Cheap bandsaw - how to get the horrible thing to cut straight?

[ford34/2]

Hey Stan, be careful with that talk of fancy spec........this is poverty spec bandsaw stuff

Exactly why mine got a make over, but anyone privileged enough to have experienced the DIY and the Professional world will well know just how far apart their respective worlds are, much of the DIY stuff is built to a market and a price, but thats not to say setting it up to the very very best you can will improve its standard performance, upgrading fences, blades, guards and tracking might prove a realistic spending option, but in fairness dont spend £50 quid and then expect to do improvements for it to perform like a multi thou pro machine. A cheap car will never be a top range Merc or Rola, no matter what you do to it. I think understanding the machine, how it cuts and if possible why it doesnt cut, keeping cutting edges sharp and clean all go towards a cheap machine performing to the best of its capabilities. There are so many many cheap diy items and in the reality world if you just get one good job out of them they probably owe you nothing, anything and everything else is a bonus, But its been mentioned before cheap is cheap for a multitude of reasons.
Stan

 

[Cret]

Yep, it certainly is poverty spec!!

Still, it's what I have. I'm lucky enough to have a lot of other higher quality tools accumulated over many years but the drill press and bandsaw are the poor ones of the family!

Anyway, I've made this, but it's not quite right. I need bearings that use M6 bolts for the clearance, and only have M8 ones where the hardware is too chunky.

 

[Newlands]

1. First check the wheels are in line, with a decent straight edge laid across them. Bigger saws will have the bottom wheel housed in some sort of adjustable bearing housing, but on a cheaper saw you have to resort to shimming with washers or shim stock. A decent saw should be correct as supplied, but a cheaper saw might need some work to get it right.
2. Get a decent blade - try Tuffsaws http://www.tuffsaws.co.uk - the guys on the woodworking forums swear by them. A cheap blade will stop you getting anywhere no matter what you adjust.
3. Fit the blade and back off the blade guides so they are well clear of the blade. Tension it up and spin the wheel by hand. Adjust the top wheel so that the gullets of the teeth are running in the centre of the wheels ** ( as you've already lined the wheels up, the blade should track similarly on both wheels).
4. When the blade is tracking in the right position set up the thrust bearing - about 2-3 mm behind the back of the blade.
5. Then set the side to side guides - as the others have said a fag paper clearance is correct. Ball races are all very well, but they quickly clog with dust, even the shielded ones (I know, I have them on my machine, and I have to change them every few months). Some of the industrial saws use ceramic blocks instead, and hardened steel and hardwood blocks are common on older saws. Lignum vitae would be good if you want to try replacing yours - find an old bowling ball and you have a lifetime supply.

If you still have problems after doing the above, then you need to do some more investigation - wheels running out of true, bearings shot to pieces, twisted frame or a frame which twists under load can all throw the blade tracking out when the machine is running, even if it looks ok when you spin the wheels by hand.

** Depending on the size of the blade and the width of the wheels you might have to use a bit of judgement here - centering the gullets is the ideal but not always possible.

Lastly, it is common to blame the set of the blade for a cut which runs off line, but it is nearly always the blade not running in the correct position on the wheel. Have a look at this guy

- if you ignore the US jazz he actually makes some good points.

 

[lexi]

Cret; Do you have a hairdrier motor like mine? I will persevere too with this. If I am breaking up anything serious I go down to mate with a giant
Startrite.....awesome!

 

[Newlands]

Here's another one that might be worth watching:

 

[norlander]

I got an Elektra Beckum some years back, thinkin as its supposed to a bit better quality, I'd have it cutting straight-nah-lent it to somebody five years ago and I aint bothered to ask for it back, and don't think I'll bother.

 

[ford34/2]

if you used the eccentric cam idea, the outer diam fits the inner diam on the bearing race, the hole through the middle of this piece is drilled offset so it provides the eccentric cam and its internal diam is that to clear the bolt, the item you made do you have movement of the two bearings??in/out to just clear the blade thickness??

Stan

 

[GrumpyOne]

fag paper clearance

I think you will find the correct technical term is "baw hair".

I have a small Jet bandsaw and it is exactly the same, after reading this thread I might just be able to get it to run a bit straighter, so thanks.

 

[Cret]

Thanks guys - yeah that's right stan. It's so you can rotate them to just the right point and it moves the bearing in/outwards as you do.
Still waiting on the smaller bearings for this mod, but I have got the new blades and I put on one. Got it sitting straight and so far so good. The difference of the 1/2" blade over a 3/8" one is a lot - it's WAY thicker metal, much stronger, and doesn't appear to want to twist. So far....

 

[Cret]

Ok, got the new bearings today, and ground some metal off some bits where required.
Bearing guide fitted now with the 'baw hair' clearance and it runs an absolute treat so far as I can tell.

New blade on crappy old guide:

New guide & old:

All put together:

 

[ford34/2]

now thats a good improvement, are you doung the bottom guide as well??--or does it not have one?
Stan

 

[Cret]

I'm really pleased with it actually Stan - really smooth and straight.
As you can probably see, even with M6 bolts instead of M8 there was still a bit of a clearance issue so I had to use the dremel and bench grinder to remove a bit of meat from the holding block so it could sit far enough back for the thrust bearing to be useable.

Yes it has a lower set that's the same rubbish pegs, and I got enough bearings to do that as well, so will get that done too. It's more of a squeeze there as it's very close to the bottom wheel so I will likely have to reposition it a bit higher, but that's no bad thing as it will improve the stability closer to the table, and reduce further the chance of blade twist. In fact, thinking about it, it seems a bit daft to have it situated so low right next to where the blade goes onto the bottom tyre, but i think I can conclude from that the lower guide is to help more towards having the blade on the wheel than for keeping it straight on the cutting table?

If I can do it easily, I might actually leave the lower one as is, and add an additional bearing one much closer under the table. Only issue with that is keeping it relatively clean I guess as it'll get tons of debris on it.

 

[CRB]

Top job there Cret.

My 'old' new job has a Startrite ?352? and I heard a blade snap one day. Replacement fitted by the bloke 'who does them all the time'. I went in to use it and found the blade IN the rear pressure rod and so far back that the teeth were behind the guide blocks. I warned the floor manager and took it all apart, and put it back together again, properly.

As Stan says, understanding the way the machine works is crucial to successful setup.

I will ask this question because I have always wondered about it.

?Why is the thrust bearing using the face and not turned 90* ? It has been niggling at me for years.

 

[Cret]

I shudder when I think about some things I've done in my workshop through lack of knowledge and making foolish assumptions. Fortunately I still have all my fingers so I've been lucky.

As for your question about the thrust bearing, the same question occurred to me - seems odd as it's surely not the face of the bearing intended to bear load compared with on the end of it. Who knows!

 

[graffian]

I would imagine the bearing is that way as it uses a lot more bearing than if it were against the outer face. If it was the other way you would be on a small area and it would wear a groove. I have a solid carbide thrust on my jigsaw the blade cuts a slot in it and I have to replace it.
A ball race can stand considerable axial loads, probably way more than your going to be putting on it.

 

[Wallace]

Also, with the rear bearing at 90° to the blade you load it up axially and stand less chance of the blade wandering than if the bearing is in-line as roller bearings have a small amount of axial play in them. The 6x4 metal bandsaws (and others) run the rear bearing in-line with the blade but they also twist the blade through 45° so all 3 bearings are constantly in contact with the blade.

 

[Cret]

Ahh, fair enough then, cheers chaps.

Well, I got the bottom set done too tonight. Much more an **** of a job because of the very limited space & clearances, but it's done, and it runs real nice now. Very happy with the upgrade. Very very happy!

Nasty old one:

Ace new one: