Worm Gear Question

Steve@Advance

Well-known Member
Well, I pulled a good one this week... Let one of the band saw gear boxes run dry.

I sent in a request for price and availability on a worm and worm gear set, haven't gotten a reply yet, but I know it's not going to be good!!!

But then I had a "what would Macgyver do" moment and came up with an idea:

I can make a spacer and do some modification, turn the bronze gear over and utilize the undamaged/unused back side of the gear teeth.

But the steel worm gear is galled and rough. It can't be turned around. This gear is part of the shaft, so it can't be replaced with anything off the shelf. I don't have any experience with having custom gears made, or even how a worm gear is made. It does appear to be hardened and ground.

My question is, could a shop with gear making capability, take the old gear and regrind it to clean up? There doesn't appear to be any material worn away, just rough with bronze embedded and stuck to the surface.

Ever hear of this being done or am I grasping at straws?

Thanks!
 
If it were mine, I would try bead-blasting the worm gear to remove the brass debris, and see what it looks like then.

Worm gears are available through power-transmission distributors. ....Most are bored through and can be welded to a shaft. ....Matching the pitch, length, and diameter of your existing worm gear is required.
 
Worms take special lubrication due to the gear design, sliding friction.

Seems whale oil was a good one, don't know what you would use today.
 
How big is the shaft? Do you have a drill press that can chuck the shaft in? Then you could ride the screw with a file to knock down the worst of the burrs and finish with various grades of emery cloth. Not perfect but could make it functional again.
 
If your talking about the inexpensey tilt metal saw, I had the same thing happen to my Carolina saw. There are many different makes on the market that are alike.
My Carolina did the same thing, and the company wanted almost as much as a new saw, they would only sell me the whole casting.
Harbor Freight has a very similar saw. The local H.F. store had one on the sales floor with the vice missing, but would not allow me to take the cover off the gear box to see if the gear was the same as what I needed. So I bought a new one, took it home and opened it took the cover off the gear box, and found that I could make that gear work in my saw. So I looked in the manual at the parts list, got the part number, and ordered a new gear. Then packed the new saw back up and took it back. I don't like doing things like that but.
I don't remember what but I did have to modify the gear a little.

Dusty
 
Steel worms get fitted to brass gears or sectors with fairly close fit and lap themselves in at first use--and the brass gear is the sacrificial part of the pair, that has been a rough industrial standard since steam engine days. bearing on end of shafts may be ball or roller- and many use a plain bronze or brass with lead coat and a relief groove for some initial oil or grease. Old standard lube for many was plain mineral oil and that translates to non detergent straight 30 or 40 weight low ash available at the tractor dealers. Splash lube for a worm gear fitted to top with toothed drive gear just below it and the bottom of the toothed gear setting in the oil bath meant toothed gear picked up oil with a 1/2 turn and the worm was fairly well lubed, open ball bearing got splashed as long as oil was above a certain level were teeth could get coated. run out of oil and the noise starts from the dry gear wearing down, with a bit of luck the brass gear noise alerts operator to check oil level and ball bearing still good using last bit of oil in their race grooves. some upright worms with side mounted sectors are dipped in the oil or grease, often have a plain bearing at that end since it is under lube level. Problem here is the slow undetected leaks that mean dry worm when last thread can't reach the oil or grease surface. design was for oil, many for field use when drip noticed will use corn head grease or outboard motor propshaft grease that won't drip while setting between use. Worm and sector/gear drive have some tolerance for wear and some mis-alignment slack and don't back feed from the sector/gear like a ring and pinion drive can do, it is a old design that has a few advantages for some applications over a Hotchkiss or Hypoid ring and pinion drive- but all the drive have a friction problem that requires some lube. clean your old worm, check the spaceing and often a stock item geared tooth wheel can be found- few applications will require a custom gear size and the existing on shelf industrial standard sized gears are economic sense when assembling. Some application have found that 10-40 motor oils from 1970s specs or the current 10-40 motorcycle oils or racing offroad oils have some advantages, the old zinc additives with the VII molecules will take a high shear, rub and pressure load at the mating surface and flow good at lower temperature into bearing surfaces, some equipment with the special lube from factory that costs $9.95 a tablespoon when needed has turned out to be Castor Bean 2 stroke formula- and Castrol still markets the castor bean oil for chainsaw and other 2 stroke engine in severe use. advantage is the bean lube has some 'sticky molecules' that like to bind to steel and bind/fit in pores of brass and bronze. the petroleum base STP or VII additives have some of the same sticky and pressure capable qualities- one reason many rebuilders will coat gears and bearings, shafts with some STP when assembling them, a initial load when put in service will have a lube coat on metal to metal contact pieces that will last awhile until oil vapor, splash or pressure feed of oil gets to the metal surfaces. Put your worm and ring gear together and use a bit of STP to coat things or pour some 20-50 Valvoline racing/motorcycle oil over the parts as assembling. Some old pictures and of early water wheel powered equipment show a mild steel or iron worm driving wooden gear made from hard maple or oak, sometime teak and the plain bearing may also be wooden blocks that were drilled and packed with lard, mutton tallow and beeswax or whale oil. Have fun, if nothing else check your firewood pile for something round of right size to carve teeth and shaft hole in. RN.
 
You can use gear oil, as long as it is NOT EP (Extreme pressure), which contain additives that are hard on Bronze gears. Straight mineral oil or 'Spindle oil' is what they used to use in the old days.

Polish the worm leads and turn the bronze gear over, if you want. The bronze gears look pitted and worn within a few hours of initial use typically, even in a new box.

What is the center distance of the gears? That usually tells a lot on cost.
 
There's a good chance the saw maker used an off the shelf gear box. Look for a nameplate and model no. on it. If you find one you could get a replacement or equivalent from anyplace that sells industrial drive components.
 
(quoted from post at 10:48:50 09/04/15) There's a good chance the saw maker used an off the shelf gear box. Look for a nameplate and model no. on it. If you find one you could get a replacement or equivalent from anyplace that sells industrial drive components.

Yeah, but you would have to go to China to find the shelf it came off of.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top