Member postings for Jim Nic

Dave

I made Stew's Vertical Cross Single which uses the same cylinder and valve chest. I found that I was able to drill and ream the hole for the valve deep enough for it to operate without going all the way through the chest. There is even enough room for the chest to be made a little longer if necessary.

In this way you need not make a plug at all.

Jim

Tricky chaps, those plonkers, they seemed to have got you going big time. I have to confess I have been victim to one in a similar way in the past.

I'm glad all is now well. After all the help and advice you have given me and others over the years I felt a little helpless not being able to offer something constructive on this occasion in return.

Jim

Well done Iain.

It's always nice to see a runner and the feeling of achievement and satisfaction, for me anyway, is always there but never again quite like the first. I would counsel caution in choosing your next project, things that move are several levels above oscillating stationary engines so I would suggest an engine with a valve, maybe if you're feeling ambitious a multi cylinder job, before a loco or a traction engine.

Just my 2 penn'orth, others may suggest otherwise.

Jim

George

You've probably pinned your cross arms by now, but if not - don't. I fixed mine with just Loctite 603 and they've been fine and, just to rub the salt well in, I saved myself the cost of a couple of 1.4mm drills.

On the down side I didn't have an excuse for the vino but then who needs an excuse anyway?

Jim

Popcorn runs!

A first trial of Stew Hart's Popcorn Engine running.  It is a bit tight and leaks air all over the place so needs 20 PSI of air to run but a bit of fettling should reduce that considerably.

It sounds as if there is a knock somewhere but the noise is coming from the exhaust which opens direct to atmosphere from the cylinder block.  Hopefully I can reduce it by adding a pipe with an angled end and reducing the air pressure when it loosens up should also help.

Now on to the governor which looks a bit tricky so should keep me well entertained for a while.

Jim

Edited By Jim Nic on 03/09/2017 12:16:19

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Edited By Jim Nic on 03/09/2017 12:36:19

Hi George

Yes the base is 10mm ali plate with the edge shaped with a ball nose end mill. Eventually it will have the top surface engine turned.

Jim

A bit more (slow) progress on the Stew Hart Popcorn engine. A trial assembly of the eccentric and valve linkage to check it all fits and moves as it should. There is a support for the valve rod to make and fit and then I plan to get it running before turning to the inlet manifold, governor and, most important, the whistle.

Jim

It's a Revell colour SM 350 which is more of a slate/blue colour than it appears in the photos. It has a semi matt finish and I applied it using a cheapish Badger 200 airbrush over rattle can primer.

I find that to my eye semi matte or satin finishes give a more scale like appearance than full gloss. I recently visited the London Museum of Water and Steam and although most of their engines are gloss painted, from a few metres back the gloss reduces to a more semi matt appearance. Having said that, I know Jason uses gloss on a lot of his true scale models and they look fantastic and I did my version of his Jowitt engine in gloss and that looks good too.

Jim

Jason got it in one.

It was done just to be different and I preferred the look with the exhaust piped away. It also gave me more room on the valve chest side to fix the banding for the lagging.

I tend to do things differently from engine designs just to put my own stamp on them and in some cases make the models look a little less "modelly" to my eye. I started this when I built John "Bogstandard" Moore's Paddleduck engine from his build log where he showed what was possible by making 2 very different looking models while keeping the same basic shape and important dimensions.

Jim

Edited By Jim Nic on 23/08/2017 12:50:21

George

You will soon be making the valve rod guide. There are a couple of ways to do this, you could make a 2 piece guide as Stew originally did and either be super accurate or leave the mounting holes loose for wiggleability or fabricate a 1 piece guide as I did. Either way, to help locate the hole in the guide I made a dummy piston valve and shortened operating rod from a piece of silver steel and formed a pointed end on the top of the rod; when hardened this became a centre pop. I assembled the valve chest with the dummy valve and the guide in place and was able accurately to mark the guide from underneath with the pointed rod. (Unfortunately the photo of the dummy rod I had was lost when my computer died a couple of months ago, I now have double backups of everything I've taken since that day. Bolted horses and stable doors spring to mind!)

Hopefully this pearl of wisdom gets to you before you've made the part and helps in some way.

Jim

I recently purchased from e-bay just such a drill which was honestly described as not very good and I got cheaply. I got it because I wanted to do some engine turning for my current project and did not want to get grinding paste on my mill/drill. When I got it home I cleaned it up, adjusted the belt tension and quill guide screw to remove some of the play and put it aside. In the few weeks it's been put aside I have used it regularly for woodwork and other less important jobs to save disturbing set ups on the mill. I've yet to use it for the purpose for which it was bought and it has now been transferred from "aside" in the garage to the corner of the workshop.

Long story short, don't be too hasty to get rid of it and if it really is not wanted put it on e-bay and get yourself the cash for something you do want.

Jim

Hi George

Here I come with advice a bit late again. I am still using carbon impregnated string as a seal medium so I use ordinary twist drills for stuffing boxes and leave the conical seat at the bottom of the hole after tapping and then the flat on the end of the gland follower tends to compress the string on to the shaft. Counterbores or such are not then necessary. Small O rings are the modern method I understand, so a flat bottomed hole will work just fine or just leave the drilled seat.

Jim

A good looking pair of engines Chris with some nice touches in the cylinder banding.

Jim

There is a non flying Defiant at the RAF Museum, Cosford.

I hope that Rik's lathe is better at it's job than the aircraft, which was not at all good and didn't stay in first line use for long before being re-roled as a night fighter.

Jim

Edited By Jim Nic on 12/08/2017 19:35:56

Vertical Cross coming along nicely George.

As I remember Stew's design calls for the piston valve hole to be made all the way through the valve chest and a plug to be inserted to seal the bottom. I found I was able to drill and ream to within a couple of mm of the bottom and the valve still had room to operate and I avoided the need for a plug and the potential for an air (or steam) leak.

Jim

Geoff

I have a set of cheap dies bought when I started model engineering and they are tapered both sides so when I need to get up to a shoulder I take the die to my bench grinder and adjust the profile of the non printed side. Simples.

Jim

Hi George

As I recall I drilled the cylinder and steam chest to drawing and luckily got it right. I do have a DRO on my mill/drill which makes that a better option for me than spotting through and picking up the marks. This part actually allows a little inaccuracy especially if you clad the cylinder

Also I normally make clearance holes a tad big, normally 0.1mm, to give a bit of wriggleability. As Stew Hart (not Hall, he was the giggling fool off "It's a Knockout " from the telly wasn't he?) says "A little bit of clearance never got in the road."

Jim

It says at the top of the write up "Interesting hand made modellers lathe."

I'm guessing the "hand made" refers to the lathe and not the modeller.

Jim

That Otto Langen top plate looks to be a fair old chunk of steel Jason, did it warp at all when you thinned it down?

Jim

They look nice George, pity the bottom one won't be seen.

Jim