Bach 50 slide out of alignment

[brassmedic]

I have a vintage 50B at the shop. Slide doesn't move well. I measured the outer slide alignment, and it's. 040" out of parallel ( yes, 4 hundredths), which is about 10 times more than what would be acceptable. It looks like the original lacquer and doesn't appear to have any dents. I suspect it was assembled that way at the factory! Anyone ever see anything this bad before?

[BarryDaniels]

My Holton TR-10 was .060" out of alignment. Instead of being a build issue, I believe the end crook opened up when the guard took an impact.

[octavposaune]

Back when I took notes in the oughts, the common span descrepency with Bach slides that I saw was .027"!!! On 42 and 50 handslides made in the 70s and early 80s. It is not explanable by solder Shrinkage due to Eutectic cooling, as all those slides were too WIDE at the top. I figured out how to fairly predictably assemble outers through trial and error and how much to offset the width of the upper brace sockets for my methods, it seems slides were very carelessly assembled back then.

Benn

[Blabberbucket]

.04" is wild. Modern Bach slides are pretty consistently .015 - .02" out, in my experience. Their slide-building fixtures are an interesting sight to see.

[Crazy4Tbone86]

Yes, I have seen a few Bach slides that were .040 to .050 out of parallel. I have seen them out of parallel in both ways: being too narrow at the top and being too wide at the top.

I have a bigger beef with the Yamaha slide alignments. I have seen hundreds of YSL-354 models in which the outer slide is perfectly parallel, but the inner slide is drastically too wide. This is because the slides are designed to have the inner slide brace tube be flush against a stopping point on the inside of flange on one side. Great design if it actually stays flush. On more than 50% of the 354 models, some solder gets in there and pushes the brace too wide. Whenever a new 354 slide doesn’t move smoothly, that is the first thing I check. If you pull the brace apart, sand or grind a small amount off the brace tube, resolder and center the tubes in the outer slide, the slide usually works perfectly.

While I have mostly seen this in the 300 and 400 Yamaha series, the problem occasionally shows up in the 600 and 800 series as well.

Sorry to redirect this from Bach to Yamaha. I actually don’t trust 99% of trombones to have parallel slides.

[brassmedic]

Back when I took notes in the oughts, the common span descrepency with Bach slides that I saw was .027"!!! On 42 and 50 handslides made in the 70s and early 80s. It is not explanable by solder Shrinkage due to Eutectic cooling, as all those slides were too WIDE at the top. I figured out how to fairly predictably assemble outers through trial and error and how much to offset the width of the upper brace sockets for my methods, it seems slides were very carelessly assembled back then.

Benn

That's wild. I bought my 42B in 1995, IIRC. The slide was perfect right out of the box. Never had to fix any alignment issues.

[octavposaune]

That's wild. I bought my 42B in 1995, IIRC. The slide was perfect right out of the box. Never had to fix any alignment issues.

1995, yeah later era and I use a 1995 42 slide on my tenor setup right now that is within .002", but maybe that was a sweet spot in Bach Manufacturing. Who knows, as repair techs we only see things that need fixing...

Benn

[hornbuilder]

When I started working at the small shop in Wisconsin, 18 years ago, they were buying complete handslides from Bach (Bach wouldn't sell components for some reason). Each slide was measured for straight, parallel and skew, before being remounted. The biggest I saw was .055" wide. None were within +/-.005".
Visiting Bach a few years ago, I noticed that there was no measurement for parallel happening after the slide was assembled. Inner slides would be "popped" to correct poor fit, but there was really no specific parameter being met there, either

[Crazy4Tbone86]

So they were just doing the assembly of the outer slide in a jig and that was it? That wouldn’t surprise me.

[hornbuilder]

Yes. That is correct

[nateaff]

Now you guys have got me curious who consistently make the BEST slides. The only brand new horn I've ever owned is my Xeno which has never had to go in for a slide service after more than a decade, and if anything feels better than it did out of the box.

[Crazy4Tbone86]

Well, Matt Walker at M&W makes great slides. He is one of the people on this thread. I’ve seen 4 or 5 of his trombones come through my shop and they were all parallel within .002 inch. The Greenhoe horns that I have seen have been similarly accurate.

I’m sure there are some other makers that maintain high standards. I just don’t see enough of some boutique horns to do enough measuring and evaluation.

[BGuttman]

Before Matt went out on his own he worked at Greenhoe. I believe Steve Shires worked at Greenhoe for a while, too, before he founded his company.

[hornbuilder]

Thanks Brian.
Yes, my tolerance for parallel is +.003". (So, the top of the slide can be .003" wider than the crook, at most. I usually sit between .000" and .002") At GH we had a tolerance of +/-.005".

[GabrielRice]

Before Matt went out on his own he worked at Greenhoe. I believe Steve Shires worked at Greenhoe for a while, too, before he founded his company.

Steve did not work "at" Greenhoe (which I'm pretty sure was founded around the same time as the S.E. Shires Company), but he and Gary did work together in the early days of Edwards and then in the development and early production of the Greenhoe valve.

Speaking of Steve Shires, he's making pretty spectacular slides for his new Stephens trombones.

[Blabberbucket]

Fairly sure Steve Shires worked at Schilke, who now owns the Greenhoe name and product.

Thanks Brian.
Yes, my tolerance for parallel is +.003". (So, the top of the slide can be .003" wider than the crook, at most. I usually sit between .000" and .002") At GH we had a tolerance of +/-.005".

I believe Shires tolerances were +/-.003" when I was working there. I never built slides for Shires so I may be incorrect on that but I believe that is what I remember from the person who was building slides while I was there.