Bandsaw "Wavy" cuts

[neilyweely]

dragon saws set me up nicely, sent me a couple of blades that really sorted my cheap little machine out.

Have just upgraded bandsaw to a startrite bandit 5, that knocks spots off the other one I have. It has come with some starrett blades, but I will still be sending an email to Dragon Saws to request advice and new blades.

Great service, and nice guys too.

Neil

 

[matt]

This is about as good as I've managed to the get the original 3/8" 3 tpi blade:

 

[Rich]

THAT'S NOT GOOD, I cut tenons on my Record BS300 and finish them off with sandpaper and that's with the original blades supplied from DM tools,
something is definitely wrong with your setup and "wander" seems to be the problem from looking at your pic.

Regards,

Rich.

 

[Scrit]

Hi Matt

Your original post seems to indicate that the blade is fluttering from side to side, which may be an indication of insufficent tension. But that might not be all that's amiss

So, what's the maximum width of blade your saw will take? If it's 3/4in then buy a 5/8 or 1/2in blade, if it's 5/8in buy a 1/2in, if it's 1/2in then buy a 3/8in blade. This is because almost every fabricated steel bandsaw out there is incapable of tensioning its maximum width of blade fully. As others have said bin the blade that came with it and buy a decent blade from a reputable supplier - Dragon and Dure Edge spring to mind for mail order. Good blades are good because they are made from decent quality blade stock AND the welds are well made and properly cleaned up (i.e. you get exactly what you pay for) - so with a decent blade you shouldn't hear or feel any heavy bumping or ticking when the blade is running. For resawing always keep a separate blade - never use the blade for curve work because that will put an uneven side set onto it permanently (and bang goes your decent rip). The best blade for ripping is always a hook tooth, followed by a skip tooth. Hook form blades cut more aggressively. For some information on bandsaw blade types, see here

When you set your new blade up track it with the guides backed off, then adjust the side guides to be the thickness of a thin piece of card/bank note off the blade on either side. Once you've done that set the thrust bearings at the rear of the blade a bit further off. Finally adjust the upper guide so that it's about 1/2in above your material.

To check if the blade is subject to drift lock the rip fence and saw half way into a 6in piece of 3 x 2 PAR or the like. If the blade is showing signs of wandering (always possible when using 1/2in or narrower blades) the adjust the fence to compensate. Make sure when you are feeding that the blade is not running hard against the thrust bearings - it will run against them but it shouldn't scream.

Good luck

Scrit

 

[BradNaylor]

almost every fabricated steel bandsaw out there is incapable of tensioning its maximum width of blade fully.

Good advice.

I had a bloke in my workshop a year or so ago who thought he knew how to set up my bandsaw. Stupidly I let him.

He ended up tensioning it so much that the whole thing locked tight. Nothing would move. It was a right bugger to sort out.

'The Bandsaw Book' by Lonnie Bird will tell you pretty well all you need to know about bandsaws.

Cheers
Dan

 

[kenneth cooke]

No amount of tensioning will make the blade cut straighter. It is all down to set up. Look to clean tyres and guide set up. The guides should almost touch the blade but should be set behind the gullet. Then run the saw, the blade should project a clear black line when viewed end on. If the line is blurred slightly slacken or tighten with the blade running. If you still do not get a solid black line bin the blade. Tensioning guides on any machine are worse than useless

 

[Tony Ward]

Hi,

Links to some very useful sites to do with Bandsaws and Blades which you may find useful.

 

[kenneth cooke]

Hi,

Links to some very useful sites to do with Bandsaws and Blades which you may find useful.

Good links Tony thank you

 

[OPJ]

From your photo, Matt, it does look as though you may be feeding the timber through a bit too fast - hence the diagonal cut lines. That doesn't account for the coarse finish though, so take Scrit's advice and buy some decent blades.

I think "washboarding" could be another problem, where the table insert around the blade isn't flush with the surface...?

 

[ivan]

Looks like a harmonic vibration of the blade. Try another similar rip and look for a side to side (blade-twisting) vibration of the teeth, usually with a different sound. Blade
(
)
(
)
looks like this from front (ie. teeth pinting towards you).

The blade is resonating like a violin string, excited by teeth cutting. Deep cut with softly tensioned narrow blade? Possible cures:

1/ tweak the tension up or down just a bit to move away from resonance.
2/ cut much more slowly (a bit tedious)
3/ try tensioning blade thus - raise top guide, make sure both guides are clear of blade, and with no cutting, gradually increase tension till blade stops vibrating, looks like a thin solid line. Then add a shade more, switch off set guides, and try a cut.
4/ if this does not work with a new standard blade try a thin 1/2" specialist variable pitch (3 to 4 tpi) blade (a Woodslicer) from Highlandwoodworking, where there's some useful bandsaw tips.
5/ It appears that some small bandsaws have rather springy frames, and this contributes to the problem; if yours is like this, you may have to try a 3/8" or 1/4" blade (narrower the blade the easier to tension correctly)

 

[matt]

Thanks for all the advice and feedback. I'll get myself back out in the garage and try some of the suggestions. In the meantime, I'll order a replacement blade!

 

[Tony Ward]

to think that we have problems getting alignment ~

Source: ~ http://www.premierbandwheel.com/

 

[matt]

All sorted!

Fitted one of my new Dragon blades this evening, set the tension and all the guides as per Alan's masterclass (as in not putting too much emphasis on it). Now I'm cutting slithers of beech about 4cm wide that are thinner than the grooves were deep on the picture I posted!

One question... Alan mentioned having enough tension to stop the blade slipping on the wheel... Obviously the blade stalling with the motor still going is a fairly clear sign that something is amiss, however, any other tell-tale signs if it's only slipping slightly?

 

[OPJ]

I've always believed that "slipping" refers to the blade coming off the wheel....? As long as you're rear thrust bearing is set correctly and you're careful whenever you need to 'reverse' out of a cut, this shouldn't be an issue.

Many sources suggest the thrust bearing should be about 1mm behind the blade in resting position, only coming in to contact when the material is being cut. I guess that if you find the blade is running against the thrust bearing (you can usually hear it) when no material is being fed then you're either pushing too hard or you need more tension.

 

[George_N]

Many sources suggest the thrust bearing should be about 1mm behind the blade in resting position, only coming in to contact when the material is being cut. I guess that if you find the blade is running against the thrust bearing (you can usually hear it) when no material is being fed then you're either pushing too hard or you need more tension.

I've just been reading Mark Duginske's bandsaw book and he recommends that the thrust bearing is set 15 thou (a little less than 0.4 mm). In practice he uses a folded banknote (about 4 thou thick) to set the guide blocks at 4 thou per side and then the same note doubled over to set the thrust bearing. A mechanics feeler gauge as used to set spark plugs and points gaps is also handy (does anyone have mechanical points anymore? Sorry that's a bit OT).

 

[OPJ]

I think it also varies, depending on the type of guides you have. As long as the blade is 'free' when it's not cutting though, that's the most important thing. Oh, and also that the thrust bearing prevents the teeth from coming in to contact with the side guides, of course.