Bandsaw rage

[sunnybob]

I have spent the morning rebuilding my bandsaw AGAIN> So I need to rant a little bit.

It has been working very well lately, cutting wood up to 22mm deep perfectly straight and in line with the fence.

today I tried to rip cut a plank of beech about 3ft long x 3" high down the middle to give me two slats. 2 inches into the cut and the blade takes a 15 degree turn to the left. I turn the wood over and try again. The same.

So I move the fence out the way and try to cut on a pencil line. I'm turning the wood right and left constantly. By the time I have the slats split, they look like a skate board park mock up.

WHY? Why does a bandsaw go "out of tune" so often?

I stripped all the top wheel mechanism and found a fair bit of slack between the lift and the two sliders allowing the whole thing to tilt a bit. Modified the sliders to a nice fit, and rebuilt. The top tyre has a small amount of damage, so I swapped them top to bottom. Readjusted all of the bearings.

The blade is not old, and has not been misused on reclaimed wood.

I have a circle cutting jig and it cuts perfect edge circles on 12 mm ply.
Try the beech again, and its obvious isnt it, it STILL wont cut 3" of wood in a straight line, with or without the fence.

50 plus years I have been working with machinery and engines. I have NEVER come across anything as awkwardly made as a bandsaw.

Rant over, move along, nothing to see here.

 

[RobinBHM]

Were you by chance doing lots of curved cutting before? bandsaw blades will start to wander if they edge or set has been altered unevenly.

 

[NickN]

I believe that the word 'bandsaw' is a corruption of the original old English term for such a device, the original word being 'bannedsaw' as they were so pesky to get working properly...

To think I am hoping to buy one soon, I must be mad. No doubt I will learn some new colourful vocabulary in time.

But it seems that it is indeed possible to fettle them to produce perfect straight cuts.

 

[marcros]

i have found bandsaws to be easy enough to set up- you do need to be methodical. When set, I do not find the need to constantly change settings- it doesnt go "out of tune". I can change a blade out and continue sawing within a couple of minutes on either my big axi, or little inca.

Assuming it cuts the ply ok, what blade are you using. For 1/2" ply, you would need lots of teeth (6/7/8 or so). For 3" beech, 3tpi skip tooth would be my choice. if you had lots of teeth, it would cause it to wander all over the place...

 

[CHJ]

Sounds like a combination of dulled teeth that have lost their sharpness and far too many teeth as already mentioned meaning that the blade is in effect presenting as a clogged up band, not a saw.

This leads to having to apply too much hand pressure to advance the cut, the moment you do this the blade is then going to try and find the path of least resistance rather than cutting it's required path.

If a blade drifts the first thing I do is change it out or at least sharpen it.

Cutting some ply's can rapidly blunt a blade, depends upon the adhesive.

 

[Steve Maskery]

All good advice above. Your bandsaw hasn't changed. You blade may have changed (become dull) or maybe your setup was not perfect enough. There is the world of difference between cutting 1/2" ply and 3" beech. It's easy to get a BS to cut true on thin material, because the material itself does not present a great deal of resistance. The thicker the material, the greater the resistance and that shows up flaws in setup that are not obvious with thinner material.
Fit a new, coarse, blade with big gullets to carry away the sawdust and start from scratch. You'll be fine.

 

[NazNomad]

... but once your bandsaw is perfectly in tune.

 

[memzey]

I always keep blades for straight work and blades for curved work separate and once I've made curved cuts on a blade I never try to get it to cut straight again. Might just be me but observing this rule seems to keep me and my circa 40 year old Startrite 352 free of the frustrations you have encountered. Not suggesting this is the answer, just passing on my experiences to date.

 

[Random Orbital Bob]

I'll "yes and" three points in that lot which echo my own experience:

Cutting ply, cutting circles and blade tpi.

Cutting circles unevenly wears the blade (which then causes drift in straight cuts)
Cutting any man made board plays havoc with new blades because the dry resin is far more abrasive than wood
The tpi rule of thumb is that no more than 3 teeth should be in the cut at any one time so gauge your tpi for the wood thickness carefully

 

[sunnybob]

OK, calmer this morning, so I'll try to answer the posts and questions;

Robin, Memzy, and Bob, I did cut a couple of circles purely to test my newly made jig, but literally only two in thin ply.

Nick, yes, when the bandsaw is working as requested, its far and away the best tool I have. But so far I have spent more time working on it than it has working for me.
Marcros, I havent managed any blade change and adjustment in less than a half hour yet. I've done a lot now but it doesnt seem to be getting any easier.
Naz, agreed.

Steve and a few others, I do feed the wood slowly, but its possible I asked too much of that blade as i suspect I dont change blades often enough to suit what I'm cutting.

The good thing that has come out of this is I have used my new thicknesser to straighten the mess the bandsaw made and I am very pleased with that.

Being self taught on the bandsaw its a long apprenticeship.
Right, group therapy over for today, thanks for the suggestions.

 

[lurker]

After making exacty the same mistake (blaming the saw set up) several times

Its always turned out to be the blade, usually things already mentioned, I'll add its easy to mess up the "set" on one side so the blade wanders.

I trust we have already convinced you elsewhere, to buy blades from Tuff saws?
I reckon a "sabre cut" would do that beech in no time.

 

[Alexam]

The blade can move more easily if the tension is not correct. When changing the blades, hopefully you do check the tension as well as the blade position on the top wheel ........ all without any of the guides being in contact or near the blade.

When I started using the bandsaw, it took me a while to realise that the 'set-up' has to be done in the right way and in the right order. If you forget this, the results will show.

You have the information from Steve Makery on the way he sets up and you also have the way Alex Snodgrass sets up. As long as you are also checking the tension, then all should do well. Personally I use blades that have 10-14 tpi from Tuffsaw and am often using the 1/4" blade for various thicknesses and simply allowing the blade to do it's work to determine the speed of the cut. Thicker material will naturally take more time, but when deeper material, 4-8" is being cut, I do switch to the 1/2" blade.

Keep going, it will get easier the more you do.

Malcolm

 

[Random Orbital Bob]

There is a "rough and ready" catch all that deals with all but the largest thicknesses and that's a 1/2" 3 tpi sabrecut from Tuffsaws. It's got the combination of beam strength and aggressive set/low tpi/wide gullets to really hog the waste out which is the cause of wandering cuts in the large majority of cases assuming tension is correct.

Order one from Ian today and without even seeing your machine I can virtually guarantee it will work....caveat being....tension setting is critical.....usually insufficient tension is the problem. Tracking and guide setting is way down the list of importance and frankly, you can cut dead straight with the blade I document here with the all the guides wound right back away from the blade ie "no guides" if you push slowly. I'm not suggesting you go with no guides, just illustrating that the tracking and guide adjustment is not the priority, it's almost always, blade sharpness, tpi and tension that thwart a decent cut.

 

[CHJ]

For 80% of my cutting I also use the extra set sabrecut blades, the freedom from clogging they give in moist wood and extra relief they give to accommodate wood tension 'spring' in dry stock means I become lazy and don't bother to change out for the odd 'refined cut' and sacrifice that little extra material lost in the kerf and the slightly courser finish clean up, which is lost anyway on the pass through the thicknesser.

The extra set blades are also a boon in circle cutting if the wider kerf is of no consequence to the finished piece, the additional kerf clearance allows the cutting of much tighter curves without the rear of the blade fouling.
Obviously not the blade of choice for the cutting bandsaw boxes.

On my machine, just a basic 14" SIP, I find that there is no advantage in fitting wider blades, a narrow well tensioned 1/4 or 3/8" blade will re-saw 200mm hardwood without drift as long as it's sharp and teeth set evenly.

My general experience however has been that just one inadvertent touch on an unseen hard inclusion is enough to ruin a blade as far as drift's concerned even though it looks OK to the naked eye.

 

[marcros]

Marcros, I havent managed any blade change and adjustment in less than a half hour yet. I've done a lot now but it doesnt seem to be getting any easier.

It really shouldnt take you that long, if the saw is setup and running well to start with. you slacken off the blade guides, take out the table insert and release the tension. take blade off and put the replacement on- can be a bit fiddly on wider blades. then re-tension until it feels right, reset guides and put table insert in. The tracking should be pretty much set, it may need a tiny tweek, but more often than not, I havent needed to alter mine. table should still be set at 90 degrees. maybe 5 mins rather than 2. I usually have a oover out of the inside of the machine when I am changing blades, from the times i havent used the extractor when cutting.

which part is taking the time? the adjustment? normally a small change to the tracking knob/wheel/handle can make a big difference, so you may be overcooking it by accident. I tension by feel and do a test cut, but i have heard of the flutter test from Alexm which I have not used. I dont use the tension gauge on the bandsaw either, because I have used m42 blades which take more to tension them than their width would suggest.

 

[sunnybob]

then re-tension until it feels right,

There, right there.
And getting the blade to run on the same spot on the top wheel.

This is bizzare, I have made two posts on this thread and they have not appeared (typically both of them long winded questions and answers.

 

[Lons]

I don't have problems with my old Startrite. If it doesn't cut straight it's invariably the blade which I can change with minimum fuss.

 

[bigbob1]

I have set my Bandsaw up with the following method and have never had a problem stick with it as its a bit long winded but also some interesting stuff at the end.

https://www.youtube.com/watch?v=wGbZqWac0jU

 

[marcros]

then re-tension until it feels right,

There, right there.
And getting the blade to run on the same spot on the top wheel.

This is bizzare, I have made two posts on this thread and they have not appeared (typically both of them long winded questions and answers.

i would do it until it is pretty tight, and has about 10mm movement from side to side. You wont have overtensioned it- do a test cut. if it is curved across the cut, from top to bottom (dished?), then you need more tension. you will soon get a feel for it. if it is way too loose, the blade will come off or slip. if the cut isnt straight, it is slightly undertensioned.

I put my blades in the middle of the wheel, so in theory once you get it right, if the next one also goes in the middle, all is good. it seems to settle on the same spot each time- i dont go to any special effort finding the exact middle.

 

[Random Orbital Bob]

Again...at the risk of offending the Alex Snodgrass fans.....crowned bandsaw wheels are designed like that to facilitate the movement of the blade back to centre. It therefore defies rational thinking to aim to put your blade anywhere other than in the centre of the wheel. If sensible thinking doesn't persuade you that that's the correct approach, it's what every manufacturers manual I've ever read advises too. The centre of the top wheel is the aim, the bottom wheel...doesn't matter as long as the blade is running North to South and it's not in danger of actually coming off. Snodgrass advocates the gullets being in the centre of the tyre. On the other hand......if it works..... Just saying that the only reason bandsaw wheels have a crowned design is to facilitate the re-centering of the band in the event it drifts away....so why would you set the tracking to do anything else?