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Stern
05-03-2013, 05:59 PM
Have a typical HF type band saw (4 1/2") and been having a lot of problems today with it throwing the blade off the inside wheels. I have tried the "tilt" adjustment on the one wheel in all possible positions but makes no difference. Got to the point today I ti9ghtened the blade so much it snapped.
Any trick to these things ?

sasquatch
05-03-2013, 06:25 PM
Gotta be an alignment problem, -adjusting these things can be pretty delicate at times, doesn't take much to get it it off track.

Stern
05-03-2013, 07:01 PM
Figured as much, guess when I get a new blade I will have to expect to take a long time to get it tweaked just right.

armedandsafe
05-03-2013, 07:06 PM
If you have replaced the tires, check that they are the proper thickness. I've found that most (all that I've used) tires are too thick for the HF saws and need to be dressed down after installation.

Pops

CCWKen
05-03-2013, 07:11 PM
Does it throw the blade just running or when you try to cut something. Check the guides too. Sounds like it may be a worn/loose bearing causing poor alignment. Or you just plain don't have it adjusted.

Bob Fisher
05-03-2013, 08:21 PM
FIRST, get a good quality blade! I have contemplated using a wrench to tighten my blades, as I sometimes have the same problem. If the blade runs OK when not cutting you may have a downforce issue. These 4X6 saws seem sensitive to too much force. And the spring counterbalance leaves a lot to be desired.Bob.

valleyboy101
05-03-2013, 08:22 PM
I agree with CCWKen. If it is throwing the blade without cutting - loosen off the guides and see if it continues.
Michael

darryl
05-03-2013, 11:04 PM
I looked at a new 4x6 bandsaw today- what a piece of junk! Sure glad I got mine before the slide-

Is the blade damaged? Best thing might be to put a new blade on it, then go through the procedures to get the tracking right. We went through this a month or so ago. A tracking problem that develops quickly is not likely to be a machine problem, IMO. Blades do deteriorate, not only in sharpness, but in the integrity of the backing. It's a waste of time trying to align the saw without a new blade on it, as all you'd be doing is trying your best to get a bad blade to stay on- with a proper alignment from the start, blade life will improve and so will the cutting action.

The upper and lower wheels should be in the same plane and parallel when the tension is on- not always easy to achieve, but measurable with a straightedge. You do need to know if the fault lies with the machine or the blade.

outback
05-04-2013, 04:43 AM
There is a cure and a few causes for the blade jumping off the drive wheel.

Below is the cure. Screw a small plate to the saw frame to retain the saw blade:
http://img.photobucket.com/albums/v30/jglass/Shop%20Demonstrations/sawbladejump.jpg (http://smg.photobucket.com/user/jglass/media/Shop%20Demonstrations/sawbladejump.jpg.html)

The primary reason the blade jumps off the drive wheel is because the blade stalls or stops, the drive wheel continues to rotate and spins the blade off the drive wheel.

Below is the downside of my sawblade retaining block. When the saw blade stall/stops there needs to be slippage somewhere this is where:

http://img.photobucket.com/albums/v30/jglass/meltedguard.jpg (http://smg.photobucket.com/user/jglass/media/meltedguard.jpg.html)

In the 12 years I have owned and used this saw I virtually melted two fan belts and the belt guard is also a gonner. For this reason I do not run the saw unattended. I'm always nearby listening for the saw motor to run but no sawing taking placed.

Why does the blade stall or stop:

1) Took me a few years to figure this one out. If you are sawing rectangle stock and you fail to clean shavings off the support area it is possible the cut piece will be lifted just before the end of the cut. The cutoff piece will work just like a disk brake caliper and very efficiently pinches the blade and stopping it in it's tracks. The blade slips on the drive wheel and they part company.

2) Sawblade lacks enough tension to prevent slippage. I added a heavy duty die spring to the tension adjustment
so the idler wheel could float if it needed to.

3) The blade gets snagged in the saw kerf while sawing. Adjust down feed.

4) I have run this saw almost everday for 13 years and have yet to ever adjust the saw buides. I can't believe the saw still runs. I have a new saw in the shed, still in the unopened box as a backup saw. Been there 12 years.

Be sure to use bi-metal saw blades with about 18 teeth per inch. Fewer teeth may cause excessive loads on the saw and cause a stall.

May as well show you this. Notice the cut piece has no support at all and can never pinch the blade:

http://img.photobucket.com/albums/v30/jglass/Automation%20Projects/barfeeder6.jpg (http://smg.photobucket.com/user/jglass/media/Automation%20Projects/barfeeder6.jpg.html)

See the bar feed work
(http://smg.photobucket.com/user/jglass/media/Automation%20Projects/barfeederfeedend.mp4.html)

Jim

dian
05-04-2013, 04:57 AM
http://bbs.homeshopmachinist.net/threads/58345-Adjusting-the-tracking-on-the-garden-variety-4x6-import-horizontal-band-saw?highlight=band

sasquatch
05-04-2013, 08:40 AM
Outback that is a slick setup. (But i still don't understand why the need for the blade retainer block .)

chevy3755
05-04-2013, 09:30 AM
what i did with mine was to remove the wheels and put them in the lathe and cut a deeper shoulder for the blade......worked great for me.....just my 2 cnts worth

Stern
05-04-2013, 10:19 AM
Thanks for all the tips, it gives me something to look for. It runs fine and only throws a blade while cutting, so its probably a blade stall issue. I figure with all the cutting I have done lately (a LOT of big stuff) the blade probably got dull, as to even get it to cut I had to weigh the arm end down a bit (about a 1lb hunk of steel). Going to see how it goes with a new blade and thanks for the "teeth per inch" as the band saw has no info on it and not sure what blade I picked up (teeth seem really fine). Will grab a blade at Princess auto today (hopefully they have and I get the right ones, old one seems to be about 64"-65")

Thanks again for the help all, and I see if this gets me running again, then just need to find a way to determine when the blade is at a point it should be replaced (teeth did still feel sharp)

Alistair Hosie
05-04-2013, 11:22 AM
If you have the max tightness on the blade and it slips might be the blade has stretched or maybe it was made slightly oversize in the first place I had this exact problem with a few blades I had the manufacturer made it about three quarters of an inch too long it's worth checking just my 2 cents. Alistair

skunkworks
05-04-2013, 12:34 PM
We have a similar sized bandsaw that was bought in the 80's.. When we have had blade tracking issues - the bearings in the drive wheel gearbox failed. Sometimes the center race splits - some times the balls fail. we once had the shaft break (atleast twice). (this has been used hard for many years)

sam

outback
05-04-2013, 01:16 PM
Outback that is a slick setup. (But i still don't understand why the need for the blade retainer block .)

When the sawblade begins to slip off the drive wheel it can only go as far as the retainer block. Once the slippage problem has been corrected the sawblade goes back where it belongs on its own. The sawblade never completely leaves the drivewheel. The sawblade isn't moving (usually) so the retainer isn't damaged. Never have replaced the
retainer block.

To replace the sawblade only one screw needs to be removed from the retainer block, the other screw serves as a pivot so the block can swing clear.

It is a simple solution for a common problem.


Thanks for all the tips, it gives me something to look for. It runs fine and only throws a blade while cutting, so its probably a blade stall issue. I figure with all the cutting I have done lately (a LOT of big stuff) the blade probably got dull, as to even get it to cut I had to weigh the arm end down a bit (about a 1lb hunk of steel). Going to see how it goes with a new blade and thanks for the "teeth per inch" as the band saw has no info on it and not sure what blade I picked up (teeth seem really fine). Will grab a blade at Princess auto today (hopefully they have and I get the right ones, old one seems to be about 64"-65")

Be sure you buy bi-metal blades if you are going to saw steel. They are well worth the extra cost. Mine usually last 6 months or more. But I'm the only person that runs the saw

Jim

whateg01
05-04-2013, 01:23 PM
18 tpi is a good starting point, but don't think that it is the "right" blade for all applications. If you are cutting a 4" dia round aluminum bar, for example, it will take far longer than with a courser blade. In fact, the rule of thumb I follow, and I think this is a standard, is that there should always be at least 2 teeth engaged in the work. So, I use a 6 tpi blade for anything over 1/4" unless it's steel and the finer blade is already on the saw. The finer pitch just takes longer, in most cases.

I also don't like bimetal blades for the 4x6. I started out buying bimetal blades, either Morse or one other name brand that I can't remember now, on the advice of the web. I never wore a blade out. It would always break. I tried tighter, looser, making sure things were adjusted right. No luck. Started buying hardback blades or even carbon blades, sometimes, and still break them occasionally, but I wear them out more now. And they don't become really worn out until long after the bimetal blades would have broken. So, if I'm going to have to replace blades after X hours, I'd rather spend 1/3 the cost.

I started out with a Harbor Freight 4x6 and had upgraded the downfeed spring tensioner so I could adjust it easier. I had also added a better work table for vertical use. Aside from those two things, once it was adjusted, it just worked. Never had any trouble with it. Blades went on easily and stayed on until they broke.

Then I upgraded to a used Dayton saw. Much better motor and switch, but plain bearings everywhere instead of the ball bearings the HF saw used. Got a better work table added but haven't done anything about the downfeed stuff yet. When I bought it, it didn't cut straight, or square in either plane. I got all that adjusted after much fanagling and all seemed great until I started cutting with it. Then I had problems with the blade jumping. Turned out I had gotten the lower guides too tight and when a chip got between the blade and the guide it stalled and jumped. Got the clearance adjusted and realigned it and it hasn't jumped yet.

One thing I've noticed is that the blade sits off of the back guide bearing until it's in a cut. I haven't found an way to adjust that out yet, so I'm not sure what to do about it, but it still cuts okay.

Dave

whateg01
05-04-2013, 01:28 PM
There is a cure and a few causes for the blade jumping off the drive wheel.

Below is the cure. Screw a small plate to the saw frame to retain the saw blade:
http://img.photobucket.com/albums/v30/jglass/Shop%20Demonstrations/sawbladejump.jpg

...

Jim

I know, to each his own. But... I don't like that. It's not a fix, so much as a bandaid. If the blade is jumping, there is a reason and that reason should be addressed. It's like a car door that won't stay closed, so you weld a strap down the side of the car rather than fixing the latch. I would rather the blade jump and the motor run freely than to have the blade forced to stay in place and risk burning up the motor, or melting the belt and belt guard. Sorry, but I just see that as a bad idea. Plus, what a PITA when it comes time to replace the blade. For example, I switch blades for different materials or thicknesses probably every couple of uses. That would get old.

Dave

Stern
05-04-2013, 02:01 PM
Thanks agian for all the advise. Went out and got a new blade (bi metal was all I could find) which was 14 tpi. After having it come off I went slow and adjusted the wheel setting and the pressure on the down cut. Works like a charm and I can only assume the old blade was far past its life. This thing cut really well and finished the other half of the cut in the 7" block in about 1/2 hour.
Next thing I need to do is fix the motor, as it seems the inside fan is either melted or come off, which makes the motor heat up really hot in about 10 min of cutting. Will see if I can find something to replace it, even if I stick it outside the motor housing on the shaft.

Peter.
05-04-2013, 02:29 PM
I always remove the guides to track the blades on the wheels, the re-fit the guides and adjust to make it cut true. Taht said - i never had much fun with that type of bandsaw, they seemed to vary their moods with the weather.

Stern
05-04-2013, 02:36 PM
OK, after all the help you all got me thinking about an obvious problem I have had since I got this. The saw will NOT self start, never has. I have to kick start the pulley belt with my palm to get it going. Checked the motor and the internal fan blade IS there and working, so something is putting a large load on the motor. Since its my first saw, Im not sure how stiff the gearbox should be. If I remove the blade and belt should I be able to spin it freely with my hand or is it going to be stiff ?

Again, thanks for helping

CCWKen
05-04-2013, 02:48 PM
The saw will NOT self start, never has.
The start capacitor is probably bad. I had the same problem with my old Craftsman band saw. A new capacitor made it like new.

Stern
05-04-2013, 04:14 PM
Well, decided to check it out and the drive mech moved free and smooth. Opened the motor up and indead the fan blade (plasitc) was melted :( At this point just trying to run the motor blew a breaker.

http://i1237.photobucket.com/albums/ff467/stern-69/Shop%20Projects/DSCF6851_zps146ae728.jpg

Time to try the 1/2 HP one I have. Put it on and it cut 100 times better, plus if it jams the motor just sits there (must be a stall protection) and restarts when the jam is free.

http://i1237.photobucket.com/albums/ff467/stern-69/Shop%20Projects/DSCF6852_zpsb161e85e.jpg

Finished cutting the large lump into blocks I can use (for a new QCTP), and now the saw works like a charm :)

outback
05-05-2013, 10:30 AM
I know, to each his own. But... I don't like that. It's not a fix, so much as a bandaid. If the blade is jumping, there is a reason and that reason should be addressed. It's like a car door that won't stay closed, so you weld a strap down the side of the car rather than fixing the latch. I would rather the blade jump and the motor run freely than to have the blade forced to stay in place and risk burning up the motor, or melting the belt and belt guard. Sorry, but I just see that as a bad idea. Plus, what a PITA when it comes time to replace the blade. For example, I switch blades for different materials or thicknesses probably every couple of uses. That would get old.

Dave

Dave, I don't usually reply to posts like yours. You are right, "to each his own". However, I explained why I thought the blade comes of the drive wheel. You can believe it or not but that is how my saw works. In 13 years I have burned up 2 fan belts and that happened because the saw was left running unattended. You missed my point because in my opinion there are risks leaving any machine running unattended. The 4 X 6 saw in particular.

Furthermore, if you read up on sawblades, you will find the flexback blades are not intended for steel particularly toolsteels, stainless, CPM 10V and so on. The stuff I'm sawing daily. But if you are satisfied with the carbon steel blades, more power to ya.
Jim

Mike279
05-06-2013, 11:28 AM
I have had a Harbor Freight saw since the late eighties. I ended with the same problem of it dropping the blade off and struggled with it for years. I ended up taking a roller blade wheel and placing it at the far end of the drive wheel. It rolls against the teeth of the blade. It keeps the blade from dropping off and although I figured to be replacing it every few weeks it is lasting years. Chewed up some but it makes the saw very usable without playing around with the adjustments which only work for a short time. And really there is no reason to not use the good bi metal blades that last really well on these little saws. Just following the directions and running a new blade in seems to give it a great service life and nice cuts. Mike

bosox
05-06-2013, 12:07 PM
I have a horizontal band saw and a month ago after I replaced the blade on it, it won't stay on tires. The saw started to throw the blade off. I tried
changing the tension but it didn't work. Check the wheel alignment, the guides and the blade. First, I doubted if the reason was the blade since it was new, unluckily , the blade was bad.So, I put a different blade. However, I made some adjustments on the idle wheel. Then, everything was back to normal again.

krutch
05-10-2013, 02:27 PM
Friend of mine had same problem with old machine. He brought the drive and idle wheels to me and I took a skim cut on the OD. That took the worn-in taper out of the blade path on the wheels. Fixed it for his saw.
So far, I have not had to do this fix for my buffalo saw. Knock on wood!