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H80 bandsaw: bronze dust in gearbox

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Rainbows09/11/2018 11:16:26
632 forum posts
181 photos

Opened the worm gearbox in my H80 to replace the OEM oil with trusted quality oil. Found at the bottom a not insignificant of bronze dust mixed with the oil.

Bandsaw has only seen light use: is this the gears wearing in as they do or a sign that something is dodgy?

Brian Wood09/11/2018 12:19:17
1942 forum posts
37 photos

Hello Rainbows,

Not a good sign I'm afraid. I had the same trouble on a similar far Eastern bandsaw, traced to poor assembly of the shaft with the worm on it, the bearing nearest the worm had failed. A second problem was with poor alignment of the bronze gear wheel with the worm being offset to the side so that wear was taking place with the worm running off axis.

I covered my repair in an article in MEW 247 if you have a copy, or can look it up in the digital archive



Alistair Robertson 109/11/2018 13:05:31
53 forum posts
6 photos


Bronze dust would be common in a basic worm drive gearbox especially one that had been assembled but never "run in". I would drain it, wash the dust out and re-assemble with good quality worm drive oil.

I worked for a company where we made worn drive gearboxes for aerospace use and the worm and wheel were lapped in in a jig. When they were assembled and run on the test rig for a couple of days, They were then stripped and if any bronze dust was found, then the whole procedure was repeated (many times!)

The inspector's criteria was that his white glove had to be absolutely clean when he rubbed around in the gearbox to allow the "run in" certificate to be issued.

It must have cost a fortune!

larry phelan 109/11/2018 14:11:08
482 forum posts
11 photos

Never thought to check that on my bandsaw. Think it might be a bit late now? [How many years ago ?,dont even ask !!! ]

I hate reading things like this !!!

SillyOldDuffer09/11/2018 14:34:13
4601 forum posts
988 photos

Don't panic! I opened my gearbox a few months after purchase because the rubber gasket started to weep oil. Inside I found obvious signs of bronze dust but no obvious wear on the worm. I changed the oil and bodged the gasket.

Because it was a bodge, the gasket leaked again after about a year. Re-opening the gearbox I again found traces of bronze dust but much less than the first time. Again no sign of damage to the worm. I'm pretty sure the dust was due just to roughly made and assembled gears bedding in.

My bandsaw is the crudest of all my Chinese tools by far. It wasn't lovingly fettled by master tool-makers to meet precision specifications! Nonetheless it works a treat, far better than appearances would suggest possible.

One problem with inexpensive equipment is that what you get is inconsistent even between tools from the same batch. You can't assume because my saw is OK that yours must be too. I'd check the gearbox after some months cutting to make sure it doesn't need remedial work. With luck you'll find nothing wrong.


Eddy Curr16/11/2018 03:36:50
34 forum posts
Posted by Rainbows on 09/11/2018 11:16:26:

Opened the worm gearbox in my H80 to replace the OEM oil with trusted quality oil.

Be cautious about the make-up of oil used to fill a gearbox containing yellow (brass, bronze) or red metal parts.

Additives in EP or Extreme Pressure gear oils (sulfur, chlorine, potassium-borate ...) can cause rapid wear.

Examine the product data sheet looking for results of the Copper Strip Corrosion Test (ASTM D130) or whatever the equivalent test is in your part of the world.

Neil Wyatt17/11/2018 13:13:37
16446 forum posts
686 photos
74 articles

When I opened the gearbox of mine it was full of 'liquid gold'.

The gear is badly worn, but I did my best to improve alignment and it has lasted years now and the oil is clear of dust.

The situation is helped as the gear only turns in one direction

At some point a new gear will be needed, though.


Ian S C18/11/2018 10:30:08
7444 forum posts
230 photos

Probably the oil should be changed early in the life of the saw, after which it should do a good few hours without any trouble, maybe a check / change every couple of years. Mine has been going about twenty years on the original oil, and at this stage I'm not looking inside.

Ian S C

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