GENERAL: What should be sent to a repair shop vs. DIY

[davewerden]

YWith a drill press -- if you have ANY experience with one -- it's a no-brainer, and you can easily feel the point at which the bit goes through the piston wall and back it out way before you go too far. A little 600 grit emery paper lightly applyed at the entry hole is all you need to remove any roughness. Make sure you carefully wash off all grit before sticking it back in the valve case.

Gary,

How do you avoid any metal shavings inside the hollow piston? That's the one part I can't figure out (even if I had the nerve to try it).

[ghmerrill]

The instructions that came with these mounts talked about using a drill-stop, which was a collar that fit around the drill bit, so only a short length of the bit was available. And typically people ignored that advice. A friend of a friend was installing his own mount, and he was typical. Can you see where this story is going? His drill went through the sheet metal that forms the hump and continued right on through the transmission casing. That turned out to be a very expensive mounting job!

There isn't too much that will save you from your own ignorance. I have a related story about putting holes in the bottom of my jon boat -- holes which I was SURE went through just an inner hull. The next time out, I was about a mile away from the dock when I discovered the boat was taking on water at an alarming rate and the little 10hp motor wasn't able to move it faster than a crawl. I managed to get it back to the ramp and out of the water (and the water out of it). Luckily, there is so much floatation stuff in it that the thing just won't sink. Once home, I filled the holes with stainless screws and epoxy and haven't had any problem since. But I felt really stupid -- and no less so because as I was drilling the holes my wife said "Are you sure those holes aren't going through?"

There is no substitute for careful thought and execution.

I've never had any luck with drill stops. Even the expensive ones never fit well and reliably. I prefer knowing how far I need to go, and using the "touch and feel and eyeball" approach. But it takes some experience and some mistakes to get there. Years ago I read a study done by the US Navy that demonstrated that the master mechanics on its ships were as accurate at torquing bolts to the required specs by feel as in using precision torque wrenches to do that. I have a torque wrench which I will use on occasion (especially for very high torque settings), but generally I just do it by feel. And sometimes I'll just use the torque wrench to check my result. However, while developing that skill, I did break a few bolts and strip a few hole threads.

[ghmerrill]

Gary,

How do you avoid any metal shavings inside the hollow piston? That's the one part I can't figure out (even if I had the nerve to try it).

First, I don't really worry about them. I think the concern is overblown. What do people think the professionals do? They don't have any special magic.

Second, a standard twist drill is designed to remove shavings up its shaft and to the outside of the hole. They wouldn't work if they didn't do this. You DO want to use a sharp bit. Very important. Sharp bits mean small shavings and ones that the bit will automatically remove from the hole. Dull bits mean larger and ragged shavings that will be resistant to removal.

Third, you want to be careful with your speed. As in all drilling operations, LET THE DRILL CUT (again: sharp bit). If the drill is cutting well and you are going SLOWLY, then what it cuts will be extracted from the hole by the bit itself. (Think of how differently things work when you're drilling in wood with a twist drill as compared to using a spade bit or Forstner bit).

If you're pushing the drill faster than it's cutting, you're looking at trouble -- not so much in terms of "shavings", but in terms of a burr that won't be drawn back up the bit at the point that you break through, and which will then be pushed into the piston cavity -- possibly remaining attached to the hole because the bit wasn't allowed to CUT it before pushing through. THAT's what you want to avoid.

If you're not used to cutting or putting holes in metals rather than wood, you may not be aware of the differences. If you go too fast in wood, your bit may bind or burn the wood from friction. If you go too fast in metal, your bit may bind, produce really ugly shavings, and then break. While a soft metal like brass or copper is "almost like wood", some of the shaving issues are more like shavings in steel -- and possibly even worse because a dull bit will also appear to "work" in the soft metal while it's doing a really crappy job.

I can't tell you how many drill bits (normally small -- 1/8" or smaller) I've broken in steel because I was careless in using a dull bit or was going too fast. There is less danger of this when drilling in brass, but the danger of burrs remains if you're using a dull bit or pushing it hard. Just let it cut. Also, if possible, drill a little, back it out to clear the hole, drill a little more, etc. That facilitates not having anything in the hole as you're drilling. Somewhat difficult to do in very thin stock; but in very thin stock, it's really not an issue -- if the bit is sharp.

Finally, I have talked to very skilled repair people about this, and what they say (paraphrased) is "Sometimes something goes into the interior. It happens. Not frequently; but it happens. If it's a minor shaving or burr, you just don't worry about it. It won't cause any problem. It may wash out through the bottom vent hole over time and with light oil added. If it does cause a problem -- such as noise in the valve -- and needs to be addressed, then you need to take the piston apart and get it out." That's a big deal.

One thing you can do to gain confidence with techniques like this is to go to Lowes or Home Depot and buy a short length of copper pipe (like just a few inches, given the current price of copper!!). Experiment with it. You'll be able to get a good feel for how the drill and bit are working, how much force to apply, how fast to go, what's a good speed for the bit to run, etc. And you'll be able to see both the exterior of the hole you drill and the interior, and any shavings that go inside. Very educational.

[John Morgan]

If you DON'T have the minimal skills, and some minimal experience, and if you DON'T feel confident and comfortable with it, then DON'T try it. Too much risk for the minor reward of avoiding the time and expense of taking it to someone who does have the skills (and experience and tools).

Gary,

You seem to have an excellent handle on all of this drilling of valves, lots of experience, and confidence in your ability to put vent holes in valves. I enjoy reading your thorough and enlightening discussions.

However, for us mere mortals with nominal mechanical skills and less than a full fledged arsenal of good quality tools, drilling a hole in a valve to me would seem like a pretty risky thing to try, and I am fearless! Your last statement above resonated with me.

Thanks for the tip on PB Blaster. I will go fetch some. I think I have the requisite skills to use that!!

[ghmerrill]

Gary,

Thanks for the tip on PB Blaster. I will go fetch some. I think I have the requisite skills to use that!!

I would -- largely as a matter of principle -- be cautious about getting on any finish. I've never had a problem with this, but discretion is the better part of valor here. The stuff has a rather offensive smell, and once it's done it's trick you'll want to clean it off thoroughly, especially any that has gotten on the inside of a slide. It really is astonishing stuff -- and not a lubricant or oil at all. Should be available at Lowes (though about a year ago it disappeared for around six months from their shelves). I've seen it recently. If you can't find it, there's this stuff called "Deep Creep" that has a big following in the automotive and marine sectors. Similar effect, but my experience is that PB Blaster works better.

Again, it may take time. I had some fasteners on a log splitter motor that I had to let it sit on (and add every couple of days) for a week or so. Then, the nuts came right off. Another thing you can do is: After you apply it, gently tap the joint you're trying to get it into. The vibration will "encourage" it to flow in the joint. I use a small rawhide mallet on brass instruments (no denting), but some similar thing (even a small piece of wood gently used) will work as well. This is one thing I'm never in a rush about (and I'm generally very impatient).

[RickF]

Interesting post Gary. I still wouldn't trust myself to vent my own valves. Working for the FAA for 30+ years we did all sort of things beside maintaining and certifying the equip. When we needed to drill a hole in metal where we had to be sure to not let any filings fall on the other side, we'd put some grease on the drill bit - up a bit from the cutting tip to help catch the filings. This helped a lot but still wasn't without some risk.

[ackmondual]

Oh wow... 3 pages! I'll have to read the in-between at a later time, but for now, I wanted to post back that I took it to my local shop (I honestly forgot I had one of these). For $45, he was able to fix most of the issues...

FIXED:
--pounded out a some of the dents
--All valves caps, top and bottom can be unscrewed
--Finger buttons can be removed
Although for some of them turning/unscrewing the finger buttons also turns the "stem" with it (not sure what the technical term is to describe the "rod" portion from the top valve cap and the finger button). His comment was this (the stem turning with the finger cap) is actually preferred, else the alignment of that notch on the valve might get shifted (when you take out the valves to oil them)

--All slides except for the 4th valve tuning slide
--we also needed a bottle of valve oil (+$7)

NOT fixed:
--as mentioned above, the 4th valve tuning slide has more corrosion than anticipated.
It was supposed to be a $75 fix that he quoted me midway through the service I'm currently describing (just buy a new slide, and Yamaha YEP-321's being around since... the 60s he said? has good spare parts lying around for that ), but [this part is "IIRC" since I'm recalling from memory] the slide part is partially missing, and the outer portion where the slide goes into may be missing. The variable now is he may not be able to fix that. Currently, it's soldered in place.

I wanted to get back to playing so I'm leaving this as is for now. For fun, I'll see if this starts to bother me (noticing that it IS indeed out of tune, coming from someone who was never good at listening for in-tune)

--There's some flattening of the bell, but I requested it be left as is
Makes it easier to stand on the ground, and won't affect sound. Now that I think of it, I'm hoping this won't be a concern if I get a case for it, but we can always revisit this if it does become an issue.

[Larry B]

Here is another question about DIY or Repair Service I have an old B&H Imperial BB Flat Bass, This instrument is about a full tone flat on the 1st valve with all the slides in. I am considering cutting a portion from the main tuning slide. This will enable me to tune each note ie make the instrument sharp and pull out slides to tune
The hard bit is how much should I cut off or is this a professional job I have no repair shop near The other option is to ship it to England

I have experience in engineering pipe work and soldering
Larry B

[ghmerrill]

Are you sure it's not flat because of a leak? Are you sure that the first valve is aligned correctly? A "full tone" flat seems WAY too much to have escaped the factory as part of the construction of the horn. By "full tone" do you mean a half step (50 cents)? I would be totally shocked if the cause of this was a 1st valve tuning slide that was too long.

Don't cut the horn unless you KNOW what the problem is.

And if you're anywhere in the continental US, there are several excellent repair facilities to ship (or drive) it to that are much better options than shipping it to England.

[RickF]

I agree with Gary. I wouldn't cut the horn until all else fails.

BTW, 100 cents is a semitone or half step.

[iiipopes]

Over the decades, I have worked on, modified and rebuilt many things around the house. I have worked on, modified, rebuilt and adjusted many things about electric instruments, guitar, bass, etc. I have worked on, rebuilt and modified many things automotive in nature, including rebuilding a Jaguar E-type cylinder head and everything that attaches to it. But when it comes to working on brass musical instruments, I leave it all to my tech. I have neither the tools nor the experience nor the confidence, in recognition of the extreme downside if something goes awry. To quote the character Harry Callahan, "A man has got to know his limitations."

[ghmerrill]

BTW, 100 cents is a semitone or half step.

Absolutely right. Don't know what I was thinking.

[ghmerrill]

To quote the character Harry Callahan, "A man has got to know his limitations."

True. We in general should avoid things that are outside our "comfort zones" if there is much at stake. One reason I bought a cheap bass trombone is so that I could do things to it that I wouldn't want to do to, say, a Bach or Getzen or Yamaha or ...

My limitations used to include disassembling and working on rotary valves. Thanks to the cheap trombone, this is no longer the case.

[oleo]

I bought a chinese alto horn, for fun, so it's kind of inexpensive. I think it's worth the money and seems to play ok. but, spare me the lecture, but the tuning slide water key came broken off. perhaps a cold solder job. I've done electrical solder work before, but I'm worried about burning the lacquer. Can a shop do a good job on it and how much will it cost. It's not worth the hassle to send back. yours also, ChinaBrand.

[ghmerrill]

Soldering that back on would just take a few minutes. All you need is a little Butane torch and the right kind of solder and some flux. Some people use electrical (flux core) solder, and I guess it works for them, but a good quality solid 60/40 that's small diameter (I use 1/32") and a decent flux works best. Then you just need to clean off the surfaces that came unsoldered, maybe sand them with fine paper to get them smooth and even, clamp the part in position (or wire it on in the correct position), flux it, and solder it. You won't burn the lacquer if you just heat the part for just a few seconds, and the solder should just be sucked into the joint (just like soldering a plumbing fixture -- in fact, that's how I practiced this). If you need to, get a little piece of copper or brass pipe at Lowes and practice putting the water key on that before doing it on the horn. That will teach you how much heat is necessary without overdoing it.

On the other hand, a repair tech can do this very straightforwardly, and I wouldn't expect it to cost much at all ($10? Maybe more. Maybe less?). My guy charges $60/hr, and this would take a max of 15 minutes -- so do the math. Some techs are still a bit prissy about working on "cheap Chinese instruments", but this is a simple quick solder job and I bet you can find someone to do it.

A final alternative (which will make any repair techs reading this explode in an emotional frenzy) is to just epoxy it back on. I've not done this myself because soldering is so easy. The big arguments against using epoxy (or similar adhesives) on musical instruments are (a) it's a real pain to REMOVE if you ever have to, and (2) Using a torch on it (as part of removal or some repair where you don't know there's epoxy in the joint) will produce toxic fumes you don't want to breathe. My attitude is that if I had a cheap instrument and wanted a quick fix and I didn't anticipate ever having to have someone else fix the fix, then I'd consider epoxy. People have done this sort of thing for a long time with inserts in aluminum arrows and similar applications.