Bending sheet metal

[Peppercorn]

J1, J2 and J6 footplate

 

I have a little tank on the go and it is slowly progressing. I do have a long term project, though, and that is to build an LNER 0-6-0 types J1, J2 and J6.

 

 

As LNER and GNR enthusiasts will know, these locomotives had the Ivatt and Gresley footplate whose centre section was raised to clear the coupling rods. I never saw any in real life, but have seen some fine 3mm examples of the J6 together with the Frank Dyer 00 version described many years ago (MRC November 1962!) and a later version built by Peter  (I'm embarrassed to say I've forgotten the builder's name - and it does look like an excellent model) and John Evans as described in Railway Modeller 1968.

 

These locomotives look good to my eye but, of course, have the complication - for scratchbuilders - of accurately making that raised section with their gentle curves at front and rear. I thought that I would circumvent this potential problem - or challenge, if you like - by purchasing an etched kit, so this is what I did, buying an ACE Products J1 that ACE reduced to 4 from their 7mm kit. I wish I hadn't. I thought that the kit would either have the footplate ready-formed (there's an optimist somewhere inside me...) or that there would be a suitable former on which to make the bends or that at least, there'd be good instructions leading me. The kit is bereft of any of these although there are instructions, but these just say "...now add the valances to the footplate after bending carefully to the correct profile..." which is about as unhelpful as it could be.

 

I have accordingly been giving the matter some thought and have the idea of a making a jig of some sort using a pair of rods of suitable diameter (about 7 mm diameter) and manipulating the curves. However, I wondered if anyone else here has already done this and has a better idea, for I'd be grateful for a steer on this, and thanks for reading this rather long message.

 

CliffH

 

[Nicktoix]

Cut two pieces of plasticard, at least 1mm thick, to the correct profile and mount a base of similar. Use the valance etches as a guide. Make sure they are parallel and about the width of the footplate apart. Shape the footplate to suit.

An etched jig with the valances on is the best way tho'.

Nick

[Peppercorn]

Nicktoix - please my apologies for not having responded sooner than this.

I have made a jig, but am not totally happy with the results from using it, but will carry on modifying it - the jig - to see if I can make it work.

[Peppercorn]

This is mark 1 of the little bending jig.  Both upper and lower parts are of 2mm thick aluminium, which is good since the step height of the raised portion of the footplate is about 2mm. The outer edge of the lower part of the jig has a rounded edge whilst the upper part likewise has a rounded edge but is set back. The idea is that the footplate blank is sandwiched between the upper and lower jaws(?) and a round rod of about 13mm (which was to hand) used to curve the footplate. The first picture shows it in use, but with a piece of rail intended for valancing in it.

The second and third photos shows what I'm trying to achieve, part of a drawing and part of a works photo. The radii both upper and lower are 7.33mm (give-or-take the thickness of the footplate, 0.25mm) The fourth shows a footplate blank duly folded whilst the fifth shows a number of test trials of valancing using the same jig. I think that I should be using different radii for the curves on the valancing (7.58mm and 5.33mm) but we'll see how really necessary that is. The little piece of brass shown in photo 1 is the allow for the thickness of the footplate.

In practice, the upper bend in the resulting footplate seems a little sharper than I'd want so I need to devise a way of making it gentler, although in this scale (4mm:ft) as long as it isn't actually sharp, it shouldn't show. However, the curve in the prototype photo is quite gentle - the working drawing radii scale out at 7.33 mm. 

My main problem, though, is with the valances - not the radii, but getting the raised section the same length to match that of the raised section of the footplate. So, on to mark 2 of the jig...

 

 

Edited February 4, 2020 by Peppercorn