POWER SAW PROBLEM

[Rob DivallParticipant @robdivall22112]

BLADE VEERINGOUT OF VERTICAL

[Rob DivallParticipant @robdivall22112]

I HAVE A "HORIZONTAL / VERTICAL METAL CUTTING BANDSAW" SIMILAR IN EVRY RESPECT TO A DRAPER UNIT. ABOUT 10 YEARS OLD. RECENTLY THE BLADE HAS TAKEN TO VEERING OUT OF VERTICAL DURING CUTS.

BLADE HAS BEEN REPLACED WITH A GOOD STARRATT TYPE, AND ALL 6 WHEELED BEARINGS WHICH GUIDE THE BLADE HAVE BEEN REPLACED.

ON BOTH HIGH AND LOW BELT TENSION SETTINGS THE PROBLEM PERSISTS.

ANY IDEAS? WOULD VERY MUCH APPRECIATE YOUR ADVICE,

ROB

[egaParticipant @ega]

These saws can be persuaded to cut true but they are essentially not precision machines.

Since yours used to be OK it may be that when the bearings were changed the correct adjustment was lost.

I set the tension on my vintage Warco by winding it to the point where the blade does not slip on the wheels.

PS Lots of advice in previous posts.

Edited By ega on 13/06/2020 18:16:01

[Brian WoodParticipant @brianwood45127]

Hello Rob,

Your problem is almost certainly caused by incorrect tracking having disturbed the bearing guide blocks. My saw came for Axminster but they are all of similar design, The fitting on my guide blocks was truly awful, cast surfaces straight onto other cast surfaces for example.

In the end I not only suffered blade run offs but breakages. I stripped out the entire blade guide system, milled decent fitting and bolting surfaces on them and rebuilt it all using a taut wire round the blade wheels so that the guide nearest the power wheel in particular steered the wire into the 'notch' on the rim for want of a better description That gave me the proper position for the rear of the cutting blade.

With a blade fitted the saw was transformed, no more running off the blade wheels and proper guidance by the ball bearings in the blocks

I hope that help Brian

[Howard LewisParticipant @howardlewis46836]

On my generic 4.5" bandsaw, the guide bearing are on pins which are eccentric, to provide for adjustment.

I would suggest adjusting then trackins so that the blade runs true on the power and idler wheels, and then slackening the fixings and adjusting the eccentric pins so that the bearings grip the blade, before tightening the nu.

This should improve matters.

Howard

[egaParticipant @ega]

Posted by Brian Wood on 13/06/2020 18:59:25:

…so that the guide nearest the power wheel in particular steered the wire into the 'notch' on the rim for want of a better description…

Am I right in thinking that the notch is the flange?

Worth mentioning that you covered this procedure in detail in an earlier thread.

[Ady1Participant @ady1]

I use a medium sized drop saw with a circular cutting disc which should cut 100% straight every time

but it doesn't

The reason as it turned out was too much pressure on the disc as it cut, backing off the cutting pressure made it run true again

Just a thought

[Brian WoodParticipant @brianwood45127]

Thank you for the input Ega and yes I did go into the subject at some length but I can't now recall the title of the posting I was responding to!.

And yes, the 'notch' is the flange/rim transition on the blade wheels. Getting the blade to sit correctly against that and avoid poor steering from the guide that directs the cutting blade back onto the driving wheel are the two critical factors in making these mass produced saws work as intended.

Regards Brian

[egaParticipant @ega]

Brian Wood:

I had in mind:

**LINK**

[oldveloParticipant @oldvelo]

Hi Bob

Try this link Band Saw Tracking

Cover most common errors of tracking

Eric

[Gary WoodingParticipant @garywooding25363]

Like Brian, I too have an Axminster 4×6 which often shed its blade on deep cuts.I use a new bi-metallic blade. I read the document mentioned by Eric and concluded that the problem was faulty tracking. Unfortunately, as Brian also mentioned, the blade guide castings were so badly made that it was impossible to align the flat of the blade vertically, so I resorted to machining them. The improvement was dramatic. I was able cut a slice from a 10×100 steel bar ( flat edge vertical) without shedding the blade, and the cut was just about a perfect 90 degrees. Problem solved, I thought.

The 10×100 cut was the deepest I'd attempted, but came the day when I had to cut a lump of 75×100. It started well and I was full of confidence, until the blade came off at a cutting depth of about 80mm. I reset the blade and continued. It came off again. After resetting the blade again I noticed that it didn't re-enter the cut properly. The top of the cut was perfect, but on lowering it carefully it was clearly 'binding' on one side, more and more as the blade was lowered. I loosened the bar in the vice and repositioned it so the blade wasn't binding at the bottom of the cut, and was then able to complete the cut, but why did the blade cut a 10×100 bar vertically but not a 75×100 bar?

I'd used a set-square to verify that the blade side was vertical – it still was. But because of restricted access near to the hinge, I hadn't bothered. That was the mistake. The blade wasn't vertical nearest the hinge – it was, in fact, slightly twisted front to back. It didn't seem to matter for the 10mm thick bar, but 75mm was another matter. After removing the twist it continued to cut the thick bar properly. YMMV.

[Brian WoodParticipant @brianwood45127]

Gary's story just confirms what I have always thought to be the case with these bandsaws, in a paraphase of Tony Blair's triple 'Education' speech—–alignment; alignment; alignment.

Another pitfall I have experienced is cutting near a weld where a hard spot often lurks. That will ruin a blade in seconds by blunting the teeth on one side,. It will struggle ever after and be cursed with curved cutting if you are lucky. I have also learned that any attempt at cutting spring steel bar is doomed

Regards Brian

PS Thank you Ega for refreshing my memory

[Author]

Posts