G’day all
Looking to start making my own tuning slides for simple system flutes. I have a rough ahem idea of a process:
Would anybody out there be willing to advise me on a suitable pressing machine for the task? 
And help me think it through in a bit more detail?
I don’t know if you’ve seen my tuning slide journey, robh82: http://www.mcgee-flutes.com/fluteslide.html
Your plan sounds interesting, but might depend on whether you can find a source of tubing convenient to start with. I have made my own slides from sheet brass, with a collar of sheet silver for the visible bit. Roughly formed into cylinders, tied closed with iron wire, soldered, punched and drawn to final size. That was clearly how a lot of slides from the 19th century were made. It’s all possible, but quite a bit of work!
Don’t ignore the lathe tailstock and chuck as a simple lightweight press. I’ve seen people removing the hand screw and replacing it with a long lever to be able to press quickly and strongly. But you might be more at the hydraulic press end of the spectrum! Hmmm rig up something using your car jack?
Oh, and consider the notion of pressing the mandrel and slide through a hole in a relatively thin steel disk rather than a fixed diameter solid die. Assuming you start with tubing of the right wall thickness. Remember to grease the mandrel well. You’re going to have fun getting the finished slide off the mandrel! (The press needed again)
Heh heh, a sudden mental throwback to the late 1960’s - my early days as a Trainee Technical Officer at the Research School of Physical Sciences at the Australian National University. They showed us a film on “explosive forming” - literally using explosives to instantly transform say a sheet of stainless steel into a saucepan. You could have lots of fun with this approach. Just don’t point it at the neighbours!
Hi Terry,
I read that with great interest – the cork lining idea is brilliant. I might try it one day!
Yes, you’re right about the convenient supply of tubing. I do come from Birmingham, England, where there’s still a good manufacturing trade in materials, so I might have some luck, we’ll see.
I was thinking of trying something like a 1 ton arbour press with a solid die attached. I hadn’t thought about how hard it would be to get the mandrel out of the tube afterwards!!
Regarding the sheet brass approach, when you say ‘drawn to final size’, do you mean by hand over a parallel mandrel or triblet of some kind?
As for your final suggestion, sounds like a historically informed approach that I can explore 
I’m very happy with it for a number of reasons, robh82. The shorter slide is much easier to make, makes the head lighter, avoids the harshness I associate with full-length slides, and of course satisfies the original aim of coming up with a slide that doesn’t cause cracking in dry climates.
Yes, you’re right about the convenient supply of tubing. I do come from Birmingham, England, where there’s still a good manufacturing trade in materials, so I might have some luck, we’ll see.
Well if not Birmingham, where? I was able to get something like 4 metres of sterling silver tube drawn in Melbourne, so that’s promising.
I was thinking of trying something like a 1 ton arbour press with a solid die attached. I hadn’t thought about how hard it would be to get the mandrel out of the tube afterwards!!
Just something to think through, ideally before you end up with the mandrel stuck inside the tube! You could hammer it out, but since you’ll need your arbour anyway, might as well have a second die that is just able to pass the mandrel though. It can catch and hold the leading end of the tubing as the press pushes the mandrel out through it.
Regarding the sheet brass approach, when you say ‘drawn to final size’, do you mean by hand over a parallel mandrel or triblet of some kind?
I must admit it’s been a while, and I’m struggling to remember what I did. I certainly have a few punches and dies down there in the workshop that suggest that’s what I did.
Of course my job is made easy by the short slides - the longer inner one is only 60mm long, the outer one 40mm. That’s much easier than having to draw a full-length slide as used back in the 19th century! By comparison, the head slide on my old Nicholson original is 200mm long!
Now, I said:
Just something to think through, ideally before you end up with the mandrel stuck inside the tube! You could hammer it out, but since you’ll need your arbour anyway, might as well have a second die that is just able to pass the mandrel though. It can catch and hold the leading end of the tubing as the press pushes the mandrel out through it.
Which is all very fine, but I’d forgotten that you are intending to solder a nose piece onto the tube before pushing it through the die and onto the mandrel. So you either need a way to back the mandrel out or you’ll need to cut off the end you’ve soldered on, to allow the mandrel to push right on through.
But perhaps we’re overthinking at this point? It would be good to know what dimensions of tube you can find out there, so we know if you are going to be in the business of shrinking an oversized tube, or expanding an undersized tube. Or may not need to do either! Does Goldilocks live anywhere near Birmingham?
Having the second die to remove the mandrel seems like the right idea, after removing the nose piece on the end. It’s quite a conundrum! I foresee that some experimenting likely to be necessary.
I imagine I’ll be dealing with quite short sections of pipe. Not intending to line the entire head at the moment.
I have a simple Des Serry flute that has a brass slide sheathed with silver. It’s very well done and looks smashing, so that seems like a good plan. Then again I was thinking brass ferrules for my first few flutes, which I think will look nice with Boxwood.
I’ve heard rumours! Will report back 
It’s a bit strange to remember that, back in the day, boxwood was the “cheap local timber” and anything harder (ebony, cocus, mpingo) had to be imported at great cost. So the military used boxwood with ivory/bone trim and brass slides, while “concert flutes” were of the imported timbers with silver trim.
Once the forming is done, and the tube is stuck on the mandrel, here’s how to remove it:
Using a smooth burnisher (or screwdriver shank), hold one end in the lathe chuck and burnish the outside with long strokes, going all the way around. Be firm. Think of what happens with a rolling pin on pizza dough: the action will displace the material just enough for it to grow in size. Burnishing will increase the circumference of the tube by several thousandths of an inch, enough to relieve the tube’s pressure on the mandrel. The diameter increases by just a couple thousandths. The mandrel can be made a little smaller to compensate. Or, burnish a little, then go to the polishing wheel: the polishing displaces metal in a similar way, and the friction creates heat. The coefficient of expansion is greater for brass than the one for steel.
Pointers: apply tallow (saddle soap) to the mandrel/inside of tube before starting the swadging. The mandrel must have good precision (a cylinder) or it must taper steadily, as Boehm heads do. These shapes will still require the burnishing to expedite the release. What you DON’T want is a mandrel whose diameter is wavy along the length (low spots); these will make removal very difficult. If you’re making the mandrel, take many measurements with a barrel-type micrometer, or use commercial drill rod (available in metric and SAE). If the mandrel is steel, clean afterward with acetone to prevent rust.
If you poke the tube thru a steel washer, make sure to round and polish the edge. Apply saddle soap.
I have a 12.5 inch rack-and-pinion arbor press. Draw steadily. Do not release pressure mid-stroke or you will leave marks.
Walt
In reply to Walt Sweet:
Quote: ¨I have a 12.5 inch rack-and-pinion arbor press. Draw steadily. Do not release pressure mid-stroke or you will leave marks.
Walt¨.
An excellent piece of gear.
A short recollection from the Golden Era of musical instrument making in America. The Olds Trombones were renowned for their flared bells and famous for the ´big, round´ sound they could produce. If you don´t recall the Olds trombones,. look at the Brass section of some of the old Classic Big Bands, for example the Glenn Miller Band. These famous, and distinctively large drawn bells were drawn with a chain drawn press as opposed to a hydraulic press. This allowed for millimetric precision in forming the metal over the mandrel. When the brand changed hands (I believe they were bought out by Conn) and the fabricating shop was sent to Mexico, this multi-ton, large piece of gear was too big to ship, and was abandonned in favor of a hydraulic system. Part of the death of a famous brand name. Smaller bells, smaller sound, and less precision in making. 
Bob
Walt, thank you so much for this advice and the details. I’ve had burnishing demonstrated to me by Paul Windridge when making my first flute, to closely fit the two parts of the tube together without sticking, but I didn’t really understand what was going on. Your pizza dough analogy is very useful!
Thanks also for confirming my suspicion that an arbour press is the way to go.
I began building a hydraulic system. 48" cylinder and a self-contained hydraulic power unit. These are commonly applied to a pickup truck for plowing snow.
My rack-and-pinion arbor press still serves well. I even used it to make tapered tubing for my Boehmflute in F above C.
I also experimented with hydraulic forming inside an aluminum mold. A grease gun gives great pressure!
I haven’t worked metal tubing, and if I were to I would choose methods mentioned above or some old school technique. So this comment is sort of tangential but I thought why not mention modern alternatives that might just possibly be of use somehow. The first is only really for copper, or adding copper, which though it can then be plated with silver is not quite as strong so would need thicker dimensions. The good part is whole shapes can be made this way
https://m.youtube.com/watch?v=TXhtRzKB4aA
Though other metals can be used, ingredients are harsher apparently. That still took 48hrs.
Then there is electro chemical machining. Most results online give industrial scale machines, but with saltwater electrolyte, a battery charger of 6v 2A if I remember, for rifling on a barrel it was being shaped at 1mm an hour. I expect it would work on other than steel.
For whatever reason, both these examples are related to firearms and I find no similar clear explanation simple common other example to link. For the ECM I will not therefore include the link, but search would be
Jeffrod’s ECM Barrel making Tutorial PDFCOFFEE