Bandsaw rage

[Grahamshed]

Put the blade in the centre of the top wheel - Thats fine Bob, but what part of the blade, front of teeth, gullet, back of blade ?

As you will guess, I am also having this problem lately.

 

[marcros]

i centre the middle of the blade on the middle of the wheel. I cant speak for Bob.

 

[Steve Maskery]

I've said this before and I'll keep saying it...

It doesn't matter exactly where on the blade it sits, but somewhere near the middle will probably work best!

What matters is that there is NO DRIFT when you rip with the fence set parallel to the mitre slot.

Put the blade on roughly central, try it and see what happens. If it drifts, alter the tracking adjustment knob until it drifts no more. That's what the knob is for. It moves the blade forward or backwards by tilting the wheel, which in turn alters the angle at which the teeth are presented to the workpiece. You will probably have to alter the thrust bearing and possibly side bearings too, depending on how far the blade needs to move. It's no good tipping the wheel back if the thrust bearing keeps the blade where it is.

I don't understand why it is such a problem. There are loads of resources out there, and I don't just mean mine. There are books, other DVDs (admittedly mainly American) and free stuff, some of it right, some of it not right, so you have to judge what is trustworthy, but there is no shortage of info. And nobody has to live with drift, it is always possible to eliminate it rather than compensate for it, which is what most people resort to doing. That might work for ripping but you can't do anything with the mitre slot if the tracking is not true North.

The time you save and the pleasure you get from it being right hugely outweighs any cost. A long, slow, poor, unenjoyable, self-inflicted learning curve is vastly more expensive than a book. Or indeed, any other media...

Lecture over. Until the next time, anyway.

 

[CHJ]

Put the blade in the centre of the top wheel - Thats fine Bob, but what part of the blade, front of teeth, gullet, back of blade ?

As you will guess, I am also having this problem lately.

Graham, My take on the subject is that none of the above criteria (in your quote) are relevant, consider the blade as a flat belt made out of steel.

On most flat belt systems (not all) there will be at least one crowned pulley to encourage the belt to stay focused in the running plane by providing maximum tension at the crown. (Look at old traction engines driving saws and machinery or line shaft systems).

In an ideal world with a perfectly made flat belt that has not been stretched or distorted then it should have a natural tendency to ride equally spaced about the crown, a steel bandsaw blade can be considered to have a less than perfect form in as much as one edge has been crimped and mangled by the forming of the teeth so will not sit flat on a pulley and its natural drive line may not be exactly in the middle of its width and should be allowed to find its comfort point on the crown of the wheel.
Where the teeth are at this point is immaterial, given that the bulk of the band is on the pulley and stays there in use.

 

[woodpig]

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.

Old Startrites are invariably better made than most hobby machines out there so I'm not surprised!

 

[Steve Maskery]

Old Startrites are invariably better made than most hobby machines out there so I'm not surprised!

Better made yes, but not necessarily better designed. We have an old Startrite at the Community Workshop and it is the most cantankerous machine to set up. You have to undo grub screws that you can't get at with a standard Allen key, because other bits of the saw are in the way. It's an appalling design. But yes, it is built like a tank, but designed by a committee. I believe more modern ones are friendlier, however, and if I were starting up now, I'd probably look out for a second-hand one myself.

 

[sunnybob]

the blade on there is a 1/4". I was using a 3/16" for my boxes with very little trouble but then saw that handbook says 1/4" is the minimum the machine is rated for. So I changed the blade. What a mistaka to maka.
It was running forwards of centre. So far forwards that all the guide adjusters barely reached it. Turning the adjuster wheel very slowly had no effect until about two turns later it suddenly moves a half inch to the rear. Try to nudge it forwards and nothing happens untill bam! its at the front again.

This why I changed the tyres top to bottom.

Its interesting to note even here there are differences in set ups.

It seems to me that I need two bandsaws, one for boxes and one for ripping, but that aint gonna happen any time soon.

 

[CHJ]

How much slack is there in the top wheel tilt adjustment mechanism?

If there is any excessive play it could be that the top wheel angle is snapping over the 'peak point' and throwing the blade over the top.

I'm very surprised you need to even touch the tilt angle between a 3/16 and 1/4" blade

 

[sunnybob]

I spent yesterday taking out all the slack on the lift and tilt. There was well over 1mm of play front to back and similar side to side. Wont have that particular problem again.

Its still all about tension, I am sure. Wish there were evening classes here, but no luck so far.

 

[lurker]

IMHO you are worrying too much about tension all this checking with devices is a mystery to me.

I just tension until it feels right, pretty much as I used to adjust my fan belt when you had to constantly muck around with cars

I trust you have taken onboard what has been said about using a decent blade?.?

All else is just a distraction

 

[sunnybob]

"I just tension until it feels right, pretty much as I used to adjust my fan belt when you had to constantly muck around with cars"

You know that the fan belt is right because you have had dozens and dozens of practice runs and its ingrained memory. I too no longer need to measure fan belt slack. But bandsaw blades are still new to me, and I havent yet found out how to do it properly and repeatedly.

Another couple years and I expect I'll get it.

Already mentioned the blades are tuffsaws.

 

[CHJ]

Everybody gets a blade or bad day when you just can't fathom what's wrong or went wrong all of a sudden.
A few weeks ago I had a blade that started fluttering on the upside, no amount of tension changes would eliminate it completely, quick check of the blade, no cracks etc. obvious, nothing appeared in error, wheel tyres reasonably clean etc. pressed on with current task with a view to sorting it out when job done.

Bang, !!! blade failed in simple cut for no obvious reason, no fault whatever to be seen with the naked eye, so, other than I should have known better than to press on?
Fitted new blade to complete task, no adjustments to anything other than tensioning new blade, ran fine, still is going strong several weeks later.

 

[sunnybob]

another question.
people here claim years from one blade. Obviously life depends on materials cut, but assuming one wood (for example beech) only, how many hours / board feet would you expect from one blade?

 

[ColeyS1]

In your situation after trying for ages to get the machine setup right, I'd take the entire thing to pieces. Might sound crackers but take loads of pictures so you know roughly how it goes back together. It might help to understand how each part works and how adjusting each one affects the blade. There is the small risk you'll end up with a pile of pieces though....

Something drastic like that will certainly give you a deeper understanding of it.

Generally I notice a blades getting blunt, when ripping with a fence. Before m42 blades, doing curvy stuff then going back to using a fence was asking for trouble. Curvy stuff would wear one side of the blade quicker and meant wanting to rip meant a new blade. M42 blades do both.
Estimating time scales difficult. 2 of us in a shop for 50hrs a week using a regular blade when we need to, and it may have lasted 4 months. M42 blades well over a year, even then they're still sharp, just not razor.
That aside I wrecked a m42 blade in under 3 months.- operator error [SMILING FACE WITH OPEN MOUTH]


Coley
Edit- cutting 95%hardwoods