The Home Machinist!

A site dedicated to enthusiasts of all skill levels and disciplines of the metalworking hobby.
It is currently Wed Jul 30, 2014 4:03 am

All times are UTC - 5 hours




Post new topic Reply to topic  [ 33 posts ]  Go to page 1, 2, 3  Next
Author Message
PostPosted: Sun Sep 04, 2011 12:15 am 
Offline

Joined: Tue Oct 05, 2010 7:33 pm
Posts: 193
Location: San Ramon, CA
I have a cheap HarborFreight bandsaw I bought used and replaced the blade. If the fastest speed is selected, the blade comes off the pulleys after less than a minute of running. I can not seem to make any adjustment to stop this. Ideas?

- Phil


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 12:50 am 
Offline
User avatar

Joined: Tue May 06, 2008 9:15 am
Posts: 364
Location: Australia
Hi Phil,
Have you tried adjusting the bearing back that runs on the back of the blade? You have to move to whole bearing unit up the slide both in and out feed ends.
Another thing I can think of is if the top pulley slide adjustment bolts are a bit loose. They are on top on the outside when the saw is down. Mine has 2 bolts their with a plate to allow the top wheel to slide in the adjustment. If this is loose it will allow the wheel to tilt over and the blade comes off.

I would almost guarantee it would be the first one I suggested, but another check you could do since the saw is second hand, is with the blade off check to see if either of the wheels have excessive movement which could mean a bearing is gone.

Dave


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 1:27 pm 
Offline

Joined: Tue Oct 05, 2010 7:33 pm
Posts: 193
Location: San Ramon, CA
I am not sure I understand what you are saying here. If you are referring to the bearing guide assembly at the opposite end of the motor end that can slide fore and aft, then yes, that is as close as possible to the other bearing guide assembly at the motor end. The bolts for the pulley, but adjustment arrangement makes it impossible to put the two pulleys in parallel. I adjusted things so that the when runnung, with the arm vertical, I could see the blade running around the pulley without any apparent interference with the pully flange. The pully bearing is tight and good.

I am trying to cut a 3" x 3" piece of 6061 aluminum. I noticed that the blade seems to come off if it encounters a snag of any kind. I think the blade may come off if the blade stalls and the pulleys keep spinning. Maybe. I adjusted feed rate to no avail. I finally cut the fpm from 200 to 120 and that definitely helps. You can still see the blade snagging and sometimes it stall and I have to stop it. The blade is definitely really stuck in the aluminum and sometimes takes a fair amount of effort to get it free. I am continuing to cut at 120 fpm, but it is taking a really long time. I don't know what is a proper feed rate to use. Not even sure what proper blade tension is.

- Phil


Last edited by Phil3 on Sun Sep 04, 2011 3:52 pm, edited 1 time in total.

Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 2:28 pm 
Offline

Joined: Fri Dec 20, 2002 11:02 pm
Posts: 13501
Location: Onalaska, WA USA
Somewhat off the beaten path, but your comment that the blade hits a "snag" sent up a red flag for me.

Saw blades create a kerf that's wider than the blade, so it can't (shouldn't) hang up. That's true up to the point that you haven't either worn or burned the set off the blade.

Have you examined your blade to determine if it is still functional? Just having teeth isn't enough, as you likely know---the teeth must have the proper configuration and be sharp in order for the blade to perform properly. All it takes is to run the blade too fast, briefly, in the wrong material, to lose all important features.

Unless your saw lacks the necessary power, slowing the blade shouldn't make any difference when sawing aluminum. Can't help but wonder if the blade is trashed.

Harold

_________________
Wise people talk because they have something to say. Fools talk because they have to say something.


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 2:35 pm 
Offline

Joined: Tue Dec 22, 2009 12:36 pm
Posts: 782
Location: Vancleave, Mississippi
If the blade comes off when you try to cut, but stays on when not cutting, it sounds like the blade guides are not adjusted properly. The ball bearing at the back of the blade should just touch the back of the blade both above and below the table. The tension should be as tight as you can get it. You pluck the blade with you finger to get a high pitch "ping". What type blade are you using. For 3x3 aluminum, you should be using a coarse tooth blade about 1/2" wide and .025" thick made for cutting metal, not wood. I would recommend a 3 tooth, hook/raker set blade. You won't find this at HF. you will have to go to an industrial supply house and have it welded up to order. Being that it is a HF BS, I question whether cutting 3x3 is not overloading it. Also what is the condition of the rubber bands on the wheels? They should have a crown on them to keep the blade centered.

_________________
Mr.Ron from South Mississippi


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 3:39 pm 
Offline

Joined: Mon Apr 14, 2008 8:36 pm
Posts: 133
Location: Castlegar. BC, Canada
Reading between the lines I would say your blade has too fine a pitch for that thickness of aluminum and your speed should be set to the highest. A little Relton A9 would also help. Peter

_________________
Difficult done right away, impossible takes time.


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 3:59 pm 
Offline

Joined: Tue Oct 05, 2010 7:33 pm
Posts: 193
Location: San Ramon, CA
Harold_V wrote:
Somewhat off the beaten path, but your comment that the blade hits a "snag" sent up a red flag for me.

Saw blades create a kerf that's wider than the blade, so it can't (shouldn't) hang up. That's true up to the point that you haven't either worn or burned the set off the blade.

Have you examined your blade to determine if it is still functional? Just having teeth isn't enough, as you likely know---the teeth must have the proper configuration and be sharp in order for the blade to perform properly. All it takes is to run the blade too fast, briefly, in the wrong material, to lose all important features.

Unless your saw lacks the necessary power, slowing the blade shouldn't make any difference when sawing aluminum. Can't help but wonder if the blade is trashed.

Harold


The blade is a new Starrett. I had troubles with it immediately. The only material it has seen is the aluminum piece. I don't know what to look for in the blade to make sure it is servicable. No question, slowing the blade helps. When running, you can heara knock occassionally, and even the arm jiggle a bit. Experience tells me this is the blade almost hanging up, but does not. On one occassion, the blade was so stuck, I had to loosen the stock, lift the arm, and wiggle the blade out of the stock. It was very stuck.

The old blade was worn and hardly cut anything. This is a small saw and wonder how long it should take to cut through 3" x 3" of aluminum. I do not know what to set the feed rate at.

Phil


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 4:07 pm 
Offline

Joined: Mon Apr 14, 2008 8:36 pm
Posts: 133
Location: Castlegar. BC, Canada
Check your pitch. Should be 8 or 10 but no finer for this thickness of stock. The gullet between the teeth is filling up before the tooth has exited the work and is grabbing on the kerf and galling. Go to top speed. Peter

_________________
Difficult done right away, impossible takes time.


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 4:14 pm 
Offline

Joined: Sun Apr 15, 2007 9:23 am
Posts: 5390
Location: Florida
Get some stick wax and wax the blade. Enco Part Number PC505-2034 on sale for $9.95

Hold the wax to the blade while it is running.

It will lubricate the blade and stop the little klinkers from sticking in the gullets, which is what it sounds like is happening.

Relieve a bit of down force on the blade as well and see if that works. I have an old Grainger 4x6 saw that will throw the blade with too much down force and not enough wax when sawing aluminum.

If the blade grabs at all, the drive wheel slips, and oops, the blade comes off.

I've also had a couple of bad blades where the weld was not aligned properly. Clunk, clunk, clunk, every time the weld passed through the cut... :roll:

_________________
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 4:35 pm 
Offline

Joined: Tue Oct 05, 2010 7:33 pm
Posts: 193
Location: San Ramon, CA
Glenn Wegman wrote:
Get some stick wax and wax the blade. Enco Part Number PC505-2034 on sale for $9.95

Hold the wax to the blade while it is running.

It will lubricate the blade and stop the little klinkers from sticking in the gullets, which is what it sounds like is happening.

Relieve a bit of down force on the blade as well and see if that works. I have an old Grainger 4x6 saw that will throw the blade with too much down force and not enough wax when sawing aluminum.

If the blade grabs at all, the drive wheel slips, and oops, the blade comes off.

I've also had a couple of bad blades where the weld was not aligned properly. Clunk, clunk, clunk, every time the weld passed through the cut... :roll:


That makes sense. Pitch is too fine from what others say for this size of aluminum at 14 teeth per inch. I need different blades for different stock and materials it seems. I get some of that clunking as well, but on a Starrett blade? Photo is attached. Blade is off.

- Phil


Attachments:
Saw_1.jpg
Saw_1.jpg [ 740.42 KiB | Viewed 1325 times ]
Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 5:08 pm 
Offline

Joined: Sun Apr 15, 2007 9:23 am
Posts: 5390
Location: Florida
Phil3 wrote:
I get some of that clunking as well, but on a Starrett blade?

I've had Do-All blades that were bad.

_________________
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!


Top
 Profile  
 
PostPosted: Sun Sep 04, 2011 7:49 pm 
Offline

Joined: Sun Jun 27, 2004 11:29 pm
Posts: 932
Location: Northeast Alabama
Be sure you have the blade about as tight as you can get it with the hand wheel. People who have actually measured the blade tension have said that it is not possible to even get the blade to the optimum tension on these small saws.

_________________
Don Young


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 33 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 5 hours


Who is online

Users browsing this forum: Google [Bot] and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Americanized by Maël Soucaze.