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Up Topic Welding Industry / Welding Fundamentals / repair band saw blades
- - By Tommyjoking (****) Date 05-18-2007 08:47 Edited 05-18-2007 08:50
Most of you guys know this already

Just broke that new band saw blade...or you want to buy them in rolls to save money:?

Grab a piece of copper or (soapstone in a pinch if your gentle)   Clamp your two ends together and line them up on the copper.  Set your tig on low range...about 16-20 amps....grab some mig wire for filler (er70s-3, er70s-6).  And run you a little bead across the joint , make sure to full the ends , dont let it burn away and go crescent shaped.  Then grab your brazing torch and gently reheat the weld to a very almost not there dull red.   You are annealing your weld with the torch so it will flex with the rest of the blade and not break. Let it cool a bit un clamp it and grind your weld down flat.  Put it back on the saw and cut away.  If it breaks at your weld you need to be more carefull annealing or grinding it down.   Dont have a TIG?   Use your torch and brazing tip!!
Parent - By gndchuck (**) Date 05-19-2007 13:18
I've always wondered if you could weld saw blades.......thanks for the info, have to put that in the back of the brain for future use.

Charles Welch
Parent - - By billvanderhoof (****) Date 05-20-2007 03:22
People used to overlap the ends a little and braze or silver solder, then grind back to the proper thickness.  From the factory I believe they are resistance welded (butt to butt).
Bill
Parent - - By aevald (*****) Date 05-20-2007 03:52
Hello billvanderhoof, there is an older gentleman who takes welding classes from me so that he can work on his metal sculptures and other things. He typically silver solders the blades and when he does this he first squares up the ends with a bench grinder and then he grinds a bevel on each of the ends, one bevel will be top up, the other bevel will be top down, this is so that he can overlap the ends and when he has completed the soldering he can grind both sides smooth and still have good adhesion between the two ends. I have done this as well and had pretty fair success, you just have to make sure that you keep the ends square so that the blade is straight when you're done. Great tip everyone. Regards, Allan
Parent - - By JA (**) Date 05-21-2007 07:49
Hello Allen , i wanted to ask you , when you say , "one bevel on top , one bevel on bottom",,,,do you mean like a single scarf brazing joint....?
Parent - - By aevald (*****) Date 05-21-2007 13:25
Hello JA, forgive my missunderstanding of your question, and forgive my original explanation. If you look at the blade from the side view the bevels are such that the pointed part of the bevel of one side of the blade overlaps the pointed part of the other end of the blade, one bevel faces up the other bevel faces down. This gives the contact portion of the two bevels a greater surface area to adhere to one another after the excess silver solder has been ground away and the joint is of the same thickness as the rest of the blade to avoid having a thick spot to go through the saw guides. Hope this explanation makes better sense.
Parent - - By JA (**) Date 05-22-2007 02:04
Allen , you and a few others on this forum are on a list of mine of people i definitely listen to.....
thanks for clearing that up for me,,,,now another question if you dont mind.......
during what ever process is used , and even if its put together in in a way where the blade thickness remains the same,,,,,,how is it that the mechanical properties of the blade are not changed to where the teeth strength would remain the same.....?

it seems that it the teeth would go to Sh*t as soon as it ran through the cut,,,,,,,,thus creating a dead spot.....?
Parent - - By aevald (*****) Date 05-22-2007 06:28 Edited 05-22-2007 06:42
Hello again JA, I wish I had a really good response for you on this one. One thing I will say is that I believe all of the teeth that are engaged in a particular cut carry some of the load of the cut, having said that, the teeth in near proximity to the splice point will likely be soft and not contribute to the cutting process and unless you are cutting very thin-walled pieces they will not tear out either. If a person pays attention to using the proper blade tooth pitch and band speed for a particular material you will not have issues with teeth being fractured or ripped from the band. When you check the information that tells you the type and pitch of saw blade to use for various materials you will notice a few things, generally shapes of material with thin walls such as thinwall tubing, thinwall pipe, light gauge angle iron etc. use blade pitches with many more teeth per inch than say solids that might be 3" or thicker. Part of this cutting theory allows for multiple teeth to be engaged in the cut at the same time so that not only one tooth is required to make the cut through the section of the material and carry the load of the cut, at the same time, in an ideal situation, a tooth that is cutting through the material section shouldn't load up with a chip completely before it passes through the section of the material, if a chip does load beyond the depth of the tooth it will cause the tooth to stop cutting and actually lift the blade and curtail the cutting action. Thus various material thickness will require different blade tooth pitches, an 8-10 vari-tooth pitch might be used for materials ranging in thickness from 1/8" to 1" and a 3-6 vari-tooth pitch might be used for cutting materials over 3" in thickness. You can get straight pitch blades also but I typically find that they set up harmonic type vibrations and don't perform as well as the vari-tooth configurations. Do-All has some very good information describing proper blade selections and applications, so does Lennox, machine manufacturers such as Hydro-Mech, Ellis, Kalamazoo, and many others usually include information for blade suggestions, feeds, and speeds. Sorry for the windy reply, I certainly don't claim to be an expert in this area, but I have worked with some very knowledgeable material processing people who have shared a bit of the finer points of sawing with me. There is a lot more to it than most people realize, the difference in most cases is the quality, speed, and accuracy of the cuts and the longevity of the saw blades. Regards, Allan
Parent - - By JA (**) Date 05-22-2007 07:13
got ya.........thanks again Allan........
Parent - By Tommyjoking (****) Date 05-22-2007 10:14
yes the teeth in the welded or brazed area are lost due to the heat...but it is a small spot and tolerable unless you require very high feed speeds.  In general you will save lots of dough buying your saw blades in rolls.   Thing is I learned it late in my career..i did not think you could weld them by hand either...I learned different...so i am sure it will help out a few out there.
Parent - - By yorkiepap (***) Date 05-20-2007 11:30
Hey Tommy,
Your suggestion will work if you are really careful and have done some practice. For many years I re-welded my broken blades on a small aluminum fixture I made with MIG, TIG and o/a. As Allan and Bill have indicated, I found silver-solder worked the best and was the easiest to grind with a Dremel tool and a sanding drum. Annealing was the factor that determined if the joint held. Since I have both vertical and horizontal bandsaws, I purchase my blade material in bulk rolls of 250' from an E-Bay company, SDI Hardware. I get the 1/2" X .025 X 14tpi & 18tpi for $55 & $66 per roll...that's 20c & 25c per foot which is a substantial savings. I bought a Harbor Freight 280A blade welder a few years ago on a flyer for $129 and it works superb and has paid for itself many times over. If anyone uses a lot of blades, this is a worthwhile investment. Hope that helps anyone using a lot of blades and wants to save some $$$$.......Denny

http://i55.photobucket.com/albums/g159/yorkiepap/bladewelder1.jpg
Parent - - By DaveBoyer (*****) Date 05-21-2007 04:56
Have You had much luck with BiMetal blade stock? I used to make up blades for my 4"x6" saw [64 1/2" long blade] at work, but the welds didn't last particularly well. On the large wheeled machines at the plant blades I welded held up fine, I think the small wheels on the machine were most of the problem.
Parent - - By yorkiepap (***) Date 05-22-2007 00:34
Hey Dave,
Yes, I have no problem welding the bi-metal carbon blades I get in bulk with the blade welder. It does a great job and buying bulk really is cost-effective. The smoothness of the joint and the annealing really makes the difference with the life of the blade....Denny
Parent - - By DaveBoyer (*****) Date 05-22-2007 01:51
Denny, I am not really E Bay savvy. How do I find the seller You get the stock from?
Parent - By yorkiepap (***) Date 05-22-2007 02:33
Hey Dave,
The easiest way is simply go to the E-Bay Home page, click on the "E-Bay Stores", then in the stores listing, type "SDI Hardware" in the search window. It will take you to SDI's listing and then just click on the listing......Denny
Up Topic Welding Industry / Welding Fundamentals / repair band saw blades

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