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Electric Traction Engine

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JasonB18/09/2019 16:58:12
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They use these type of tracks cut to fit the wheel size and bolted through. The rubber strakes are vulcansied and cut just like tread on a forklift tyre.

Ron Laden18/09/2019 17:05:54
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Thanks Jason, seeing those tracks it makes perfect sense.

Ron Laden18/09/2019 18:30:44
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Going to have a go at grinding a radius form tool in the morning, not done one before so will see how it goes. I need it for the conrod and blending in the tapered rod to the rectangular small and big ends. I think the Minnie rod is produced from flat bar but I,m going with round bar and then mill the flats on the ends. I will use flat bar for the the big end strap but prefer round for the rod, should have material tomorrow.

Ron Laden19/09/2019 08:23:54
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Ground a radius form tool this morning, did it freehand so the rad wont be perfect but its not a million miles away checking it against a 8 mm hole. I,m sure it will be ok for blending in, quite enjoyed making it. I used a 360 diamond card around the cutting edge and there is approx 5 degrees front relief that came from the shape of the wheel so not knowing any different just went with that.

Tried it out on some brass which seemed ok and the conrod is EN1A so it should cope with that...I hope.

p.s. I just wondered with the radius of the work piece falling away from the tools cutting edge, maybe it didnt need any front relief..?

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Edited By Ron Laden on 19/09/2019 08:25:44

Edited By Ron Laden on 19/09/2019 08:44:19

Ron Laden19/09/2019 13:15:06
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Rear wheel rims..?

Obviously I am pinching most of the design from the Minnie but I have also sized some parts from the 1 inch Greenly and Steel model which is similar to the Minnie. At my scale (1.625 inch) the rear wheels come out at 9.75 inch from the Minnie but 9 inch from the Greenly. I was thinking of middle ground at 9.5 inch but having just found some 9 inch seamless steel tube at M-machine I am tempted to go 9 inch. There are a couple of advantages, the tube would fit on the lathe (just) and with a wall thickness of 30mm I could machine the webs so the rim/webs is a one piece part.

I appreciate that it would be quite a lot of machining but I cant see why it couldnt be done. With rims at 2 inches wide cost would be about £30 each which I dont think is too bad.

I will think on it some more.

mal webber19/09/2019 22:31:01
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Hi Ron, just caught up on this build very interesting, I started building a 2inch scale minnie traction engine few years ago now[ still not finished yet ] the rear wheels I rolled out of 4mm plate and welded the t rings in, it's surprising how true you can get the wheel to run if you make your self a good wheel jig when fitting the spokes ,as for rivets lots of practice worked for me before I was happy with the out come.

Mal.

Ron Laden20/09/2019 08:22:36
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Thanks Mal, I am certainly finding it interesting though a traction engine is a big learning curve, well it is for me but Jason and Paul have helped a lot. I think a T/E is probably a great teacher on the machining front especially when you dont have too much experience as there is so much of it to do. I was thinking of a rolled rim and T rings welded in, but having found the 9 inch steel tube I think I am going to give that a go. A fair bit of machining but I wont need the rings or the welding, worth a try anyway.

I have been following your Howitzer thread, you should be proud of it some lovely work and an unusual subject.

Ron

mal webber20/09/2019 09:29:07
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Thanks Ron, looks like you will be making a lot of swarf in the next couple of days be nice to see the finished rims

Mal.

Ron Laden20/09/2019 17:34:45
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I meant to phone M-machine but ran out of time would anyone know how their pricing works. If the material is priced per inch and I order 2.125 inches does the extra 1/8 inch mean I pay for 3 inches or is it based on a per inch price and you pay for the actual length you order if you see what I mean.

Ron

JasonB20/09/2019 18:11:39
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I think it is pro rata so you won't be paying for 3 inches. That may not apply for less than 1" of something though as they would not cover their time cutting it.

Ron Laden21/09/2019 17:50:22
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Crankshaft parts made though not fixed together yet as I need to finalise the shaft length. The webs need cleaning up but it fits together nicely and should run true when assembled.

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Ron Laden21/09/2019 20:25:22
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Posted by JasonB on 20/09/2019 18:11:39:

I think it is pro rata so you won't be paying for 3 inches. That may not apply for less than 1" of something though as they would not cover their time cutting it.

Thanks Jason, thats good to know.

Ron Laden22/09/2019 10:10:02
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Made a start on the conrod, turned and tapered the rod to size though I have only given it a taper of 9mm down to 7.5mm over 90 mm. It needs some more probably 9mm down to 6mm to be a more visible taper, also the radius corners at each end I think would be better larger. I turned the taper by off-setting the tailstock, first time I have tried this and it worked well enough but you may just see a spiral pattern along the taper. Its very shallow and a couple of minutes with emery and its almost gone, would this have come from the flexing of the workpiece away from its normal centre..? Thats what I thought it must be but maybe something else..?

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Edited By Ron Laden on 22/09/2019 10:35:35

Ron Laden22/09/2019 14:30:09
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Added a bit more taper, happy with it now.

Also looking at the Minnie drawings the blended rads at each end are quite small so will leave as is. To the mill next to machine the big and small ends.

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mal webber22/09/2019 14:56:28
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Looking good Ron ,are you going to pin the crank or silver solder it.

Ron Laden22/09/2019 15:14:45
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Hi Mal, I dont have any means of silver soldering at the moment, its something I need to gear up for as its something I would like to learn.

So I am going to assemble it with 638 retainer and then pin it just to be sure, some say there is no need for pins others think it belt and braces and thats my sort of thinking.

Ron

SillyOldDuffer22/09/2019 20:31:48
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Posted by Ron Laden on 22/09/2019 10:10:02:

... it worked well enough but you may just see a spiral pattern along the taper. Its very shallow and a couple of minutes with emery and its almost gone, would this have come from the flexing of the workpiece away from its normal centre..? Thats what I thought it must be but maybe something else..?

...

I blame vibration for this kind of effect. It can be caused as you suggest by the work flexing under the cut as a kind of junior chatter, but can also be the lathe itself vibrating at particular frequencies due to excitation by the gears and motor rattling around rhythmically.

Deadening the lathe by bolting it down on a stiff stand will help, perhaps with rubber padding underneath as well. Loose gibs & worn bearings make the effect more obvious. Conversely, a flimsy stand, not bolting the lathe down, springy wooden floors, an uneven concrete floor, or mounting on wheels all tend to make the effect worse.

It may be worth experimenting to identify if particular settings cause trouble. Put a saucer of water on the lathe bed and bounce a beam of light from a torch off it on to a wall several feet away. Any disturbance of the surface due to vibration will be obvious in the reflection. It may be possible to avoid or minimise the effect by not cutting at certain speeds. Bit like ordering troops to break step whilst marching across a bridge.

Dave

Edited By SillyOldDuffer on 22/09/2019 20:32:20

Paul Kemp23/09/2019 00:14:19
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Ron,

Ont the rivet snaps, beware, some commercial snaps do not have the cup detail that matches the rivet head! I have various snaps from various sources, one pair if you put a round head rivet in the snap does not fit down nicely over the head and if you use it you get a nice round bit in the middle and an ugly flat ring round the edge! Worth checking before you get a mess!

On the tyres there are three major companies and several smaller ones offering vulcanised tyres for traction engines. This is done in one of two main ways, either vulcanising the rubber which is would on as thin strips directly onto the wheel (if not straked) and then chucked in a giant autoclave. The other is to make a "press on band" that fits over the original steel strakes and then vulcanise onto that. If you go either route you have the choice of smooth circumferential rubber or some companies will mould / cut strakes into it. Believe me it's not cheap! I had my 6" wheels done with smooth tyres by a very nice man but it was still over £1k! Some full size rollers have had rubber faces vulcanised on, that goes into the 10's of 000's! The tractor type tyres are colloquially known as quad tracks. Sections are cut from the tracks using a large angle grinder (they have wire running through the core of the rubber!) and then the sections are bolted through the rims. Usually it's easy to spot ones done like this as you can see the bolts. It's a very messy and tough job to do the latter although a lot cheaper!

All the best,

Paul.

Ron Laden23/09/2019 16:56:35
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I had a mishap today whilst shaping the conrod small end on the rotary table, the part moved and the tool dug in. My fault, I found that I had only secured one of the two clamps..blush

I thought the part probably scrap but I set to with the files and shaped it by hand, its the best I could do in an attempt to save it. What do you think, acceptable or bin it and start again ..?

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JasonB23/09/2019 17:04:44
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That'll do. Hardly shows inside the cross head anyway.

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