Member postings for Stewart Hart

From time to time I delve into the black art of making injectors, I've been quite successful in making the 24oz size but struggled with the smaller sizes mainly due to the difficulty with drilling the small holes, my lathe just hasn't got the speed. What I need is a high speed drilling attachment, I've been pondering this problem for some time had a couple of ideas that I've rejected:- finally I came up with this:-

What the hells that I can hear you saying well it started life as this.

A 24V high speed motor with chuck that I found on the internet (5mm output shaft) a M3 morse taper threaded 1/2" UNF and a 2 1/4" dia chunk of ally.

Cut a slice of ally off and machine up the end cap,

Now its important that everything lines up with the centre of the lathe. The motor is screwed to the end cap, so the end cap must run true with the motor shaft.

Make a temporary female centre.

Grip one end of the shaft in a chuck that you know runs true and suport the other end with the feamle centre and skim up the register dia and face of the end cap.

Clock the body up true and drill bore and tap to take the M3 morse taper abour.

Don't fix it in permanent yet

Flip it round clock it up again and rough out the bore.

Drill a few holes for cooling and wiring.

Now fix it to the Morse arbour, my lathe is M3 in the head stock so mount the assy in the head stock, and face and finish the bore to give a nice fit to the cap.

Check that everything lines up.

Proof of the pudding.

It took me just over two days to make it it seems to work OK I'll post a video over the weekend of it working

Stew

Edited By Stewart Hart on 29/01/2020 15:22:27

Just to add a bit more interest to the thread, when drilling thin sheet with a normal drill you can run into trouble with a ragged hole or even worse.

I was shown this little trick when I was an apprentice, grind a drill up with a little teat and a slightly undercut flat, this way the teat acts as a pilot and the under cut means that only the edge of the drill cuts, it cuts out a washer out and you end up with a nice clean hole.

Stew

I had the same thought Bryan it does look like a pair of Y fronts

Thanks for your interest gents and comments

Lets see some veggie based blowers

Stew

Why do they call steam raising blowers when they suck ?. 

On with the mater in hand, I've tired various blowers and I found the best to be the ones made from 24V ex-military radio cooling vans you could get these quite cheep at one time but with scarcity they are getting expensive. And as is my natural curiosity I've stripped a fair number of blowers down. Then when making myself a lunchtime Tuna sandwich I looked at the empty tin and had the idea of making a blower out of it, I took the empty tin with us when we next went to the supper market looking for a suitable tin to make the inner fan out of to me delight I found that the smaller tins of Tuna they sell would just fit the bill. 24V electric motors are easy to obtain of the net.

A few manufacturing shot

Material

Drilling the base of the fan the vanes were put in with a wood chisel whilst the inside was supported by a lump of wood.

The gap for the exhoust vent

The exhaust with its paper pattern

Soldering the exhaust

Machining the top and bottom plates these were made from 100mm dia ally blanks bought of the net.

Completed blower

And yes it does work I recon at that size it would be fine for smaller 5" gauge and 3 1/2, 2 1/2 locos

If you need a bigger blower you'd just have to find some bigger cans.

Stew

Edited By Stewart Hart on 22/01/2020 13:54:23

Hi artful

Thanks for your interest in my helping dad mill engine there have been a lot built I hope you enjoy the build if you need the drawings just send me a pm with your email address

Stew

Well I guess its time for a progress update:- I've spent the last 12 months building the tender its now more or less complete just a little bit of tidying up required.

I'll crack on with finishing off the loco next year.

Stew

Thanks for your endorsement Dave. If anyone wants a set of drawings just send me a PM with your email address

Stew

Thanks for the tip John I have two on order

Stew

Thanks Brian I forgot about them they do good stuff so two ordered via number one son as Christmas/birthday presents

Stew

Hi can anyone point me to a supplier of clutch type lubricators, I've tried all the usual suppliers:; Blackgates, MaccModels, Polly and they only do the ratchet type although they will supply the clutches to fit in your own lubricators, but I want to short cut the process and by a finished lubricator.

Stew

Hi Jim

Thanks for your interest in my grasshopper engine design unfortunately despite encouraging noises from editing team I don’t think it will be published in the near future you could try giving the Ed a gentle push

Stew

Yes I made a 100mm one this makes the calculation easy my version is different in that it has a swivel base, this also makes it easy to set up. I submitted an article to ME workshop but as yet its not been published if any one would like a set of drawings just PM me.

Stew

I’ll ask tomorrow Dek if it’s ok I can give you a lift

Stew

South Cheshire Model Engineering Society will be holding its annual Gala on Saturday 7th Sept 11:00am - 4:00pm Steam Train Rides, Exhibition of model Refreshments. www.southcheshiremes.com

Thanks for your valuable input again Juilian

When I attempted to make a 12oz injector I wondered about the need for the 6 deg reamer for the delivery cone at some point in the future I'll have another go at making a 12 oz. For my first attempt I used the 24 oz basic cone sizes one of the difficulties with this was the hole depths its bad enough drilling a No 70 hole but when your trying to drill it nearly 1/2" deep is a bit tacking. Especially with dodgy quality drills I got some of flea bay supposedly German Manufacture of a make I'd not heard of 50% were next to useless with the point not ground correctly or not at all. When I worked for a living we use to swear by Titex small drills but these are eye watering expensive unless I can drop on a good supply of cheaper drill I'm going to have to bite the bullet and buy some.

For my next 12oz attempt I'm going to reduce the length of the cones to give myself a fighting chance of drilling the holes.

I would agree with Julian and Nigel its not a Black Art its just a matter of gaining an understanding of how they work and how to make them (I have a good coach) and this only comes with having a go, being patient and persistent learning by your mistakes and not giving up and taking the easy rout and resorting to cheque book engineering and buying one.

As an aside I've just tested the second vertical injector to my own design, and it worked though we did have to reseat the ball to get it to work. The test boiler is electrically heated so when we got it to 90psi we turned the electric off started the injector and watched the pressure drop as it put water into the boiler:- when it got to about 55 psi it started to splutter (stop and start) but it didn't stop completely until it got to 45 psi.

The design for this vertical injector is very much in the development stage I want to try refine it further.

Stew

I'm pleased you like my grinder set up Nigel.

I have covered the slide ways some time back, I used the lorry curtain side material its ideal for the job.

I've only ever used it for cutter grinding but yes it would be possible to adapt it for surface/cylindrical grinding but just how accurate it would be would be the ?.

The injectors I make have quite a large delivery rate about 24oz. I run my simplex with one of them along with the axle pump the axle pump does the job of a small injector. I'm planning on using two injectors on the Crab I'm building along the lines of Dags suggestion one large one small. I've tried making a 12oz delivery injector using the sizes from Dags book but failed miserably.

I think I failed on a number of accounts, I was far from happy with the reduced size turned D bits, and I used the body and basic cone sizes as for the 24oz injectors and just changed the hole sizes. At some point in the future I will have another go with ground D bits with a smaller body and cones.

Cheers

Stew

Sorry if I gave the wrong impression. But I had a few frustrating days trying to get a lbsc injector working it was only when a friend pointed me in the right direction and gave me some coaching on the subtleties involved did I have some success, there are a number of not obvious features that are critical to function and the only place I’ve seen them dealt with is in Dags book

Stew

If your going to try and make an LBSC injector "good luck", I've no doubts that his worked but many have tried and many failed the trouble is that LBSC doesn't tell you exactly how to make them he has had many rants at people who couldn't make them:- all he said if you make them EXACTLY to the drawing and they will work but he doesn't say how to achieve this. Also he published quite a few different design that suggests that he was doing quite a bit of development work.

Can I suggest that you get a copy of Dag Browns Book "Miniature Injectors Inside and Out" its very comprehensive and is a good starting point for any one wanting to make there own injectors, but I find some of Dags, methods long winded and the bodies of his injectors are far to complicated there are other simpler designs around.

These are mine

and a vertical one

Stew

Thanks for your interest Harry

Here are some more pictures of the set up.

The grinder it self was quite easy to put together Its just a Myford vertical slide with an ordinary bench grinder mounted on it you have to remove the base of the grinder and do a little rewiring to mount it securely and a X,Y table mine came from axminster but there are plenty of other suppliers of these tables out there. and it all mounted on a bit of ally plate but a friend made one and mounted his on a kitchen work top off cut.

As well as the end mill grinding jig I've also made jig for sharpening slitling saw and lathe tools.

Its far easier to put together than a Quorn cutter grinder or one of the other home built cutter grinders designs around.

Stew

Its usual to make Injector D bits from silver steel by machining the taper on the lathe then sectioning with a file or mill then to heat treat, whilst this method can produce a perfectly functional D bit there are a number of draw backs:- you need a razor sharp turning tool to machine the taper to avoid distortion like wise when it comes to sectioning and heat treating can be a bit hit and miss.

This got me to wondering if it was possible to make some D bits from High Speed Tool Steel in a home workshop.

The starting point was to buy some 5mm Dia HSS tool blanks these were 4" long so I cut them in half then using the hand drill I roughed them out on the bench grinder.

I have a "home Brew" cutter grinder that I put together using commercially avaiable parts:- Grinder, an X,Y Table and a Myford vertical Milling attachment

The first job was to dress the wheel up square to the table, using a diamond.

I have a home made grinding attachment that uses a Er32 collet and an index plate for sharpening end mills by taking the pin out of the index plate I could rotate it by hand. The attachment was set over at the required angle

And the D bit ground to the required angle

To section the bits I first roughed them out on the bench grinder then with a grinding point in the mill set a max speed the Bits were sectioned off to size

I've just used them to make some injector cones and they cut far better than the silver steel bits and it looks like they are keeping their edge well.

Stew

Edited By Stewart Hart on 15/06/2019 10:04:07