SteveB
Western Thunderer
I wonder if you would be interested in my way of making leading crankpins. When I was building my std 4 tank I tried to find on this forum (and others) what other people do. I couldn’t really find much. Even Adrian skirted around the subject in his build notes (please don’t be offended Adrian, I’m certainly not having a go at you, quite the opposite actually). So I came up with my own idea. It may have been dealt with before and I just didn’t spot it. If so, then I apologise.
Here’s a couple of close up photos of my 8F. Having taken the close ups, I realise how cruel they can be and how far I’ve got to go before I get close other kit builders on this forum.
If you’re still interested, then read on. I start off with an M2 x 6 countersunk stainless steel socket screw. Incidentally, the AF size of the key is 1.27mm, the same as used on Slaters wheels. I then take an M2 brass nut and countersink it until almost all of the thread has gone. Then screw the nut onto the screw. I measure the distance between the outer faces of the nut and screw head and adjust the position of the nut until it’s the overall thickness of the coupling rod plus a bit (0.1mm). I then silver solder the nut an screw so it’s a single piece.
If you’ve never used silver solder, then its dead easy. Easier I would say, then using a soldering iron and soft solder. It needs a different flux and it needs more heat (well within the range of a micro torch, for these items at least) but that about it. I dare say that a high melting point soft solder would suffice, but I think you’ll find silver soldering easier. I think you’ll need a special flux for the soft solder and stainless steel combination anyway.
The next bit is much easier with a lathe, but at the time I did the 2-6-4T I didn’t have one and just used a needle file with the screw in a mini drill. Turn or file the brass to a suitable diameter (I’ve done mine to 2.5mm) and reduce the flange thickness to slightly more than the thickness of the recessed coupling rod etch. An M2 washer is held captive against the wheel to provide clearance, especially if the coupling rods don’t have thicker ends. Obviously, the hole in the coupling rod outer etch needs to be slightly bigger (0.1 to 0.2mm) bigger than the head diameter of the screw. The screws I bought were 3.8mm diameter. It is also possible to use a bit more silver solder and actually increase the outer diameter of the screw if needed, although you have to go careful, not to fill the socket!
So far, I’ve only done wheels provided by S7 Group. These are made by Slaters but they have a steel or brass bush for the crankpins. I don’t see any reason though why a ‘normal’ Slaters wheel would object to being threaded M2.
Incidentally, one of the best tools I have in my workshop is a special hex key for Slaters wheels made by Peter Roles. It just makes fitting the screws ten times easier than a conventional Allen key. I came across it quite by accident. I debated whether it was worth it, but I can assure you it is.
Regards
Steve
Here’s a couple of close up photos of my 8F. Having taken the close ups, I realise how cruel they can be and how far I’ve got to go before I get close other kit builders on this forum.
If you’re still interested, then read on. I start off with an M2 x 6 countersunk stainless steel socket screw. Incidentally, the AF size of the key is 1.27mm, the same as used on Slaters wheels. I then take an M2 brass nut and countersink it until almost all of the thread has gone. Then screw the nut onto the screw. I measure the distance between the outer faces of the nut and screw head and adjust the position of the nut until it’s the overall thickness of the coupling rod plus a bit (0.1mm). I then silver solder the nut an screw so it’s a single piece.
If you’ve never used silver solder, then its dead easy. Easier I would say, then using a soldering iron and soft solder. It needs a different flux and it needs more heat (well within the range of a micro torch, for these items at least) but that about it. I dare say that a high melting point soft solder would suffice, but I think you’ll find silver soldering easier. I think you’ll need a special flux for the soft solder and stainless steel combination anyway.
The next bit is much easier with a lathe, but at the time I did the 2-6-4T I didn’t have one and just used a needle file with the screw in a mini drill. Turn or file the brass to a suitable diameter (I’ve done mine to 2.5mm) and reduce the flange thickness to slightly more than the thickness of the recessed coupling rod etch. An M2 washer is held captive against the wheel to provide clearance, especially if the coupling rods don’t have thicker ends. Obviously, the hole in the coupling rod outer etch needs to be slightly bigger (0.1 to 0.2mm) bigger than the head diameter of the screw. The screws I bought were 3.8mm diameter. It is also possible to use a bit more silver solder and actually increase the outer diameter of the screw if needed, although you have to go careful, not to fill the socket!
So far, I’ve only done wheels provided by S7 Group. These are made by Slaters but they have a steel or brass bush for the crankpins. I don’t see any reason though why a ‘normal’ Slaters wheel would object to being threaded M2.
Incidentally, one of the best tools I have in my workshop is a special hex key for Slaters wheels made by Peter Roles. It just makes fitting the screws ten times easier than a conventional Allen key. I came across it quite by accident. I debated whether it was worth it, but I can assure you it is.
Regards
Steve
