Valve oil and plastic valve guides

[PMonteiro]

Not sure which forum this should go in, but this one made the most sense. When I oil valves I like to put a small amount on the valve guides and guide track (it really makes a difference in valve action). Not a problem for my horn with metal guides, but what about student trumpets and their plastic ones? Since petroleum and plastic products don't tend to mix well, can oiling plastic valve guides damage them over time?
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YTR-6335HSII
YTR-2320
Accord in C

[Crazy Finn]

Hmm.... don't know, I've never done it and never needed to.
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LA Benge 3X Bb Trumpet
Selmer Radial Bb Trumpet
Yamaha 6335S Bb Trumpet
Besson 709 Bb Trumpet
Bach 184L Bb Cornet
Yamaha 731 Bb Flugelhorn

[Beyond16]

I can't imagine any type of valve oil attacking the plastic. After all, the valve oil itself is sold in a plastic bottle. The guides are probably made of HDPE, nylon, delrin, or something like that. I don't know of any solvent or lubricant that attacks those.

[deleted_user_687c31b]

Chances are some of the oil has already touched the valve guides anyway, and even if it hasn’t, manufacturers have probably considered the possibility. If there were an oil that could melt valves, I’m pretty sure we’d have heard of it by now as it would be a pretty great story to share.

[etc-etc]

The parts of the valve guide that would have any benefit from lubrication are the ones that would not hold the lubricant well - these are:
1) the "wing" protruding at opposite sides from the cage (cage is holding the valve guide and the spring), and
2) the slot from which the wing protrudes.

[Bflatman]

This is actually a very good question and in answering it I will begin with some anecdotal evidence to reassure you.

I have instruments that are well over 50 years old. They have plastic guides and there is no evidence of any attack from oil.

This is the general rule:-

Typically, lubricants based on silicone, PFAE (perflourinated), most synthetic hydrocarbons (SHC or PAO), or mineral oils work well with plastics. Lubricants based on esters or polyglycols are generally not compatible with plastics, although there are exceptions depending on the type of plastic.

Valve oils are generally mineral oils. We do not see lubricants based on esters or polyglycols in the valve oil world.

Some musicians experiment with their own oils and here can be an issue.

Oils containing graphite can attack plastics the graphite being the culprit.

This extract goes further and indicates the problem:-

Typically, lubricants based on silicone, PFAE (perflourinated), most synthetic hydrocarbons (SHC or PAO), or mineral oils work well with plastics. ... For example, solid additives, such as graphite or molybdenum disulfide (moly), can penetrate and weaken a plastic component and should generally be avoided.

A home brew valve oil could conceivably have moly added and without realising it threaten the integrity of the plastic guides.

This is why you really need to know what you are doing when creating your own home brew oils or you can inadvertently cause damage.

If however you stick to using commercial valve oil the possibility of dissolving or damaging plastic guides is non existent.

On the other hand I am not a chemist so I cannot give a definitive answer.
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Conn 80a Cornet
Boosey & Hawkes Emperor Trumpet
Olds Fullerton Special Trumpet
Selmer Invicta Trumpet
Yamaha YCR 2330II Cornet
Selmer Student Trumpet
Bohland and Fuchs peashooter Trumpet
Boosey and Hawkes Regent Cornet
Lark M4045 Cornet

[GeorgeB]

I wouldn't use oil on the guides, especially the small metal ones like the Selmer Paris horns have . I had an occasion when a guide on one of the valves slipped out of its slot and jammed. This happened in the middle of a Christmas concert and it took me three songs to correct the problem. These days I am careful to wipe the metal guides after oiling the valves.
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GeorgeB
1960s King Super 20 Silversonic
2016 Manchester Brass Custom
1938-39 Olds Recording
1942 Buescher 400 Bb trumpet
1952 Selmer Paris 21 B
1999 Conn Vintage One B flat trumpet
2020 Getzen 490 Bb
1962 Conn Victor 5A cornet

[PMonteiro]

[Crazy Finn]

To elaborate a couple of points.

- Any oil that has causes problems for plastic probably shouldn't be a valve oil. After all motor oil is sold in .... plastic bottles. Valve oil as well. If there was problems with plastic valve guides and oil, you'd see that happen for repairs with student horns, because students aren't as careful with the oiling as professionals. Well, you don't see that.

- Oil works on valves because it's a largish smooth, flat surface for the lubricant to work on against another smooth flat surface. Flat is relative, obviously, because both the casing and valve are round, but essentially, you could make those surfaces out of a piece of paper.

- The part of the valve stem/guide/barrel that would/could theoretically use lubrication is the edges of the valve guide slot. I suppose that that would decrease the amount of friction for a short time, but there's no way oil would stay on such a small surface for any meaningful length of time. The guides themselves could have some, but again, small uneven surface is not conducive to lubrication. If the slot is not smooth when you manually move the guide up and down, then that's a problem that a tech might be able to smooth out, but good manufacturing should result in a fairly smooth surface.


Basically, you're overthinking this and it's not really doing anything. Feel free to keep doing it, lots of people do things that are only "effective" because they "think" it is, which is fine, but just be aware that there is no actual mechanical/scientific basis that it does anything after 1-5 minutes.
_________________
LA Benge 3X Bb Trumpet
Selmer Radial Bb Trumpet
Yamaha 6335S Bb Trumpet
Besson 709 Bb Trumpet
Bach 184L Bb Cornet
Yamaha 731 Bb Flugelhorn

[LittleRusty]

Note that there are different types of valve guides.

My Yamaha flugelhorn has a finger at the top of the piston that moves with the piston and travels in a slot in the side of the valve casing. If memory serves this finger is plastic and should be essentially self lubricating.

My Bach’s have a guide that rests in slots in the casing sides and remains fixed as the piston moves up and down. The barrel that holds both the spring and the valve guide has a slot on each side that the guide travels up and down in.

Lubricating the Bach style seems a little futile to me. I have never lubricated them, but if I did, I would consider slide grease as it might be more likely to remain in place and effective.

[Bflatman]

What you need to understand is that many valves with top springs have a guide with a spring sitting on top of it and a retaining ring or cap above that that is fitted by turning it while the spring below it is in contact with it.

The spring is supposed to sit slightly compressed but not twisted in its position. But assembling the valve always twists the spring and this then affects the clean running of the guide in its slot.

When you disassemble the valve and reassemble it you put the guide in its chamber then the spring on top and then screw the retaining part above that to secure it all.

This of course only applies to guides and springs in enclosed chambers with slots in the chambers the guide runs in

What normal assembly causes is the top retainer when screwing it all together, to twist the spring a couple of revolutions as it is tightened and the spring then slips under the twisting action.

But after the valve is fully assembled the spring remains slightly twisted and this twist forces the guide to spin in its slot and sit tight against the slot the guide rides in and this causes binding and wear.

The guide is not supposed to run in contact with the slot under the tension of the spring.

This causes problems that oiling appears to fix.

The correct fix is to assemble the valve and when it is complete to lift the spring off the guide so the spring can relax and the guide then will run smoothly and no lubrication to the guide is needed.

This twisting of the spring and binding of the guide is one of the causes of valve action noise.

All my valves run sweet and silent due to good cleaning and attention to detail but you have to know what the issues are before you have a chance of eradicating them.

Always when you assemble valves take the tension out of the assembly and the parts can then run true and silent.

Lift the spring allow the guide to center itself then allow the spring to sit on the guide in a relaxed state all will then be good.
_________________
Conn 80a Cornet
Boosey & Hawkes Emperor Trumpet
Olds Fullerton Special Trumpet
Selmer Invicta Trumpet
Yamaha YCR 2330II Cornet
Selmer Student Trumpet
Bohland and Fuchs peashooter Trumpet
Boosey and Hawkes Regent Cornet
Lark M4045 Cornet

[PMonteiro]

Bflatman - great advice! My 6335H in particular is sensitive to spring tension and I will admit I've tried to quiet it down with oil before.

[LittleRusty]

[etc-etc]

You are trying to remove the residual torque caused by incomplete slipping of the spring when the valve stem is screwed in.

When assembling the valve, insert and rotate the valve guide into its proper position (through the slits; mark the correct orientation before assembly) and drop the spring into the cage from above. Before screwing in the valve stem, slide a straightened paperclip through the valve cage slits. Using the paperclip, compress the spring enough to prevent its contact with the valve stem. Once the valve stem is completely screwed in, remove the paperclip and you will have zero residual torque.

[ayryq]

My Yamaha flugelhorn has plastic valve guides (and bottom springs, if I want to wade into that aspect of this thread). I have started always oiling the guide slots after reassembling the valves, and I think it's helped. I use Hetman synthetic valve oil and I've noticed no interaction between oil and plastic.

I kind of hate the valves on this horn, and I think the valve guides are part of the problem. Oiling the guides seems to give me a little longer before they start sticking again.
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Yamaha YTR6345HGS Bb
Bach "Philly" C
Bach 239 Eb/D
DEG Signature 2000 Bb/A picc
Yamaha YTR-9835 Bb/A picc
Yamaha Bobby Shew flugel
Yamaha Neo cornet

[etc-etc]