Band Saw Blade Blues

[RAJ]

O/K it's an old bench top one I bought for £30 off ebay.

Blade 1 - managed to cut some straight lengths of Beech. approximately 60mm x 800mm. took about half an hour. I don't push the timber it just stops the blade. I naturally thought the blade was old and not so sharp.

I made some gentle curve cuts in some Spalted Beech, now as you know spalted Beech isn't as hard as Beech. I tried not twist the blade, doing some gentle forward and back moves. Anyway the blade broke, again I thought, old blade.

Blade 2 - I found a supplier and was charged £8 something + £8 post. I was stuck so said o/k.

I made some cuts again tried some gentle curves. Nope' it broke again.
Complained to the supplier who said the blade he'd supplied was to thick for my saw and it was my fault for not ordering the correct blade. O/K maybe he had a point. I ordered another one at the correct thickness. Another £8 something plus another £8 post.

Blade 3 - Didn't do much just some Spalted Beech then a small piece of Pine. Came to a knot. You guessed it. Now I wasn't pushing the blade just letting it cut in it's own time, but it should take a knot. Well I'd have thought so. Or stop the blade if it's too much.
This time I really complained, it had broke on the weld. o/k they said if it's broke in the weld we''l replace it.

Blade 4 - I'd totally lost confidence and put it away without making anymore cuts.
Anyway I've started another project and needed to make cuts. With some gentle curves. Yeah! it's gone again.

Now I've spoke to a guy who has an old bench top saw. He said he cuts small brass, steel and stainless with his blade and it's never broke.

Am I wrong here in making these gentle curve cuts? Can you only make straight cuts with a band saw?

Ray :roll:

 

[paulm]

I think you need to check a few things on the saw set-up Ray.

Firsly blade tension. Move the top guides up as far as they will go then see how much the blade will flex sideways from it's central position if pushed gently. I believe that a rough rule of thumb is 5mm deflection one side of centre will mean the blade is probably tensioned about right. Others will correct me if I have got this wrong I am sure! If you have less deflection than this then slacken off the tension a bit. Blades breaking at the welds can be due to overtensioning I believe. Blades stopping on the other hand could well be due to under tensioning, although it could also be the drive belt from the motor slipping.

Secondly, adjust the top and bottom blade guides to ensure that the back of the blade is supported. You should have a tiny amount of clearance behind the blade so that it runs freely but then when you push the wood against the blade the blade flexes very very slightly before being supported behind by the guide. Again, if the blade is unsupported it may lead to breakage.

Thirdly, you need to match the type of blade to the type of work and to the machine. If you have a small machine with small diameter wheels then you will need blades made from thinner metal to enable them to flex around the wheels without breakage. You will need narrower blades for cutting tighter curves. Best contact an experienced and reputable supplier, such as Dragon Saws 01443 834491 and they will give you more specific advice and guidance for your machine and what you are trying to do.

I am sure there are other things I have probably forgotten to mention but the above sound the most likely issues I think. Sounds like it is all a bit complex but it's not once you know what to look for and how to set it up correctly.

Cheers, Paul.

 

[RAJ]

Thank's Paul,

I didn't mind the slipping belt so much. I thought, better than breaking it :roll:

5mm either side, I wasn't far off. Maybe I could have moved the back pulley a little closer.

I could feel the chug chug of the weld as it went through. I didn't like that.

Dragon are the people, but not the supplier. The first replacement blade was their's. But they said their blade is too thick for the small wheels on my saw. So they buy them in from Dakin Flathers.

Ray 8)

 

[paulm]

Dakin Flathers are a good manufacturer as well, so seems likely it's problems in the set up or the type of blade.

Forgot to mention lowering the top blade guides to just above the height of the wood you are cutting so that the blade is supported from behind just above and just below the cut. Helps avoid a long length of unsupported blade being pushed against by the timber which can cause the blade to bow backwards and break the weld.

What tooth pattern and width of blade are you using and how tight are the curves you are trying to cut ?

Cheers, Paul

 

[CHJ]

....snip...Am I wrong here in making these gentle curve cuts? Can you only make straight cuts with a band saw?

Ray :roll:

See this post and link for how tight a curve you should be able to cut.

Do you have under table guides, and are they adjusted?
How much clearance is there in the table (insert?), is the blade catching on the table.
Is the blade tracking adjusted so that the blade is vertical to the table and the teeth are clear of the hard metal drive wheels?

Do a google search on "Setting up a bandsaw blade" and you will get many helpful returns.

This is a very basic one troubleshooting one

 

[RAJ]

Dakin Flathers are a good manufacturer as well, so seems likely it's problems in the set up or the type of blade.

Forgot to mention lowering the top blade guides to just above the height of the wood you are cutting so that the blade is supported from behind just above and just below the cut. Helps avoid a long length of unsupported blade being pushed against by the timber which can cause the blade to bow backwards and break the weld.

What tooth pattern and width of blade are you using and how tight are the curves you are trying to cut ?

Cheers, Paul

It's a 4mm blade, 12 t per inch.

The curves are gentle, working back and forward to try and not put strain on the blade.

I'll keep my eye on the top guide.

I'll just stick to straight cut's and bin it next time.

I can do most of what I want with the jig saw. I havn't broke one jig saw blade.

The band saw is o/k for the long straight cuts. I've managed 60mm x 1mm biscuits over a metre in length in Beech. Couldn't do that with the jig saw.

So what kind cutting hours would you expect from a table top 4mm B/S blade?

Working occasionally with 60mm Beech. It takes me about 20 minutes to cut a 1 metre length. So I'm not pushing it, it stops if I do. I just let it cut in it's own time.

Ray 8)

 

[paulm]

12tpi is a very fine cut Ray, and a 4mm blade is very narrow.

Unless you need a very fine finish straight from the bandsaw, and unless you are doing very tight curves, I would suggest trying a wider blade, say 3/8" or 1/2" assuming your saw will take it, and would definately reduce the tpi to no more than 6tpi possibly even 3 or 4tpi if you are not concerned about the finish.

The lower tpi will speed up the cutting performance no end and may also give a wider kerf for the cut (not 100% sure about that though) which should give more clearance for the blade to turn for curves.

As long as you are not trying tight curves then a wider blade will basically just have more metal behind the teeth and will be less prone to breaking as it is inherently stronger.

Cheers, Paul.

 

[devonwoody]

RAJ,
Are you having us on?
20 minutes to cut 1 metre.
that equals 1 minute to cut 2 inches???????????????????????????

 

[paulm]

Just a wacky idea, but I assume the blade is mounted with the teeth pointing downwards in the direction of cut ?!!! :shock: :lol:

Cheers, Paul.

 

[DaveL]

Ray,

I think Paul has hit on your problem, the blade has too many teeth on it for the thickness of the timber you are cutting. What happens is the gullets fill with saw dust and the teeth can no longer cut, hence the very slow cutting speed.
How much set does the blade have? If its not much then backing up the cut is tricky as the blade may well bind, you may find that rounding the back of the blade helps. To do this you need a fine oil stone. Run the saw and apply the stone very gentle to the back corners of the blade, some high quality blades have this done when you buy then, so check first.

I think if you are doing almost straight cuts then a 1/2" 3 or 4 tpi or even better a 3-4 tpi variable tooth pitch design blade would be the best choice.

 

[bluesman]

just a newbie her but I just bought a new small bandsaw - you might want to scroll down a bit and look at my topic on bandsaw tracking - got some good replies. 20 minutes to cut 1 metre - wow something wrong there alright. I just ripped some oak about 50mm thick and it took about a minute and I was taking it easy. I'm using 6 tpi as supplied with machine which seems a good general blade.

 

[RAJ]

Just a wacky idea, but I assume the blade is mounted with the teeth pointing downwards in the direction of cut ?!!! :shock: :lol:

Cheers, Paul.

:lol: :lol: :lol: Nice one Paul

no not having you on Devonwoody.

I must say both Saws U/K and Dakin Flathers have been very supportive.

However one replacement blade I received, I have drawn their attention to.

It has a decided kink in the weld area.

http://pic20.picturetrail.com/VOL1443/6 ... 946840.jpg

I've only unwrapped it not used it at all. I've sent them a pic'.

I was hoping for a smooth cut to reduce sanding. I have a 6t/inch blade now.

Ray 8)

 

[devonwoody]

RAJ, you cannot take one minute to rip 2", the blade would have melted down in that time.

Start from scratch again and rip a piece of waste 2" thick softwood, one metre should take around 20 seconds.

And report back if you like.

No offence meant by any of my remarks by the way.

 

[Scrit]

As a point of comparison I've ripped-down some 6in thick pitch pine this morning on a 1HP Startritea saw - 3 tpi hook tooth 3/4in blade - rate approx. 3 metres/minute (they were 5ft pieces and took 30 seconds or less to rip). If you want to rip then hook tooth low tooth count is the way to go, "normal" or "regular" tooth blades are for working thin stock because the gullets clog so easily.

Scrit

 

[DaveL]

I cannot match the feed rates that Scrit achieved, but on my eb 315 fitted with a wood slicer I have just resawn 3 lengths of 6 1/2" oak. It took 2 minutes per 30" length, taking it gently.

 

[RAJ]

RAJ, you cannot take one minute to rip 2", the blade would have melted down in that time.

Start from scratch again and rip a piece of waste 2" thick softwood, one metre should take around 20 seconds.

And report back if you like.

No offence meant by any of my remarks by the way.

No problem Devon' I like a joke and a bit of wind up when it's in good taste.
As I've said if I put any pressure on it would stop the blade. I had to let it do its own cutting.

I wanted a piece of Pine about 100mm. It didn't cut much faster than the Beech and broke when it came to a knot

O/K you've twisted my arm. I've just fitted another blade 6t/inch and timed the cut.

1 @ 500mm x 55mm Beech 10 minutes.

1 @ 250mm x 45mm Pine 1.5 minutes.

Mabe I'm expecting too much, it's only 1/4 hp.

If I break anymore I'll just silver solder em'.

Thank's for the help lads. I'll just stick to straight cuts.

Ray 8)

 

[DaveL]

As I've said if I put any pressure on it would stop the blade. I had to let it do its own cutting.

I assume that you are stalling the motor?

Mabe I'm expecting too much, it's only 1/4 hp.

That does explain a lot, under powered is the problem, I think it may only of been intended for use as a big scroll saw. :evil:

 

[RAJ]

As I've said if I put any pressure on it would stop the blade. I had to let it do its own cutting.

I assume that you are stalling the motor?

Mabe I'm expecting too much, it's only 1/4 hp.

That does explain a lot, under powered is the problem, I think it may only of been intended for use as a big scroll saw. :evil:

No the motor doesn't stall the belt slips.

I just wont have to be in a hurry :roll:

Ray 8)

 

[devonwoody]

O/K it's an old bench top one I bought for £30 off ebay.


Remember this is the opening line of this thread, so perhaps the machine is a lemon.

 

[RAJ]

O/K it's an old bench top one I bought for £30 off ebay.


Remember this is the opening line of this thread, so perhaps the machine is a lemon.

I've been wondering that myself :roll:

But what can be wrong? A blade runs around three wheels, quite simple really.

Ray 8)