band saw advice

[powderblast]

Hi all i have just purchased a band saw and i had to install a new blade because the machine did not come with on (snapped on the previous owner)

I purchased a blade from a company of ebay called misterrbandsaw, its a 8-10tpi the full machine works fantastic however i have noticed two issues one is that band saw head appears to judder after inspecting it appears to be the weld joint running through the guide pads, is this normal also the blades cuts great on thick material but when i try to cut hollow box section it vibrates look at the pics to see the cut quality.

I was wondering could these two faults be down to a poor blade and possible wrong tpi for the material.

I think i need a blade with more teeth but unsure as this is the first band saw i have ever used

 

[powderblast]

8-10tpi is some of the teeth are 2.54mm pitch and the others are 3.2mm pitch...

Using the old 'rule' of 3 teeth in contact with the work, the thinnest 'should' be 7.5-9.5mm.

I know you can cut thinner with smaller tooth counts, but you have to be careful with the feed when it gets close to 1:1 and even more careful if the pitch is bigger than the work.

As for the joint catching on the guides, you could grind the weld down so it's flatter (use a stone to do by hand, or be careful about heat and maybe anneal if using a die grinder etc.) and maybe file a bit more 'lead' into the front edge of the guide block - that's one nice thing about using ball bearings though, a bit more forgiving.

I will have a go at filing the guard pad more and the joint on the blade.

The cuts are great other than the vertical cut on the box.

The actual machine runs great

 

[scott0031]

I would suspect it's very simply a case of the blade you have its far to coarse (which it is) for doing those boxes you have there, As PGD said the rule is 3 teeth in contact at any one time and that blade does not follow that rule on those boxes. Assuming those boxes are about 2.5 to 3 mm wall then technically the blade tends to impact when it starts the cut rather than feeding in a controller manner due to the pitch being to big, this in turn rips teeth off, induces judder and jumping on lighter built machines and the problem only gets worse the more teeth you lose. I suspect this also the judder you are experiencing and is because of teeth being lost off the blade and not the weld joint on the blade. Of course its possible to have a bad weld joint but its very rare to see them these days. Check the blade and don't be surprised if you find teeth missing already. Again as pdg said you can run a blade that is a but to coarse on thinner material but you have to be careful with but you always run the risk of losing teeth and waving bye bye to the blade. For the sake of changing the blade to the correct pitch its not worth the risk.

Don't look as blades as a tool in its own right. A blade is a consumable and one size does not fit all. Decent bi metal blades will do huge amounts of work if looked after properly. This means having a selection of blades in stock and changing them to suit what you are cutting. Nearly all blade failures are down to human error and laziness to use the right blade for the right material or bad set up etc.

 

[powderblast]

I would suspect it's very simply a case of the blade you have its far to coarse (which it is) for doing those boxes you have there, As PGD said the rule is 3 teeth in contact at any one time and that blade does not follow that rule on those boxes. Assuming those boxes are about 2.5 to 3 mm wall then technically the blade tends to impact when it starts the cut rather than feeding in a controller manner due to the pitch being to big, this in turn rips teeth off, induces judder and jumping on lighter built machines and the problem only gets worse the more teeth you lose. I suspect this also the judder you are experiencing and is because of teeth being lost off the blade and not the weld joint on the blade. Of course its possible to have a bad weld joint but its very rare to see them these days. Check the blade and don't be surprised if you find teeth missing already. Again as pdg said you can run a blade that is a but to coarse on thinner material but you have to be careful with but you always run the risk of losing teeth and waving bye bye to the blade. For the sake of changing the blade to the correct pitch its not worth the risk.

Don't look as blades as a tool in its own right. A blade is a consumable and one size does not fit all. Decent bi metal blades will do huge amounts of work if looked after properly. This means having a selection of blades in stock and changing them to suit what you are cutting. Nearly all blade failures are down to human error and laziness to use the right blade for the right material or bad set up etc.

Could you reccomened the appropriate blade for box up to 4mm wall?

 

[scott0031]

Post a pic up of the blade weld, its pretty easy to see if the joint is at fault. If there is no rise or fall in the back of the blade and the grinding is flush then blade weld is not at fault. Another simply test is to put a marker on the blade where the join is with black pen and run the saw if you hear a clonk and it coincides as it passes a guide then you know there is a problem at that point. Its a simple test if you don't really know what you are looking at with the blade itself.

 

[scott0031]

Could you reccomened the appropriate blade for box up to 4mm wall?

The best thing to so is go on a website like cromwells or msc and educate your self on blade pitches, this is stuff you really need to know yourself. The thing you need to take note of is the thinnest wall boxes/ tubes you will be cutting, this will be the governing factor with blade choice without destroying blades. Follow the rules of 3 teeth in contact at any one time and stick with variable pitch blades as they are designed for boxes and sections materials. Solid materials are better with non variable pitch Although i was told by a manufacturer that non variable pitch blades are being fazed out totally in due course.

 

[powderblast]

Post a pic up of the blade weld, its pretty easy to see if the joint is at fault. If there is no rise or fall in the back of the blade and the grinding is flush then blade weld is not at fault. Another simply test is to put a marker on the blade where the join is with black pen and run the saw if you hear a clonk and it coincides as it passes a guide then you know there is a problem at that point. Its a simple test if you don't really know what you are looking at with the blade itself.

I know it's we're the weld joint is because when the blade is running and you let the blade run through your tips it grips on the weld joint whereas the rest of the blade is smooth it is also when it judders when the joint runs through the guard pads I also think that the judders is to do with the coarse blade on the thin steel only 1 1/2 teeth actual cut into the steel wall so I'm thinking that the blade is ok for solid steel but I need finer toothed blade for box section.

 

[powderblast]

What sort of downfeed control is on it?

You cannot change the speed of the moter and the downfeed is hydrolic or I can use it with a pull down arm

 

[Woody.v8]

Nice saw , when you have sussed it you with love it

 

[scott0031]

Well if you are convinced its the weld that is at fault then send the blade back, it very simply should be a perfect joint and don't buy from them again if their quality is suspect. Use a reputable saw company or a big supplier as i mentioned like Msc or cromwells, saws uk etc or one that was quoted in your other thread about this saw. Tons of good suppliers out there.

Can you post a close up pic of the joint?

 

[scott0031]

And are you sure that saw is single speed? Saws of that style or normally 2 fixed speeds. Hard to say not having a decent of the panel.

 

[scott0031]

I Just looked at that spec age you posted on the other thread it is a duel speed as is typical of that style of saw.

Nop..... ignore that, yours is a single phase machine i think you said.

 

[powderblast]

And are you sure that saw is single speed? Saws of that style or normally 2 fixed speeds. Hard to say not having a decent of the panel.

Dosnt mention anything in the manual about been able to change the motor speed

 

[powderblast]

I'll take a pic of the box against the blade

 

[scott0031]

Yep i just twigged that and edited my post as you were posting apparently.

I have a feeling that his problem may well be the blade guide he made up looking at the other thread. Unless the guide is flat and square etc this could well be the problem and really it needs a proper hardened guide at the bare minimum. It will wear pretty quickly and will require replacing frequently if its just M/S

 

[powderblast]

Blade and box pic

 

[powderblast]

I can actually feel a ripple in the weld joint it's not smooth like the rest of the blade

 

[powderblast]

this is the weld joint of the blade and its not flush to the touch it feels like it has been sanded in to far??? could this be the cause of the judder???

 

[scott0031]

Hmm that does visually look concave, although images can be deceiving. Does it feel concave as in you can physically feel it? If it is physically concave then send it back because that is also a weakness in the blade. I have to say it is unusual to see something looking as bad at that, but its down to a cheap supplier if it is as bad as the image suggests.

 

[powderblast]

Hmm that does visually look concave, although images can be deceiving. Does it feel concave as in you can physically feel it? If it is physically concave then send it back because that is also a weakness in the blade. I have to say it is unusual to see something looking as bad at that, but its down to a cheap supplier if it is as bad as the image suggests.

yes you are able to feel it easy when running your finger tips over it this is were you get the snag in the guard pads as well and i think that is what is causing the saw arm to bounce and judder, i dont know if this looks bad as i have nothing to go off as this is the first time using a band saw, also the blade was purchased of ebay from a company called misterrbandsaw for £19.00 delivered???? https://mrbandsaw.wordpress.com/