Author Topic: Tiny Vertical Based On G. Britnell's Design (Read 43885 times)

vtsteam · « **Reply #50 on:** January 10, 2015, 01:04:31 PM »

I'm wondering, Stewart, if the brass-suitable dies have the same reduced cutting angle that we put on drills and lathe tools for brass? And if so wouldn't that make it hard to cut ferrous metal? Dunno, myself.

edit:
Don't know if this applies at all, but I've been digging through my books, and this caught my eye (from 1924 popular Mechanics book on drilling and thread cutting).

greenie · « **Reply #51 on:** January 10, 2015, 03:50:54 PM »

Quote from: sbwhart on January 10, 2015, 08:27:18 AM

Thanks for the tip greenie I've just ordered some off ebay

I must admit I'm having a real problems cutting the M1 thread in these little bolts the first lot I made I made from an old bicycle spoke I had problems with the die ripping the thread the nut only just gets an hold in fact the nuts are dropping off, I've just made some more from stainless steel S303 I was thinking this would be better than the spoke, but again no go, the die I used cut a clean thread on some brass rod but I do have another die that I can try.

I've just got my engineering books out and checked out the major/minor diameters of the nuts and bolts of these little buggers and to be honest there isn't much to play with.

Any suggestions from you guys would be greatly appreciated.

Stew

A possibility with the spoke material and the ripping threads, is the quality of the material - like what grade of steel is the material that the spokes are made from ?

There are two cutting edges on a die as well, one side allows the thread to be formed as a taper, the other side is for cutting up to a shoulder, be careful of which side your trying to cut any hard material with.
Have a real close look at the die your using and check out which side is what. Normally the side that has the brand on it, is the 'starting side', BUT, I have other dies that prove that wrong as well.
It all depends on the maker of the die too, the old theory of - "you only gets what you pays for " - is sure going to rear it's ugly head about now.

As for the die cutting too small a thread, what you need is a split die, with these you can push/jamb a piece of ‘whatever’ into the split and force the die cutting edges apart. This will be a bit of a ‘suck it and see’ until you get it just right. What I used was a bit of brass and filed a long slow taper onto it, then tapped it in to the split on the die, cut a thread and tested it with a home made nut, kept tapping this bit of tapered brass into the split and testing, until the thread was just right.
I have cut thousands of 10 BA, 12 BA and 14 BA threads, using the bronzing rod as the preferred material for making miniature coach bolts, using the appropriately sized dies for many years, it's them little bleedin' skinny taps that cost the money, when they roll of the bench and break as they hit the floor.

Others will have their own 'special tricks dept' for working with stuff that is a bit on the small side, possibly somebody could add some more.

regards greenie

sbwhart · « **Reply #52 on:** January 11, 2015, 03:14:48 AM »

Thanks for your suggestions Chaps

The die I've been using is from a set of small taps and die that are readily available the dies are not of the split type so I guess they are more like a die nut, its hard to tell even with a strong glass what the cutting angle is and on what size of the die gives the correct lead in, but swapping it round is certainly worth trying. In the mean die I've ordered a split die of eaby, I gave myself a freight when I looked up the cost of dies from a UK trade supplier they ranged from £65 to £90 each :- OUCH.

Strangely enough the spoke material turned up nice better than the 303 even, I figured that for its application it would have to be good quality stuff, and spokes are threaded:- so it points to the problem being with the die.

Cheers and thanks again

Stew

Pete W. · « **Reply #53 on:** January 11, 2015, 09:16:28 AM »

Hi there, Stew,

Regarding threaded spokes - if you're talking about bicycle spokes, I believe the threads are rolled rather than cut.

Manxmodder · « **Reply #54 on:** January 11, 2015, 10:36:57 AM »

Hi Stew, you've done some absolutely amazing work on this little engine

On the threading subject I can second what Pete W is suggesting about spoke threads being rolled. They are done that way because the rolled thread is stronger than a cut one.

In amongst a recent haul of tools I was given there are a couple of old spoke thread rollers and various roll dies,though they have all seen better days.

Below I have linked a YouTube video of a spoke being thread rolled on a Cyclo brand rolling device,these small rollers may be really useful for some of you chaps doing miniature threads.

Hope this helps......OZ.

chipenter · « **Reply #55 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 .

sbwhart · « **Reply #56 on:** January 14, 2015, 11:31:47 AM »

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 .

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 · « **Reply #57 on:** January 14, 2015, 12:52:20 PM »

Nice!

sbwhart · « **Reply #58 on:** January 16, 2015, 08:04:11 AM »

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 · « **Reply #59 on:** January 24, 2015, 11:10:22 AM »

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

Stilldrillin · « **Reply #60 on:** January 24, 2015, 03:19:57 PM »

Stew.

Sounds like your little bit of clearances, are getting in the road........

Good luck, with the tightening process!

David D

sbwhart · « **Reply #61 on:** January 25, 2015, 03:24:22 AM »

Yes its a case of too much clearance getting in the way.

I think I failed to appreciate the small size effect on clearance:- 0.1mm clearance on a 10mm shaft is 1% but 0.1mm clearance on a 1mm shaft is 10% magnify that by each bit of linkage and you lose a lot of movement.

Still it keeps the old grey cells working.

I've just got to get a bit more precision into the job

Stew

Stilldrillin · « **Reply #62 on:** January 25, 2015, 04:14:10 AM »

Quote from: sbwhart on January 25, 2015, 03:24:22 AM

I've just got to get a bit more precision into the job

Nah!

Just remod, the modded cam. To give 1.5mm throw.........

David D

sbwhart · « **Reply #63 on:** January 25, 2015, 07:49:35 AM »

Quote from: Stilldrillin on January 25, 2015, 04:14:10 AM

Quote from: sbwhart on January 25, 2015, 03:24:22 AM
I've just got to get a bit more precision into the job

Nah!

Just remod, the modded cam. To give 1.5mm throw.........

David D

That's Plan B and eccentric eccentric

HE HE HE don't need plan B

Made some closer fitting pins and took out a fouling point on the linkage.

That's got it sorted, you need to keep your finger on the handle but I can sort that and it runs in both direction.

I'm a little chuffed at that

Stew

RussellT · « **Reply #64 on:** January 25, 2015, 07:58:35 AM »

Tht's nice.

Russell

Stilldrillin · « **Reply #65 on:** January 25, 2015, 08:20:43 AM »

WOW!!

That's a little cracker, Stew!

Blummin, well done!

David D

vtsteam · « **Reply #66 on:** January 25, 2015, 10:01:00 AM »

Wonderful work!

mexican jon · « **Reply #67 on:** January 25, 2015, 10:17:20 AM »

Brilliant

Well done that man

modeldozer · « **Reply #68 on:** January 25, 2015, 05:56:59 PM »

Well done.

Abraham

sbwhart · « **Reply #69 on:** January 29, 2015, 11:33:58 AM »

Thanks for your interest and comments lads

I've been doing a fair bit of tinkering with it this last week as I wasn't getting a consistent running out of it, I tweak this and that, then I thought I wonder if it will run without the valve guide as its not really doing anything and it was tightening things up so I took it off and wow what a change. What with all my tinkering I'd broken off some of the M1 screws in the valve chest :cussing: so I decided to make a new one with no provision for the guide and with a M2.5 inlet port instead of the flange inlet arrangement I was using.

So heir's a video of the improved run, I didn't check the RPM as the battery on my taco was flat, I'll check that tomorrow and get back to you on its speed.

Now that I'm happy with how it runs:- I'm going to add a bit of Glam.

For this I've made a tiny stop valve that I will plumb into the wooden base.

Stew

Stilldrillin · « **Reply #70 on:** January 29, 2015, 12:12:24 PM »

So you should be. "Pleased with that".......

Well done, Stew!

David D

vtsteam · « **Reply #71 on:** January 29, 2015, 06:51:20 PM »

Sounds wonderful, and that valve is amazing!

S. Heslop · « **Reply #72 on:** January 29, 2015, 08:37:12 PM »

I've been watching this thread and i've been holding off just saying something like 'brilliant!', hoping i'll think of something better to say that'll do it justice. But i've been literally speechless the whole time.

So I guess i'll have to settle with just a 'brilliant!'. It's a really amazing little engine.

Manxmodder · « **Reply #73 on:** January 29, 2015, 08:58:56 PM »

Hey Stew,that is a really neat miniature engine

Just one thing bothering me is that Jack fella,he seems to be your typical middle management grade.

Appears for the photos at the start of the project,then delegates responsibility to his underling only to then show up when it's time for the credits to be awarded.

I advise Liz to knock his block off with her wrench

.....OZ.

steampunkpete · « **Reply #74 on:** January 30, 2015, 02:56:43 AM »

A work of art. A stunning exhibition of talent.

All you have to do now is to try and avoid losing it because it's so small!

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Author Topic: Tiny Vertical Based On G. Britnell's Design (Read 43885 times)