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Re: Ricardo no longer with Backun?

Author: clarnibass
Date: 2018-08-28 09:19

>> When they get to the point where you can't screw them in all the way and they are a little too loose... <<

That isn't really a problem... if the screws are made in the best way, which is regular screws (with head), made accurately so there is no play when tightened. There is eventually wear but, first, it's very slow, and second, it's usually easier and faster to repair than wear in keys with rod screws.

One issue is many companies try to find ways around making them this way, to lower cost. Headless screws, plastic sleeves, set screws, etc. Some of these do actually make adjustments easier, but not as good at keeping it. Depending on method, it could be cheaper both because of the part itself but mainly because it saves a lot of fitting time.

Statistically, I see much more wear on keys with rod screws than pivot screws. It is very common for a clarinet to have hinge tubes with axial and end play, while having barely if any play on the hinge rods. It's not anywhere near 100% of the times, but just more common than the other way around.
Some hinge tubes can't even be swedged, so have to be repaired by other more expensive methods.

Another main reason hinge tubes are usually not used for long keys is manufacturing costs. It is harder (more expensive) to make a long hinge tube and rod screw to fit accurately.

A small advantage, which I don't think has much to do with manufacturers' decisions, is that a long hinge tube is likely to bind if bent, but a key with pivot screws can still work. For example I've seen a lot of bent left side F/C levers to a degree that would absolutely bind on a rod screw, not allowing the F/C key to open once pressed, but still worked with pivot screws.

>> That's because a bent key means a bent rod. <<

Sometimes but not necessarily.

>> Of course you can just machine a new one, but then the time and expense are probably worse than the fixes one would use for a loose pivot. <<

You're right, usually it is. Sometimes bent rod screw take a long time just to remove.
For example, a 0.05mm inaccuracy in a hinge rod (with pivot screws) might be invisible and completely insignificant to the reliability of the instrument, while the same inaccuracy in a hinge tube with rod would prevent it from working at all.

>> Perhaps these will be headless pivot screws like Leblanc used at one time which will allow for easy correct adjustments. <<

Let's hope not, for whoever is going to buy it

Unless they come up with some new brilliant method to counter their issues. To be honest weak thread locker is better than the usual alternatives and is very reliable until you want to adjust them again.

Though the type of screws is irrelevant to what I was curious about before. Do you know when this model is going to come out?

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Ricardo no longer with Backun? new

Reed B Chirpin

2018-08-24 22:20