Stupid bandsaw question

[bob_c]

This may sound daft as ive had bandsaws for years but when the bandsaw is in operation are the thrust bearings and side rollers/guides supposed to be close enough so that they spin??

 

[Steve Maskery]

Bob there are no daft q's, only daft a's.

The thrust bearing behind the blade should not spin when the machine is idling, but start to spin as soon as you start to feed in the workpiece.

The guide rollers should be set a hair away from the blade. Traditionally people wrapped a cigarette paper around the blade and tightened up on to that. When the paper is removed there is just the right amount of clearance. If they are too tight they will cause friction and heat and slow everything down, if there is too much clearance they will not support the blade and you will get a poor cut.

HTH
Steve

 

[bob_c]

HI Steve, thanks for the straightforward answer. On my last bandsaw the blade used to dig into the thrust bearing all the time whilst feeding stock through (actually cutting into the bearing making it useless),do you think maybe the blade tension wasnt high enough? Another question,when the blade is running ,and you look at the blade from the front of the machine ,how much `wander?` is acceptable,ive fiddled around with the tracking but it still moves around from side to side by about 1/16".Is this normal?

 

[caretaker]

Not so much as a reply but a second question.
The side guides on my Delta bandsaw are round pins, what happens when they ware out.
Can I fit the tufnel square ones and how?
The machine is new but was bottom of the range £83 from Yandles.
Reg

 

[Digit]

Bob C. One of the reasons for wander, especially with a narrow blade is the condition of the tyres.
They are supposed to be 'crowned' so that the blade tends to climb to the highest point.
Wear on the tyres often results in the loss of the 'crown' or indeed grooves and the blade can wander as it tries to climb to the highest point.
Also check that one or both wheels are spinning without a warp in them.

Reg, I can probably turn you some round ones if you get stuck.

Roy.

 

[Steve Maskery]

Bob
I would not be happy with 1/16" variation in line.

The most common problem is the condition and quality of the blade. Few bandsaws come with a good blade. Various people on here rave about Dure-Edge (including me) Hamilton Edge (including me) and Dragon (I've not tried them yet).

Start with a good b lade, get the tension right, sort your tracking out, compensate for drift and you should be fine. If you have a collection of GWs I did an article about 18 months ago on how to set one up. If you don't, send me your email address I'll see if I can dig out the original article.

BTW, if your bandsaw blade was cutting a groove across the face of the rear thrust bearing, then either it was set way too far forward, or it was gummed up and unable to spin. If it's grooved you have little option but to replace it.


Cheers
Steve

 

[bob_c]

Bob C. One of the reasons for wander, especially with a narrow blade is the condition of the tyres.
They are supposed to be 'crowned' so that the blade tends to climb to the highest point.
Wear on the tyres often results in the loss of the 'crown' or indeed grooves and the blade can wander as it tries to climb to the highest point.
Also check that one or both wheels are spinning without a warp in them.

Reg, I can probably turn you some round ones if you get stuck.

Roy.

Roy, the tyres are ok now that ive cleaned them,there was a line of sticky gum or something around the middle of the top tyre forming a slight ridge.I think the college where the saw came from must have had a 1/4" blade on it since new.I bought a blade from axminster ,just to try it out as i was ordering something from them at the time.Its a 3/4" blade.

 

[Digit]

Do they have a decent 'crown' on them, if they haven't the blade will always wander?

Roy.

 

[bob_c]

Bob
I would not be happy with 1/16" variation in line.

The most common problem is the condition and quality of the blade. Few bandsaws come with a good blade. Various people on here rave about Dure-Edge (including me) Hamilton Edge (including me) and Dragon (I've not tried them yet).

Start with a good b lade, get the tension right, sort your tracking out, compensate for drift and you should be fine. If you have a collection of GWs I did an article about 18 months ago on how to set one up. If you don't, send me your email address I'll see if I can dig out the original article.

BTW, if your bandsaw blade was cutting a groove across the face of the rear thrust bearing, then either it was set way too far forward, or it was gummed up and unable to spin. If it's grooved you have little option but to replace it.


Cheers
Steve

Steve,The blade is just a 3/4" one from axminster to try the saw out.The saw is a 3 phase Jet JWBS-18 that i mentioned in another thread about either changing the motor or getting an inverter.I went the inverter route after finding one cheap and it seems to work fine.The tracking is obviously off somehow,i intend getting some better blades from Dragon or one of the other suppliers. Another thing i,ll mention is that there is quite a bit of vibration in the top half of the saw that i dont particularly like.I dont really want to bolt the saw down to the floor as i need to move it out for cutting long pieces of stock.I dont know if the tracking can cause this vibration or not??
The grooved thrust bearing was on my previous bandsaw and your probably right about being too close or gummed /rusted up.

 

[bob_c]

Do they have a decent 'crown' on them, if they haven't the blade will always wander?

Roy.

Yeah Roy they look ok to me ,ill try and take a picture tomorrow without the blade on it ,and you can let me know what you think.

 

[Digit]

Sounds like you might have a duff bearing up top Bob.

Roy.

 

[bob_c]

Sounds like you might have a duff bearing up top Bob.

Roy.

Might be worth checking,thanks

 

[Steve Maskery]

The blade is just a 3/4" one from axminster .

Well I'd say that is the start of your problem.

First of all, I've never heard anyone rave about the high quality of Axminster blades. Now they might be, I don't know, I'm not trying to be defamatory about Ax here, I hold them in high regard as a company, but you do need a good blade to start with.

Secondly, 3/4" is actually quite wide for most domestic bandsaws. Sure the wheels may be an inch wide, but that doesn't mean that the rest of the machine can support such a blade. A 1" blade, even a 3/4", needs a lot of tension to get it to saw straight. Even on my mammoth Basato 5, 3/4" is its realistic limit. So you may get better results simply by buying a new 5/8" blade from a recommended source.
S

 

[Digit]

It's the vibration bit that worries me, I think Bob has to find the cause of that PDQ.

Roy.

 

[OPJ]

Bob
BTW, if your bandsaw blade was cutting a groove across the face of the rear thrust bearing, then either it was set way too far forward, or it was gummed up and unable to spin. If it's grooved you have little option but to replace it.

Steve, I think he's actually talking about the back of the blade cutting a groove on the egde of the thrust bearing, rather than the face (slightly different design; very common on cheaper bandsaws).

I've just noticed something similar on my 12" SIP saw. Sounds like the thrust bearings will need replacing (Axminster for a JET machine) but I've also been told that rounding over the corners on the back of a new blade can help to prevent/reduce this. You can use a spare oilstone, if you're careful. Or, you can buy mini oil stones on wooden sticks.

I think I forgot to do this before putting a new blade on my saw recently and, after sawing all that oak and stuff, it's taken it's toll. :?

I also agree with what Steve said regarding the width of your blade. I found that on my saw, despite the manufacturer's claims, the frame couldn't stand to tension a 5/8" wide blade - which led to excess vibration and noise, as well as the blade appearing to twist and 'wobble' from side to side as the saw was running. So, I stick with 1/2" blades max. and I'm very happy.

 

[bob_c]

The groove problem was on a smaller Jet,an older model,not sure the model,it was one of those solid cast iron frame types on a stand .(JBS300??)
My new (used)saw is a Jet JWBS-18, according to the manual,it can take a 1 1/2" blade ,but i doubt that claim and dont intend trying it,but id like to get a 1" from Dragon saws for resawing..