Looking for advice rolling taper boiler

[mickoo]

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

Brian, indeed you will always get a flat at the start and end of the roll no matter what rollers you get, basically the material is not being supported between the two fixed rollers so the pressure roller cannot bend it.

There are two ways around this, make the piece overly long and then trim back once rolled, that's fine for scratch building, the second is to use a scrap of material bigger than the bit you are rolling, place it 'under' the work material or make sure the work material is between the sacrificial scrap and the pressure roller. It is important that it is longer than the work piece, as you feed this in it will bridge the gap between the rollers and force the work piece above to bend sooner, it won't be a prefect start to the roll but it won't be flat either, I use 0.010" or 0.015" as the backing piece.

It's one of those things that's easier shown than explained, I'll get the rollers out tomorrow and snap some pictures if you want.

10" is what I have and they suit all my needs and I prefer the GW has it has a mangle type handle, I find it easier to turn that than a knurled knob, but that's personal preference, I changed my lathe round disc type feed handles to mangle type and find it gives a smoother feed as you never have to let go of it to twist your hand and feed it some more, again, personal preference.

Addendum, re-read your post, you already know about the backing scrap material trick

 

[Donald Campbell]

Mickoo your suggestion of using a biscuit tin lid cut to the size of the boiler etching sounds a very
good idea I will try this.

 

[Dog Star]

When I have not been able to find a piece of "scrap" metal to back an etch I have used 30thou plastikard to achieve the same result.

Taking this aside for a moment, the MMP Dogfish kit has etches for the curved doors in the base of the hopper... I fixed the etches to some plastic sheet with masking tape and then rolled the two parts together using my 10" GW rollers.

 

[oldravendale]

Thanks, Mickoo. Seen it done, so I'll have another look at the GW roller when I next see George. I believe he'll be at the Reading Trade Show on 5th December and I intend to be there, so that may be the major item on my list.

I assume that, when rolling roofs etc, you also feed in a scrap piece to get a uniform curve?

Best regards.

Brian

 

[mickoo]

Thanks, Mickoo. Seen it done, so I'll have another look at the GW roller when I next see George. I believe he'll be at the Reading Trade Show on 5th December and I intend to be there, so that may be the major item on my list.

I assume that, when rolling roofs etc, you also feed in a scrap piece to get a uniform curve?

Best regards.

Brian

Brian, exactly, but I've found with roofs that the curve is much more gentle and the material usually thinner, so a simple bog roll interior cut and flattened works just fine, or one or two layers of cereal packet, or Plasticard as mentioned above, anything really to support the leading and trailing edges of the material as it passes through.

All the best.

 

[Ian@StEnochs]

My home made rollers have two geared rollers on the bottom with a single removeable pressure roller on top and pressing down between. The rolls are 21mm dial and 200 long and will roll almost all 7 mm scale boilers.

To get over the short flat at each end I use a hide mallet to curve the edge over the top roller before inserting the sheet in the rollers. The metal is rolled through and back increasing the presure until a cylinder or cone is formed.

Ian

 

[adrian]

I assume that, when rolling roofs etc, you also feed in a scrap piece to get a uniform curve?

Do you mean loco/van roofs or coach roofs? Unfortunately coach roofs are little more complex as they are often compound curves, i.e. built up from multiple radii.

There are two ways around this,

I'd like to suggest the "third way" - get a decent rawhide mallet for tidying up the edges. Gentle tapping and rubbing with a rawhide mallet along the edge over a suitable former will finish off the curve nicely - this was my 2mm effort but I have done the same process in 7mm
2mm - Adrian's 2mm workbench. | Western Thunder

It's also useful for flattening out strip that's got bent, I use it for tender flares and many other jobs. As the rawhide is softer than the metal sheet it doesn't leave tool marks in the sheet. It is another useful tool I'd always recommend having in the toolbox.

 

[oldravendale]

Intetresting and helpful further observations, Adrian.

In 7mm a set of 10" rollers won't be long enough for a coach roof anyway, so I was considering cab roofs etc, as described by Mickoo in his description of the uses to which he puts his rolling mill. However, Adrian and Ian, the suggestion to use a rawhide mallet is an interesting one I've not seen before. That's well worth a go, although for coach roofs the former would have to be made, and while doing that why not just fit the carved out roof to the model? I usually find a supplier of the correct profile roof and buy from him!

I was also considering tender flares last night, and in most cases these are one long strip, so again 10" rollers would not be long enough. They (and coach tumblehomes) have always been a bete noir of mine, even using the "tape attached to a roller method" so a former and mallet may be the answer. I'm guessing, but the former for tumblehomes and flares could be a bar of suitable diameter, with the work piece taped to it?

I'm off to the tool shed to see if I have a hide mallet. I know I had one once, when I did all my own car repairs, but I've not seen it for years......

Brian

 

[Ian@StEnochs]

Intetresting and helpful further observations, Adrian.

In 7mm a set of 10" rollers won't be long enough for a coach roof anyway, so I was considering cab roofs etc, as described by Mickoo in his description of the uses to which he puts his rolling mill. However, Adrian and Ian, the suggestion to use a rawhide mallet is an interesting one I've not seen before. That's well worth a go, although for coach roofs the former would have to be made, and while doing that why not just fit the carved out roof to the model? I usually find a supplier of the correct profile roof and buy from him!

I was also considering tender flares last night, and in most cases these are one long strip, so again 10" rollers would not be long enough. They (and coach tumblehomes) have always been a bete noir of mine, even using the "tape attached to a roller method" so a former and mallet may be the answer. I'm guessing, but the former for tumblehomes and flares could be a bar of suitable diameter, with the work piece taped to it?

I'm off to the tool shed to see if I have a hide mallet. I know I had one once, when I did all my own car repairs, but I've not seen it for years......

Brian

I also have a big set with 1 1/2" diameter rollers 20" long that I made when I was building 3" scale traction engines and needed to roll the chimney and boiler cladding plates. It is ideal for coach and van arc roofs. I need to do additional work with a mallet and smaller bar if it is an elliptical roof but thank goodness most of mine are not!

Tender flares are a bit too small and long for rollers to be of much use. Long thin rollers do not have enough rigidity and will bend in the middle and not give a uniform curve.

It is well worth making a former from thick steel plate and teasing the metal over with a stiff bit of hardwood. For most of the tenders I make the curve is not too severe and I can manage without any problems. However on one model it was a 1/4 circle and I had to anneal to get it right round. Careful use of the hide mallet can help get it down but even a soft mallet can stretch the metal and introduce a curve along the side.

Ian.

 

[Donald Campbell]

Mickoo

Many thanks re your advice on rolling taper boiler, much more straightforward than I would have imagined.
Onward and upward to next piece of the construction.

Donald

 

[mickoo]

Mickoo

Many thanks re your advice on rolling taper boiler, much more straightforward than I would have imagined.
Onward and upward to next piece of the construction.

Donald

Your welcome, glad you got it sorted

 

[mike evans]

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.

Heather
If the etch has been developed so that a tapered boiler will result from the rolling, if you roll the sheet as a normal cylinder that is what you will get.
In the flat, the end with the larger diameter will have a longer circumference that the smaller diameter end
Therefore to form a tapered boiler the top roll has to have slightly more pressure applied at the small diameter end.
All being equal a tapered boiler will result.
Mike

 

[chigley]

Hello Donald, i use GW rollers and i use a piece of card under the boiler so as to
roll right up to edge
Ken

 

[Heather Kay]

All being equal a tapered boiler will result.

Cheers Mike. As it happened, the model was a GWR tank engine where the only full part of the boiler was parallel (a relatively easy roll) and the tapered parts were partial curves. It all more or less worked well, and now I needn’t worry about any of it any more because most coaches have don’t have coned roofs!

 

[Robert Dawson]

There’s a great piece by Malcolm Mitchell on YouTube where he shows how he rolls his tapered boilers (using rollers) : ’Malcolm Mitchell on Etched Locomotive construction.’ I haven’t tried it myself-yet- but the day approaches…