A week or two ago I changed the tires on my Delta 14″ band saw, and it gave me so much available horsepower that the ragged blade that I had flipped off the wheels WAY too many times just took a dump. I had a situation where the band saw was ready to run, but the tank was empty. I didn’t have any blades for the saw. Time to fix that. A year or two ago I had bought myself an MSC blade welder (circa 1984) to feed my three band saws, and a few rolls of coil stock. The welder worked initially, and then developed some problems (like most all my tools), I figured it wouldn’t be too tough to fix. I had invested a couple of hours to clean my bench off, and tonight was the night to square it away.
The blade tensioner (that squeezes the blade halves together when the weld takes place) was inop. I took the welder apart and found the cam shaft that does the actual tensioning was loose. About 5 minutes later that was fixed. While I had the works out, I looked at the wiring; my machine is a 110V/220V machine, and I had always suspected that 110V was just not enough voltage to get the job done. I found out that I would need to swap just one wire (and the plug) to change it to a 220 Volt machine. I figured that would solve all my problems, but that would have to wait till tomorrow, and popped the machine back together. (After testing the repaired welder; I think that 110V is plenty, and decided NOT to change it to 220V).
After trying my welder (after the repairs), I decided to do a little more detailed bit on welding the blades, so this will be just a warm-up. After all, I WAS trying to get my band saw back up and running after all.
OK, whats a blog without a little tool porn, anyway? Heres the blade installed, and running true. I had spent alot of time cleaning my bench off, fixing the welder, and experimenting on the welding process. I’m glad I didn’t just go with my usual routine of welding the blade and start cutting; I found a few things out. My friend Eric had stressed that annealing the blade was key. I will now agree (if done properly!). I had been doing it wrong from the get-go, and was experiencing a high ratio of weld breakage. The problem seems to be two-fold; The compression rate of the weld and the annealing are both VERY IMPORTANT. I will detail this later (as I am still experimenting), and post it when proven.I think I’ve got it down pat at this point, but want to prove it before posting the process. I’m sure that all welders are different, and the results will be applicable to MY machine.
So far, I think my success rate on welded blades just doubled or tripled, and I want to try a few more things before posting any more “wisdom”. After all, I have three different band saws (all different size blades), and I see a portable band saw in my future, you would think this is something I SHOULD get right! More later……………………………………………..
OK, here is the welder itself. Its an MSC 110/220V machine built around 1984. Literature (user’s manual) is no longer available from MSC, and I haven’t found anything on the web yet, so blade welding has been something of a hit or miss kind of thing. I will apologize in advance for any disinformation. The pointers I am showing here have worked for me, on my machine. YMMV.
This is the blade cutter on the side of the welder.
STEP ONE: Cutting the ends
Most band saw blades come off a roll, or coil stock. The ends have to be prepped; square and clean. Dirty, rusty, or out of square blades will not make for a good weld.
This is the raw cut. It needs to be dressed a little before it gets welded.
The welder has a built in grinder, which is used to clean the edges up before the welding. The more prep work that is done at this point will pay off in either a weld working or breaking.
The final fit-up. Good and square, and no small parts of the teeth left. The weld will be better if it is placed in the kerf.
At this point the balde is in the welding jaws. Notice that the jaws are made of brass for better conductivity. There is a step in the rear, to align the back edge of the blade (most blades ride against a roller when cutting). The rear of the blade needs to be straight and smooth, so it should be pushed back into the blade guide.
Once the blade jaws are tightened by flipping the levers upward (and blade halves touching), the tension adjuster is set. My welder will handle blades up to 1/2″, so this being a thinner blade; the setting is set to the first position. I have found that the wider the blade; the more tension is needed. Too much tension, however will cause the weld to bunch up and be weak. Here is where having the original users manual would be a great help. I had to find this out by trial and error. The jaws close when the weld takes place, and should be a fluid movement. If the jaws spring shut too quickly, you probably have too much tension on the jaws. This will take some experimentation.
STEP TWO: The weld.
Heres a real nice blurry shot of the actual weld. I found out that you can’t weld or anneal and take pics at the same time. You will notice that the button I’m pushing is the annealing button. This will be what you see if you stand on the button too long.
Skip ahead to the actual weld. You can see that there isn’t too much buildup on the joint, the back is straight, and the teeth have good spacing. Now the excess weld has to be ground off.
While grinding its best to keep the blade moving, so that you don’t end up with any low spots on the blade. Don’t forget about dressing the back of the blade.
This is what your blade should look like after a few minutes of careful grinding, ready for annealing.
STEP THREE: The annealing process.
This is NOT what you want to see when you anneal the blade. This is what will happen if you hold the button too long, and this will happen faster with a thin blade than a wider one. You want to let off the button when you see a dull red, NO LONGER. You will probably see some smoke from the oil that is on the blade at this point; thats OK. I prefer to anneal the weld to about 1/2″ to each side of the weld. This will mean three or four movements of the jaws. This is probably the most important part of the whole process.
With any luck at all, this is what you will see after the annealing. The annealing process softens the metal that has been embrittled by the welding process. If you get the blade too hot when annealing, it will stay brittle. Dull red is best. Remember the blade has to bend around the round wheels of the band saw, and it is under tension also. Its a wonder that the blade can hold up under that, let alone the shock of the cutting process itself.
This is the acid test. The blade HAS to be able to bend. This is beyond what you will ask it to do, so I use this as the test. if it is too brittle; it will break, and if you have made it too soft; it will stay bent. From this configuration it should return to pretty much straight. If it does, it should be ready for the saw.
If the sun and the moon are in the right position, and you’ve done everything JUST RIGHT, this is what your home-made band saw blade will be likely to do. Good Bi-Metal blades are not cheap, so having the ability to make your own with blade coil stock that you can get on Ebay fairly inexspensively is a real plus. I haven’t sharpened my pencil, and figured out what each blade has cost me, but being that I have three band saws (with three different sized blades), and commercial blades being very pricey, I know that I am saving a bundle.
The last blade I bought for my Johnson B model saw was about $35, and that is the smallest blade I use. I tend to be very hard on my blades (torturous would be a better term), and have been through lots of blades since I bought the welder and coil stock. The welder and blade have paid for themselves long ago, and I am ahead of the game now. I still have a couple of hundred feet of coil stock left, and should be set for some time to come (no matter how hard I get with the blades). Its also nice not having to wait for a blade to arrive in the mail when I’m right in the middle of a project, and a blade goes down.
All in all, having a blade welder around (and becoming proficient with it) is a good investment for anybody who owns and uses a band saw to any great extent. Infrequent users will have a tough time justifying the expenditure, but I’m glad I did. Its saved me a ton of money over the years.