Tiny Vertical Based On G. Britnell's Design

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chipenter:
Iff the set is the same as mine http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Tap-Die-Sets with a custom tailstock die holder I still need to start on a taper .

sbwhart:
Thanks for all your help chaps

--- Quote from: chipenter on January 11, 2015, 02:46:08 PM ---Iff the set is the same as mine http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Tap-Die-Sets with a custom tailstock die holder I still need to start on a taper .

--- End quote ---

Yes that's the set I have

I remember that I'd passed onto my wife a small pocket microscope I had for here to use in her science classes to look at creepy crawlies, and I asked her of she still had it and she had.

Used it to look at a commercial thread along with one I had cut and they looked the same nice and clean so the problem is not the die, tried the new nuts and they seem to fit better.

On the down side I took deliver of the cheep split die, one look at it and could see loads of burs on the back side and even around the holes for the pinch screws so it doesn't indicate that it had been made with care, Just for a try I ran one of the commercial screws part way down it a took a look under the microscope and it had truncated and torn the thread, so I think its a no no.

I've made the last couple of parts the valve guide and the air feed.

I've assembled everything but I still need to do a fair bit of fettling before I can try it on air to stop things catching and to set the valve events, and I think I will change the design of the piston valve to allow for a larger diameter stem:- I'm not giving up yet.

Stew

vtsteam:
Nice! :thumbup:

sbwhart:
The trouble with the valve stem was that I had made it from 1mm brass rod and it just wasn't up to the job it kept bending, so I remade it from 2mm stainless rod, and with the fabricated piston valve screwed to it.

That seems to have stiffened thing up a lot better, I've got all the bits made now I've turned it over by hand and its not too bad a little bit of fettling her and there is required, but I still have to figure out how to set the timing I have a few ideas about that, this job is all about patience and having an extensive vocabulary of Anglo Saxon swear words.

The screw problem seems to be sorted the new nuts helps a lot.

Stew

sbwhart:
I'd thought I'd give you an update on this little beast.

I've been slowly working on it over the last week fettling this and that:- as you do, I made a new eccentric as I wasn't getting the valve travel I required, to make sure I got the throw correct I used the mill to get the off set in the jig instead of the packing method on the chuck jaw this gave me exactly the 1mm throw I wanted, but I'm only getting about 1.4mm valve travel, the best run I can get out of it is about a 3sec run in one direction only. I think I'm losing the valve travel to play in the linkage, so I'm going to have a look next week to see if I can take some of the play out with new pins a closer fit to the holes.

Stew

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