Baldric's 3" Foden

[baldric]

Whilst I have posted on several other threads I thought I would put a few details up about the model that I am SLOWLY working on, I do put some details up on "Traction Talk" as that is probably a better fit for the model as it is road steam.

The latest part that I have been making has been the 3/8" diameter, twin start, 4TPI square screw thread for the steering, on the drawing this has no run-out so I did not want to do this in the lathe, not only because of the run-oun but also being 4 TPI would be quite fast moving. As I have a universal dividing head I decided to use that on my mill, however I did not have the correct banjo or the correct gears to drive the table from the dividing head. Having worked out what I would need I set about 3D printing the gears, designed using a macro in Fusion 360 which made the job easy, there were printed in PLA with thick walls to give them more strength. I "hoped" these would last long enough to do the job, while I could have made these in steel or similar I went for the easiest approach using the tools I have, with the expectation I will probably not use those particular gears again. This shows the setup of the gears.
2-start square thread by Mark Baldry, on Flickr

This is the front view of the setup.
2-start square thread by Mark Baldry, on Flickr

I used the handle on the dividing head to drive it all, there was an awful lot of handle turning, there were 3 cuts per thread, 2 threads on the part, plus 2 taps to make the nut, I did use an electric drill to reverse the head/table when the cutter was clear of the job.

This was a 1/16" cutter, so quite delicate, I did break 2 of them..
2-start square thread by Mark Baldry, on Flickr

The result
2-start square thread by Mark Baldry, on Flickr

Then I had to make the taps, 2 so that it was not a single, long tap.
2-start square thread taps. by Mark Baldry, on Flickr

I cut 3 flutes in the taps, then hardened and tempered them. When I cut the thread in the nut, as there was no relief, I took it slowly, 1 turn then take the tap out to clean it. The tapping was started in the mill to guide it, until I ran out of room as the tap was going to hit the bottom of the vice, at this point I continues using a bench vice. THis worked surprisingly well and the nut fitted straight on!

2-start square nut on thread. by Mark Baldry, on Flickr

[cplmickey]

Great work. I've never been successful with screwcutting on the lathe (just not tried hard enough I suppose) so really nice to see something done so well. Ian

[baldric]

Having prepared to move last year, then there was a covid delay, and a workshop to build, it has been a long time since I have done any work on my Foden. I have now made the steering wheel and fitted it temporarily. It was a flat sheet with a hole, to this I attached the centre bub, then used the mill to leave just the spokes from the flat sheet. The ring was rolled using a small roller.

Forden Steering wheel by Mark Baldry, on Flickr

I am happy with the result!

Forden Steering wheel by Mark Baldry, on Flickr

I will be adding additional support to the steering shaft, this is not on the drawings but is on the full size wagons.

Baldric.

[baldric]

It has been a while since I updated this, but I have been doing some jobs.
I found out that the cross member of the chassis fouls the chain as designed, so I replaced the straight beam with one with a bend in it, I beleive this is far closer to the original than the drawing. There was still a bit more finishing to do when these pictures were taken.
20211030_120727 by Mark Baldry, on Flickr
20211030_120818 by Mark Baldry, on Flickr

The next job I decided to tackle was the water tank, I got a 10mm plate cut, I then attached 10mm ply that I ran a router round to form the curved edge. I decided to use brass for the tank to avoid rust issues, I used CZ106 as it should form easier, even then I did anneal it regularly.
20220521_142813 by Mark Baldry, on Flickr
20220521_155020 by Mark Baldry, on Flickr
Here it is with the sides attached to the two baffles
20220610_112334 by Mark Baldry, on Flickr
To form the rest of the shell, I ordered a long piece of brass cut to width with a view to forming this from one piece to save joins, if I fail to bend it correctly plan B being to do it in several parts. I didn't have a bender available, so a bit of tube, u-channel & 2 bolts did a good job.
20220611_164828 by Mark Baldry, on Flickr
I am happy with the result
20220611_180429 by Mark Baldry, on Flickr
I will need to trim the joint on the top, then solder it in to place.

[noggin]

Nice work, i am watching this with great interest.

[baldric]

I have been doing some work on the Foden, I stalled whilst trying to get gear hobbing to work, I am sure I could have got there, but I wanted to crack on with the Foden, so went down the involute gear cutter route rather than hob the gears.
20230617_093837 by Mark Baldry, on Flickr
Having cut the gears, it was time to make them lighter, I started by drilling lots of holes
20230714_161917 by Mark Baldry, on Flickr
Then joined the holes up
20230714_165949 by Mark Baldry, on Flickr
And more joining, just leaving a few thin webs to cut by hand.
20230714_180618 by Mark Baldry, on Flickr
Here are 5 complete gears, one pair had to be silver-soldered together, another bolted together, the largest there is just under 7" diameter & 95 teeth.
20230722_151426 by Mark Baldry, on Flickr
There is still one to do, that is over 8" in diameter with 111 teeth, I am awaiting the material to make that out of.

I am looking at possibly making the crankshaft next, just got to decide if it will be from solid or fabricated, I want to make it of of EN8 for added strength, so it may be fabricated, a single shaft with the webs & big-ends soldered on, then, shaft cut away between webs & finish machined last to reduce distortion. I am not sure if I will bolt the balance weights to the webs or machine the middle pair of webs & a balance weights from solid, doing that would mean the quartering is fixed by the boring of the holes in one piece.
Baldric.