Bandsaw throwing bands - forwards!

[agg221]

As per title - my Ripsaw bandmill has developed a nasty habit of throwing its bands forwards in the cut, grinding them into the casing.

 

The bands are 3/4" wide - some light, some stiff. They are good quality (Tuffsaws) and run true. The saw is tracking fine, slightly to the rear of the pulleys. I have tried setting the tension on the correct setting or cranking it up as hard as I can with the saw still able to pull it - doesn't seem to make a difference. The pulleys are aluminium with rims on the front face - to throw the band forwards it is jumping the rim.

 

The saw has started throwing the bands whilst milling. It does it intermittently, with new or old bands. Put the band back on, resharpen it and carry on and it may not do it again, or it may do it in six inches time.

 

Anyone encountered this (maybe on a vertical bandsaw?) and more importantly does anyone have any ideas what might cause it and how to fix it? Yesterday was quite frustrating.

 

Alec

[slackbladder]

Hi Alec

Are there rubber tyre on the wheel.

[agg221]

Hi Alec

Are there rubber tyre on the wheel.

 

Hi Steve, no it doesn't have rubber tyres - never has had though so this isn't a change.

 

Alec

[se7enthdevil]

could it just be that with the inevitable wear you get on all the metal the bits the band rides on they are just too worn to stop the bands jumping???

[PeakOakFrames]

Have you checked the bearings? if they are worn you could be getting excessive play in the band wheels when they are under load. Also check to see there is no build-up of sap/compacted sawdust on the wheels that could be throwing them out of balance and popping the band off the wheels.

[Cae Ffynnon]

Excessive wear in the band wheels? Is it possible any welds have cracked allowing the band wheels to move towards each other. I can only imagine the problem id down to loss of tension in the band. I would be interested to see some film of the ripsaw in use.

 

Chris

[gensetsteve]

I had a woodmizer and remember once a band had come of or been knocked off then it would need to be reset even if still sharp. Once it's been off its a waste of time reusing. There was several adjustments on my band saw to stop this happening but I found the way to set it up was start at the begining and follow the manual. Trying to tweak a problem out used to make things worse.

[Stubby]

The band will always climb to the highest point on the wheels so if there is un even ware or a loose bearing tilting the wheel it will ride up and off .

[agg221]

Thanks for the thoughts.

 

The wheel scrapers are set well and the wheels are free of sawdust and resin - they are also true (can check this against the scrapers).

 

Set up is as good as I can get it - there isn't a manual as such. It is also very forgiving about working well with bands which have been thrown (so long as they are re sharpened), probably because they are so light.

 

Bearings look like a strong candidate - I'll strip it down and take a look.

 

Alec

[agg221]

Well I stripped it down this evening. The bearings are sealed units and the main wheel bearings feel smooth with absolutely no play, however the guide wheel bearings may be the issue. They should be sealed units - first picture shows the back face (how they should look), second shows the front face which the band has been running on...

 

Alec