New member and need to drill some big-ish holes

This forum is dedicated to those hobbyists with the 3-in-1 metalworking machines. Mill-Drill-Lathes. Tips, techniques, modification and use of these machines is topical.

Moderator: Harold_V

Harold_V
Posts: 17143
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Post by Harold_V » Sun Feb 14, 2010 11:23 pm

snowkilts wrote:I'm delighted to find someone on this forum involved in the piping world! What did you do with the band?
You mean aside from making over 80 telescoping blowpipes??

Nothing. I was an aspiring piper, but, much to my chagrin, I learned I am not a musician. Love music, and have an extensive sound system, but I have great difficulty with my fingers. I tend to be dyslexic, which manifests itself when I type, too. It's not uncommon for me to type a three letter word in reverse. Needless to say, spell check and I are very good friends.
I don't have a sketch, but what I'm trying to do is make a tenor drone stock with a brass tube inserted in it. I want the tube to be suspended in the delrin stock, not touching it, held in by threads at one end. I have some 7/8" brass tube, on one end of which I have soldered a piece of 1" brass tube about 1-1/4" long. I plan to cut threads on this, and screw them into mating threads on the delrin piece.

I recently spoke to a friend who is an instrument repair guy, and he says the way he does stuff like this is just use a drill for the initial hole through the delrin, then size it with a taper shank reamer held in the tailstock. I think I will give this a try with my spade drill and a 29/32" reamer. I will then need to bore out an inch or so of the delrin piece to the pre-thread diameter and tap it. How does this sound?
If I'm following you correctly, it should work, but I think I'd lose the idea of buying a reamer. You already must use a boring tool of sorts to prepare for the threads, so you might just as well use the same bar for the slight amount of oversize you require. Machining Delrin is very unlike metal, so you can use a 3/4" steel bar with HSS with excellent results. You can run the machine at top speed, using a fairly coarse pitch feed, so you can open up the pre-drilled hole in about the same amount of time that you'd spend reaming. It would provide the added benefit of correcting the bore, which, as I've already stated, will move about when you open the material. Do keep in mind the idea of roughing both the exterior and interior before you take any finish cuts, to avoid problems associated with excessive movement.

You would be far better served to spend the money you'd pay for a reamer in buying a solid carbide boring bar, for that matter. Then you'd have a bar that will be useful for other purposes, very unlike a reamer of the size in question.

I am a bit curious about your desire to isolate the drone from the stock. Do you expect to gain something in the way of better sound? Is the stock dampening the vibrations?

Harold

snowkilts
Posts: 8
Joined: Fri Feb 05, 2010 2:36 pm
Location: Detroit, MI

Post by snowkilts » Mon Feb 15, 2010 9:54 pm

Harold_V wrote: I am a bit curious about your desire to isolate the drone from the stock. Do you expect to gain something in the way of better sound? Is the stock dampening the vibrations?

Harold
Sort of. I am actually trying to improve the stability and "tunability" of the drones.

Many pipers will tell you that when everything is just right on a bagpipe, the drones will "lock" and remain perfectly in tune in a way that is almost a bit unnatural. This is difficult to achieve, and even more difficult to maintain over long periods of time (such as for playing piobaireachd, if you're familiar with that...)

I believe that the drone reeds are acting on each other inside the bag, much the same way that a tuning fork will start to vibrate when brought near (but not touching) an identical tuning fork that is already vibrating.

I put brass tubes in my stocks about a year ago, and got a stunning improvement in the "lock" phenomena. Unfortunately, the method I used to put them in did not work well. I basically used an upside-down cutting tool to plough a thread on the OD of the brass tube. Then I opened up the stock to a slip fit on the tube with a hand reamer, and screwed the tube in as sort of a self tapping screw. This did not hold, the tubes eventually started to work their way out. They also leaked air between the tube and the stock.

A few months ago, I removed the tubes, and re-installed them with epoxy the full length. They're in solidly now, and not leaking, but unfortunately I have lost the improvement I had in the "lock" phenomenon. I suspect the tubes are being dampened by the wood. So, I am now trying to get the best of both worlds.

Long answer to a short question. Does it make any sense?

-- Jon

Harold_V
Posts: 17143
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Post by Harold_V » Mon Feb 15, 2010 11:40 pm

snowkilts wrote: (such as for playing piobaireachd, if you're familiar with that...)
Yes, I am.
Long answer to a short question. Does it make any sense?
Yep! I have it straight now. Looks to me like you're on the right track. If there's anything I can do in the way of making suggestions on machining, feel free to inquire.

Might be nice to see the end results of your work.

Harold

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