brass sleeves to cover threaded rod in linkage conversion

[arpthark]

Hi all,

Sorry for spamming the Repair forum so much but I am in the thick of it, learning things hands-on and enjoying it.

Does McMaster-Carr sell sleeves to cover 4-40 threaded rod? I am not sure I know the right term to search for it.

Barring that, is there an alternative available?

Thanks again!

[bloke]

Hobby stores, other places, and the Internet sell shrinkable tubing. Black shrinkable tubing shrunk down over all thread looks pretty good, and you simply leave the ends exposed (and trim it up with a single edge razor blade or something) to screw on your links.
Otherwise, yes: there is some thin-wall brass and aluminum tubing that you can buy to hide the all-thread. I would look at McMaster.com

About the smallest metal tubing that will slide over 4–40 all thread would be something with a 1/8 inch inner diameter, which would offer about 8/1000ths clearance. Something with a 3mm inner diameter would offer even a tighter clearance (only about 6/1000ths).

[the elephant]

I buy my 4-40 all-thread rod at a local RC hobby shop.

I'm going back to the shop to see what I use.

Be right back…

[arpthark]

Aha- "tubing" was the key word that I was neglecting to search on McMaster-Carr's website.

Something like this is what I'm thinking (with a .124" ID):

https://www.mcmaster.com/8950K522/

Buy a couple feet of it and trim to size as needed?

[the elephant]

NOTE: There are two links to look for below. One is right here at the top, but the other is all the way down below the last photo. Cheers!

Wade
__________________

Get this stuff.

I bought this years ago. The stock number now has an "8" in front, so it is #8128. Likewise, the SKU/UPC code is different. This is just to show you what their labels look like if you opt to go to a hobby shop. In one of their K&S display racks these are not packaged, so you have to fish around to find the exact, same size. Here is the brand…


SAE size…


Metric size…


The fit is a little loose but works very well, and looks decent against the Team Associated sockets I use.






The last time I made these specific links was a set of four for my Cerveny Piggy. These same parts, assembled, look like this…




To keep the rods flat (with just the offset at the tip) I had to Dremel the heck out of the stop arms.


These are the sockets. I think the balls sere sold separately. I can't remember, though. I am not sure you can still buy these, but they do NOT break. I have had some on one of my tubas since 1995 and have never had to replace them. The snap on and off, and there is an initial fit point where you think it is on, but it won't turn. Keep pressing, and then it will suddenly pop on and work very well. I use whatever grease is at hand to lube them, but they do not really *need* lubrication.






Okay, I looked that up, and they are no longer available. Here is a 14-pack on eBay.

[bloke]

If you’re looking to fake a nickel silver appearance, you might consider aluminum tubing.
You can buff it to a shine and spray lacquer on it, but I would not polish it until the all-thread is inside it.

Aluminum is also slightly easier to work with, if you plan to curve the all-thread action arms.
Aluminum is also soft enough so that you could leave the aluminum covers slightly long and compact the ends by tightening the links down against the aluminum, which could function as sort of substitutes for locknuts.

If you decide to upgrade to metal links, you will probably need metric all thread – 3 mm.

[arpthark]

Great info here folks, my sincerest thanks for your help!

[the elephant]

The nickel hinge tube sold by Allied fits 4-40 a little better than the brass stuff, but it is thicker and much heavier. (The entire arm will still be lighter than a solid nickel silver "S" arm, though.) It is also not cheap. I have used it on a few horns and it looks great and is very rigid. Not recommended unless you are very picky and know that this is what you want.

Good luck!

[arpthark]

This will be my first foray into linkage conversion. I am working on a Chinese tuba marked WURZBACH but I am sure it's a 15-year+ old Chinese tuba... if you remember what Chinese tubas were like back then. The linkages are just garbage pot metal with stripped threads. Can't get much worse than that, so I figure I don't have too much to lose!

That said, I do want it to look a little nicer than the bare all-thread so I will see what I can manage.

[bloke]

A few more skills are required, but if you can find some solid nickel silver or hollow that’s not too large, you can just take a hand drill, take care to drill into the ends of your premeasured/(and pre-bent, if they need to be bent) pieces right in the center and straight through – but only about a fourth of an inch or so, insert some steel 3 mm all-thread, braze the all thread pieces in place carefully, chase the threads with a 3 mm dye - to clean off the braze, and you end up with some legitimate solid action arms and without having to use a lathe to cut down the ends of the nickel silver - which would be in order to tap threads into the nickel silver itself.
You can even pre-bend the nickel silver prior to drilling the ends, if you decide that the nickel silver action arms need to be bent.
There’s more than one way to skin a possum… at least, I thought I heard someone say that once.

main point here:
using some basic skills and basic tools – along with pre-threaded material – as workarounds for not having a lathe

[arpthark]

A few more skills are required, but if you can find some solid nickel silver or hollow that’s not too large, you can just take a hand drill, take care to drill into the ends of your premeasured/(and pre-bent, if they need to be bent) pieces right in the center and straight through – but only about a fourth of an inch or so, insert some steel 3 mm all-thread, braze the all thread pieces in place carefully, chase the threads with a 3 mm dye - to clean off the braze, and you end up with some legitimate solid action arms and without having to use a lathe to cut down the ends of the nickel silver - which would be in order to tap threads into the nickel silver itself.
You can even pre-bend the nickel silver prior to drilling the ends, if you decide that the nickel silver action arms need to be bent.
There’s more than one way to skin a possum… at least, I thought I heard someone say that once.

main point here:
using some basic skills and basic tools – along with pre-threaded material – as workarounds for not having a lathe

Oh, interesting idea. noob question: why would you need a lathe for the nickel silver in the first place?

I have soldered plenty, but not been brave enough to braze yet.

[bloke]

You would probably want nickel silver that is larger than 3mm in diameter, so - typically - you would want a lathe handy to turn the ends down to 3mm, so they could be threaded with a 3mm die (or – OK – 4-40 SAE).

[arpthark]

Thanks, I see what you are saying now. I thought it might have something to do with nickel silver being harder than brass, but yes, thicker stock.

I'll keep that solution in my back pocket for some day that I want to make something real nice and purty... after trying and failing a handful of times, which is how it's been going lately. But I am learning a lot!

[bloke]

It’s just not all that hard, but it’s slow going for someone who’s not done some of those operations before… and chasing threads with a die – to clean them up – is certainly easier than tapping with a die (as far as a novice is concerned). After doing a couple of ends, the other eight or so will become easier and easier. People on YouTube - I’m sure - show how to braze things.