buying copper for boiler makeing

[michael burton 1Participant @michaelburton1]

probley going to buy the coper to make the tich boiler tonight and was jus wonder is copper copper the stuff im looking a c106 grade would this be sutible i know you can buy boiler kits but funds wont allow this so do it this way i can spread out the cost

 

 

thanks mikey

[michael burton 1Participant @michaelburton1]

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi MB1 ,

 

C106 is entirely suitable for Tich boiler making . Always a good idea to have an approved material – though it has to be said that my Tich boiler was made from an old fire extinguisher many years ago .

 

Couple of thoughts :

 

Never a good idea to scribe deep lines on copper sheets for boilers .

 

Not shown on the drawings but useful to use a few copper rivets and screws to basically hold the boiler together for silver soldering . The parts do have a nasty habit of moving otherwise . Put clean rivets or screws in just before heat up if possible to keep them bright .

 

Soaking the parts and assemblies in mild pickle bath and then washing off just before heating will always make silver solder flow much easier .

 

After soldering let boiler cool down a lot before pickling again . Often given instruction to pickle from high temperature is not only dangerous but it can weaken the just made joints .

 

Ask any questions .

 

MW

[michael burton 1Participant @michaelburton1]

hello michael many thanks for the reply most helpful, how would you suggest the forming of the the boiler shell makeing a wooden form the size and shape off the boiler? or is there an easier method?

 

many thanks

 

[nigel jones 5Participant @nigeljones5]

you may want to go for a lower grade of copper. c106 is top notch stuff and damned expensive, its qualities are designed for tig welding, so it doesnt crack on reheat. Silver solder doesnt affect copper the same way so lower grades are fine. You will also struggle to get c106 in plate form at the thickness you require, and its always best to join same grades of cu.

[michael burton 1Participant @michaelburton1]

hi nigel i managed to get enough plate for the whole boiler for less then 30 pounds of c106 grade

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hello again ,

 

No need to make a complete former for a Tich boiler shell . As I remember it the barrel and firebox are made in one piece rolled up from a T shaped piece of copper . What is needed is a simple round former the full length of the boiler plus a couple of inches over . Metal ideal but hardish wood quite ok . Make diameter of former just fractionally less than the calculated inside diameter of boiler .

 

You will find it quite easy in this small boiler to push the copper round the former a bit at a time by hand – ideally using one or two straight pieces of wood so as to push all the way along at the same time rather than just here and there . Gentle taps with mallet may be needed towards the end when barrel is getting tight around former .

 

Copper will need annealing before starting and up to 5 times during bending . On each occassion heat the copper evenly until you can see bright patches and oxide colours dancing around on the surface of sheet . This occurs at just under red heat though it doesn’t matter if you overheat provided its not too severe . Let to cool off a good bit and then drop into mild pickle for about 15 minutes . Remove , wash and if needs be scour odd places with saucepan scraper .

 

Once the boiler is basically round with the firebox legs left straight as far as possible it will be easy enough to anneal one final time and push everything into shape .

 

MW

 

Next thing will be the long joint in the barrel .

 

 

Edited By MICHAEL WILLIAMS on 14/02/2012 13:08:10

[David HaynesParticipant @davidhaynes53962]

Hi Michael,

 

Besides the Tee section approach discussed by Michael W for the small and large boiler, I have wondered about the Belpaire boiler that LBSC published as an improvement. It may be too much for you at the moment, but it uses a single 2 5/8″ 16g tube, no long joint in the barrel, and the performance looks to be the best of the three of them, with a larger grate and heating area. The following is a spreadsheet comparing a few 3 1/2″ gauge boilers. It may need to be magnified, but you can do this by either adjusting you browser (View->Zoom) or downloading the image and looking at in a viewer.

 

Dave

 

 

Edited By David Haynes on 14/02/2012 22:23:36

[michael burton 1Participant @michaelburton1]

hi all again the barrel is nearly done just a couple more bending sesions then we should be there as mw said the next thing is the long join down the boiler tube, im guessing that a strip of copper the same as the boiler is used and rivited in a zig zag patten alternating side to side. will 1/16 copper rivets be ok to do this and how wide should the strap ideally be?

many thanks once again mike

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

 

Hi MB1 ,

Strip about 7/8 inch wide would be OK . Just enough rivets to hold strip in place .

Holding boiler barrel closed and clamping the strip in place at same time can be a bit awkward .

If you've made a wooden former plane a flat on one side , assemble the boiler on the former and close it up with string then slip the cover strap in – gives you a solid set up and something to hold for drilling .

MikeW

PS Before doing any actual silver soldering you might like to work out the order of assembly of the various parts and how many different heats will be needed . Generally the fewer heats the better .

Also decide means of staying firebox . LBSC suggested screwed rod and solder but better now to use silver soldered stays . I mention this because the order of assembly of the boiler is different in each case .

Always a good idea to do the main barrel joint using a slightly higher melting point silver solder .

Remember that the joining strip has to be cut short at the front end to allow the front tubeplate to go in far enough .

Edited By MICHAEL WILLIAMS on 20/02/2012 14:54:03

[GoCreateParticipant @gocreate]

Hi

When riveting for silver soldering should you stop short of completely closing the rivet in order to maintain a few thou gap the for silver solder to flow between the joining surfaces.

I understand it's important to maintain a few thou gap to get a sound joint?

Nigel

[michael burton 1Participant @michaelburton1]

ah ok so the strip goes on the inside i imagined it going externally il look in to the solder and when i can il make an order as for the staying well i will go for the best method, iv been looking in to the copper for the back head it calls for 13g would 2mm be ok as the fittings wont be screwed straight in i will be making bushes 2mm is .337 smaller then 13g i can get a small peice big anougth to make he back head as i dont have the money or the need to buy a big 300×300 sheet

many thanks mike

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

LBSC almost always put his joining strips on the inside . Most real boilers had them on the ouside or one inside one outside .

If you want to do some real engineering in your Tich put strip on the outside by all means but in a very small boiler its just a little easier to sort out when inside .

As TE42 says barely close the rivets . Slightly oversize hole . Small head inside the boiler and just tap into tiny countersink outside . Trim back after silver soldering . Useful to put some very wet flux in the hole before rivetting

Just for interest :

The lower temperature free flowing silver solders have some remarkable properties . Whilst a controlled gap is essential in a properly designed job I have several times seen EF2 silver solder go clean through a tightly fitted joint . Whether the latest Cadmium free silver solders will be as tolerant I don't yet know .

MikeW

[michael burton 1Participant @michaelburton1]

ok MAJOR muck up riveted the boiler togethor ready for soldering and after all that work it seams its come out 3/16'' bigger so an external diameter of 3-3/16'' im not gonna remake the thing now i know were it went wrong so im gunna try my best to work round the problem bigger tube plate bigger smoke box on and on and on admitally the boiler shell does look nice just went a teeny weeny bit wrong oh well hopefully i can make it work =(

mayby it will work mayby it wont if not it can live on my shelf

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi MB1 ,

I wouldn't worry too much – make the tube plates and the smokebox that much bigger to match .

Best to make sure firebox will still drop between frames . I don't think there was ever any clearance problem on Tich but best make sure .

Always best to put rivets in just before brazing but anything up to a day or two probably OK .

Barrel seam and throatplate can certainly be brazed at same heating . You might like to put the dome bush in as well .

MW

[michael burton 1Participant @michaelburton1]

well that was reasonbly sucsefull for my first time at flanging a plate……. yes i started the tube plate and to my surprise has come out rounder then the boiler barrel so not all bad never done it before so im fairly happy wih myself solder and flux is on order going to get some fire bricks next week so should be getting the seem brazed up i must admitt with the little patiance i have im doing very well hehe

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Sounds good !

You might like to take some pictures as you go along – mostly for you own nostalgia when your 102 but you could put one or two on this site for general interest .

[michael burton 1Participant @michaelburton1]

will soon be purchsing the tube for the boiler tubes haveing trouble finding 3/8 24g i can easily get 20g that is 0.355 smaller wall thickness would this be much of a problem? also im going to fit bushes in the tube plate for the stays and cant really afford to buy a foot so was wondering would anyone have a few inches of sutible material i will gladly pay for a few inches probley arround 1/2'' diameter should do

on a side note i have some meteral that is 3/8 and should do the job now it was sold to me as bronze but im doubting it as it machines like copper and has the look of copper is there and shure fire way of telling what it is i made two bearings for a little model i built and they wore out very quickley of running so also makes me belive it may be copper

thank you mb1

[David HaynesParticipant @davidhaynes53962]

Thank you David for your occasional edits where threads go askew!

[nigel jones 5Participant @nigeljones5]

Contact Joe at Macc Models, he will sell you everything by the half inch if needed.

[michael burton 1Participant @michaelburton1]

hi thank you iv got to order some bits from macc models anyway so il have a ask when i do, as for the tubes would 20gauge be ok

regards

[nigel jones 5Participant @nigeljones5]

hi…20g is 0.9mm, thats the same as the stuff in b&q (wall thickness) its critical limit is about 600 psi so in theory its strong enough, but i would go thicker if i could – bottom line is it will easily pass for your requirements

[TerrydParticipant @terryd72465]

Posted by michael burton 1 on 27/02/2012 21:04:46:

will soon be purchsing the tube for the boiler tubes haveing trouble finding 3/8 24g i can easily get 20g that is 0.355 smaller wall thickness would this be much of a problem? ………………………..

thank you mb1

Hi Michael,

what exactly are you worried about? 20g is thicker than 24g, so are you concerned about the reduced internal diameter (0.305" as opposed to 0.331" ) reducing air flow?

Terry

Edited By Terryd on 29/02/2012 04:16:19

[TerrydParticipant @terryd72465]

Posted by nigel jones 2 on 29/02/2012 00:11:06:

hi…20g is 0.9mm, thats the same as the stuff in b&q (wall thickness) its critical limit is about 600 psi so in theory its strong enough, but i would go thicker if i could – bottom line is it will easily pass for your requirements

Hi Nigel.

according to (British Standard) 2871 – Dimensions and Working Pressures the maximum working pressure of 10mm x 0.6mm thick standard half hard copper tubing is 7.7N/sq mm which is around 1116 psi (annealed 0.8mm wall thickness has limit of 8.2N/sq mm).  Allowing for a safety factor of 2 that would be about 600psi as you say. However that is internal pressure which causes a tensile force in the tube (I've forgotten the formula to calculate exactly after so many years ). In a boiler tube the pressure is external, inducing a compressive force in the tube wall which means that the tube can withstand a much greater pressure. So Michael should be ok with 20g (0.91mm).

Best regards

Terry

Edited By Terryd on 29/02/2012 05:21:27

[TerrydParticipant @terryd72465]

Posted by michael burton 1 on 27/02/2012 21:04:46:

will soon be purchsing the tube for the boiler tubes haveing trouble finding 3/8 24g i can easily get 20g that is 0.355 smaller wall thickness would this be much of a problem? ……………….

thank you mb1

Hi again Michael,

don't forget that BS EN standard copper tubing 10mm dia tubing is 0.6mm thick which is very close to 3/8 (9.3 mm) x 24g (0.559mm),

Terry

[Author]

Posts