9 replies to this topic

[Hewlett_T]

Hey,

Let's say I have the cone off (it fell off), how can I remove the knuckle joint. The new one looks like a straight shaft so a good whack should do it I feel but worried about breaking the trumpet.

I just wanted to make sure it just needs a good whack before I whack it harder.

Thanks.

[wile e coyote]

The trumpets are exceptionally strong trouble is they're alloy and the knuckle is steel so corrosion has a field day......put it in a vice near the knuckle (material is thicker there) get a suitable steel bar the act as a drift (I don't often misuse tools but a very worn sds masonry bit dit the job last time out...) and hit it with a bfh - if you've got a bit of time pop some proper penetrating oil in and wait a week then whack it....(i'm betting its a back one - but if a front an 8-10mm pin punch instead of a decent steel rod)

 

Reassemble with  a decent smear of copper grease and with a bit of luck it won't happen again...

 

In the unlikely event of trumpet damage drop me a line - I'm not far from you it seems and probably have spares....

Edited by wile e coyote, 18 July 2017 - 08:17 PM.

[AeroNotix]

Everything Wile E Coyote says is correct and has worked for me in the past so I thought I'd drop a humorous story about getting these apart.

 

I was in the same situation as you and my go to method is heat, hitting and hammers. I was heating the knuckle joint while holding the trumpet in grips. I wanted to shock cool it so I dipped the end in a bucket of what I thought was water and to my surprise a HUGE tower of fire erupted from the bucket and scared the life out of me. Turned out I had wet a rag in there a few hours earlier and there was a layer of oil and other crap on top of the water that the hot knuckle ignited!

[tiger99]

Please do not put the trumpet in a vice or use excessive heat. You will damage it and it will fail later.

A hot air gun on the small end of the trumpet is ok, and may be all that you need, but there are other possibilities such as putting lots of penetrating oil (not a water dispersant like WD-40) down the trumpet and standing it vertically to soak.

But ultimately you will perhaps try holding it in your hand (gloved if it is hot) and putting a steel rod of less than knuckle shank diameter down it. A few sharp blows with a Calibrated Persuader aka Birmingham Screwdriver osually starts it moving.

Don't grip the knuckle in the vice and try twisting the trumpet. Even if the knuckle us not abysmally tight, the torsional strell will take the end of the trumpet way into the fatigue region, and if it does not break immediately, it will do when you least expect it.

A variation on the steel rod and hammer trick is to clamp the rod vertically in the vice and bang the assembly down on it by hand. You can take that to its extreme and fit a large tube over the trumpet, butting against the flange, and use the Persuader on the end of the tube. Or do it upside down, large tube standing in vice (works best in a Workmate with lots of space below) and use the Persuader on the steel rod. You may even manage to get the trumpet sitting nicely in the Workmate with no tube, in one of the notches in the plywood jaws. Don't tighten fully.

The secret of success, ie being able to use the trumpet again, is to go at it firmly but gently, and load it only longitudinally. Have fun!

[AeroNotix]

Sage information again tiger99. Every day is a school day with people like you around.

[Tommyboy12]

I stack up a couple of steel wheels and put the trumpet, knuckle down, through the central hole of the wheel. It's the perfect size to support the rolled edge of the cone. Then you can knock out the knuckle with ease.

[Spider]

I drop the trumpets in to a length of 2-1/2" water pipe and then bash the knuckle out from the inside with a length of 1/2" rod. Once it's out, reem the hole back to size (1/2") and grease the shaft of the new knuckle when fitting.

[AeroNotix]

When you say ream out the hole to 1/2" is that larger than original?

[Spider]

When you say ream out the hole to 1/2" is that larger than original?

 

The knuckle is a slip fit in to the trumpet, the original ID is 1/2".

[nicklouse]

so cleaning it back to original.