China 4" x 6" bandsaw -- blade keeps popping off...

[stevec]

RRTom, OK, now I know what you mean.
Mine is an oldie too and it ate it's worm wheel and bearing a while back. I found replacements form a local bearing supplier (Motion industries?) the worm wheel is a Union Gear, Quincy, MA # BWG-1220-SR and the bearing is an NTN 6202 ZZNR/ZA.
I bought 2 of each and prolly won't need the second set until shorty after I sell or give them away.

[EdK]

Thanks for those part numbers Steve. Especially the worm wheel. I've been wondering where you could get those from.

Ed

[Mayhem]

Ed - sounds like you could get them cheap from Steve!

[roundrocktom]

Steve, thanks for the part numbers.

Google turned up zip on the worm gear, but found a Union Gear catalog online and the BWG-1120S listed:

Bronze gear, single turn ratio. 20:1 gearing
http://www.traceygear.com/UnionGear/Unio...atalog.pdf

1/2" face, 20tooth, 1.666" pitch diameter, 1/2" shaft, 1.25" hub diameter.

Gearbox... I used 90W, but have some OLD (like 40 year old) bottles of magic stuff (Molybdenum Disulphide) gear additive that I squirted in. Yep, bought four bottles for my '67 Datsun Gearbox... still have some sitting around. Never realized it would be a lifetime supply! :)

[PixMan]

(06-09-2014, 05:59 PM)roundrocktom Wrote: Gearbox... I used 90W, but have some OLD (like 40 year old) bottles of magic stuff (Molybdenum Disulphide) gear additive that I squirted in. Yep, bought four bottles for my '67 Datsun Gearbox... still have some sitting around. Never realized it would be a lifetime supply! :)

Here's another amazing use for that molybdenum disulfide: TAPPING!!

It's the active ingredient (EP additive) in Castrol's "Moly-D" tapping compound, as well as a new product without Castrol's petroleum base, Green Gold GG-80. I have a jar of that, it's 97.5% soy oil paste, 1.5% fumed silica, and 1% molybdenum disulfide. Great stuff, even in very small doses.

[kenne]

(06-02-2014, 08:00 PM)roundrocktom Wrote: I have one of the original "Smithy" bandsaws, bought used in 1995 or so. It was probably 10 years old by then.

In the last year it seems like the blade just pops off more often. New blades, spring tension adjusted full tight, bushings still good.

Only thing Ive noted is the wheels do have a bevel to it. Tapers away from the flange. Before I go and "trim" the cast iron wheel, wanted to ask if anyone else has seen that issue. Keep in mind this has had 25 years of service, but still frustrating to be fitting the blade popping off.

If I use the saw in vertical mode... everything works fine, only when I put it to horizontal mode does the blade have problems.

I have the same problem with a Johnson bandsaw , the cure for mine was to find an inner tube that fit tightly on the wheel diameter ,cut a strip ,glue it to the wheel . due the same thing for the other wheel and adjust the tension carefully .
Having said all that the wheel angle and blade guides have to be perfect , as well as the tension on the stand in horizontal position .
Mine has an adjustable weight to allow for different types of materials .
Good Luck , hope this helps .

[roundrocktom]

PSA Announcement.... I commented I used Hypoid 90W gear oil... friendly tribologists warned me it will EAT UP THE BRASS. Opps.

Use gear oil meant for a worm gear. Mobil SHC-634 (do not confuse with Mobilgear 634) for the Worm Gear.

http://www.grainger.com/product/MOBIL-Oil-4ZF30

[stevec]

Tom, I would venture to say that the poorly built worm gear / worm setup on these saws would cause the consumption of the worm gear long before the 90W gear oil would. But I guess the right oil is the right choice, for any situation.

[roundrocktom]

(06-21-2014, 06:52 AM)stevec Wrote: Tom, I would venture to say that the poorly built worm gear / worm setup on these saws would cause the consumption of the worm gear long before the 90W gear oil would. But I guess the right oil is the right choice, for any situation.

Steve -- very true, but I've heard reports of "we serviced it, but the worm was completely destroyed a few years later.... ". If you flip back a page, you'll see the photo of my worm gear. I think I used plain non-detergent 30W when I serviced it over 20 years ago. Worm looks fine, so might as well treat it to the good stuff... hopefully good for another 30 years (kids can figure what to with by then... )

Tom