Bandsaw woes

This topic has 16 replies, 10 voices, and was last updated 12 April 2017 at 15:55 by steve de24.

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10 April 2017 at 21:16 #292850
Alan Waddington 2
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@alanwaddington2
I have an Axminster bandsaw, bought secondhand but not done a lot so not worn out. Im using blades M42 Bi metallic blades 10-14 vary pitch from Tuff Saws.

Up to now its performed faultlessly, then yesterday the blade that was in suddenly jumped off the wheels while cutting some 16mm mild steel round. I put it back on and two cuts later it snapped.

Its been in a while, so although it still looked in good nick, no teeth missing etc i thought fair enough, no drama, stick a new blade in. only had one more cut to make.

Second cut today on some 40mm EN8 round and a quarter of the way through the new blade snapped. I only had a very light feed on (saw is hydraulic downfeed) was stood at the lathe and just heard the ping as it let go…..bugger!

Just ordered 4 new blades, but at £17 a pop I'm reluctant to kill another new blade.

Could it be the tension that is too high ? or something else……Thoughts on a postcard please.
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10 April 2017 at 21:16 #18476
Alan Waddington 2
Participant
@alanwaddington2
10 April 2017 at 21:38 #292856
not done it yet
Participant
@notdoneityet
Saw blades or machine?

One or t'other.

Change blade type/supplier to find out?
10 April 2017 at 22:01 #292862
Mikelkie
Participant
@mikelkie
Check if the blade guide or roller hasn't come loose and/or pinching the blade when it comes to rest on the stock being cut. Bad alignment can also cause nasty things
11 April 2017 at 12:13 #292936
Ian S C
Participant
@iansc
Check that the(usually)wheel at the nose is running true, parallel and in line with the driven wheel when under tension, there is usually an adjustment for this.

Did the blade break at the joint? If so it may not have been annealed after welding, the firm I get my blades from had this problem for a while. Don't complain about 17 pounds, my last blade for my 4' x6' horizontal/vertical bandsaw was $NZ 52 (I think).

Ian S C
11 April 2017 at 15:22 #292976
Martin Connelly
Participant
@martinconnelly55370
I have had problems with the guide rollers being too tight for the blade thickness. Over time the blade was squeezed enough to thin and stretch the part that went through the rollers. The blade did not stay straight as a result and the weld snapped with very little wear on the teeth. I opened the gap slightly on the guide rollers and now the current blade has been in a long time with no sign of the distortion to the blade that was showing up before. Industrial bandsaws often have some sort of indicator to let you know when the blade is at the correct tension. I have seen pressure gauges on some and on others a Belville spring system with a coloured ring on part of the tensioning mechanism. When it was tight enough the coloured ring was in line with a pointer. It is surprising how much tension is put on some of these blades.

Clarke CBS7MB I got for half price because it had been dropped in its crate.

Martin C
11 April 2017 at 16:51 #292988
Alan Waddington 2
Participant
@alanwaddington2
Thanks for the replies, yes both blades broke on the weld. But the original one had been in for months so probably not a bad batch. Had a quick shufty round the saw and nothing appears to be loose or different.

Will have a good check of things once new blades arrive.
11 April 2017 at 17:56 #292992
Brian Wood
Participant
@brianwood45127
Alan,

Check the saw blade alignment right through with a wire tensioned over the pulleys and through the guides, if the tracking is still good then I think your problem might be tension related. I've had a 10 TPI Tuff Saw bimetal blade on my Axminster for months, it has done a great deal of work and I've cut 24 mm diameter hardened and tempered spring steel as well with that blade without complaint.

My guides, especially the one just prior to the blade running back round the drive pulley were quite dreadful, cast surfaces on cast with no real hope of getting alignment. Milling put those faults right and blade failure became a forgotten memory

I hope that helps
Brian
11 April 2017 at 20:35 #293007
michael howarth 1
Participant
@michaelhowarth1
Way back in 2012 I remember Ian at Tuffsaws offered a free reweld if one of his saws broke at the weld and on one occasion I did take advantage of this offer. Excellent service.
11 April 2017 at 21:07 #293012
Alan Waddington 2
Participant
@alanwaddington2
Some good tips there Brian, wouldn't have thought of using wire to check alignment. With regards to tension, is it best to just have enough tension for the blade to stay on the wheels without slipping or are you supposed to have a set amount of deflection in the centre between the guides ( bit like checking a motorbike chain ). Iv'e only had dealings with large industrial bandsaws in the past, which had tension guides.

I might Contact Ian and see if he can re weld the last blade, although by the time I've covered postage each way, it probably won't make economic sense.
11 April 2017 at 21:27 #293013
Roger Provins 2
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@rogerprovins2
Posted by Alan Waddington 2 on 11/04/2017 21:07:49:

………..

I might Contact Ian and see if he can re weld the last blade, although by the time I've covered postage each way, it probably won't make economic sense.

I've only had one of Ian's blades come apart at the weld. He replaced it free and didn't charge me return postage.
12 April 2017 at 08:25 #293045
Brian Wood
Participant
@brianwood45127
Hello Alan,

Blade tension should be such that you can pluck a musical twang from the blade on the return leg between the blade wheels. It does not have to he a high note and more than a dull thud, I am no musician!

Deflection might be about 1/4 of an inch or so

The wire will show you where all the alignment problems in the guides are. Another point to check with a blade on is how it sits against the rim of the blade wheels; you may well have to attend to that as well.so that the back of the blade is fully seated.

Brian
12 April 2017 at 10:07 #293057
Ian S C
Participant
@iansc
My supplier in NZ, and a number of others will depending on the condition of the blade will reweld blades that break at the weld. The usual reason for rejection is any cracking from the bottom of the tooth gullet anywhere else on the blade.

Twenty odd years ago I could get carbon steel blades welded free while I waited (less than 5 minutes), but now they only do bi-metal blades, and they have to go to Auckland!, come back in a fortnight, you might be lucky.

Ian S C
12 April 2017 at 12:59 #293081
Alan Waddington 2
Participant
@alanwaddington2
Well Brian, you were bang on the money, did the wire test and the guides were so far out, it's truly a wonder it ever cut straight or the blade stayed on for more than 5 minutes.

Quickly ran out of adjustment, so had to mill a bit of material off the castings to get things lined up. Just waiting for new blades to arrive now.

Was originally looking to buy a Femi bandsaw, but couldn't find a UK supplier of the model I fancied, might have another look.
12 April 2017 at 13:59 #293088
Brian Wood
Participant
@brianwood45127
Hello Alan,

That is very gratifying to hear.I suspect it will be an end of your trouble.

I do have to question whether buying another one [it will surely be generic and maybe equally diabolical] is a sensible move now that you have the current machine sorted out. For me I would stick with what you have and give it adequate time to prove itself when it isn't saddled with trouble—-my own has been through all the fire and brimstone stage and it actually works as I had always hoped it would

Regards
Brian
12 April 2017 at 14:52 #293091
Neil Wyatt
Moderator
@neilwyatt
Don't forget the adjust the tracking to make sure the blades don't jump, it may have been well out to keep blades on with misaligned guides.

I did post (yet another) link to the excellent pdf that explains how a few weeks ago, but i can't find it now.

Neil
12 April 2017 at 15:55 #293099
steve de24
Participant
@stevede2433577
Neil, is this the one you are thinking of?

**LINK**

Steve
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