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Bandsaw Blade Tension Problem

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Forum topic by greenwoodbob posted 10-31-2011 06:51 PM 1580 views 0 times favorited 11 replies Add to Favorites Watch
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greenwoodbob

20 posts in 1899 days


10-31-2011 06:51 PM

Topic tags/keywords: blade tension tension blade tension problem powermatic bandsaw bandsaw question

I am having trouble with my Powermatic 14” bandsaw tension. I’ve owned the saw for about 2 years and it’s worked great. Recently the blade became very loose. I could not seem to get it tensioned properly. I tried new blades and so messing with the tension arm and so forth.

The sliding bracket (the piece that slides the upper wheel up & down) seems to be catching on something, because as I crank the tension knob, the spring continues to compress; but the sliding bracket stops moving. If I remove the blade completely, the mechanism moves up and down just fine. But once the blade is back on, the bracket “hangs up” again just as it starts to tension the blade.

After trying a number of things I called the help desk. Long story short, I’ve now replace all of the moving parts around there, including the entire sliding bracket assembly and the quick tension assembly. Same problem.

The Powermatic rep says there is nothing more to do. Huh? My blade still is slack.

Has anyone else had this problem with the sliding bracket sticking on something; but only when the blade is on?

-- Bob Card


11 replies so far

View MrRon's profile

MrRon

2834 posts in 1900 days


#1 posted 10-31-2011 09:03 PM

Sounds like the blade tensioning rod threads are stripped.

View Bertha's profile

Bertha

12951 posts in 1350 days


#2 posted 10-31-2011 09:08 PM

^that’s what I was thinking. I don’t know the mechanics of these saws, are both wheels tight and the blade centered on the crown? I wonder if something is causing some twist/angulation in the tension mechanism, causing it to bind? I have tension problems too, but I haven’t reall started to investigate them.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View greenwoodbob's profile

greenwoodbob

20 posts in 1899 days


#3 posted 10-31-2011 10:26 PM

Mr. Ron, and Bertha – Those are valid thoughts, but indeed, all of the moving parts have been completely replaced. New tensioning rod, bolt, etc. along with the quick release mechanism…...all new. All are in working order.

The strange thing is that the problem occurred suddenly – and of course it occurred before I got all these new pieces. Now, I’ve replaced all of these parts (and they are the only parts that move relative to the tensioning of the blade), and yet the same problem remains.

I even have tried a different blade thinking that perhaps something strange was going on with the blade. But the problem remains.

Thanks for weighing in. I’ll keep scratching my head….

-- Bob Card

View NBeener's profile

NBeener

4806 posts in 1831 days


#4 posted 10-31-2011 10:32 PM

When the bracket “hangs up,” does the tension at the tensioning knob increase (meaning: suddenly harder to turn it) ?

The way you describe it, my guess would be that it does. If it does, then it sounds like some small part, in/near the adjustment mechanism, bent/broke loose, and is literally jamming the bracket’s travel path.

That make sense ?

-- -- Neil

View NBeener's profile

NBeener

4806 posts in 1831 days


#5 posted 10-31-2011 10:33 PM

”If I remove the blade completely, the mechanism moves up and down just fine.”

Without the blade, does it “move just fine” PAST the point where it hangs up WITH the blade on it …. for sure ??

This IS a weird one.

-- -- Neil

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NBeener

4806 posts in 1831 days


#6 posted 10-31-2011 10:34 PM

Last post (I promise <grin>).....

“Logic” says that—unless there IS a mechanical blockage in the mechanism, then … somewhere during installation … the blade is getting hung up on something. I know you said it’s a new problem, and not a new saw, so … I know it sounds like a pretty simplistic solution, but … possible ?

-- -- Neil

View greenwoodbob's profile

greenwoodbob

20 posts in 1899 days


#7 posted 10-31-2011 11:08 PM

Hi Neil -

I think you totally understand what I’m trying to say. And I TOTALLY agree with you that “this IS a weird one!”

Without the blade, the mechanism does indeed move PAST the point where it hangs up when the blade is on. I’ve removed and replaced the blade literally about a dozen times over the last 3 days, and this has happened each time. I’ve replaced the blade. Same thing.

You also are right: when it “hangs up” and when I tighten the tensioning knob, it keeps getting harder to turn, and indeed, the spring (with the little tension indicator) continues to depress; meaning that something is still moving. But the sliding bracket itself stops moving, and the blade does not tighten up any more.

So I agree: something is getting in the way and blocking. But I just can’t find it! I’ve even filed the sliding bracket, cleaned all the parts that touch each other, and dry-lubed them all. Still, it hangs up.

I think the next thing may literally have to be to have someone come out and take a look at this. I’m just trying to save the expense, and was hoping someone else may have had this same problem.

Thanks for your comments.

-- Bob Card

View jim C's profile

jim C

1452 posts in 1755 days


#8 posted 10-31-2011 11:32 PM

Bob
I looked at your profile but you don’t give your location.
If you can, there may be some woodjock/machinist close by that could take a look at it.
2 heads are better than one.

-- When I was a boy, I was told "anyone can be President", now I'm beginning to believe it!

View DS's profile

DS

2131 posts in 1077 days


#9 posted 11-01-2011 01:19 AM

It is hard to try to diagnose this from a distance.

From your description of the problem, I would look at the linear channel that the top wheel slides in when you adjust the tension. This may have a worn, or corroded spot that it hangs up on when tightening.

Cleaning and lubricating this area might do the trick. If it has worn a detent there, you may need to have it machined flat, or add a thin flat plate to act as a bushing so it doesn’t hang up there.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View oluf's profile

oluf

256 posts in 1696 days


#10 posted 11-01-2011 02:03 AM

I would look very close to the mounting of the frame whare you would add a rizor block. The bolts may have failed or gotten loose and the saw frame bends rather than tension the blade. This condition could happen all at once. I do not have that model of saw ,so have nothing to look at. Jost my deduction from your posts. Please let us know what you find.

-- Nils, So. Central MI. Wood is honest.Take the effort to understand what it has to tell you before you try to change it.

View mrg's profile

mrg

521 posts in 1656 days


#11 posted 11-01-2011 03:19 AM

So the tensioner has the full range without the blade. It hangs with the blade at a certain point. Does the blade tension up at all? If it does get a helper. When you are tightening the tensioner gently apply pressure to the wheel to keep the blade fro pulling it down. If that works then take the wheel off and see if the bushing may have worn and the blade is applying just enough pressure to bind everything up and keep the wheel assembly from sliding up the channel. Hope I made sense. Let us know what you find.

-- mrg

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