but since I never could just do as I am told I have added a second threaded bush for the steam take off. I'm about to start making a few unions to attach the steam pipes and looking through my bits box (all ebay grabs) I see there are 2 different methods of obtaining a seal. Either a flat face on the end of the male thread and presumably a flat washer soldered to the end of the pipe (1/8 od copper in my case) or a tapered seat and matching olive/nipple soldered to the end of the pipe.
Is there any rationale to the choice, one better than the other, I intend making the relevant bits rather than buying - more fun that way and I need the lathe practice!
forgive me if I'm wrong but I get the impression that you tested the boiler by connecting it to a compressor? If so, that method could prove to be extremely dangerous if something gives and is not to be recommended. The correct way ( safe way!) is to hydraulically test it with water as described elsewhere in the forum:
If something does give then all you will get is a puddle of water! Better to be safe than sorry
Re your question - you'll probably get the joint to seal easier if you use the coned seat and matching olive. That's the most common type of joint used. Just make the female seat with a centre drill and turn the olive to the same angle (60º)
How bizarre, I haven't spent much time on here the last few days but I came straight to this thread which is linked to my site. What's more I gave the 'kit' engine a run earlier tonight for the first time in months. Weird!!
The book I've been using for my two latest engines is Stan Bray's 'Making Simple Model Steam Engines' in which he suggests making nipples/unions rather than using the ready-made coned variety purely because they fit the scale of his designs better.
Personally I'd go with whatever Baggo suggests as he is invariably right and a jolly nice chap too!
Thanks gentlemen, coned nipples it is - done Tel's way because that sounds quick and neat - exaltation deserved.
I did test the boiler with a compressor, but it was full of water and the 20 bar rated gas hose connecting to the compressor was the only thing with just air in it - point well taken though, now where did I put the bits for that hand pump?
Remember before following the above, if the tool digs in (wide cut and brass, not if but when!) if the chuck is screwed onto the mandrel it will rapidly wind itself off. This is why rear mounted parting tools are upside down, the lathe is still run in the 'correct' direction. Golden rule not to be broken lightly, never reverse a screwed on chuck. One fitted on pegs, usually larger lathes, can be safely reversed. Another heads up, check the recomended maximum diameter of chuck for the speed your lathe runs at. We have a 5" 3 jaw for the old ML7. My father now has a super 7 and ran the 5" chuck at top speed. Fine until the clutch was disengaged when centrifugal force very rapidly removed the chuck to the floor via a ding in the lathe bed.
Simon. Tich, Invicta, Clayton lorry, 0.3cc Diesel, FD3/64 gas turbine. Weise Flying Scotsman part built, Seal 15cc part built. Currently researching 8th scale 14xx 0-4-2t and a 7.793 scale 2-6-2..... Now got a 3/4 acre garden to put a track round :-)
Good safety point Simon - not an issue on this Sieg (toy) lathe - chuck bolted on. This was just quicker than using the qctp on the back and setting up the parting tool for upside down. Now of course if the supplier of my qctp had spare tool holders I could get another dozen..........mutter, mutter
That pic was a bit big, sorry guys, fast broadband has spoiled me.