Member postings for Jim Nic

Yesterday I was boring a couple of holes 45mm deep in brass.

To get around the problem of my boring tool grabbing in the brass I elected to use the fine feed feature of my WM 16 mill, which is a wheel with a straight knurl. This worked well to give me a consistent smooth finish in the bore but my ancient arthritic hands were protesting a bit. To make life a little more comfortable I lashed up a toolmaker's clamp to give me something to get hold of.

Today I made a permanent solution in the form of a tommy bar

to be screwed into the fine feed wheel, or not, as required and give a bit of leverage.

Not an original idea I'm sure but a worthwhile way to spend half an hour.

Jim

That's a good looking "wobbler" Geoff, good work and a good runner too. I like the upside down look like which is a long way from the run of the mill oscillator design that I did for my first engine. Well done.

Jim

After completing my version of Ray Hasbrouck’s No 3 Rocking Valve engine I was at a bit of a loose end because that engine seemed to finish all of a sudden and I hadn’t seriously considered “What next.” I gave a lot of thought to Julius de Waal's drawings of the Monitor engine from Model Engine Maker site. I have never been keen on his drawing layouts, I find them difficult to follow (probably due to my advancing years and retreating brain power), but downloaded them and gave them a good looking at while I spent some time cleaning my workshop and attending to machine maimtenance. I had got to the point of deciding to give it a go when I happened upon a ME forum query regarding Stew Hart’s Over Crank engine. I remembered following Stew’s build 7 or so years ago and thinking it was well beyond me, but that was then and this is now so I messaged Stew to ask for a copy of the drawings and he very kindly sent them to me.

The result:

Somewhere amongst this pile is an Overcrank Engine (I hope). It’s a fairly complicated twin cylinder beast so should keep me occupied for a while. I’ll do my best to do the design justice and may post random thoughts on my progress when anything significant occurs.

Jim

According to my copy of the Model Engineers Handbook EN15 is a plain carbon steel, modern designation 150M36.

Jim

Geoff

I think that model engines at this scale running at representative speeds don't need balancing weights on the crank. However, for appearance sake sometimes they are included.

Here is my Potty Vertical Cross with a balancing extension because the piece of steel I made it from was big enough to do it and the cut off excess would just have ended up in the waste bin.

Jim

Edited By Jim Nic on 30/06/2018 10:56:42

Good work George, well done.

The problem you have now is what to do next!

JIm

Certainly looks good George, do she run yet?

Jim

I use a 2MT mandrel in the centre of the rotary table as per Maurice, albeit with a 10mm rod.

I loosely position the rotary table on the mill table with the rod inserted in the mandrel then tighten it down.

Jim

+1 for a Dremel

Jim

I can thoroughly recommend Stew Hart's version; although it is not a true scale model I believe it is based on a Dunbar original. Stew very kindly sent me his drawings in response to a request via a Personal Message on here.

Jim

"A twirl or two on the rotary table". I really must read up and practice twirling if that's the kind of result possible.

Jim

Geoff

To achieve the distinctly non prototypical polished rim on cast iron flywheels, after machining them to size and painting them, I mount them on a mandrel the same diameter as the crankshaft and chuck them up in a 3 jaw chuck on the lathe. Then it's a matter of turning it at a slowish speed (250 - 300 RPM ) and using a file and then progressively finer grades of abrasive paper until a smooth finish is obtained and finally finishing off on a buffing wheel.

Before I made my buffing wheel I left them on the lathe and used Solvol Autosol automotive metal polish. This is not recommended, being a bit risky in the event the polishing cloth catches in the chuck.

Jim

Edited By Jim Nic on 22/06/2018 14:07:19

Although my latest engine is fairly straightforward it seems to have been taking a long time to get it finished. However, I have now managed to turn this:

and a few other bits into this:

Plus of course a medium size pile of swarf and scrap parts.

It's an Oscillating Rotary Valve engine designed by Ray HasBrouck taken from his book "The Steam Engines of Ray HaSBrouck" and I've done it with a reduced bore and stroke of 15mm by 20mm . It's a lovely little runner as can be seen here: **LINK**

Jim

Nice job Chris, a lovely runner to boot.

Jim

The light blue looks a bit pale for my taste George but plenty of engines were grey so it doesn't look out of place. The finish looks too good to remove and sometimes overthinking something makes the dilemma worse.

Keep it as is, mount the dark flywheel for a good contrast and call it done.

Jim

Edited By Jim Nic on 20/06/2018 20:19:36

I used 3 in 1 oil in my first couple of models and found that it does indeed go gummy after a fairly short time. I ended up stripping a couple of engines that were only a year or so old to get rid of all the residue. I only run my engines on compressed air.

I have no idea what is in the oil to make it gum up, I only know I don't use it now.

Jim

It appears to my old eyes that the drive pulley is made for a flat belt while the governor pulley is made for a round belt. How about remaking the drive pulley with a round groove similar in size to the pulley groove on the governor. If you use the existing drive pulley as a basis you would keep the hole you made to fit the crankshaft and the threaded hole for the grubscrew so it would then be smaller and result in a slower turning governor.

Your Mamod spring belt may then work.

Jim

Nicely done Eric, love the floor.

Another fine advert for Stew's Vertical Cross design.

Jim

A roll pin will be visible, of course. If you never want to get the arbor out then cross drill and use a steel pin Loctited in. A couple of strokes with a fine file and it'll be invisible.

Jim

Thanks for sorting out the link Jason.

The engine was straightforward to make and the valve operation was simple to work out as I could see it through the air inlet. The only puzzle for me was when I came to the first run, it didn't. The air just leaked right through the engine and out of the exhaust. After a bit of head scratching I fixed it by fitting the piston O ring which I had left off for the trial run.

Jim