Rob Pulham
Western Thunderer
I have had the most frustrating time since my last post on the 8F. It started when I made my first attempt at improving the return crank offerings in the kit. Like pretty much all etched LMS loco kits, the four retaining bolts (which are in reality recessed into the face of the return crank) are represented as four half etched bumps. Or rather the bumps are full thickness, but the surround is half etched. They usually have a second backing layer to make the return crank up to the full thickness.
The original plan was to drill through the bumps and insert some rod to represent the bolt heads. I confess that I failed miserably to get four holes centred on the bumps. Luckily, I had an additional pair of etched fronts in the spares box which I tried first.
Then I thought perhaps I would make a better job if I drilled out the backing layer and placed that over the ‘front’ layer to leave the etched bumps inset. This I have to say worked perfectly. Sadly, it all fell apart when I soldered the two together. Solder leeched into the holes and filled them completely covering the bumps.
I tried plan B, which was drilling the holes out again and inserting stubs of rod into them. This too failed miserably in so much as the holes ended up offset and the results looked a bit like Marti Feldman.
It was at this point last Monday when I inadvertently rubbed something (I am not sure what but it may have been flux) into my eyelid. It immediately started to itch like mad. By Tuesday morning my eyelid was so swollen that I could barely open it. Tuesday and Wednesday were spent sat listening to audiobooks, with frozen teabags on my eyelid trying to get the swelling to go down. By Thursday I could open my eye a little and I was feeling a bit stir crazy, so decided to go into the workshop and do something.
I started by scanning and importing the outside motion GA from the Wild Swan book into Fusion 360. I scaled it to 7mm scale and sketched the return crank creating a 3D model from it and then from that created a working drawing.
Taking measurements from the drawing for the holes, I transferred them onto some strips of nickel silver which I had cut at 6mm wide. I had prepared 3 strips one for the front layer with 1.6mm holes, one for the back with 0.9mm holes and a third which I drilled with small holes at one end and larger holes at the other. Having something firm to grip in the vice of the Proxxon Mini Pillar drill and using the coordinate tables I was easily and repeatably able to drill the multiple sets of four holes. I also drilled the hole in the other end to tap 12ba for the fixing. More on this later!
At this point I decided to solder them together, then make and fit the simulated fixing bolts. With the view that if I couldn’t get that right at this stage of the proceedings, then there was no point in wasting time filing them to shape.
On my first attempt, I had filed some hex ends on some nickel rod and soldered that into the holes, but this time I decided to see if I could improve upon that. I cut a short length of 1.4mm nickel rod, fitted it in the 3-jaw chuck on the lathe. I would normally have used a collet but the chuck was already mounted so I thought I would see if it tightened close enough to grip such a thin rod. It did so with some movement to spare.
With a very sharp HSS cutting tool, a fast RPM and a very light feed rate, I was able to cut the end of the rod down from 1.4 to 0.9 in one pass. The secret is don’t have too much sticking out of the chuck. I would guess that I had no more than about 6mm protruding. I did this on each end of the rod and then transferred it across to my hex headed pin vice. Using the hex head as an index I filed a short length of the full width rod into a hex to represent the bolt head. Then using my trick of gripping the tail end in a second pin vice to prevent it flying off into space when it cut through, I sawed it off with a piercing saw.
I confess that I found making them quite therapeutic and I got a little sidetracked. I was also amazed at how much of the rod I was able to actually use.
Remarkably quickly I had the eight that I needed and a few for the spares box.
The original plan was to drill through the bumps and insert some rod to represent the bolt heads. I confess that I failed miserably to get four holes centred on the bumps. Luckily, I had an additional pair of etched fronts in the spares box which I tried first.
Then I thought perhaps I would make a better job if I drilled out the backing layer and placed that over the ‘front’ layer to leave the etched bumps inset. This I have to say worked perfectly. Sadly, it all fell apart when I soldered the two together. Solder leeched into the holes and filled them completely covering the bumps.
I tried plan B, which was drilling the holes out again and inserting stubs of rod into them. This too failed miserably in so much as the holes ended up offset and the results looked a bit like Marti Feldman.
It was at this point last Monday when I inadvertently rubbed something (I am not sure what but it may have been flux) into my eyelid. It immediately started to itch like mad. By Tuesday morning my eyelid was so swollen that I could barely open it. Tuesday and Wednesday were spent sat listening to audiobooks, with frozen teabags on my eyelid trying to get the swelling to go down. By Thursday I could open my eye a little and I was feeling a bit stir crazy, so decided to go into the workshop and do something.
I started by scanning and importing the outside motion GA from the Wild Swan book into Fusion 360. I scaled it to 7mm scale and sketched the return crank creating a 3D model from it and then from that created a working drawing.
Taking measurements from the drawing for the holes, I transferred them onto some strips of nickel silver which I had cut at 6mm wide. I had prepared 3 strips one for the front layer with 1.6mm holes, one for the back with 0.9mm holes and a third which I drilled with small holes at one end and larger holes at the other. Having something firm to grip in the vice of the Proxxon Mini Pillar drill and using the coordinate tables I was easily and repeatably able to drill the multiple sets of four holes. I also drilled the hole in the other end to tap 12ba for the fixing. More on this later!
At this point I decided to solder them together, then make and fit the simulated fixing bolts. With the view that if I couldn’t get that right at this stage of the proceedings, then there was no point in wasting time filing them to shape.
On my first attempt, I had filed some hex ends on some nickel rod and soldered that into the holes, but this time I decided to see if I could improve upon that. I cut a short length of 1.4mm nickel rod, fitted it in the 3-jaw chuck on the lathe. I would normally have used a collet but the chuck was already mounted so I thought I would see if it tightened close enough to grip such a thin rod. It did so with some movement to spare.
With a very sharp HSS cutting tool, a fast RPM and a very light feed rate, I was able to cut the end of the rod down from 1.4 to 0.9 in one pass. The secret is don’t have too much sticking out of the chuck. I would guess that I had no more than about 6mm protruding. I did this on each end of the rod and then transferred it across to my hex headed pin vice. Using the hex head as an index I filed a short length of the full width rod into a hex to represent the bolt head. Then using my trick of gripping the tail end in a second pin vice to prevent it flying off into space when it cut through, I sawed it off with a piercing saw.
I confess that I found making them quite therapeutic and I got a little sidetracked. I was also amazed at how much of the rod I was able to actually use.
Remarkably quickly I had the eight that I needed and a few for the spares box.
