forumula
SFM= bandsaw wheel diameter x RPM x .262
Or, with my saw, say running at 35 RPM 14" x 35 RPM x .262 = 128 SFM

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Yeah, speed kills blades usually in metal! I think my wood bandsaw is 550 sfm at the slowest setting, so it is a bit fast for blade steels.
 
Taz575 said:
I have been using these M42 blades from Amazon on G10, Micarta, my home made laminates, etc on a wood bandsaw with good success in the 14 and 14/18 TPI. I tried putting my 14" bandsaw down to it's slowest speed to cut blade blanks and it didn't work well at all! Even at it's slowest speed, I think the HF 14" I have is still too fast for metal blank cutting. Cutting stainless, brass, etc, it is fine, but it didn't do well even with mild steel bars or Nitro V/AEB-L barstock or 440C or 1095.

I have a PortaBand and when using 14/18 TPI blades on 1/16" thick knife blade steels, the teeth get knocked off very quickly due to the thinness of the metal. I may have to try putting wood under it! I gotta get some 24 TPI blades for my Portaband since I do a lot of fillet knives. The Dewalt blades and Morse seem pretty good for 3/32" and thicker steels, but 1/16" blade steel kills my blades in 14/18.
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Again - feed pressure/feed rate. On my portable, I only use 14 and 14/18. Just feed slow and use light pressure. Dress the teeth right after the blade weld so they don't snag.

I'm assuming you're using a vertical stand/table. Freehand is a totally different story - harder to control the feed pressure.
 
Yeah, I made my own version of a SWAG table for my Portaband. Once a few teeth go, the rest pop off easily!
 
Gotcha. I use a speed controller on my bandsaw. The speed controller is laying on the bench and the saw is plugged in to that. I keep the trigger zipped and the saw on the highest speed. Just look for a "15A Universal Motor Speed Controller". Mine came off a Vibco vibrator from a shaker table.

I'm using Lenox Wolfband blades. They see to hold up really well. BIM blades, of course. I think being able to vary the speed so precisely really makes a difference to the longevity of the blades. I can turn the speed down to where the saw only turns a couple RPM (don't do that - overheats the motor)
 
For a cheap variable speed, you can use a foot pedal like one that came with my Chicago electric rotary tool. Just plug the saw into the foot pedal, and there's your variable speed. I use this with my portaband set-up all the time.
 
billyO said:
For a cheap variable speed, you can use a foot pedal like one that came with my Chicago electric rotary tool.
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Good idea. Does that kind of controller provide a constant torque at low speeds?

Here is a chart for bi-metal blades that offers guidance on SFM recommendations for various metals. I think regular mono-blades would have similar SFM recommendations, though slightly lower.
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It's worth pointing out that the iMachinist blades I purchased on Amazon are CHI-COM blades. I'm a strong believer in buying US made products and favor either Starett, Lenox or similar bandsaw blades. But, I have yet to find any US based manufacturer that offers 24 TPI. Perhaps someone offers this size, but I haven't found them. I've only found 24TPI from this CHI-COM outfit. We'll see just how long these blades hold up.

Recently I read several articles about slowly breaking in a bandsaw blade. As noted in #6 below, apparently conditioning a bandsaw blade initially with light cuts will improve the blade life. I've never taken this step, but will try it on a new 14-18 variable tooth blade.

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I've used Lenox bandsaw blades both in my profession and in the hobby of knife making for eons. As far as I'm aware they are still American made. But without a doubt I've never been disappointed in a Lenox blade.
 
I've used several of theses Emachinist blades and thought they were great cutting .o80 AEBL and 3/32 and 1/8 154cm and never a problem. I did buy what was a custom made blade in 20 TPI to cut some very thin 410 and 416 stainless. I do run the band saw at the slowest pulley speed possible.
 
MTBob said:
Good idea. Does that kind of controller provide a constant torque at low speeds?
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Kinda? Portabands have crazy deep gear reduction. I wanna say the motors run around 20K to 30K RPM wide open, usually. The speed controller I use is basically just a dimmer switch. My saw doesn't stall. If the blade stops, at minimum it throws the blade off the driven wheel. Some times it does that and walks the tire off the wheel (PITA).

The speed controller on my forge blower is literally just a 15A dimmer switch. It isn't ideal. Works great, but when it's below freezing, it doesn't like to vary the speed till the switch warms up. It's a few feet from the forge, so between the radiant heat from that and the heat from resistance in the switch it doesn't take long. I just leave the ash dump open till the blower slows down enough.
 
I've had the same Starrett Intenss Pro 18TPI blade on my saw since July 2019. I've cut lots of blade steel on it. I buy 6"+ wide material and cut off the left side of the sheet then add the shaping cuts.
 
I'm about due for a blade change right now. I'm going to write the date that I change blades on the saw and see how long it lasts. I know I've had the current blade on (Lenox Wolfband 14/18) on for at least 6 months and I've cut a lot of thick steel with it. Mostly 3/8" or thicker, probably up to 1-1/4" square.
 
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