TromboneChat

It occurs to me that the rods and paddle on the 2nd trigger of my Holton TR181 probably have as much mass and inertial resistance to moving as the actual valve does.

Does anyone make carbon fiber substitutes for these things?
Is there way I could craft it myself?

Knowing very little of carbon fiber outside of bikes, I would assume that it would take quite a bit of money. You can't really melt or bend carbon fiber without it losing its strength, so you would have to make a mold, but I doubt you could actually make a carbon fiber bent rod so thin. Maybe you could get creative with the linkage.

Short answer: No, unless your wallet is big enough.

Could I suggest cutting down the inner tubes of the attachment tuning slides as an alternative weight saving measure?

Peacemate wrote: ↑Wed Mar 09, 2022 3:21 pm Could I suggest cutting down the inner tubes of the attachment tuning slides as an alternative weight saving measure?

inner tubes?

robcat2075 wrote: ↑Wed Mar 09, 2022 3:28 pm

Peacemate wrote: ↑Wed Mar 09, 2022 3:21 pm Could I suggest cutting down the inner tubes of the attachment tuning slides as an alternative weight saving measure?

inner tubes?

The male part of the tuning slide, connected to the tuning slide crook.

Hmmm.

It's not the mass of the whole horn that is a problem.

It is the mass of the trigger mechanism. Things with mass resist motion. It's like a law of the universe.

The 2nd trigger has much more metal to move than the first and it has always been slower than the first. The valve itself turns freely.

I see that I can get 6mm CF tubes fairly inexpensively.

I could at least replace the straight rod with a piece of that.

I wonder if there is a way to miter cut and glue together portions to make bended shapes.

If the valve turns freely, it's probably the spring that is giving more resistance; or possibly the bearings need lubrication. Try putting some spindle oil (3 in 1 is a good one) on the ends of the spindle. If necessary, a Tech can replace the spring with one a little weaker. Weak springs require less effort to move, but will operate a little slower than strong springs.

I guess you have a small problem with your cello grip

robcat2075 wrote: ↑Wed Mar 09, 2022 3:52 pm It is the mass of the trigger mechanism. Things with mass resist motion. It's like a law of the universe.

I could at least replace the straight rod with a piece of that.

I wonder if there is a way to miter cut and glue together portions to make bended shapes.

Oh, that makes more sense. The straight rod would definitely work, but the miter cut and glue would (I'd assume) put all the stress right at the glue connections, so you'd have to have some strong glue/epoxy, and probably 3D print some kind of connector, which could definitely save some weight. As someone who has used TinkerCAD a bit before, it probably wouldn't be too hard, but I wouldn't jump into it without a bit of experience with 3D printing, since strength would be quite crucial.

Thinking about it, you could use two different sizes of tube, and then drill holes into the tubes to allow another tube to go through, and then just do that over and over again. Maybe using like 6mm external 4.5mm internal and then another with 4.5mm external tubes, and then put the smaller one in with a bit sticking out. Maybe also miter the outer tube to provide some extra strength and support. Seems like a cool project for sure.

You could certainly replace the straight rods with CF if you really want.

Assuming everything is working fine rotorwise, you can always speed up the 2nd valve with a stronger spring (or the existing spring installed with an extra turn).

If you find the levers comfortable, perhaps leave them alone, but it would definitely be possible to speed up the mechanics with changes to the lever and linkage design, with or without the original saddle/pivot positions. I haven't spent long with a TR181, but the last time I held one the ergonomics and mechanics struck me as pretty awful, with a particularly long throw for the thumb. Part of it is the mechanical advantage of the levers, but there's also the radius of the ball-and-socket position relative to the rotor spindle... there are plenty of variables.

The touch point of the 181 thumb lever is particularly offset relative to the plane of the saddle (ie down towards the slide), which significantly increases the horizontal component of its travel. I'm sure this suits some paws.

Peacemate wrote: ↑Wed Mar 09, 2022 3:21 pm Could I suggest cutting down the inner tubes of the attachment tuning slides as an alternative weight saving measure?

If you want to rebuild the wrap with shorter inners and outers, sure. (And rethink the bracing while you're at it.) Chopping down inners alone is straightforwardly bad idea, giving less than half the potential weight loss and creating massive bore gaps for no good reason. (If you think these don't matter, tell me your F side doesn't blow and slot less evenly when fully pulled... it's not just the extra length.)

You could buy one of these rods for your DIY project

https://www.racedayquads.com/products/1 ... -your-size

The theory is good; inertia is relative to mass.
That said, in this case it looks like mass is an insignificant part of the problem.
The inefficient design of the existing linkage is probably much more to blame.
I would focus my effort on improving the geometry of the (brass) linkage.

If I were going to improve the brass linkage geometry I'd get rid of the brass linkage geometry and make it a string but I don't think that's feasible.

robcat2075 wrote: ↑Wed Mar 09, 2022 11:14 pm If I were going to improve the brass linkage geometry I'd get rid of the brass linkage geometry and make it a string but I don't think that's feasible.

Converting your rod linkage to a string linkage is possible. I asked my tech Graham Middleton to do this on my Bach 50B3 bass recently. You need a tech with experience and imagination. If you’d like Graham’s contact info send me a pm.

Kbiggs wrote: ↑Thu Mar 10, 2022 9:56 am

robcat2075 wrote: ↑Wed Mar 09, 2022 11:14 pm If I were going to improve the brass linkage geometry I'd get rid of the brass linkage geometry and make it a string but I don't think that's feasible.

Converting your rod linkage to a string linkage is possible. I asked my tech Graham Middleton to do this on my Bach 50B3 bass recently. You need a tech with experience and imagination. If you’d like Graham’s contact info send me a pm.

It's very possible - but it's more complicated here because the existing rotor stop doesn't have any raised shaft/spindle length around which the string can loop. On a Bach, you may still have to braze on an extra tab for the string fixing point (assuming you're not refitting the bumper plate 180 deg on the rotor casing), but the overall shape of the rotor stop is still usable. On the Holton you'd need to fabricate new rotor stop fittings with much longer screws reaching down into the rotor spindle, in which case it's probably easier to retain the existing stops, cut down the ball fitting and drill/thread for miniballs. The angle of the 2nd valve linkage and its attachment point may or may not need to change. (For examples, see Yamaha - horizontal, Greenhoe/Shires - diagonal, Rath - vertical.)

It all depends on what you're trying to achieve and what you're willing to pay. If you're happy with the existing lever positions, then converting to string linkage with a new rotor stop spindle of conventional dimensions will give you a smoother action and somewhat shorter throw than the current arrangement, with the same ergonomics and relative travel between the thumb and finger levers.

If you also wish to change the ergonomics, and/or potentially alter/equalize the relative travel of the two levers, then you need new levers. In this case, you might as well go for the simpler conversion of the existing stop arms and use miniballs; reducing travel can be achieved through the mechanical advantage of the new levers.

CharlieB wrote: ↑Wed Mar 09, 2022 7:13 pm The theory is good; inertia is relative to mass.
That said, in this case it looks like mass is an insignificant part of the problem.
The inefficient design of the existing linkage is probably much more to blame.
I would focus my effort on improving the geometry of the (brass) linkage.

I tend to agree; geometry rather than mass.

You mentioned that the valves turn freely on their own. I'll bet that the levers move with almost zero effort when they're not attached to valve, too.

Check out the new linkage...

https://trombonechat.com/viewtopic.php?p=173460#p173460