Donald Campbell
Member
Looking for advice on rolling taper boiler, I have seen conflicting items one saying roll as normal and 7an item which said they can be difficult to roll properly. Advice would be most appreciated.
Looking for advice rolling taper boiler
- Thread starter Donald Campbell
- Start date
Heather Kay
Western Thunderer
Hello Donald!
I hope you get some good replies, because I have a taper boiler to roll at some point.
My head says it should be possible to roll as a normal cylinder. The etch has been made with the cone developed to flat, so as long as the rolling occurs centrally along the barrel it should "just work".
I'll wait on what the cleverer members say, though.
I hope you get some good replies, because I have a taper boiler to roll at some point.
My head says it should be possible to roll as a normal cylinder. The etch has been made with the cone developed to flat, so as long as the rolling occurs centrally along the barrel it should "just work".
I'll wait on what the cleverer members say, though.
oldravendale
Western Thunderer
I have never rolled one myself, but Bob Alderman rolled one for me (a section of an A3 boiler) through a set of GW rollers. He achieved this by putting more pressure on one side than the other. The result looks somewhat twisted but can be brought back to shape when soldering the internal formers in place. It worked for me!
An alternative I've seen recommended but never tried is to create a parallel rolled section and then insert a "V" shaped piece. This sounds like hard work to me but maybe someone else has had a go at this technique.
Brian
An alternative I've seen recommended but never tried is to create a parallel rolled section and then insert a "V" shaped piece. This sounds like hard work to me but maybe someone else has had a go at this technique.
Brian
Dikitriki
Flying Squad
I've rolled a good few myself. I've not found any other way but to roll it as normal as if it were a parallel boiler, and then hand-manipulate to shape. Just take some care and time and it can be got to a taper without too much difficulty. What you must do is make sure that the top of the boiler is parallel to the rollers so that the whole thing is not rolled on the skew.
I always reinforce the bottom seam on the inside with scrap etch, and using front and rear formers, it's not going to move.
Richard
I always reinforce the bottom seam on the inside with scrap etch, and using front and rear formers, it's not going to move.
Richard
oldravendale
Western Thunderer
Hi again Donald.
Do what Richard says! He's done it - I haven't.
Brian
Do what Richard says! He's done it - I haven't.
Brian
mickoo
Western Thunderer
Good rollers will have an adjustment at each end, if they are both set the same then you will roll a parallel boiler, if you lower one end (increase pressure) then it will induce a taper toward that end.
I roll all mine as parallel boiler first until the widest end just forms a completely circular tube, this will leave a v notch all the way down the seam. When I'm happy it's all square at each end I slowly increase the pressure of the roller at the end that needs to be tapered, half a turn will do. The end that hasn't been adjusted will still roll the same radius so we can forget about that really, but the other end will slowly begin to get smaller until the gap closes, do it in small steps and eventually it'll close up of it's own accord. depending how long your rollers are and where you placed the work, you may need to back off the other end off a little as the taper effectively starts way back at that end adjustment. The best bet is to have the work as close to the end that you do not wish to taper. If your work is in the middle or all the way toward the side that is being tapered then it will also (marginally) begin to taper the other end. It's not unmanageable, just something you need to be aware of, besides over rolling a little helps hold the formers in place inside better.
Rolling a taper is easy, getting it square is the tricky bit but take your time, better yet, practice on a bit of scrap material first, rough cut it to the shape of your kit part and then roll, an old biscuit tin lid is ideal, you know, the ones left over after Xmas that eveyone just throws away
I keep all mine and cut the top and bottoms out with tin snips and use as trial pieces of scrap, dead handy if your scratch building and don't want to waste brass or expensive nickle silver, especially when trying to form taper boilers and belpair fireboxs or just testing a jig you've made for folding cab roofs or tender flairs.
There are other ways, hand rolling and such like, but good rollers, whilst not Oxfam cheap, really are the best tool for the job and take a lot of the stress out of the procedure.
I roll all mine as parallel boiler first until the widest end just forms a completely circular tube, this will leave a v notch all the way down the seam. When I'm happy it's all square at each end I slowly increase the pressure of the roller at the end that needs to be tapered, half a turn will do. The end that hasn't been adjusted will still roll the same radius so we can forget about that really, but the other end will slowly begin to get smaller until the gap closes, do it in small steps and eventually it'll close up of it's own accord. depending how long your rollers are and where you placed the work, you may need to back off the other end off a little as the taper effectively starts way back at that end adjustment. The best bet is to have the work as close to the end that you do not wish to taper. If your work is in the middle or all the way toward the side that is being tapered then it will also (marginally) begin to taper the other end. It's not unmanageable, just something you need to be aware of, besides over rolling a little helps hold the formers in place inside better.
Rolling a taper is easy, getting it square is the tricky bit but take your time, better yet, practice on a bit of scrap material first, rough cut it to the shape of your kit part and then roll, an old biscuit tin lid is ideal, you know, the ones left over after Xmas that eveyone just throws away
I keep all mine and cut the top and bottoms out with tin snips and use as trial pieces of scrap, dead handy if your scratch building and don't want to waste brass or expensive nickle silver, especially when trying to form taper boilers and belpair fireboxs or just testing a jig you've made for folding cab roofs or tender flairs.There are other ways, hand rolling and such like, but good rollers, whilst not Oxfam cheap, really are the best tool for the job and take a lot of the stress out of the procedure.
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Heather Kay
Western Thunderer
How would one approach rolling a taper boiler barrel if one doesn't own a set of rollers?
mickoo
Western Thunderer
Buy a set of rollers
?Honestly
, I've no idea, I use my rollers all the time, cab roofs, bodysides, boilers, splasher tops, footplates, basically anything curved that is larger than the radius of the roller bars.When I started out in this malarky a few years ago I didn't even consider any other approach, just paid the cash and to be honest, never looked back. Rollers, riveting tool, pillar drill, jewellers vice were what I considered core items.
There must be a way to do it but I wouldn't know where to start, perhaps like hand rolling a parallel boiler but apply more pressure to one end ?
adrian
Flying Squad
I must admit initially this left me very puzzled - you should be able to roll a taper boiler without it being twisted or distorted - requiring no hand manipulation to get it to shape. However in trying to work out what is going on I had a look at the GW tools rolling mill and this might explain the difference, Bob is using the GW Tools rolling mill, are you doing the same Richard?
It appears that not all rolling mills are the same. The GW Tools rolling mill doesn't appear to clamp the metal and forms the curve by moving the rolling bar internal to the cylinder to be rolled.
The Cherry Scale Models rolling bar which was later taken on by Metalsmiths works differently. On this the top and bottom bar are used to clamp the sheet, the top bar is internal to the cylinder to be formed. The rear bar which produces the curve is outside of the cylinder and is wound in to tighten the curve. See the photo on this page, you can see the angled slot for the rear roller.
4MT Boiler - Cherry Clan
This makes it a doddle to form a taper boiler because as you wind in the rear roller you apply a couple of extra turns on one side rather than the other. The result is a taper boiler because one side is forming a smaller circle than the other. No twisting occurs*, no hand forming - it does just pop out of the rolling bars as a taper.
* the caveat on the twisting is that if you don't clamp the sheet square to start with it can turn out twisted a little - but nothing significant and with a little practice is very minimal.
adrian
Flying Squad
Rather glib answer I'm afraid but find someone who does have a set of rollers. Either at the local club or see if a suitable builder is demonstrating at an exhibition.
AndyB
Western Thunderer
I find I can always roll a taper, even if I'm trying to roll a cylinder - by any method!
So if you are using the 'rolling pin and rubber mat' approach the taper is achieved by putting more pressure on one end of the rolling pin, replicating the effect of tightening one end of the rolling bars.
Andy
mickoo
Western Thunderer
Adrian, the GW rollers work in a similar vein but as you note do not clamp the material as such, it is up to the user to make sure it is fed in straight and square, if not then you will end up with a twisted tube.
As you also note it's nothing major and playing about with a few bits of scrap before hand soon teaches you how to get the best out of it. On the GW rollers you adjust the height of the top middle roller to get the curvature required.
As you also note it's nothing major and playing about with a few bits of scrap before hand soon teaches you how to get the best out of it. On the GW rollers you adjust the height of the top middle roller to get the curvature required.
Ian@StEnochs
Western Thunderer
Hi Heather.
I have made quite a few taper boilers in my time and do own a set of home made rollers.
However forming a boiler barrel isn't all that difficult if you use a piece of bar and a resilient surface onto which the metal is rolled. A couple of mouse mats or even a rubber backed floor mat is fine. You just place the metal on the pad and roll back and forward with the bar applying a bit of downward pressure. It's a wee bit like rolling pastry!
To make a tapered boiler just apply more presure to the small end.
However you need to know what shape the barrel needs to be before starting. If a kit it should have been worked out for you by the designer but not always that accurate. If a scratch build I make a basic former of two discs, one for each end, joined with a piece of screwed rod and nuts. You can roll a piece of card round the former and get the correct shape but I always make the wrapper a little too big and trim back after forming.
There are differing types of tapered boiler. A straight cone where both ends share the centre line, the rod fits in the centre of both formers. An offset cone where the ends are at right angle to one side of the cone. On these the centre is found by placing the small former on the large one and marking through from its centre onto the larger one. I find with the later it is easiest to make the barrel oversize in length and file back after soldering in the ends.
In all cases when joining the barrels I reinforce the seam with a piece of tee section brass with the leg outwards. It is easy to locate along the joint and the leg gives you something to hold with pliers. To make it easier I always make the barrel slightly too small so that it doesn't quite touch but comes against the leg of the tee. Solder fixes the lot and the surplus leg is easily filed off. I have tried using just strip brass to reinforce the joint but it is very difficult to hold it in place unless you can get a support inside which with end formers is impossible.
One last tip, do not anneal the metal! Annealing makes the wrapper soft and very prone to kinking or denting which are impossible to remove. Leave the brass or nickel silver as supplied, usually half hard, and you will find that it gives a nice smooth finish to the boiler. It might take a wee bit more work but worth it.
Ian
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Heather Kay
Western Thunderer
Thanks chaps!
I did look into getting a set of rollers, but when I worked out how many kits coming through the works actually required intensive rolling - current count = 1 - I felt I would be better served investing in other tools first.
The kit for which I will need to form the boiler is an original Mitchell GWR small prairie. By the time I get to it, I may well possess rollers!
I did look into getting a set of rollers, but when I worked out how many kits coming through the works actually required intensive rolling - current count = 1 - I felt I would be better served investing in other tools first.
The kit for which I will need to form the boiler is an original Mitchell GWR small prairie. By the time I get to it, I may well possess rollers!
Dikitriki
Flying Squad
Hi Adrian,
I am using a fairly elderly Leakey set of rollers.... I think; it's a long time since I purchased them. I only have minimal adjustment in the bottom roller - the boiler is rolled between the top two which are pretty much fixed (just enough adjustment to allow the metal to be fed in).
Whenever I tried varying the pressure on one side, all I achieved was a curve along the seam which caused more trouble than it was worth. I never found it very difficult to manipulate to the right shape.
Richard
oldravendale
Western Thunderer
Thanks for this, Adrian.
I've been considering the purchase of a set of rolling bars for a while and Mickoo's advice about the items he uses them for makes me think it'd be a good investment for me. I've never been able to make the roller and telephone directory/mouse mat/carpet method work so rolling bars as used by Mickoo may be what I need.
In fact I considered buying a set when I last saw George, but now wonder, following your post, whether a set of the Cherry rolling bars would be more appropriate. What's the consensus? I commented to George that the problem I'd noted with using his bars is that the initial "roll" tends to be flat, ie the roll is not consistent through the length of the work piece. He demonstrated the use of a piece of scrap to start the thing off, followed by feeding in the work piece. He produced a perfect cylinder and I would imagine that some sort of differential adjustment to the rollers would produce a taper.
Finally what size of bars is best for 7mm. Would that be 10"?
Brian
Eastsidepilot
Western Thunderer
I use a set of G.W.'s rollers, the pressure can be adjusted either end to suit when rolling tapers etc.
If you'r scratch building use 0.010" material for the boiler and perhaps 0.024" for the formers.
Col.
If you'r scratch building use 0.010" material for the boiler and perhaps 0.024" for the formers.
Col.
Donald Campbell
Member
Many thanks to all your advice is valued, I have a set of GW rollers which I only used once for a parallel boiler but with your help I hope to be successfull in completing a taper boiler. Heather I hope this thread has also helped you.
Thank you all.
Thank you all.
Heather Kay
Western Thunderer
It has, and thank you for your original post that has prompted so many useful answers.