Dempster #12 Hub

[LoTec]

I am FINALLY getting back to the 6' Dempster #12 that's been sitting in my shop for about three years. The hub had gotten loose on the shaft, wearing the hole in the hub and the shaft. (Of course the mill had other problems, too, such as a broken mast pipe so it was hanging upside down by the pump rod when I was called to fix it).

I was unable to find a replacement hub, and the machinist I usually go to did not want to try to bore and sleeve the existing hub. Last fall I found a different machine shop that agreed to tackle the job. It only took them eight months to get around to it.

They turned the worn area of the shaft down less than 1/32". I hope the remaining shaft is strong enough. Then they bored out the main hub and the spider, and made sleeves to fit the shaft.

Unfortunately, in the process of pressing the sleeve into the spider they broke the casting. It's a clean break, I think I can nickel weld it. My question is, should I weld a steel plate on the flat side for reinforcement?

DSCN5124.JPG

I was cleaning parts this morning and trying to get all the goo out of the little passage under the front bearing race seat in the snout, and cleaning out the oil return passage in the bottom of the snout. I noticed that when that return passage gets back to the motor, there is what looks like a casting seam that sticks up and partially blocks the oil from flowing back into the motor.

DSCN5129.JPG

Is there any reason not to grind this seam down so it's not blocking the oil return? Even if I do this, the bottom of the oil channel is lower than the bottom of the motor at this point. Seems like a poor design to me.

[JBarker]

Lo Tec, I had the same question about the oil passage. I just noticed the same thing on my #12 when putting it back together today. Seems to be a small dam from casting just on inside of the gear box oil return. 9 Maybe, Windy or others will enlighten us. Thanks.

Jerry

[windybob]

Here's the enlightenment. it is a dam. As far as I know, it keeps the oil level up the where the spiral can pick up the oil. I have take it out in the old days, but not for many years. What you need to make sure you check, is the drainback in the bottom of the front, under the race mount area. That has to be clean. I have seen roller bearings clog it up, and also bad castings where it's virtually cast closed. If you have the setscrew under the snout, put sealer on it so no leak occurs, however if it does drip, the brake will never squeal. lol

Yes you can put a plate on to match the front hub, and weld it.

On both hubs, drill and tap a hole in the thick part, and install another setscrew or two. Put other places in the brake hub above the keyway. I have had hubs sleeved, and had good luck. I have had hubs bored and sleeved, and not had to turn the shaft down.

[JBarker]

Thanks Windy

[LoTec]

Here's the enlightenment. it is a dam. As far as I know, it keeps the oil level up the where the spiral can pick up the oil.

I was working on this critter again today. I find it hard to believe the casting ridge is an intentional dam. I don't see that it in any way can keep the oil level up where the spiral can pick up oil; the spiral is like an inch higher than the level where the oil would run back into the motor.

For that matter I don't comprehend how any of the hub oiling system works.

The cast spacer riveted to the shaft has a spiral ridge that should move the oil out toward the hub (after the gears and the pumping action of the crosshead slop oil on it). That's all well and good, but once the oil gets to the end of the spiral, there is a spring between that and the front bearing. And that blinkin' spring is wound in the opposite direction from the spiral. As the rotating spiral pushes oil outward, it sure seems like the spring would be trying to make it move inward.

If any oil actually gets to the bearing, and makes it through to the front side, it looks like it is supposed to drain down into the return channel at the bottom of the snout through the passage under where the bearing outer race is mounted. But, there is a set screw sticking up into this passage, and into the slot in the spacer ring, and there is very little open space for oil to drain into the channel. And if oil does make it into the bottom channel, as I said, that channel is lower than the motor it seems like it should be draining into, and the end of the channel is dammed.

I am thinking once I get the hub on this thing I should rig up a way to put a belt and electric motor on it and run the windmill motor for a few hours with oil in it and see if the bearing is getting lubed and if the hub leaks.

[windybob]

All good points.

[LoTec]

An update on this project, which got supplanted by other jobs for a while.

I did rig up a pulley and a motor to run the mill for a while. And the hub leaked oil.

I had done my best to pack the 01202N snout with felt, which I cut out of an old felt boot liner. But the oil was drip dripping out of the drain hole in the snout.

So, I took some measurements and went online on grainger.com and ordered an oil seal that I hoped would work. Here's a photo:

dempster snout w oil seal.jpg

This seal seems fairly snug on the shaft. It fits in the snout but loosely. I plan to set it in place with RTV sealant.

My main question now is, do I still need a felt dust seal? Like I said, I have been trying to cut a piece out of an old felt boot liner. But it's hard to get a clean cut on that stuff, and it's hard to pack into the smaller diameter part of snout, which is where it seems like it belongs:

where felt goes.jpg

I also have some 5/8"x3/16" felt weatherstripping I thought about using, but am not sure how to pack that into the snout tightly enough to sorta seal on the shaft, and get it to stay there while I slide the snout over the shaft.

Any suggestions appreciated.

[windybob]

If the aftermarket seal you are installing does the job, then a dust seal of any kind will help keep it clean.

[Todd]

If I recall correctly, there was a discussion on the old forum about the oiling springs being wound with the wrong spiral from the factory. I think Paul Cowley and Dave Straub had input on that old thread. Also, "Grezmonki " may have some insight on this as he has rebuilt quite a few of them.

[Wayne]

Yes Dave Straub can tell you all about the the backward wound springs. I don't know if it would help but I have some packing material that I get from gas engine part suppliers. It is a rope about 1/4 inch diam and made up of smaller size material. It is coated with something. We use it in packing our fuel pumps and other things. You might try Starbolt out of Md 301-874-2821 good people easy to deal with e-mail Starbolt4U@aol.com. Or Hit and Miss Enterprises out of Ohio.