Member postings for Andrew Johnston

I think I see where the confusion has arisen. The order of the sides is LRRL, but are shown two inside and two outside, as Nick says.

The sides follow the full-size engines, except for the one in the Burrell museum which has the driver cutout and brake on the other side to all the other engines for which I have pictures.

Andrew

Further exposition will have to wait until the new, improved, website is in operation. But here is a taster of progress to date; the lefthand side:

And righthand side:

The steps and water pocket were made over a year ago to my own design, based on the full-size engines. I don't think I posted any details here at the time. I am happy to do so if people are interested.

Andrew

I'm not sure I understand the question?

I am building two engines, hence four sides in total. The right and left hand sides are different. The RH side has the rectangular cutout for the water pocket. The LH side has the bigger cutout at the top so the driver can get into position without damaging himself.

Andrew

Thanks to one and all for the kind words; it does help.

Skinpins are still available. I bought mine online from the manufacturer:

Skinpins

The online ordering process was simple, just how it should be, but often isn't. I bought 20 for £35 including VAT and delivery.

Andrew

No, it's more subtle than that. The learning in a steep curve may be conceptually easy, but there is an awful lot of it before one can do anything at all.

Andrew

Not directly, but I have designed the LP valve on my compound traction engine so that it uses a simple flat leaf spring to keep the valve in contact with the valve face. The design is based on the full size valve.

Andrew

Edited By Andrew Johnston on 03/10/2023 21:31:19

I take a steep learning curve to mean that an awful lot has to be learnt before anything, even simple things, can be done.

Andrew

The first task on the tender sides after flanging was to add the angles on the inside that will form part of the frame for the water tank:

The rivets are 1/8" diameter steel. The inner side will never be seen so a whack with a hammer to close the rivet is all that is required. The rivet dolly, setting tool and "bolster" are home made from hardened and tempered silver steel. The items with yellow bottoms are skinpins. They are normally used in aircraft sheet metalwork for holding sheets in place while they are being riveted onto frames. Yellow denotes a skinpin suitable for 1/8" rivets. To start with rivets were placed at each end and at several places in the middle. The gaps were then filled in. This avoids cumulative issues with the pre-drilled holes failing to line up as the metal stretches very slightly when a rivet is closed.

Once the angles are fitted the two sides can be held apart ready for the bottom/back sheet to be riveted in place.

The spacer bars are machined to an accurate, 1 thou or so, length of 9.5" which is the outside spacing of the hornplates that the tender needs to fit over.

Andrew

NB: An alternative to skinpins are Clecos, which are fitted using special pliers to compress them for insertion and then released. I have some Clecos, but no pliers, so I decided to stick with the manual skinpins. I had a few in stock but was able to buy more online as mine are old and not in the best of shape.

Personally I'd use a broach and arbor press. But I have cut a 1/8" wide keyway, in steel, in a 1/2" diameter hole over a length of 1-3/4" by slotting:

I used a slotting head on the Bridgeport but that is no different to using the saddle on a lathe, just a bit quicker. The trick is to add top rake to the toolbit so that it doesn't push outwards and ideally has a slight tendency to pull in.

Andrew

You were right and I was wrong!

Andrew

Yes they are the ones you are holding. They fit in the headstock same as the normal workholding collets. They are intended to hold short, larger diameter, work for second operations. They were available up to 1-3/4" according to my manual. I've never seen one until now, so I suspect they are quite rare and were probably made to order.

To second Baz the mechanical high/low lever is very stiff. Mine needs a good shove but there is a positive stop when it is fully home. In reality I never use it. The electrically selected slow speed is fine for power tapping and using the Coventry diehead.

Andrew

Good to see you here; and I am still grateful for the advice you gave me when I first got my Britan.

Andrew

Looks to be fair range of collets, including hex, although I can't see any square ones? Also a good selection of smaller collets for the tailstock and even smaller collets for the indexing tailstock. There are even a few oversize 2nd operation collets; never seen one of those in the flesh.

I spy a spring loaded backstop, which I find very useful. There's a good selection of toolholders, a couple for parting blades and one for boring.

There is what looks like a die holder but the body doesn't look like the ones I have with dog clutches? Are there any similar units for taps?

Andrew

I stopped posting about progress on my traction engines on here some time ago. However, yesterday at the Forncett Steam Museum model engineers day, I got a flea in my ear about not posting. Sadly I didn't get the name of the gentleman that gave me said flea, or more likely I've forgotten it.

Over the summer I have been busy in the garden and flying. For both gliding and power I needed to do revalidation flights, and CAA paperwork in the case of power.

More recently I have been working on the tenders for my engines. The first job was to machine, and flange, the sides from 3mm steel sheet. For economy reasons I used oxy-propane for heating rather than oxy-acetylene. Previous duff attempts had shown that I needed to use a lot of clamps. Initial flanging was done with a home made wooden mallet, followed by a steel bolster and copper mallet to tap the flange into close contact with the steel former:

After forming the sides were convex, due to the flange shrinking as it cooled. Ideally I wanted the sides to be slightly concave as this would make assembly easier. The distortion was removed by clamping the side over a steel rod, heating the flange to red along it's length and then letting it cool. Excess concavity was removed by heating an inch or so of the flange and letting it cool with the plate unclamped:

All four sides flanged, the flanges machined to size and cleaned up with files and an abrasive rotary wheel in the electric drill:

Note: One of the reasons I gave up posting was due to snide comments. I have a well equipped workshop with, mostly, ex-industrial machine tools which I run to the limits. Time is precious and I don't like to waste it. I also use 3D CAD, CAM and CNC milling. So if any member doesn't like what I do keep it to yourself, I;ve heard it before, and it is your problem, not mine!

Andrew

I held off posting as Baz is clearly in a different league to me in terms of experience. But I still have my Britan and it is getting regular use at the moment making 1/4" BSF/M6/2BA nuts,bolts and studs for the tenders on my traction engines. My Britan came with a good range of collets and accessories, Shortly after I bought it there were two boxes of accessories for sale on Ebay, both in Essex so not far from me. I made sure I won the auctions.

Andrew

For a fixed rotation point of the head and a given angular error with an extended quill the point of rotation of the Dti will be further off true centre, but I am not convinced it makes any difference to the vertical readings fro the DTI. I always have the quill retracted and locked when milling, so it seems reasonable to tram in that position.

Andrew

I'll be there with a few bits and pieces on display.

Andrew

Yes; I start using the acute angle corners and when those are worn/broken I move the insert to the other holder and use the obtuse angle corners.

Andrew

Even better use a Coventry diehead that opens up as it moves forward thus cutting a tapered thread:

Andrew

Use a hydraulic copy unit with a simple tapered pattern:

In this instance set up for cutting 3/8" BSPT threads:

Andrew