Another band saw blade snapped – Have I got the tension wrong.

hi all i had the same problem i found that cutting big lumps of steel the blade got very hot as have the same problem i had the guards off when switched off i put my hand on the drive wheels as you do and they was very hot so i can only assume they expand in diameter putting extra tension on the blade??.

I also found a build up of scum on the drive wheel as well. my plan of action was to fit a brush to keep the wheel and blade clean i also fitted a coolant system that keeps the wheel and the blade clean.

also I take the tension off when not in use and i no longer have a problem.

hope this also helps

Kevin

If you run coolant the best location I find is after the cut not in front. This washes some of the swarf off the blade before it goes around the drive wheels. There is enough coolant carried around to do the job retained in the teeth gullets as it goes around.

I run a variable pitch blade in my saw all the time, it works well.

**LINK**

Regards
John

We used to make our own blades at work and the main failure was incorrect annealing of the weld, after that it was badly ground welds jamming.

Steve

Hi

Just a final thought, have you checked the state of the tyres on the wheels. If damaged this can cause BIG problems, and tends to be overlooked.

It is a good idea to go through all the settings by the book, not a quick look ' that seems ok'. measure gaps, check free running, watch and listen when running the blade. It is surprisin how much better a bandsaw will work with the right settings!

Good luck

Keith

Leeds UK

Keith these metal cutting band saws don't have tires, the blade runs on the metal (cast iron)wheel rim, this should have a smooth surface.

Ian S C

I've had an email that also suggests grinding down any lump at the weld, and also annealing the weld by heating to cherry-red with a very small hot flame.

Quote: Keith these metal cutting band saws don't have tires

Sorry about that, but is the blade running smoothly within the cast wheel? any lumps and bumps?

Is the blade sitting centrally?

I shall take a look at all the things suggested – it’s all very helpful so I should be able to get the saw into good shape.

posted in error -wrong thread so text deleted!

Edited By David Cambridge on 03/11/2015 12:35:35

I'm not sure whether my findings are relevant to your problem but I bought an M42 14TPI blade from Tuffsaws because I'd been so impressed with the M42 blades on my big wood bandsaw and then had two of them break on me in close succession.

I reported my difficulties to Ian at Tuffsaws and he suggested that flexible carbon steel would be a better choice because of the tight curves and repeated flexing one way and then the other, inherent in the CY90 and other small bandsaws. He suggested that the thickness of the M42 blades was partly the problem.

Since switching to a SuperTuff Carbon steel blade I've not had any breakages.

HTH

Jon

I would check if the blade is obviously bending each side of the work due to alignment of the guides or blade too loose and wondering around. On mine it isn't good idea to have the final guides too close to the work but I've never broken a blade in it.

I usually use a lubricant - what ever is about even motor cycle chain spray left over from running a 1200 Bandit. WD40 or what ever, even a few drops of 3 in 1. Part down to the saw being in a damp messy place.

The first time I looked at buying a normal bandsaw I asked were the grinder and welder was. The person feel about laughing. However some might find out what goes on with those useful. The kit is built into the side of the bandsaw. 2 types. One sort of spot welds the ends together and the other type simply pushes them together and passes a current so that it gets red hot at the joint - a bit of brazing rod is then applied. There is also a small grinding wheel on both types built in to flatten the joint. The brazing type joint could be made with a micro torch and a very simple jig. Lengths of blade work out a lot cheaper than buying ready joined one and offer a bigger range if needed.

LOL I hoped to find a small one done properly.

John

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John, the weld is not brazed - it is made under pressure and as the joint heats up and melts the two ends push excess material out and form a welded joint without the need for flux or atmosphere. you then grind the excess off and anneal the joint. It is the same method used for joining rod/wire in the rolling industry.

Mark

I've used both braised and butt welded built into the bandsaw itself Mark. The butt welding could probably be done with a capacitor bank but pass on volts and farads.

I have never ever seen a horizontal bandsaw with this facility but a number of conventional ones with it. I happen to have joined up blades on 2 bandsaws.

I didn't mention that there will also be a means of squaring up the ends of the blade.

I'd better add that what I used on one may well have been welding rod. I just used what was there.

John

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Edited By John W1 on 03/11/2015 19:25:37

Edited By John W1 on 03/11/2015 19:47:39

My first bandsaw, a vertical, had a built-in butt welder with grinder, it operated as Mark posted.

Blade ends clamped into a jig that applied pressure at the joint, power on via a push button, blade ends heat up and melt together, power off.

Let cool, release pressure, clamp again but without pressure and successive presses of power button to anneal the joint starting at bright red and degreasing with each press of button.

Integral grinder used to smooth the joint and Bob's you know who.

I wish I still had that machine.

Geoff - Why oh why do we do stupid things?

Edited By OuBallie on 04/11/2015 10:04:17

I must have used a cheap skate version as well OB that needed the flux and etc. To be honest I can't remember anyone bothering to anneal after butt welding but it was brief and a long time ago. The flux and etc is more recent.

When I asked where it was on a much smaller affair I was naive and expected what I had seen and used in industry. The question caused some amusement, the company employed a lot of older ex tool makers. This was my 1st real life intro to home machining. Then I bought a Peatol. I was impressed with that for what can be done at that size. It lived up to my expectations which are pretty extreme really - till something, probably the head bent and wrecked what was brilliant alignment. Then a Hobbymat pretty good too, no complaints other than having to deburr the dog clutch periodically. At that point due to job change it was more difficult to use larger machines so went Raglan. Pretty good too but some wear in the bed that was corrected and I had to remake one of the sides of var speed pulley. Then rust started kicking in so moved into the house. I was aware of the reality of used lathes. Then moved indoors so bought chinese, Disaster compared with what I expected and not a suitable design to sort out Then came a Myford so went for an ML7. Spent ages sorting it out and had missed that the seller set the belts super tight to get round rather loose bearings. Another dose of reality. Then came a super 7 head to fit to it - yet more sorting out and an intended trip to myford for a bed regrind. Then I noticed my current Boxford and bought it more or less blind off ebay. I did ask a couple of questions and got the right answers. Luckily not much needed doing, just a few adjustments. It just leaves me with a couple of niggles that I periodically try to sort out.

That's life for a home machinist, in my case anyway. One interesting aspect is my Dad pointed out that Boxfords were not bad machines when I was at school. Not bad because in his youth he had spent time on lathes when they were intended to offer excellent finish and accuracy and they got near to offering that and aren't too big and heavy. His idea of a small general purpose lathe was a CVA tool room lathe. More complicated bearings than most lathes and extremely expensive. He always reckoned that plain bearings in excellent order are the best. I'll bottom that out one day. He also mentioned that the first job on a new one is to make the next set while you can.

John

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