[Bkenes]

I rarely repair brass instrument but I have a customer with a trombone slide that has a weird suction-thing going on when you move the slide.
Do anyone here know of any possible problems that might be the cause to this?
It's a bach something with rose gold bell, don't remember what model. He said it was bought in the 90s(?).

 

[simso]

Need more clarification on what “suction thing “means

 

[Bkenes]

Sorry simso,
You can feel how there is suction inside of the trombone that are making the slide harder to slide. It's not that there are any bends or dents... You can clearly feel a suction that makes resistance.
I'm not sure if this is clear enough. I find it hard to explain this better in English. But I will give it another shot if this isn't clear enough.

 

[Dr G]

Sorry simso,
You can feel how there is suction inside of the trombone that are making the slide harder to slide. It's not that there are any bends or dents... You can clearly feel a suction that makes resistance.
I'm not sure if this is clear enough. I find it hard to explain this better in English. But I will give it another shot if this isn't clear enough.

Are you describing a time-dependent viscous response? It sounds like there is a lubricant buildup that provides more resistance when you accelerate the slide. Is that what is happening?

If so, clean the slide and tubes, and relube the slide.

 

[simso]

I think your description of suction is drag or resistance, when you move the assembled slide it feels heavy and not free moving, is that what happening?

Does each inner slide move freely with its outer slide when tested individually.

Steve

 

[Bkenes]

I think your description of suction is drag or resistance, when you move the assembled slide it feels heavy and not free moving, is that what happening?

Does each inner slide move freely with its outer slide when tested individually.

Steve

It doesn't feel heavy but yes there is some resistance, but not every time you pull the slides. I've tested the slides individually and had mixed results. They did still have that feeling of air suction recistance when they were tested individually. But not all of the time. You can only feel it sometimes...

Are you describing a time-dependent viscous response? It sounds like there is a lubricant buildup that provides more resistance when you accelerate the slide. Is that what is happening?

If so, clean the slide and tubes, and relube the slide.

No it doesn't feel like that. It feels like air suction. My first thought was this though. I asked him and he said that he has cleaned it from old oil several times without any improvements.

 

[simso]

Get a set of verniers out and measure the distance between the outer tubes at the crook end and near the handpiece, they should be within .1mm.

Another trick for quick assessment, slide one inner and one outer together, rotate the other inner to lay alongside its respective outer, this will show if the inner slides are splayed or twisted.

There is still the possiblilty also of twisted outers, you really need a flat stone to check for this.

Inner slides running individually with respective outers should be perfect, as when you run both inners and outers together it exasperates any issues

I do a lot of trombone slides.

Steve

 

[saxoclese]

Get a set of verniers out and measure the distance between the outer tubes at the crook end and near the handpiece, they should be within .1mm.

Another trick for quick assessment, slide one inner and one outer together, rotate the other inner to lay alongside its respective outer, this will show if the inner slides are splayed or twisted.

There is still the possiblilty also of twisted outers, you really need a flat stone to check for this.

Inner slides running individually with respective outers should be perfect, as when you run both inners and outers together it exasperates any issues

I do a lot of trombone slides.

Steve

Excellent answer Steve. Truing professional trombone slides is truly an "art". I think a description of how the inside of the outer slide was "cleaned" would be a good question to ask at this point.