5G Leaf Springs

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5G Leaf Springs

This topic has 10 replies, 5 voices, and was last updated 2 May 2023 at 17:40 by Roy Birch.

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30 April 2023 at 22:11 #643309
Roy Birch
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@roybirch29994
Hello All

I am trying to make the Spring Link below, Can anyone tell me if this is suitable to be fabricated rather than filed from solid, I would like to turn the body for the pin from 5/16 and drill 5/32 for the pin hole and then mill a 1/8 slot into the round body and silver solder the tab into this after first forming the shape of the tab and drilling. I do have a very good jewellers oxy/Acetylene torch that fits my bottles and has a needle point flame. Is soldering strong enough for this component?
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30 April 2023 at 22:11 #2196
Roy Birch
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@roybirch29994
30 April 2023 at 22:43 #643318
Nigel Graham 2
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@nigelgraham2
I suspect it would be easier to make it from solid. Properly silver-soldered it may well be strong enough but not a very easy fabrication. Either way I would form the radius afterwards, using filing-buttons.

It might be feasible to fabricate it as a "stick", sliced afterwards then drilled, reamed and radiused. The designer does specify reaming the holes, presumably for a good reason, but this should be done after any hot work.

If from solid, can you mill the sides of the body round, rather like the end of a connecting-rod? If so I would be inclined to form each one on the end of a length of bar held in the rotary-table chuck, drill reaming diameter to about 5/8" or so depth while the body is still on centre; mill the two tab flanks, then cut it off the stock, drill the second hole and ream both, finally file the tab to shape and face the cut end.

Do that final shaping last so you've still a reasonable amount of steel to hold and measure from, for the tab drilling and reaming.
1 May 2023 at 09:29 #643343
Nicholas Farr
Participant
@nicholasfarr14254
Hi Roy, you could mill a keyway about 1/16" deep at the most, and 1/8" wide into a piece of round, and then silver solder a piece of flat into it. But it might be a bit fiddly to get the piece of flat in line with the centre of the piece of round and holding it there while silver soldering, but I think it could be done.

Regards Nick.
1 May 2023 at 10:20 #643355
Roy Birch
Participant
@roybirch29994
Many thanks for the replies, the ones that have alrady been made by a previous builder are too short between the hole in the tab and the hole in the shaft and were not pleasing to the eye, they were also too short from the base to the top of the tab, I made some buttons to re profile the round shaft and got them to size and only then realised the other errors, would this be better if I just turned the shaft and soldered the tabs in unprofiled as a square and over length? that said it may be easier to just cut pieces from bar and do all the drilling and reaming whilst it is still a rectangle, I think the problem is that the previous builder made the shapes first and then decided to drill and got that part wrong.

Kind Regards

Roy

Edited By Roy Birch on 01/05/2023 10:32:41
1 May 2023 at 12:49 #643367
Martin Johnson 1
Participant
@martinjohnson1
Whether you go for solid or soldered, they will be easier to handle as a strip of 6 plus sawing allowance plus a spare or two.

I would go for solid. Set raw stock up in rotary table (spindle horizontal) two endmill passes to get the flat feature, then several passes with table rotated to form the round feature.

Martin

Edited By Martin Johnson 1 on 01/05/2023 12:51:41
2 May 2023 at 12:07 #643577
Roy Birch
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@roybirch29994
So I was a bit unhappy about the overall look of the axleboxes and the spring links that had already been completed, you guys who are seasoned model engineers know when something just does not look right, the lugs on the axleboxes were too thick and the tops had been very roughly filed as were the completed spring links, not a filing button in sight was evedent on the .156radius, the axleboxes were all steel solid bored 1" to take needle bearings which were installed. I decided to take all 6 out and put them on a surface plate and square them up to see if the axles lined up, they did not and the boxes were all different heights, the holes for the spring pins were in different places and different sizes all above the .156 reamed that they should be. I think it is now time to make new axleboxes, I don't know why someone has decided to make solid boxes out of steel with needle bearings, it is not called for or shown on the drawings, I assume it knocks out the need for lubrication but does anyone know if there are any advantages to the needle bearing setup or any disadvantages?

Kind Regards

Roy
2 May 2023 at 13:38 #643595
Nigel Graham 2
Participant
@nigelgraham2
I believe some model locomotives have been built with needle-bearing axleboxes, as long as they compromise neither function nor visible appearance; but they still need lubricating (e.g. with grease on assembly) and protecting from dirt. Their disadvantage is that replacing such a bearing entails pulling the wheel from the axle, not a good idea.

The real problem though in that area is as you describe – badly-made parts, and to the extent of needing replacing. So I would advocate making them as they should be, with split bronze liners in split boxes. Note that phosphor-bronze is not recommended with mild-steel shafts though.

One way to consider for making those links, as a stick, is to mount the stock between chuck on a dividing-head or rotary-table and its tailstock, and mill along the length with a small end-mill. Cut the lug part first, as if it is a spline. It will leave little facets on the round part, but these can be blended by careful filing.

While the chassis is apart, verify the spacing and squareness of the horn guide faces to each other and to the frame. If the axle-boxes are all irregular, I'd not trust the frame and horn-plates too much either!
2 May 2023 at 15:11 #643613
Roy Birch
Participant
@roybirch29994
The frames and horn side are square, I checked that very early on, to be fair this loco looks like 2 different builders were in play, I will go back to the split axleboxes now though as that is what the drawings indicate for both leaf springs and coil springs and it does make more sense especially if they have to come apart at some point, I think I will get the boiler tested now as well.

Kind Regards

Roy
2 May 2023 at 17:34 #643637
Buffer
Participant
@buffer
Just solder the bits together they will be fine. I didn't bother making slots I scalloped the edge of the flat bit where it joins by just running an end mill down the length of it. This made it a very nice fit to the bar and also located it in the centre of the bar.
2 May 2023 at 17:40 #643640
Roy Birch
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@roybirch29994
They look excellent, I will give it a try.

Kind Regards

Roy
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