88H Rotor Cork Diameter

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Driswood
Posts: 308
Joined: Mar 24, 2018

by Driswood »

What is the diameter of the rotor corks on an 88H? I want to replace mine but I don’t know what diameter to order.

5, 6, 7, or 8 mm?
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marccromme
Posts: 457
Joined: Mar 30, 2018

by marccromme »

I suggest you take your calipers and measure the existing ones. .. if you insist on ordering cork.

Also, you can try to use round glue sticks , the kind used for kids warm glue pistols, availabe at any hard ware shop. These are easily shaped with a scalpel, are sufficient hard to not compress, but sufficiently soft to eliminate noise.

Works very well for me. Most important: make sure you cut the bumpers such that valve ports align perfectly, both open an engaged.
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Driswood
Posts: 308
Joined: Mar 24, 2018

by Driswood »

[quote="marccromme"]I suggest you take your calipers and measure the existing ones. .. if you insist on ordering cork.

Also, you can try to use round glue sticks , the kind used for kids warm glue pistols, availabe at any hard ware shop. These are easily shaped with a scalpel, are sufficient hard to not compress, but sufficiently soft to eliminate noise.

Works very well for me. Most important: make sure you cut the bumpers such that valve ports align perfectly, both open an engaged.[/quote]

I’m looking at silicon for this. Not cork.

But the glue stick sounds interesting. I may have to try that.
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Posaunus
Posts: 5018
Joined: Mar 23, 2018

by Posaunus » (edited 2025-05-18 4:08 p.m.)

[quote="Driswood"]I’m looking at silicon for this. Not cork.[/quote]

Silicone may be too elastic or "bouncy" (depending on the durometer) and cause your valve to sort of double-actuate. This happened on my 88HCL, and was VERY annoying. John Sandhagen diagnosed it and replaced the bumpers with a stiffer rod. Works great now!
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marccromme
Posts: 457
Joined: Mar 30, 2018

by marccromme »

Thats why I like the stiffer glue sticks. No double bounce there. ... and easy to obtain
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ghmerrill
Posts: 2193
Joined: Apr 02, 2018

by ghmerrill »

[quote="Posaunus"]Silicone may be too elastic or "bouncy" (depending on the durometer) and cause your valve to sort of double-actuate.[/quote]
Yeah, I tried silicone for a while and just found it to be irritatingly bouncy. Also, I worried a bit about its compressibility and how uniform the valve action would be. I went back to the usual black rubber ones -- but even those you can get in different hardnesses.

If you need to measure the diameter, measuring inside diameter with a standard caliper is a bit tricky. A good way is to use pin gauges. Of course, if you don't have a collection of several hundred pin gauges, it's hard to cover all alternatives. But drill bit shanks work really well as long as you're confident that you're measuring a pretty standard size, or don't care much if you're a little bit off.