A question of tubes

"Andy Sollis- Churnet Valley model Railway Dept." wrote

Try hammering it down over a cone, but don't ask where to get a suitable cone. ;-)

John.

No a cone will flare the front and back you just need a steel bar of the same Dia. as the boiler [One with a locating stud to slip the chimney on is a >

superb] then anile the tube base and hammer down the sides over the bar

Try using masking tape, you should be able to sand any edges down using very fine emery

Countersink the bottom and then hammer against a round steel bar of the diameter of the smoke-box it is to sit on.

If you actually mean that you want a stepped straight tube, then you either need to turn off some metal in a lathe, or you can build-up the chimney using K&S thin wall brass tubing. I wouldn't recommend sleeving steel and brass in the same component where heat and moisture are liable to be though.

Sorry Guys, I think I didn't give enough info so some missed the point...

First of all, it is for a boat, so will not be going into a smokebox ! Effectively I want to put a collar on the tube (chimney) but am unsure how to go about it... I will probably use layered plasticard, but am looking for suggestions on how to curve this so it fits the diameter of the tube. Do I roll it, or heat it or any other suggestions...

Andy

Not quite a railway question, but modelling in general.

I have a steel tube, that will be a chimney, but I want to make the bottom thicker in diameter - any suggestions how to do this?

It will be stepped, so no need to round of edges etc and will be painted red on completion (it's a boat chimney by the way)

Andy

Dipping in boiling water (holding it with tweezers not fingers) would allow you to wrap it round the tube, however I think the masking tape or sellotape idea is probably a better bet. Military modellers have to do this all the time (moulding plastic), WWII lorry mudguards were the worst I ever tried, cockpit canopies using a male and female mould were easier after some practice. If you lay plastic sheet on a layer of silver foil under the grill it'll go floppy and can be moulded. I did a couple of ship ventilators for a

1:72nd model using plastic tube heated up in boiling water and played/bent with a hot nail (get a cork, slice it in half, cut a channel for the nail and add electrrical tape to hold it together. Took a few attempts.

Have a jar with ice cubes in it handy, if you get the ice onto the burn immediately and holding it there long enough it stops the blister forming and you just get some dead skin.

HTH

Mike

"Andy Sollis- Churnet Valley model Railway Dept." wrote

What diameter are you talking about? Why not use two pieces of tube of slightly different diameter, but use ones which telescope together?

John.

Before I bought a lathe I used to coat hard paper (laser document would be ideal ) with araldite and roll it around the tube, sanding down after setting. Easiest if the tube is small enough to hold in a hand drill clamped to a plank or held in a vice. For a larger tube, plug the end and centre a headless nail in the plug. Cutting the paper as a right-angled triangle makes life easier. Try a few dry runs to get the angle right.

Ken.

"John Turner" wrote What diameter are you talking about? Why not use two pieces of tube of slightly different diameter, but use ones which telescope together?

John.

Sorry, Been away on Holidays in Pickering, and didn't take in the NYMR ! Just for once.

The Size is 14mm to begin with and is larger than any plastic tube I have seen for purchase, unless anyone can tell me otherwise. As it is cosmetic, I may find that getting some dowel and putting a hole in the middle for my metal tube to go trhough will suffice, failing that, I will try some of Mikes suggestions from his military modelling experience. ice cubes at the ready ... Aim... Fire...!

Andy