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View Full Version : Band saw problems - Heads up.



John Stevenson
11-30-2012, 07:20 PM
Having had quite a bit of experience on building and trouble shooting large band saws, up to 36" capacity, I have learn a fair bit over the years.

First thing, top of the list is if the machine cuts OK then has problems it's the blade, full stop.

Well over the last couple of weeks I have noticed that mine is cutting at an angle, no great shakes the blade is a good year old and that's very good for me but although it's at an angle it still cuts well. 2" steel in about 2 minutes and I have been getting by with packing the end up so the bar is tilted to start.
Yes I know a bodge but it works. Anyway ordered a new blade up so I can swap this over.

Today I noticed that as it started cutting on some 4" bar the blade took a skip and wobble ??

Side roller are fine and adjusted correctly so pulled the back roller assembly off to get a better look and the top support bearing had a groove in it, enough so that it it rode out of the groove it twisted the blade.

http://img.photobucket.com/albums/0903/registered_user/bandsawbearing.jpg

Slammed a couple of new bearings in, fortunately the rewinders were bringing a job down so asked them for two bearings.

Gave it a quick check and 98% better.

So a heads up to check those top bearings from time to time.

randyjaco
11-30-2012, 08:19 PM
Hey John,

Carter Product http://www.carterproducts.com/index.asp has some nice thrust wheels that have the squared slot ground into them. You might give them a look. They are a little pricey but they will help keep that blade square.

Randy

dfw5914
12-01-2012, 12:50 AM
Thanks for the heads up.

+ or - Zero
12-01-2012, 03:27 AM
Probably one of the best arguments for canted back rollers I've seen in quite a while.

darryl
12-01-2012, 03:31 AM
Good reminder- I'm going to check mine right now.

John Stevenson
12-01-2012, 05:10 AM
Thanks for that randy but can't see the point, it works fine on flat bearing faces and the back will follow the roller no matter where the eccentric side rollers are.

The heads up was the fact that those top bearings were only about 4 years old, same age as the side rollers which are still good and if I had not spotted the skipping I would have just dropped the new blade on.

It's got a very slight taper on it even with the new bearings but i put that down to the set of the blade wearing on one side more than the other because it's been forced off track.

Now here's a brilliant bodge but anyone of a delicate disposition please look away now.

Cutting some old girders once and hit a hard spot, knew at once by the noise.
Stopped the machine and took a second cut a bit further up, cut Ok but now cutting tapered as the inside teeth had taken the hit from the hard spot.

Didn't want to put a new blade on and have the same problem so ran the saw out of the cut and took a gentle swipe with one of those square grey carborundum stick you clean grinding wheels with on the opposite side, held it on long enough to do 1 rev of the blade.

Did another cut and it was better, second touch up got it perfect.

Obviously cut slower due to both sides being slightly blunt but at some point in it's life it would have reached this anyway.
That blade want on to run another 3 or 4 months [ and for me that's a lot of cutting ] before I needed to fit the new blade.

Done the same trick a couple of times since then to extend blade life, in fact I was just getting ready to do it to this blade before I spotted the skipping.

Might not bother with say a 6 x 4 bandsaw but this puppy takes a 12' 6" x 1" blade

Forrest Addy
12-01-2012, 05:25 AM
You mean stuff doesn't last forever? Man! You realy know how to distress a guy.

Rex
12-03-2012, 05:05 PM
I wonder if those bearings were Timken or an import?

I am changing out all the bearings on my Marvel 612 with the cheap ones. I don't know that it will get enough use to see a wear pattern, but if so I'll will replace with Timkens.

vpt
12-03-2012, 07:05 PM
Yup, good tip!

When I got my bandsaw I went threw it before even using it and replaced all the blade guide bearings right off the bat. I believe they cost me something like $30 for 10 of them.

bosox
12-05-2012, 02:58 PM
By the way, what's your band saw?

John Stevenson
12-05-2012, 03:42 PM
By the way, what's your band saw?


If that question is related to me then it's an early Startrite, capacity is 13" round or 12 x 18" rectangular. The bearings were all new about 10 years ago and would have been decent but not expensive bearings. Side bearings are still OK and the back bearing on the exit side of the blade which in my case is the one nearest the end you stand was also OK but it was still changed just in case.

One point on my saw is the blade is set to run opposite from what you expect, it runs uphill from the back fixed vise jaw forward toward the moving jaw. most blades run downhill to wards the fixed jaw. Presumably because it's the fixed jaw.

However when the work is clamped firm does it matter which one is the fixed jaw ? If it's secure then both jaws are fixed.

When you run a blade downhill if it snags in the cut it wants to bite in because it's being forced down.

If you run a blade uphill, if it snags it tries to jump up and out of the cut making it more gentle on the blade. As an experiment I fitted a new blade on the generic 4 x 6 saw and ran it until the blade was worn out and it lasted 6 weeks. Bear in mind my saws do some serious work.

Motor was reversed and the new blade spun inside out and fitted, new blade lasted 10 weeks doing the same type of work. Bear in mind my 4 x 6 never ran vertical so reversing the blade wasn't a problem.

Abner
12-06-2012, 07:03 AM
Sir John,
A year on a blade? That sounds like forever to me. How big of a machine do you run? How big are the wheels?

I have used one of those import 4x6 for years and if I get 2 months on a blade then I'm lucky.

John Stevenson
12-06-2012, 08:20 AM
Abner, details in the post above, wheels are probably about 15" to 18" and the blade is 12' 6" x 1" wide.
Only use Lenox blades, vari tooth 5 -8 tpi

Abner
12-06-2012, 08:34 AM
Sir John, man oh man what you describe, running your blade reverse of "normal", is very intelligent! By my math, and your 6 vs. 10 wks works out to (edit) 66% longer life from a blade.
Thank you!

bosox
12-06-2012, 09:21 AM
Sir John,
Did you encounter other problems with your band saw? Like the motor screwed up , stuff like that?
How old is your band saw and are using cutting fluid?

My blades are Haltbar blades. I've been using them for couple of years already. It never gave me frustrations so far.

EVguru
12-06-2012, 09:31 AM
Sir John,
Did you encounter other problems with your band saw? Like the motor screwed up , stuff like that?

It's odd, I'm often seeing comments from the US about how poor the motors are on these generic 6x4 bandsaws. I don't recall ever seeing one from the UK.

My saw bought from Axminster Power Tools has run for years with no problems. The motor never gets too hot to comfortably put a hand on and the second saw I bought to build up on to a better stand (later sold to a friend) was just the same.

Are US importers pushing the cost to them too low, or is it the enforcement of the CE standards that means that the motors we're getting seem to be better?

rollin45
12-06-2012, 10:49 AM
I've got a little 4x6 bandsaw that I bought from Enco. The saw is about ten years old and when I bought it, one could opt for a UL motor, or one that was "untagged". The difference was about 10 dollars as I recall, I fell for the UL "spec", but I've not had any problems with the saw either.

rollin'

bosox
12-07-2012, 09:23 AM
Are US importers pushing the cost to them too low, or is it the enforcement of the CE standards that means that the motors we're getting seem to be better?


The latter part. I'm not sure though if that is what really going on . I have a metal cutting band saw with 2hp motor. Got it couple of years already and I never had a problem .

John Stevenson
12-10-2012, 08:08 PM
Got it all sussed.

http://www.stevenson-engineers.co.uk/files/gear%20blanks.jpg

Two hours work tonight, 50 gear blanks cut out of EN8 at 2" diameter, nominal size, 7/16" wide.

Random checks show 0.007" error in width.

Toolguy
12-10-2012, 08:43 PM
Looks good! Now you need to get that POS Bridgy back together and finish them so you can make some money!;)

John Stevenson
12-11-2012, 04:28 AM
Bridgy is still running, it's slated for a Christmas week transplant, still trying to get my head round the inverter book.
I thought Siemens was obtuse but this one is close.

Bridgy isn't used on these gears, lathe, broching press and the old faithful Victoria U2 converted to an electronic gear hobber.

bosox
12-11-2012, 02:29 PM
Got it all sussed.

http://www.stevenson-engineers.co.uk/files/gear%20blanks.jpg

Two hours work tonight, 50 gear blanks cut out of EN8 at 2" diameter, nominal size, 7/16" wide.

Random checks show 0.007" error in width.

I didn't realize I can make coins from band saw. Kidding aside, that's a very nice work.

outlawspeeder
05-06-2013, 10:39 AM
Is there a good source for these rollers? I have one of the cheap one Buffalo frrom New York. I normally cut small stuff but last night I found out how to waste a of stock when cutting 1.5 squire using the #@^@# band saw.

bruto
05-06-2013, 10:47 AM
Jumping to the end of the thread, I would just like to add that on saws in which the rear roller is 90 degrees from the one shown (in other words the blade back rides on the face of the bearing) similar problems can occur and you should keep a close eye on the bearing face and how freely it turns. If the bearing or (on cheap saws) the plate on an axle stops turning, it will wear a groove very quickly, and never turn again. It may behave pretty well for a while until the groove is deep enough to twist the blade.

Weston Bye
05-06-2013, 11:45 AM
For the more parsimonious among us:
What would be the effect of "rotating the tires," swapping a bearing with a groove worn in the outer race with one of the side bearings, provided that the bearings were otherwise functional?

becksmachine
05-07-2013, 01:56 AM
Parsimonious?? You don't know the meaning of the word! :rolleyes:

To do it properly, you initially offset a new bearing to one side as far as you can. When the groove becomes deep enough there to bother blade alignment, just turn the bearing around to wear a groove near the opposite edge.

And if your are really good, the third stage is to center the bearing to wear a groove in the center, between the previously formed grooves on each side.

Dave

Mark Rand
05-08-2013, 07:02 PM
Old thread, but I think I've got another use for John's 'back to front blade'.

I've been cutting a number of slices off 3" aluminium bar with an Axminster sourced 4x6" saw and having problems with the chips not falling away before the blade gets to the guide rollers. Once the chips jam in the rollers, the blade stalls and comes off the drive wheel. The only way I've been able to run it reliably is to run the blade at the lowest speed and use the vacuum cleaner to catch the chips off the blade.

If I reverse the blade and motor, I can adjust the position of the guide rollers to give more than twice the distance for the chips to fall off the blade before it gets to the guide rollers. That might mean that I can run the blade at a sensible speed and not have to stand over it while it's cutting.

I hadn't thought of it before, but the 16" bandsaw I sometimes borrow at work has the blade running 'uphill'.

flylo
05-09-2013, 12:37 AM
Sir John,any chance of a couple of pics while hobbing on the lathe?

Bridgy is still running, it's slated for a Christmas week transplant, still trying to get my head round the inverter book.
I thought Siemens was obtuse but this one is close.

Bridgy isn't used on these gears, lathe, broching press and the old faithful Victoria U2 converted to an electronic gear hobber.

+ or - Zero
05-09-2013, 02:03 AM
Old thread, but I think I've got another use for John's 'back to front blade'.

I've been cutting a number of slices off 3" aluminium bar with an Axminster sourced 4x6" saw and having problems with the chips not falling away before the blade gets to the guide rollers. Once the chips jam in the rollers, the blade stalls and comes off the drive wheel. The only way I've been able to run it reliably is to run the blade at the lowest speed and use the vacuum cleaner to catch the chips off the blade.

If I reverse the blade and motor, I can adjust the position of the guide rollers to give more than twice the distance for the chips to fall off the blade before it gets to the guide rollers. That might mean that I can run the blade at a sensible speed and not have to stand over it while it's cutting.

I hadn't thought of it before, but the 16" bandsaw I sometimes borrow at work has the blade running 'uphill'.

My old horizontal Wells Saw had nice brushes that cleaned the blade, well they wore out/got lost long before I got the saw (1948 vintage), so I replaced them with a set of tooth brushes --worked so good that I rigged a set on my 1938 Delta 892 14" vertical wood saw (it also has the internal tire brush, which is a good add on).

On the Wells Saw I also put a set in front of the work --I put cutting fluid on them, works like a slow cutting fluid feed (it has a flood coolant system but I rarely use that, just to small a hobby shop use to need it very often).

Zero.

whateg01
05-09-2013, 11:34 AM
Old thread, but I think I've got another use for John's 'back to front blade'.

I've been cutting a number of slices off 3" aluminium bar with an Axminster sourced 4x6" saw and having problems with the chips not falling away before the blade gets to the guide rollers. Once the chips jam in the rollers, the blade stalls and comes off the drive wheel. The only way I've been able to run it reliably is to run the blade at the lowest speed and use the vacuum cleaner to catch the chips off the blade.

If I reverse the blade and motor, I can adjust the position of the guide rollers to give more than twice the distance for the chips to fall off the blade before it gets to the guide rollers. That might mean that I can run the blade at a sensible speed and not have to stand over it while it's cutting.

I hadn't thought of it before, but the 16" bandsaw I sometimes borrow at work has the blade running 'uphill'.

It sounds like you have the guide wheels set too close. How much clearance do you have?

I have seen saws that the blade was reversed on. Not sure if the factory did that or if somebody was trying what you describe. On my saw, doing that would mean I'd have to make a new vise that extends out to the blade for stock that needs the support there. I don't think the moving jaw on the vise is capable of providing the same support.

Mark Rand
05-09-2013, 06:51 PM
It sounds like you have the guide wheels set too close. How much clearance do you have?

I have seen saws that the blade was reversed on. Not sure if the factory did that or if somebody was trying what you describe. On my saw, doing that would mean I'd have to make a new vise that extends out to the blade for stock that needs the support there. I don't think the moving jaw on the vise is capable of providing the same support.


On the side after the work as far back as it can go. I suppose I could extend the fixed jaw of the vice or fit spacers to move the work as far as possible away from the 'down stream' guides.

Thinking on it, over several pints, I reckon that the aluminium that I'm cutting makes chips that are so grabby that brushes or a permanent coolant or air system are the way to go. I haven't done that much work with aluminium before this job and find that the chips stick together in blocks and clumps, rather than separating like steel cuttings do with the bandsaw.

Maybe I'll buy some toothbrushes when I do the household shopping tomorrow:)

Mark Rand
05-11-2013, 05:20 PM
Bought some toothbrushes, Fitted with some scrap 1/2" ally with a couple of slots milled in it. Had to also space the work a couple of inches further forward as well to completely avoid problems.

Cut off half a dozen 3 1/4" slices at 180fpm 4tpi blade, no problems whatsoever. Nice fast cutting, not throwing the blade, dont have to stand over the ruddy thing all the time.



On the next slice, with the shaper clonking away in the background, surfacing some blocks and me working on the lathe, turning some washers, the bandsaw stopped. I finished the cut I was doing and turned to pick up the slice and advance the stock another 16mm.

As I turned round, the magic smoke left the motor. It appears that the cut off slice had turned instead of falling away, derailed the blade from the upstream guide rollers and jammed the blade. It looks like Axminster didn't fit a 3A fuse as they should have done for a 1/2hp 240V motor.

New motor on order!

Maybe I shouldn't be trying to do semi-production work on a home-shop toy, but it's for the Mrs. Maybe she'll see the advantages in dropping a couple of grand on a better bandsaw:cool:

John Stevenson
05-11-2013, 07:23 PM
As I turned round, the magic smoke left the motor. It appears that the cut off slice had turned instead of falling away, derailed the blade from the upstream guide rollers and jammed the blade. It looks like Axminster didn't fit a 3A fuse as they should have done for a 1/2hp 240V motor.




Clumsy Bastard :D

+ or - Zero
05-11-2013, 08:16 PM
Bought some toothbrushes, Fitted with some scrap 1/2" ally with a couple of slots milled in it. Had to also space the work a couple of inches further forward as well to completely avoid problems.

Cut off half a dozen 3 1/4" slices at 180fpm 4tpi blade, no problems whatsoever. Nice fast cutting, not throwing the blade, dont have to stand over the ruddy thing all the time.



On the next slice, with the shaper clonking away in the background, surfacing some blocks and me working on the lathe, turning some washers, the bandsaw stopped. I finished the cut I was doing and turned to pick up the slice and advance the stock another 16mm.

As I turned round, the magic smoke left the motor. It appears that the cut off slice had turned instead of falling away, derailed the blade from the upstream guide rollers and jammed the blade. It looks like Axminster didn't fit a 3A fuse as they should have done for a 1/2hp 240V motor.

New motor on order!

Maybe I shouldn't be trying to do semi-production work on a home-shop toy, but it's for the Mrs. Maybe she'll see the advantages in dropping a couple of grand on a better bandsaw:cool:

Probably the wrong brand of toothpaste...

Zero.

Mark Rand
05-12-2013, 07:33 PM
I'll have to ask John S what brand he uses, though I thought he just got the vetinarian to come round and file them every six months:rolleyes:

+ or - Zero
05-12-2013, 11:59 PM
I'll have to ask John S what brand he uses, though I thought he just got the vetinarian to come round and file them every six months:rolleyes:

I though he had Black Forest bring this around every so often; http://bbs.homeshopmachinist.net/threads/56121-Lets-play-name-this-tool?p=799626#post799626 --saves on the vet bills and probably gives BF a good chuckle each time.

Zero.