Member postings for David Fox 3

Last year I decided to make the Simplex 5 inch gauge tank engine. It was described as a beginners locomotive. Now I have been on a very steep learning curve and have produced a very high quantity of swarf and various paperweights which now stand on the sill in the shed! BUT I am learning and slowly progressing in my task. But certain items are, I'm sure, there to defeat me. One is the axle pump. Now the pump itself although it holds a few large challenges is not the problem but the outlet tee is. It seems to combine the top of the outlet valve the two outlets and nut to tighten it down all in one piece. How are you supposed to machine an item like that and when tightened down it points in the right direction? Is it supposed to be silver soldered from more than one piece of brass or what?

In the book of words for Simplex - although I'm trying to build the later alternative pump - there are no construction details whatsoever! Beginners?

Hoping for a positive response

Dave F

Thanks. It's too late to change the order of machining, and next time I will do as suggested, but the suggestion of tailstock support though is certainly worth doing. Thanks.

Well I've been busy in the workshop and I think - surprisingly - that it WAS the reamer as it seems that if I re bore the wheel it is again all ok. I mounted the wheel on the faceplate (thanks Duncan) centred as accurately as possible then skimmed the bore until a continual cutting noise was heard from the boring tool then one more fine cut passed through twice. I then used the old mandrel. There was sufficient mandrel stock left to remachine to the new diameter thankfully. Now all I have to do is machine the other wheels to the same size as the mandrel. So I'm using Bobs suggestion here.

I still think it is a bit of a mystery, as each wheel was so similar, but why a four jaw rather than a self centring three jaw? Well the simplex wheels are just over the maximum capacity for that while the four jaw was ok - just.

I was conscious of the dirty taper potential but did clean with cloth and finger!?!

Thank you one and all for all your suggestions and I hope I can finish these wheels without any more fuss.

Great thoughts. Will report back in a couple of hours when I've been in the workshop. I did use an insert tip but. Cut slightly further and use its side face to give a slight inner taper on the mandrels side thus avoiding that small radius if you get my thoughts!!

Thanks. I think this will have to be the way forward!

Thanks it certainly seems to have released some stresses. But mine have gone through the roof. Bizarre!

That's what I would have thought but surely if that were the case the rear face of the wheel would be slightly off or am I making assumptions here?

Hand held. But all the wheels are exactly the same.

The six wheel on the Simplex shouldn't be too difficult surely? I am fairly new to model engineering but thought this should not throw up any great problems. I mounted each of the castings on a 4 jaw independent chuck and faced the back of each. Then whilst still in the chuck centre drilled then drilled through with a 1/2inch drill. Then bored it out to just under 11/16" and finished off each with a 11/16" hand reamer.

I had bought a 3mt soft end 40mm x 40mm arbour which I turned down 15mm of which to be a tight fit on the newly bored and reamed wheels leaving a shoulder to support the back of each wheel. I then tapped an M8 thread in the end of the arbor so a bolt could then hold each wheel firmly in place.

On trying the wheels on the arbor they fitted perfectly sliding on tightly with a little friction but on running the lathe the rim of each wheel moves from side to side by about 2mm when firmly against the shoulder! WHY? What have I done wrong?

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The lathe is a Seig SC4 about 8 years old but not at all heavily used. The wheels cast iron and the 3 mt stub bought recently from the midlands model engineering exhibition.

Any help gratefully received!

Dave F

Edited By JasonB on 28/10/2017 08:19:03