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Author
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Topic: R3 Soundhead Shafts
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Manny Knowles
"What are these things and WHY are they BLUE???"
Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002
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posted 06-22-2002 11:23 AM
What causes these soundhead shafts to go bad?I've got several that need replacement. Holdback sprocket can be wiggled by hand.
Loss of film tension over the sound drum upon startup.
Rattling, knocking sound on startup.
Grooves worn into shaft at bearing points.
Metal filings visible in the equipment. I did a complete replacement of one of these already (shaft and bearings) and the machine is working just fine now. Once I'm done with all of these other ones, how can I prevent the damage from happening all over again?
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Paul G. Thompson
The Weenie Man
Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000
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posted 06-22-2002 11:49 AM
R-3's? Well, the biggest thing I have seen that cause them to go bad is improper belt tensions. The brearings will usually skin the shafts, rendering them useless. If the belt or chain tensions are ok, then they are just worn out. If I recall correctly, the bearings are basically a slip fit, and if the shaft turns in the inner race, it won't take very long to wear the shaft. Some of those shafts are made from very soft iron. Belt tensions are very critical in just about any belt-driven application.
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Paul G. Thompson
The Weenie Man
Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000
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posted 06-22-2002 12:39 PM
Manny, what kind do you have? The Cineshitties also had the bushing Gordon describes. A little drop of oil now and then keeps the shafts rotating nice and free. Just recently, I had a call where the operator was complaining that the belt was jumping cogs on start-up, and the motor was getting too hot. At the end of the movie, he shut the machine down, and it would not re-start. The shaft was seized. I could not free it up. I had to literally beat the damn thing out with a hammer.
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Manny Knowles
"What are these things and WHY are they BLUE???"
Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002
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posted 06-22-2002 03:18 PM
These are Westar models. I know for sure that they use 3 bearing rings.Would they also have an oiler hole in addition to bearings? I think I've seen such a hole, but I'm not sure. How tight should the belt be?
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Pete Naples
Phenomenal Film Handler
Posts: 1565
From: Dunfermline, Scotland
Registered: Feb 2001
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posted 06-22-2002 03:38 PM
If these are the earlier design with the Oilite Bronze bush, then it's oil starvation that causes this wear. The bushes are running right at the top of the rpm range for such bushes, and thus good lubrication is VITAL to their longevity. There is also a problem with design on the lubrication system, firstly the oil cup is in a daft place, round the back, and as said above gets forgotten about, secondly there is no breather, so often what happens is that you fill the oil cup thinking all is fine, but actually there's not enough oil to get anywhere near the bushes, what's worse is that when the machine warms up the air in the cavities around the bush expands and pushes the oil back up out of the cup, which makes a mess and leads the operator to believe that he/she is overoiling, so they oil less......
This is why you should oil that cup last thing at night before you go home, so that as the mech cools it sucks the oil in. Alternatively you can do as I do with those tye of R3 heads, and drill a small breather hole from the operator side, at the top of the hold back shaft boss casting. Point of fact Westrex issued a modification bulletin way way back just after they first made 2002 (R3) rep-sets, instructing their engineers to drill the small breather hole. All Westrex 2002 rep sets I've ever seen have this breather hole and I've yet to have to re bush a Westrex head. By comparison I've re bushed the same pair of Century R3 heads twice in 4 years before I remembered about the breather hole and got my drill out.Word to the wise, when you replace the shafts, make sure you get them of the correct grade of steel. I once made the error of fitting a ball bearing grade shaft to a Oilite bush machine. The shaft was too soft or maybe the steel had too high a carbon content, anyway it deteriated very quickly. I had a shaft made locally with new bushes, and asked the machine shop to make it from a steel suited to the Oilite bushes, and to this day it's fine. The ones supplied from Strong are obviously for ball bearing machines and don't work on the bushed type. or didn't in my case.
If the heads you're having trouble with ARE ball bearing types, then you've obviously got some siezed or brunelled races in there. Replacing them is easy but it's getting harder to get decent quality ball bearings these days. I tend to put a tiny spot of Loctite bearing seal on the inner and outer journals, in case the fit of the shaft to the race is a bit loose. Also be wary of the shaft enfloat, too little will excessively pre-load the bearings and they'll fail again very quickly. I, along with Gordon, strongly second what Paul said about belt/chain tensions too! Here endeth todays sermon!
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