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Electric Traction Engine

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Ron Laden01/10/2019 17:19:31
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Posted by JasonB on 01/10/2019 16:17:20:

You only need a very shallow CSK infact just deburring the holes will do. Then cut the rivits so they will be just about flush with the inner face and all you need do is ctr punch them which will expand them enough to hold. Dab of Loctite won't do any harm.

If you start trying to pein then over to fill a CSK then you will end up with a distorted plate.

You could reduce the number of stays by at least 1/3rd and then it is not such a job to reduce the rivirt heads in teh lathe to make them look like stays

Thanks Jason, great advice as always.

I was only going to go with a shallow csk but never thought about distorting the plate which I can see now. The ctr punch method sounds quick and easy so thats good. Also reducing the number of stay rivets is good news as I did wonder if I had too many and seeing your picture above I can probably reduce by half.

Thanks again.

Ron Laden02/10/2019 13:59:08
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Just ordered a 3.5 inch square piece of ali for the cylinder block, I am going to try and machine it in one on the mill using the rotary table. I think it can be done or at least I hope so, I have worked out a plan of attack but we will see.

Also I have been searching the Minnie drawings for the pin which connects the crosshead to the conrod but of course there isnt a drawing. The pin is described in the build though as a piece of hardened silver steel which runs in the conrod with no bearing. I am going to turn up a thin walled bronze bearing as Jason suggested to me and fit that to the conrod. I have also been thinking about the crosshead guide which on the Minnie are the pair of parallel bars but I do like the idea of the cylindrical guide I have seen on other engines. The ones I have seen have been from castings but I wouldnt imagine too difficult to produce from round bar, dont know yet, undecided.

Ron Laden03/10/2019 08:00:04
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Another of my basic working sketches showing the cylinder at actual size, I have indicated the 3.5" block it will come from.

I have drawn the bore at the size it would be with a piston and liner but of course there is no piston so it will come down to 12mm dia. I am going to extend the cylinder cover into the bore to offer a bit more support for the piston rod, probably by about 5 mm that will make the cover 20mm deep overall, the piston rod is 6.5mm dia.

Thats the plan anyway.

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Ron Laden04/10/2019 16:08:48
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I came across a picture of a Wallis and Steevens roller, what an odd looking engine with the boiler slanting steeply down towards the rear. At first glance it looks as if the boiler is broken into two and collapsed, certainly different though from a modelling point of view, I cant imagine there are too many of those around.

Ron Laden05/10/2019 16:50:14
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Should have the alu block for the cylinder Monday and not having milled an outside radius before thought a bit of practice could be useful. The length of the cylinder block will be 60mm but I only had a piece of 30mm but ok for practice. I was thinking of cutting the rad with the side of an end mill but at 60mm and even with a long series cutter I would still need to turn it over and cut it from both ends.

I then remembered from one of Jasons build threads him cutting a radius with a series of facets and finishing by hand, that seemed a good idea so gave it a try. I worked around the rad in 3 degree increments and must admit it wont need too much work with the file for a good finish (thanks Jason). I did machine away the bulk in advance so it wasnt too many cuts for the rad, really enjoyed doing it.

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Edited By Ron Laden on 05/10/2019 16:55:04

Ron Laden06/10/2019 08:58:42
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Finished the test rad with a medium and fine file followed with an emery wrapped file. I thought a couple of light coats of paint would show up the finish and shape, quite pleased with it, if I can copy that on the cylinder I will be happy. .

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JasonB06/10/2019 09:59:54
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Looks good Ron.

Ron Laden06/10/2019 10:33:29
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Thanks Jason, as I mentioned it was seeing the method of cutting facets around the rad which was in one of your threads that got me there. In another set up I did, I,ve got my boring head adjusted for the boiler rad in the bottom of the cylinder, did a test piece and its a nice close fit.

Ron Laden06/10/2019 10:50:51
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I know I really should set out my stall and start building the engine from the ground up, its just that I keep finding parts that take my fancy or look interesting to make. It all needs to be made at the end of the day though, well thats my excuse anyway.

mal webber06/10/2019 14:29:02
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Looking good Ron, think I started my 2inch minnie build with the conrod ,as long as you got a plan it will all fit together did find that the wheels did suck up a awful lot of time though but worth it when you sit back and look at what you have achieved .

Mal.

Ron Laden08/10/2019 12:37:06
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I am wondering if cast iron would be ok for the cylinder rear cover, I know CI is a good bearing material but would it be ok in this application. Having no piston I am extending the cover into the cylinder to offer more support to the piston rod, it will be running in a bearing length of 22 mm plus the piston gland.

Its just that I have the CI on the shelf but if it would be better to go with bronze I will have to get some in.

Paul Kemp08/10/2019 21:48:59
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Ron,

In your case you can make the gland the bearing, just make it long necked with a step and fit it in the cover. Cover can be anything then, ally of you want! The gland isn't going to have to do much sealing after all with no piston on the rod.

Paul.

JasonB09/10/2019 06:56:30
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Or you could do as Fowlers did and put a neck bush into the hole in the cover, a dummy gland solidly fitted would have a similar effect.

neck bush.jpg

Ron Laden09/10/2019 08:12:54
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Thanks Paul/Jason I will look at doing something on those lines.

Ron

Ron Laden09/10/2019 10:58:59
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1708 forum posts
309 photos

The largest lump I have had on the little mill so far, even had to remove the vice jaws to fit it in. Hopefully a one piece cylinder will come out of it. First job reduced the height by 15 mm with the flycutter, faster than back and forth with an endmill. I do most of my fly cutting now with an insert tool robbed from the lathe, works really well. The radius is 45mm which is about as much as I would want to go but it worked, dont think I would go that large with steel, well not in one pass. The slight tool out of balance vibration disappeared above 1500 rpm so I ran at 1750 with 0.030" cuts which sailed through it. I dont have any GT inserts, maybe I should get some and use those for ali.

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Ron Laden10/10/2019 08:42:55
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Dont think I will need the rotary table just working around the radius by eye, should blend in with a file ok.

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Edited By Ron Laden on 10/10/2019 08:55:14

Ron Laden11/10/2019 17:42:00
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Jason, I looked at the R C Machines link you posted on another thread. In their "flying" wheels range they do a partly machined 6 inch wheel for 29 euros, looks really good to I cant buy a C/I blank for that price.

Edited By Ron Laden on 11/10/2019 17:42:19

Edited By Ron Laden on 11/10/2019 17:43:35

JasonB11/10/2019 17:47:55
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I can, but they are a lot less work.

Ron Laden12/10/2019 10:28:19
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I have probably taken the long and winding road approach to making it but its worked out so far and its getting there slowly.

p.s. The notch along the length of the left hand saddle is still outside the rad (just) so should be ok when it comes to hand finishing...smiley

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Edited By Ron Laden on 12/10/2019 10:33:40

Ron Laden14/10/2019 08:27:26
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Just about there with the one piece cylinder block from bar stock, a couple of angles to mill on the left hand edge of the saddle and then hand finishing. I am glad I had a go at doing this, a few lessons learnt I think and if I had to do another one there are areas which I would do differently. I will be away tomorrow for 3 days so wont get back to the shop until Friday when it will be a case of getting the files out.

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