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Boucher
10-23-2012, 09:35 PM
I hate it when things like this happen. The end of the pipe had been bored slightly to smooth and remove any internal weld bead then a center was cut to run on the tailstock center. The OD was being threaded when this occurred. The cuts being taken were light. Post event examination revealed that the gummy black pipe was contributing to BUE. It finally grabbed and rode up over the threading tool with the center ripping through the thin wall where it had been bored.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0294Small.jpg

Time to take a few days off and change the scenery.

oldtiffie
10-23-2012, 09:49 PM
If I had to guess I'd have assumed that it was wrought-iron (old and had been buried) domestic water supply line pipe.

It is difficult to get a good result.

I'd have expected the live centre to restrain it but if the work had caused the pipe to slip left in the chuck (to clear the live centre - gradually) the conditions required for that result were there.

Otherwise perhaps there was too little material between the pipe bore and the root diameter of the thread you were cutting.

Most Plumbers use a dedicated pipe vise and dies.

Dr Stan
10-23-2012, 11:17 PM
Time to take a few days off and change the scenery.

Are you sure that's all you need to change?

BTW, glad nothing was injured except your pride.

vpt
10-24-2012, 08:10 AM
Thread first then bore.


I have done some very very thin stuff before, even threaded both sides and made a helicoil type sleeve to tighten up a connection I was having problems with. When it gets real thin I will make up a plug that snuggly fits inside to hold the walls up while threading then pull it out when done.

Mcgyver
10-24-2012, 08:18 AM
I'm trying to think of something worse to thread....maybe sewer pipe? lol.

what are you making? I would be looking to a design change - thread a length of free machining and braze to a pipe or something....

The cut also looks fairly long on a long thin piece....maybe borderline but up around where you might want to use a travelling steady. You can get good results cutting threads in long spindly stuff but in my experience its difficult to do with out using good material and a travelling steady

Boucher
10-24-2012, 08:58 AM
This is a Oil supply tube for chamber reaming that Rod Henrickson posted over on the PM Gunsmithing site.
http://i109.photobucket.com/albums/n50/boucherbyron/RodHenricksonoilswivel4.jpg

This shows the interface a little better.
http://i109.photobucket.com/albums/n50/boucherbyron/RodHenricksonoilswivel5.jpg

I started making a copy and in the process realized that 3/8 black pipe was not perfect but close to the right size to just thread the ID for attachments and the OD for the Adjustment nut. I think it will still work. Andy’s comments are spot on. I just did things in the wrong order. I was taking very light cuts intending to finish with a die. The copper pipe and solder joints would have been quicker and easier. I will have another go at it when I have some time. Retirement is busier than most would think.

browne92
10-24-2012, 09:37 AM
Sir John?