Thread: Bi-metal Blade

Any saw sharpening place will make you one, my local one does it while I wait. I just take a blade with me and they copy it.

I have the BS-4 (the Taiwan made model). By the looks its the same as yours. I use 12.7x0.64x1638mm or 1/2x0.025x64.5" bimetal saws that I order from eBay USA. If cutting steel, they outlast carbon blades by a factor of 20 or better. One blade lasts me 1 to 2 years. Do an eBay search for "1/2x0.025x64.5 bi-metal", they are currently about AU$37 postage included (used to be cheaper, currently the USD exchange rate is bad....).

example:
http://www.ebay.com.au/itm/BI-METAL-...item1e77ccd29d
http://www.ebay.com.au/itm/BI-METAL-...item1e77ccdb80
http://www.ebay.com.au/itm/64-1-2-x-...item259a048b8f

If you can find Lenox brand, they are excellent but cost a little more.

Alternatively www.minitech.com.au in Brisbane sell them too, AU$52 plus postage makes them a bit pricey though...


PS: I use the 18TPI pitch and never change blade, no matter what metal or what cross-section I cut.

Just be careful when cutting thin walled sections, I always take the weight myself when cutting thin walled sections, nothing worse than an expensive toothless blade...

Originally Posted by cba_melbourne

I have the BS-4 (the Taiwan made model). By the looks its the same as yours. I use 12.7x0.64x1638mm or 1/2x0.025x64.5" bimetal saws that I order from eBay USA. If cutting steel, they outlast carbon blades by a factor of 20 or better. One blade lasts me 1 to 2 years. . . . . ..

Is that with or without lube?

The sorts of lifetimes I have read about for Bimetal over Carbon is anywhere between 4 and 10 times.
The upper ends are claims made by manufacturers, while the lower tend to be by users (e.g. posts on homeshopmachinist) .
I do appreciate they can cut harder materials and are less troubled by processing, oxy or plasma cutter scales.

What would be interesting to hear about is novice experiences about how easily bimetal blades break.

I got my 6x4 bandsaw about 4 years ago and soon after fitted a lube/pump, and since then have gone through ~6 carbon blades.
Given that I was away from my workshop for some of that time that works out to an average of ~7 months per blade.
All except 1 (which I accidentally tried to cut hardened steel with) had plenty of "cut" left, when they broke at the join.
From what I could determine, the other blades broke because I did not understand the tension requirements on a metal cutting bandsaw blade, or how to properly tighten, or present, work pieces for cutting.
I guess this is a learning process for everyone, or maybe I'm just a slow learner
Unless an operator has the ability and gear to rejoin BS blades, maybe it's worth learning on carbon rather than Bimetal?
Anyone know how easy is it to rejoin a bimetal compared to carbon blade?

The lubed carbon blade I have on there at the moment is nearly a year old and still cutting. albeit slower than usual, and looks like being the first one to run out of cut.
At this stage I'm seriously considering a bimetal replacement - it would be great to get 20 years out of it?

I gave up with bi-metal on my BS5 when i had it because they broke. The carbon ones did not break nearly as easily. I was finding the life was about the same due to the breakages.
Since my new saw uses 3550x27mm blades and has a belt tension guide i have not broken one, and i have cut a hell of a lot of steel with it.
18TPI might be fine for cutting thin walled tube and small bar, but it will clog up real quick in anything of reasonable size.

Bob,

No flood coolant for me, but I do apply a cutting oil with a brush for steel, and WD40 with a hand pump sprayer fro Aluminium.

When I first had that bandsaw, for the first year I only used Starrett carbon blades. Went easily through a dozen, probably more. And I got real sick of constantly changing blades, I had blades only for stainless, for steel, and Ally/brass. Cause if you use a carbon blade once on stainless its not going to cut Ally/brass anymore, even if it still has some life left in SS and steel.

Since I got my first Bimetall blade I have not changed blade anymore until its worn. For me, worn is when too many teeth have broken out. I am careful never to cut hardened steel, happened to me once and the blade was instantly shot (was a chunk of salvaged tool steel that was hardened on one side only....). I never had a bimetall saw break. But the blade needs to be tensioned very hard, as hard as one can tighten that small tensioner wheel by hand. The blade guides have to be perfectly aligned, and the ball bearings not too tight on the blade (too tight CAN indeed cause a bimetall blade to break, because the softer backing steel will expand more than the hard toothed section due to the rolling action of the guide bearing!). Follow the blade maker's instructions on how to run-in a bi-metal blade (my first blades were Lenox, see here how to break in, click on the break-in instructions tab: http://www.lenoxtools.com/pages/clas...aw-blades.aspx). I do change speed according to material, slow for SS, medium for Steel, fast for Aluminium. I do hand feed thin sections. I hang some extra weights on the arm for SS. Yes the 18TPI blade clogs when cutting thicker stuff, but I rather clear more often and wait a bit longer, rather than go to the hassle of changing blades. Most of what I do is smaller cross sections anyway. And BTW, I replaced that cheap V-belt for a link belt, the saw runs much smoother, no more thump-thump when the stiff V-belt splice hits the pulleys.

Chris

PS: I cut plastics and thin section alu/brass sheet and profiles on my variable speed woodworking bandsaw, using carbon blades. That is what carbon blades are good for. Not for SS.

Bi-metal blades on smaller bandsaws can be a problem as the wheels on the saw are small and so the blades can fatigue as it goes around them. I have a 4x6 portable saw and was told that carbon is all I should run for that reason. Wheel size is around 5" from memory.
Another option is to make your own blades up. Like everything it takes practice but is cheaper than buying blades all the time.

https://www.woodworkforums.com/f65/tig-welding-bandsaw-blades-143247

I also find that if one snaps at the weld I can rejoin it.

Michael

I have several broken carbon blades here, not one broken bi-metal blade (have one or two fairly blunt ones though).

Ever since I bought my first bi-metal blade I have not bought any carbon ones, I cut a fair bit of SS (mainly 303 and 304) and carbon blades take forever to cut 25mm bar, bi-metal doesn't take very long at all.

I paid about $32 for my last bi-metal blade IIRC.

My blade supplier (Henry Bros) recommended bi-metal multi-pitch for the H&F 6x4.
He supplied 10x6 pitch.
Cutting aluminium and mild steel I can safely cut to within 1mm, perfectly square and a good finish.

I only use carbon, I had one bi metal when I first got the saw, but I cut a lot of thin walled tube and the teeth just kept breaking off. I used to use Starret and they lasted a while, but my supplier switched to another brand (can't remember the name) and they tend to break quite frequently, I'll be going back to Starret when this lot run out I think. I use 18tpi most of the time, but if I have to cut any big slabs I usually swap to a courser blade, takes too long otherwise.

I've also noticed if I use the table a lot I go through blades like crazy - too impatient me thinks.

Thanks guys - lots of great information. Have emailed a few of the sources identified and I will see what comes back (should have guessed a 6 x 4 machine would have the blade length in inches rather than millimetres). I have been cutting some stainless tube and the carbon blades are only lasting a couple of days (lots of cutting though). Willing to give a couple of bi-metal blades a go and see how they turn out.

Grant

I have made contact with one of the eBay suppliers CBA identified and they can make the blade at 1645mm L (which is a couple of mm longer than 64.5") for the same price so I am just sorting out to buy one of these. Will try an 10-14 variable pitch (although probably would have preferred more TPI for the thinner wall).

Will let everyone know how it goes.

Grant

All I ever use is Bi-metal blades, they usually last me about a year or so. Mind you I run coarse and fine tooth blades, depending on what is being cut. Fine tooth is 24 while the coarse is 18. It is best to use a blade that has minimum of 3 teeth in the material, less than that you loose teeth. The coarse blade is used for anything from 3 mm flat (on the flat) to 50 mm plate, in both positions. I have about 30 years experience with these saws.
NEVER cut flat bar on it's edge in the saw.

To join the blade, I use a MIG set low, grinding across the welds, then use a gas torch, heat the join till it starts to turn light - med. blue, (doesn't take long) to temper the blade. Some of my blades have several joins in them.My jig is a piece of 50 X 50 X 3 angle with a 15 X 3 flat tacked on the edge, and a 30 X 30 X 3 angle tacked inside to create a box section, for vice mounting. At the halfway point I've cut a shallow groove and the flat cut out for the torch to travel through, the groove is for penetration with out sticking to the jig. I'll put a picture on here tomorrow if anyone wants to see.
Kryn

I'll certainly be interested in a picture Kryn.
Thanks in advance.

Phil