Rotor Bumpers

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walldaja
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Rotor Bumpers

Post by walldaja » Wed Nov 24, 2021 2:04 pm

At practice with nothing to do but count 30+ measures of rests I gave my horn a close visual inspection. I discovered one of my rotor bumpers was torn and about to fall out of its holder (the bumper you hit when the valve is activated). I can't think of when I ever gave those bumpers more than a cursory glance.

Took it to a local music store who are very good about replacing small wear items while you wait. The person at the counter took it back and reappeared in a couple of minutes. The torn (neoprene?) bumper was out and a nicely sized piece of good old cork was in its place.

Later when I played the horn I noticed a much more firm stop as the valve was activated. I imagine the valve was over rotating with the neoprene bumper and actually constricting the air passage to the F attachment. Also noticed that the low C and F are much more stable.

I was surprised
Dave

Antoine Courtois AC280BO with Christian Lindberg 5CL
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BGuttman
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Re: Rotor Bumpers

Post by BGuttman » Wed Nov 24, 2021 2:24 pm

It's entirely possible the neoprene bumper was worn or compressed and the replacement is fitted better. Cork isn't inherently better or worse than neoprene, but you will find it a bit firmer than the rubber.
Bruce Guttman
Merrimack Valley Philharmonic Orchestra
"Almost Professional"
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TriJim
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Re: Rotor Bumpers

Post by TriJim » Wed Nov 24, 2021 2:48 pm

Speaking of firmer - I use the stock Bach replacement bumpers (black neoprene rubber) on my Bach A47 (MLR) trombone valve; [Hickey's (item #054017)]. However; they quickly (4-6 mo) become firm/hard and make a lot of noise when the rotor is applied or released. The bumpers are not exposed to heat, cold or sunlight, but they do come in contact with rotor lube.

Anyone recommend a better bumper option (to replace stock Bach bumpers) that retain their flex and remain quiet?
CalgaryTbone
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Re: Rotor Bumpers

Post by CalgaryTbone » Wed Nov 24, 2021 3:17 pm

A little drop of valve oil will soften the bumpers, but will hasten them wearing out (slightly).

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OneTon
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Re: Rotor Bumpers

Post by OneTon » Wed Nov 24, 2021 3:39 pm

I lubricate valve(s) every day by removing the tuning slide(s). I put a few drops of Holton Rotary Valve Oil down the open tubing and replace the tuning slide(s). Once a month I take the valve cap off and put one drop of Holton Rotary Valve Oil on the bearing. I don’t get or put oil on the bumpers. I pack Bach’s goofy ball and socket fitting with Vaseline as required, once a week or once a month, just to keep the racket down.

Treat it like it was a combine during harvest, and replace the bumpers and strings, every winter, if they need it.
ithinknot
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Re: Rotor Bumpers

Post by ithinknot » Wed Nov 24, 2021 4:26 pm

If you want to be really pretentious like moi, then use firmer rubber (black Perbunan et al) for the engaged position, and softer (clear silicone rubber) for the resting position.

The firmer rubber stops the alignment from varying under inconsistent thumb pressure, and the softer stuff gives the quietest possible return, which is only subject to spring tension (more or less a constant).


Anyway, yes, alignment makes an embarrassingly obvious difference if you've let it go for a while :good:
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TriJim
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Re: Rotor Bumpers

Post by TriJim » Wed Nov 24, 2021 6:03 pm

Thanks for the tips and suggestions.

I use a drop of Ultra-Pure Light Bearing Oil for the piston spindle (under the valve cap) and a drop at the piston pivots near the bumpers. I also place UP Valve oil down the interior of the tubing as suggested. I use Hetman 15 on the Ball joints which keeps them quiet. No problem with operation of the valve (except the noise of the stops falling against the hard bumpers)

I would also note that the Bach A47 MLR trigger has two springs which contributes to a firmer trigger and return than models with a single trigger spring.

I haven't noticed if the Ultra-Pure Light Bearing Oil softens the neoprene bumpers and am suspicious that oil residues are contributing to the hardening of the bumpers.

Wondering - What is the experience of other trombone players with neoprene bumpers hardening? How long does it take and how often should they be replaced? ([On my trombone, the recommended Bach bumpers are 'noisy' hard in less than 6 months and disintegrate in less than one year). Is there another material that lasts longer and provides a quiet 'bump?' TIA
Kdanielsen
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Re: Rotor Bumpers

Post by Kdanielsen » Wed Nov 24, 2021 8:26 pm

Osmun outside boston has some kind of bumper material that they claim lasts longer and doesn’t dry out/harden. I like it so far.
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BGuttman
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Re: Rotor Bumpers

Post by BGuttman » Wed Nov 24, 2021 8:40 pm

Kdanielsen wrote:
Wed Nov 24, 2021 8:26 pm
Osmun outside boston has some kind of bumper material that they claim lasts longer and doesn’t dry out/harden. I like it so far.
They may be using polyurethane. 70 durometer is plenty hard and never seems to change, even if exposed to solvents. We used to use the stuff for screen printing squeegees.
Bruce Guttman
Merrimack Valley Philharmonic Orchestra
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hornbuilder
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Re: Rotor Bumpers

Post by hornbuilder » Wed Nov 24, 2021 9:35 pm

OneTon wrote:
Wed Nov 24, 2021 3:39 pm
I lubricate valve(s) every day by removing the tuning slide(s).
Instead of pulling the tuning slides, turn the horn so the bell points up, and drop the oil down the handslide receiver. Hold the valve "activated" so the oil lands on it, then, wiggle the valve.to distribute.

The problem with dropping down the tuning slides is the possibility of dragging grease and gunk into the valves from the insides of the tubes.
Matthew Walker
Owner/Craftsman, M&W Custom Trombones, LLC
Bass Trombonist, Opera Australia, 1991-2006
Mamaposaune
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Re: Rotor Bumpers

Post by Mamaposaune » Thu Nov 25, 2021 9:38 am

hornbuilder wrote:
Wed Nov 24, 2021 9:35 pm
OneTon wrote:
Wed Nov 24, 2021 3:39 pm
I lubricate valve(s) every day by removing the tuning slide(s).
Instead of pulling the tuning slides, turn the horn so the bell points up, and drop the oil down the handslide receiver. Hold the valve "activated" so the oil lands on it, then, wiggle the valve.to distribute.

The problem with dropping down the tuning slides is the possibility of dragging grease and gunk into the valves from the insides of the tubes.
You can also use a plastic straw to get the oil directly on.the valve, and bypass the tuning dlide grease.
baileyman
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Re: Rotor Bumpers

Post by baileyman » Fri Nov 26, 2021 5:58 am

Slices of vacuum cleaner belt last seemingly forever.
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harrisonreed
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Re: Rotor Bumpers

Post by harrisonreed » Fri Nov 26, 2021 4:48 pm

The Osmun buna bumpers are what I've heard about. Never got to try them!
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