Yorkie's Connoisseur 4F build

Ok thanks Rob, I'll measure the depth between boiler surface and smokebox and get back to you if I may please. I have some 2.5mm copper wire strands which may work and last night have been thinking about the best sort of jig to make but again whatever the jig is it needs to have a top surface height of half the thickness of the wire. I also got a bale of 32 amp copper earth bonding wire down in the bottom shed ... I will measure that too as the strands are a tad over about 1.25mm.

Taking about the jig I wondered if a circle cut into a suitable etch sheet which had a base where the soldered wire circle would comfortably sit into and remain stable whilst being filed, imagine the jig looking like a round paddling pool, because once the wire is re soldered the flat face would then butt against the outer circumference of the circle for being filed. Just a few first thoughts.

 

I've a reasonable supply of various thickness etch sheets and a box full of scrap but if I made a tool which allows me to file quarters from round yes it will add time to this build but I'd sooner go down the road of putting a bit of my own fingerprint on it and also to have a tool I can reuse again.

 

Ah but Mr S 'tis a complex matter for authenticity... tune into my new forthcoming thread on Make a Simple Measurements Device, seriously Andy the 4F has a quarter curve bend behind the smokebox and next to the first boiler cleat, this is actually the outer rim of the tube plate as it connects to the smokebox wrapper via a line of rivets. On the model Jim suggests using soft wire soldered to mimic this feature, I'm not convinced this is the way I want to take this build although it is quite reasonable to model this feature like that. Rob is saying if you take a length of suitable thickness wire and file it into a half moon shape then turn it 90 degrees and file it to a quarter shape this will create the profile required to reflect the tube plate curve when soldered on, it is then just a matter of soldering the first boiler band in place. we are just discussing a good way to make a tool which holds the wire firmly whilst filing to shape. Leaving this feature off the model is not an option for me really.

 

Thanks Pete for the idea which could well work but it sounds like entering the realms of machinist work making such a tool... I not frightened to say that is beyond my skill level, I'm looking into how to hold a piece of round copper wire rigid in a former whilst it is manually filed to shape, I think it may not need to be a round former as the radius can be met once the shape is made. It could even be a straight clamp holding the wire on the correct plane for filing down... I'm off into the workshop now to test a few different sections of wire to see which works then I'll know how deep to make the jig / former.

 

I actually developed that idea this afternoon Rob.

 

Today I set to making a very simple former tool to fashion the smokebox ring into a quarter segment with inspiration coming from Rob, no need for something complex I went with a simple tack solder fix onto a piece of etch sheet with a floating disc to gauge with. The wire I've used to form the ring is 32 amp soft copper which will give me a thickness of 1mm once filed into a half circle, this will be about right for the 4F, so I formed the wire into a circle and ensuring it sat perfectly flat I tack soldered it to the brass sheet so that it didn't move. I'dalso made a floating circle with a piece cut away to sit inside the ring, this was my gauge as its thickness is 1mm and the cut out allows free rotation and won't clog up with filing dust.

 

So now its just a matter of filing around the circumference of the ring making sure the file always contacts both sides of the ring at any one time, this way it helps to keep the flat level as it were and really is a matter of eye.

 

I'm not far off now and a few more strokes with a fine flat needle file now should see the ring at the correct depth, the floating circle tells you when you are near as it starts to rotate around once the correct depth is reached and of course won't allow for any over filing. The underside has two strengthening pieces added so that it maintains the correct level in case of clogging up from waste filing dust. Really simple and it works ... well so far it does. I've run out of daylight now so tomorrow i'll release the ring and reform it again to file the top quarter off, this will involve another little jig support to keep the flat filed plane of the ring perpendicular, i cannot afford it to twist as this filing is critical in achieving a 90 degree right angle on the wire. anyway here i am so far.

 

Thanks Toto, tomorrow will see a result hopefully if not everything done today will have been for nothing, I think the secret of success is to resolder the ring with the flat face perfectly upright and then to hold the ring securely during the last part of the filing. I can reform the ring around a wooden bar such as a rolling pin, this will ensure the flat face is upright and I can use the floating gauge again. We will see.