Workholding question

[Gavin Newman]

Here's a curly workholding question. The background is that a mate of mine has a CIGWeld Colt oxy welder. The #6 and #8 tips are beyond repair and are now unavailable.

My thought was to take a larger Comet 3 welding tip (which is available everywhere) and turn the end down to the size of a Colt tip and turn the appropriate thread (3/8" 26 TPI).

The problem is that the tip is bent at the heating end (see here for image http://cgi.ebay.com.au/ws/eBayISAPI.dll?VISuperSize&item=120598305016 ) and I'm trying to work out how to hold it so I can turn the end down and cut a thread, the problem is compounded because the tip is made from soft copper which tears and distorts very easily.

I tried chucking up the threaded end with the idea of "necking" a section next to the chuck down to size, cutting the thread and then parting off. Two problems (1) I lose a lot of length in the final result if it works and (2) it didn't work, the pipe distorted and tore apart.

Any ideas?

[RayG]

Hi Gavin,

How many do you need to do? Is it sufficient quantity to justify custom fixture?

If it were me, I would look into making an adaptor to fit the colt so that you can use standard tips without modification. (assuming that there isn't a standard plumbing fitting that would already do the job).

If you absolutely have to do it, I would make a soft "collet" (wood or plastic), large enough to contain the diameter of the bent section so that you can fit it in the chuck. If the material distorts very easily, it might be worth the extra effort making a brass plug that fits neatly inside the copper tube, and can be located with a center on the tailstock.

I'm sure there are a million other ways...

Regards
Ray

PS I couldn't open that link, ebay doesn't let you directly link to images. Here is the link to the auction instead
http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=120598305016&ru=http%3A%2F%2Fshop.ebay.com.au%3A80%2F%3F_from%3DR40%26_trksid%3Dp3984.m570.l1313%26_nkw%3D120598305016%26_sacat%3DSee-All-Categories%26_fvi%3D1&_rdc=1

[Stustoys]

Hi Gavin
Couldn't you cut the threaded section of the old #6 and #8 and off the new tips, then silver solder them into a sleave?
(I do like Rays idea of an adaptor better though)

Stuart

[Stustoys]

Oh and to hold it if you still need to. If I'm understanding what you want to do correctly.

Get a piece of wood that will go into the bore of your four jaw. Drill a hole the Dia of the tip all the way through. Cut a slot in the sides at one end so the bent part of the tip slips in. Cut I slit down one side so it grips the tip when you tighten the chuck.
Depending on the size of your lathe is might stick out a long way so go easy.

Stuart

[Gavin Newman]

Thanks to you all for your suggestions, I did think of making an adapter but the female part of the thread put me off, turning the male 5/16-26 part to go into the Colt handpeice is simple but trying to accurately single point a 3/8-26 female thread 3/4" would be quite difficult and buying a tap for this one-off job is not worth it - this seems to be an odd-ball thread, I think it's a British Cycle thread.

The sleeve & silver solder trick is what we've decided to do but Stu's idea of the wooden holder is worth a try so I'm going to try that one 1st. I only need one or two to get us by for the next umpteen years. We normally use a Henrob (aka Dillon) torch for most of the gas welding we do but it's no good when making 2-stroke expansion chambers.

Thanks again for the help.

[franco]

Here's a curly workholding question. The background is that a mate of mine has a CIGWeld Colt oxy welder. The #6 and #8 tips are beyond repair and are now unavailable.
Any ideas?

Gavin,

As you probably know the Colt torches were originally supplied with a cutting/welding attachment which took type 91 solid brass flat bottomed flanged unthreaded tips.

As an extra, an adapter, part 304672, to replace this attachment was available so swaged type 561 threaded swaged welding nozzles could be used. I presume the torch you are working has this modification.The flame from the swaged tips is much better shaped for welding than that from the solid tips.

If so,

http://www.statewidefastener.com.au/images/uploads/C307045.JPG

still have the type 561 nozzles available according to their catalogue page in the link - might save you an awkward job on the lathe.

Their contact details;

http://www.statewidefastener.com.au/contactsw.html

Frank.

[Gavin Newman]

Frank

Thanks for that, yep the Colt we have is equipped with the threaded pipes. I rang that source and they don't have them any more. Back to the lathe methinks.

Rgds - Gavin

[matthew_g]

Gavin, After tea this evening I will whip out to the shed, I sold my colt set-up as I have now 3 or 4 comet setups..
From memory I have an assortment of tips and such in a draw someplace..If I can find them they are yours...
Matt

[matthew_g]

Gavin, Sorry to have taken my time mate..I have gone through a few boxes of gear and managed to find.............................................a number 6 and a number 8 tips. All yours if you still need them..No charge think of them as a XMAS gift..PM sent also.
Matt

[Gavin Newman]

Matt

Thanks very much for the offer, PM sent. You're a gentleman amongst gentlemen.

Rgds - Gavin

[matthew_g]

:) all good Mate. It's sorted
Matt