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Bandsaw woes - but now fixed :)

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Re: Bandsaw woes

Postby Trevanion » 28 Jun 2021, 18:18

sunnybob wrote: But I still say that frame is never going to work harden, let alone crack. 8-)


I would agree with this, I've never seen a noticeably bent bandsaw frame nor one that was broken (or at least, one that wasn't dropped from height) either made from welded steel or cast iron. After 200 years or so of bandsaw technology, you'd think there would at least be one case if it was a design flaw.

Likewise, with "flat spots" on the band wheels, has anyone actually ever seen this happen themselves? With the blade bearing on half the wheels and the tyres being quite stout I can't really see it ever being a big issue in the short term. I've definitely seen (and I'm sure some of you have also) bandsaws that have been abandoned with a tensioned blade for many years with no use and they get put into service without any "flat spot" issues.

Just those "engineer" types with too much time to bloody think about problems that are absolutely non-consequential, same with those daft "Carter" bandsaw guides, they cost a small fortune and they will not improve the cut of the machine, extend the life of your blades, or make you a magical woodworking wizard once installed despite claims. I've had the good fortune to have used pretty much all kinds of bandsaws from the little Burgess three-wheelers, to the middle of the line Startrite 352s, all the way up to the big Stenner re-sawing bandsaws, the thing that made the biggest difference across the board to the cut quality was how sharp your blade was, with tooth geometry and feed rate coming in close behind, differing types of blade guides make very little to no difference, a sharp blade is absolutely key.

Rant over... :lol:
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Re: Bandsaw woes

Postby Woodster » 28 Jun 2021, 20:13

Trevanion wrote:
sunnybob wrote: But I still say that frame is never going to work harden, let alone crack. 8-)


I would agree with this.


So do I. I don’t know why Bob has suggested work hardening and cracking. Probably just a slight over exaggeration to support his position?

What’s with the rant about Carter products?
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Re: Bandsaw woes

Postby Trevanion » 28 Jun 2021, 20:27

Woodster wrote:What’s with the rant about Carter products?


It was more of a general rant about people who overthink bandsaws to the Nth degree. The Carter guides being a prime example of said overthinking, it's a solution looking for non-existent problems.
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Re: Bandsaw woes

Postby sunnybob » 28 Jun 2021, 21:14

No, its a very clever marketing ploy :D
But the single wheel guide does actually have some effect with super thin blades cutting sharp curves in bandsaw boxes.
No, I cant afford them :eusa-naughty: , but I knew a boxmaker who had a single wheel and spoke highly of it.

My reference to the frame cracking was an extrapolation of the quote from the axminster comment about the frame not taking kindly to constant changes in stress. the only way a steel box section frame can not take kindly to anything, is to bend and subsequently crack. Either of which I find very hard to believe, except on the smallest and cheapest bandsaws.
Even the truly awful Fox machine that was my first bandsaw was stronger than that.
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Re: Bandsaw woes

Postby RogerS » 28 Jun 2021, 21:31

Steve Maskery wrote:Yes, it's always tensioned. Quite possibly that might be a bad idea...


Nope...if it's good enough for Peter Sefton to leave tensioned up then it's good enough for me.
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Re: Bandsaw woes

Postby Eric the Viking » 28 Jun 2021, 23:15

My little SIP saw is similar to probably hundreds of others from China over the last few decades. It has huge annoyances, one of which is that it _does_ bend with big blades, so that the top guide support goes significantly out of alignment when a big blade is well tensioned. One thing that has always annoyed me is that, although it ought to be strong enough, the frame is only tack-welded in places up the main column (a pair of rectangular-section steel tubes side-by-side), and it's not continuous. Given the paint is getting a bit manky now (it's old!), I am tempted to grind it off and fill in with weld between the tacks, to see if that improves matters.

But Trevanion is spot-on - with a sharp blade and decent tension it still cuts really well. I just have to double check squareness to the table, if that matters for the job in hand.

That said, I changed the bearings (top + bottom wheels) recently, and that's brought it back to nice smooth kerfs again - it was getting a bit ragged, which I think was wear. A cheap "upgrade" though, likewise the guide bearings too, but with a big blade only the back bearing ever touches whe it's cutting, and even then only if I push too hard.
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Re: Bandsaw woes

Postby sunnybob » 29 Jun 2021, 04:54

out of curiosity only, have you tried reducing the tension until the cut visibly deteriorates?
I have a theory (substantiated by nothing other than my own feelings) that most people over tension bandsaw blades because they feel they should.
I was recently cutting a block of walnut 18 cm thick for a bandsaw box, and got a really nice cut surface, then 2 days later while cleaning the machine I realised the blade was quite poorly tensioned.
I wound it up three turns to make it "ping", and the cut became rough. :shock:
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Re: Bandsaw woes

Postby Woodster » 29 Jun 2021, 16:42

Eric the Viking wrote:My little SIP saw is similar to probably hundreds of others from China over the last few decades. It has huge annoyances, one of which is that it _does_ bend with big blades, so that the top guide support goes significantly out of alignment when a big blade is well tensioned. One thing that has always annoyed me is that, although it ought to be strong enough, the frame is only tack-welded in places up the main column (a pair of rectangular-section steel tubes side-by-side), and it's not continuous. Given the paint is getting a bit manky now (it's old!), I am tempted to grind it off and fill in with weld between the tacks, to see if that improves matters.


Modern hobbyist bandsaws simply aren’t as rigid as they could be, a consequence of being affordable. As you’ve noticed most are just welded mild steel sheet. Provided you don’t use overly large blades on them though and take the tension off when you’re finished they can work very well with a good blade. Some of the modestly sized American bandsaws of the recent past seem to have cast iron frames so I expect they may be better in some respects.
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Re: Bandsaw woes

Postby Eric the Viking » 01 Jul 2021, 07:02

sunnybob wrote:out of curiosity only, have you tried reducing the tension until the cut visibly deteriorates?
I have a theory (substantiated by nothing other than my own feelings) that most people over tension bandsaw blades because they feel they should.
I was recently cutting a block of walnut 18 cm thick for a bandsaw box, and got a really nice cut surface, then 2 days later while cleaning the machine I realised the blade was quite poorly tensioned.
I wound it up three turns to make it "ping", and the cut became rough. :shock:

Well I usually don't fuss too much about tension, but do what you say - try a test cut to see. I like it tight enough to not need much from the guide bearings. Proportionally, I probably tension small blades more than big ones.

But I think there's a bit of 'no free lunch' about frame rigidity. The few bigger Stenners etc. that I have been up close to (annoyingly I cannot remember the detail of my grandfather's one, which I think was Wadkin, as all the other mill machines were), seem to have a suspension arrangement (springs) for the top wheel axle, to allow some give - wouldn't be there if it wasn't needed. I would think frame elasticity helps on smaller saws, although mine also has a spring...
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Re: Bandsaw woes

Postby Doug » 01 Jul 2021, 07:29

RogerS wrote:
Steve Maskery wrote:Yes, it's always tensioned. Quite possibly that might be a bad idea...


Nope...if it's good enough for Peter Sefton to leave tensioned up then it's good enough for me.


But Peters will be used very frequently isn’t the point that it’s a good idea to release the tension if the saw is going to stand idle for a while?
I imagine flat spots on a tyre also has a lot to do with the quality of the tyre.
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Re: Bandsaw woes

Postby sunnybob » 01 Jul 2021, 10:26

My axminster 350 does have a spring on the top adjusting wheel support.
Sadly it seems to be there for looks only as its utterly useless. It fully compresses way before the blade gets even close to tension.
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If I could find a spring with double the strength it might just be useful.
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Re: Bandsaw woes

Postby Steve Maskery » 01 Jul 2021, 10:34

Mines the same, actually.

I'm just off out to pick up the repaired casting.
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Re: Bandsaw woes

Postby Woodster » 01 Jul 2021, 11:06

I’m pretty sure the spring is the same on mine. Strange design?

sunnybob wrote: But the single wheel guide does actually have some effect with super thin blades cutting sharp curves in bandsaw boxes.
Last edited by Woodster on 28 Jul 2023, 10:15, edited 2 times in total.
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Re: Bandsaw woes

Postby Steve Maskery » 01 Jul 2021, 21:30

Well I've got it back.
bs fixed 1.jpg
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bs fixed 2.jpg
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You can see how the hairline fracture has opened up as he straightened it. That was invisible when I took it off. Stuart has filled the cavity with a 2-part metal epoxy amd an aluminium bar, then plated it front and back and pinned it top and bottom. The bottom bolt also now acts as a bearer for the tracking thrust knob. It weighs a ton, now.

It may not be the prettiest job in the world, but I bet it is 10x stronger than it was originally and, as I've had the saw 20-odd years, I fully expect it to see me out.

The saw is up and running again and I can get on with my project, yippee!
S

PS - On a Facebook group yesterday, someone was saying that their BS was drifting and what could they do about it. I explained how the tracking knob tilts the top whell, alters the position of the blade and therefore changes the cutting direction.

Another gentleman said you just need a sharp blade and it will be all good. When I pointed out that you needed both, he said that I should watch "the American guy" who "knows what he's talking about".

I maintained a dignified silence, at least online.
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Re: Bandsaw woes - but now fixed :)

Postby Woodster » 02 Jul 2021, 12:08

Glad you’re sorted Steve.

I wonder which American guy he was referring to?
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Re: Bandsaw woes - but now fixed :)

Postby Eric the Viking » 05 Jul 2021, 07:18

Woodster wrote:Glad you’re sorted Steve.

I wonder which American guy he was referring to?

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Re: Bandsaw woes

Postby Woodster » 29 Jul 2021, 12:22

AJB Temple wrote:What has caused it though? Over tensioned wide blade?


Looking at this again Steve admitted he never detentions his blades. I personally think this is a contributing factor to the part bending like that. It my be a poorly designed part but if the manufacturers instructions to detention the blade after use had been followed it may have taken another 20 years before it failed.
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Re: Bandsaw woes - but now fixed :)

Postby Steve Maskery » 10 Oct 2021, 15:06

Well there is Development on this.

Sadly, despite Stuart's best endeavours, the repair did not last and a few days ago I was back to square one. Worse, actually, because as it failed it took a brand new blade with it :(

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So I rang Stuart to see if it came with any sort of Warranty :)

He grumped and said I must have over-tensioned it. Well I'm pretty sure that I didn't, it was only a 1/4" blade, it doesn't need a lot, but for whatever the reason, it's gone. Unfortunately, Stuart is in Spain, taking the Sol feor a few more weeks before coming back to Blighty, so I was faced with a month of no BS.

But fortunately, Stuart is not the only engineering friend I have.

So yesterday morning, I email Pete. "Pete, I have a problem. I think you can fix it for me. Can I come round please?"

I'd already been shopping for some steel and Pete said, "Leave it with me for a couple of days". What? He wasn't going to drop everything and do it while I waited? Huh. Some people have no sense of urgency.

So I went home and started doing some work on my currently illegal trailer. Can of worms job, that one, but I digress.

3pm the phone goes. "Are you coming to collect this or what?" Really? "I'd have finished it earlier but I stopped for lunch".

So I go back to Pete's to find a really superb piece of engineering, It's beautiful. He'd even sorted out the thread that I had knackered getting the old part off.

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I've had a bit of a struggle getting the assembly back on to the saw, largely because you really need three hands. I can see how this saw could quite easily have been engineered differently at zero extra cost and in a way that would have made this job a whole lot easier, but it's done now.

It's all set up and the tracking behaves as it should, it's not been like this for years. The original part may have lasted 23 years, but this will last 123 years.

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Re: Bandsaw woes - but now fixed :)

Postby Pete Maddex » 10 Oct 2021, 16:08

I did have to get the lathe out of the shed first, not sure about P on my chest, underpants yes.

:D

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Re: Bandsaw woes - but now fixed :)

Postby Trevanion » 10 Oct 2021, 17:30

It's so strong that something else has got to give and break now, eventually, if you replace every part gradually you'll have a machine comparable to a Centauro :lol:
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Re: Bandsaw woes - but now fixed :)

Postby Andyp » 10 Oct 2021, 19:01

Pete Maddex wrote:I did have to get the lathe out of the shed first, not sure about P on my chest, underpants yes.

:D

Pete


You certainly cant’t go around with PM as a moniker. Although perhaps if you were mistook for the current incumbent........ :)
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Re: Bandsaw woes - but now fixed :)

Postby Pete Maddex » 10 Oct 2021, 21:15

My initials are PMM so I could be PM PMM.

I have two sons their initials are SAM and TOM.

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