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View Full Version : A Gadget Too Many, part one (of three).



Dennis
31-05-2011, 07:16 AM
Here are some of my gadgets for flexshaft and their brief descriptions. As I don’t have interchangeable collets, they are all with 2.23mm shanks.

Burr Box 1. The round burr is the very king of burrs. It will make a seat for a round faceted stone in tube or sheet. It will bevel the edges of a hole, or make the countersink for a screw. In a small size it will quickly drill a hole through thin sheet, or make a pit to locate a twist drill in place of a punch.
Finally, if heated at the neck with a mini-torch and bent slightly while still red, the eccentric action will turn it into a texturing tool.
Stone setting burrs (top right) are size specific and will perfect the seat for a stone, begun with a round burr. As they are expensive, they are best used in a pin vice with a little oil to save on wear.
Cup burrs (top left) will round the ends of wires and prongs and also perfect the domes on rivet heads.

Burr Box 2. My twist drills (top) are all different lengths from re-sharpening them, but I rarely need a new one.
Diamond Points and Stones (mid right) are slow to cut metal, but safe to use as they are easy to control, have little tendency to run away, and are unlikely to damage fingers. They are also used by glass engravers.
Tungsten-carbide burrs (bottom right) are great for carving silver and other soft metals.

Burr Box 3. Cylindrical burrs with flat ends will improve the seat for small cabochons, which otherwise have a disconcerting habit of turning over during setting. Use by hand in a pin vice for this.
They are also very effective rotary files for shaping metal, but have a strong tendency to jump out of control so badly scoring your work, or worse your fingers. To spare you the gory details just avoid doing this.

The optimum speed for burrs, in terms of revs per minute, is a matter of experience and must be varied according to the size and coarseness of the burr. Run them too fast and they will turn blue and become useless.
Beginners are disconcerted by the difficulty in controlling burrs, but this is addressed by finding the right speed and adjusting your grip. Rather than holding your handpiece like a pen, I would suggest holding it in your fist, like a potato peeler. This seems cack-handed at first bit is worth learning.

Dennis.

MeadMoon
31-05-2011, 08:22 AM
Thank you for this, Dennis, it is most useful. I often look at the bits & pieces which came with my Proxxon and wonder what they are all for although, as yet, I don't have a Flexshaft (it's on my list). The only things I currently use are the saw (with a Koil Kutter) and the drill bits (in a pin vice).

ps_bond
31-05-2011, 08:34 AM
Strangely, cup burrs are something I rarely use. The round burrs are probably my most used, followed by bud burrs - which are particularly useful for cutting taper bearings for stones. As the round burrs are usually cheaper, I tend to grab those first; they can be blunted and binned (well, put in my "useful bits of metal" box anyway) without too much worry. As for drill bits, I tend to use 1mm jobbers drills from Screwfix in the chuck handpiece (not so useful in the QR handpiece) - very cheap, unlike my carbide bits. There's a tip on Ganoksin for making a cylindrical burr out of an old lighter wheel; I'll see if I can find it. As they seem to be carbide, they cut very effectively.

A while ago I picked up a large assortment of burrs from a Russian dental supplier on EBay - all perfectly adequate for jewellery use, and very, very inexpensive. If I can find him again I'll post a link.

With all the cutting burrs, I always use a lubricant - mostly Burr Life, but sometimes beeswax or oil depending on what is closest on the bench... All these burrs should be run fairly slowly; it is the linear speed (how fast the perimeter is moving) that is critical, so smaller steel burrs should be run more slowly. There is a slight problem there that if you're cutting with e.g. a stone setting burr, the outside edge is cutting faster than the pavillion - which is another reason why it is a good idea to only use them once the majority of the bearing metal has been removed.

At the finer cutting levels (abrasives), I've started making my own split mandrels for sanding out of short lengths of silver steel - they're much stronger than the commercial ones.

rubylily
31-05-2011, 10:09 AM
Hello Dennis and Peter, thank you very much for this thread. I'm new here (hello everyone!). Can I just ask a question about setting burrs, as this seems the appropriate place to ask? I've recently been trying my hand at tube setting with 5mm and 6mm pieces of silver tube, with 4mm and 5mm setting burrs, but I'm finding that I tend to get tooth marks / a jaggedy edge on my seats, and consequently the stones tend to sit rather wonkily. Is this just a matter of inexperience and not finding the correct drill speed, or am I using blunt burrs? I do use Burr Life each time I drill anything, and am trying to run the drill slowly. I'm going to try your suggestion of using ball burrs instead, and then finishing off with the setting burrs, as this makes alot of sense to me. Thanks!

ps_bond
31-05-2011, 10:34 AM
Setting burrs are a sod for that :) Chatter, once it starts, isn't easy to remove - I'm not sure if it is just the teeth of the tool bouncing, or if there's an element of work hardening going on as well. If it happens, I try to take it out with the burr in a pin vice; that usually works. If you cut away most of the metal before you use the burr, you'll only have the outside edges cutting *and* you'll not be wearing an expensive burr out as quickly. Very slow speeds are usually best - doesn't always follow, but most of the time it is the case.

If you use ball burrs in combination with the setting burrs, try for one just a little bit smaller than the stone (and therefore the setting burr too).

rubylily
01-06-2011, 09:17 AM
Great, thanks for your advice Peter.

Dennis
19-02-2012, 08:59 PM
Here are some of my gadgets for flexshaft and their brief descriptions. As I don’t have interchangeable collets, they are all with 2.23mm shanks.

Burr Box 1. The round burr is the very king of burrs. It will make a seat for a round faceted stone in tube or sheet. It will bevel the edges of a hole, or make the countersink for a screw. In a small size it will quickly drill a hole through thin sheet, or make a pit to locate a twist drill in place of a punch.
Finally, if heated at the neck with a mini-torch and bent slightly while still red, the eccentric action will turn it into a texturing tool.
Stone setting burrs (top right) are size specific and will perfect the seat for a stone, begun with a round burr. As they are expensive, they are best used in a pin vice with a little oil to save on wear.
Cup burrs (top left) will round the ends of wires and prongs and also perfect the domes on rivet heads.

Burr Box 2. My twist drills (top) are all different lengths from re-sharpening them, but I rarely need a new one.
Diamond Points and Stones (mid right) are slow to cut metal, but safe to use as they are easy to control, have little tendency to run away, and are unlikely to damage fingers. They are also used by glass engravers.
Tungsten-carbide burrs (bottom right) are great for carving silver and other soft metals.

Burr Box 3. Cylindrical burrs with flat ends will improve the seat for small cabochons, which otherwise have a disconcerting habit of turning over during setting. Use by hand in a pin vice for this.
They are also very effective rotary files for shaping metal, but have a strong tendency to jump out of control so badly scoring your work, or worse your fingers. To spare you the gory details just avoid doing this.
Dennis.

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