Author Topic: Retlas  (Read 52878 times)

Offline Steamer5

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1015
  • The "Naki" New Zealand
Re: Retlas
« Reply #30 on: January 17, 2016, 10:44:52 PM »
Hi Andy,
 Nice setups for a tricky shape.
Following along, & enjoying!

Cheers Kerrin
Get excited and make something!

Offline Alyn Foundry

  • Full Member
  • ****
  • Posts: 731
  • North Wales, Great Britain.
Re: Retlas
« Reply #31 on: January 18, 2016, 05:58:15 PM »
The Cylinder Yoke casting would be mounted on a lathe faceplate to bore the water jacket out for the liner. My Colchester Chipmaster has an eleven inch swing which was sufficient for the set up I envisaged.
To prepare for milling the base of the Cylinder Yoke I filed the top of the casting flat so it could be bolted down firmly onto the milling machine table using a length of 1/2" allthread. The angle plate was positioned to help keep the casting still and the set up was pretty rigid. I also milled what I could reach of the underside of the casting where the cylinder liner exits.
The casting was then mounted with a temporary support pillar on a piece of 5/8" thick gauge plate which was in turn bolted to the lathe faceplate. I took my time positioning the casting also taking into account the raw cylinder liner casting, to decide on the best position/compromise to start boring.
The job proceeded taking 10 - 15 thou cuts at about 150 rpm to avoid chatter.
How's that Graham?  ;D
Andy

Hi Andy.

Hmmm...... Very similar, Vincent made a heavy " C " section steel jig that would fit into a 4 Jaw chuck but otherwise the rest of the machining was identical.

You're taking me on a very nostalgic journey, I'm enjoying every step!! Thank you. The prototype  Retlas was shown to the world at the very first 1000 engine rally held at Tatton park, Knutsford Cheshire. It's been so long I'm afraid I've forgotten the year!!  :)


Kind regards, Graham.

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 527
Re: Retlas
« Reply #32 on: January 19, 2016, 09:37:57 PM »
The cylinder liner was too heavy to rely on my four jaw chuck to hold it without additional support, particularly as  the job would be subject to many interrupted cuts. I also wanted the liner to remain in the chuck for boring out and the machining of the exterior.
My first move was to use a shaper to square off the top of the cylinder and machine it flat so that it could be pressed against the body of the chuck. The other end of the cylinder was carefully machined so that I could use a fixed steady. I bored out the liner to just under 1.75" leaving a little for honing to remove then a bung was fitted so that the job could be supported by a live centre whilst the outer surface was machined.
Andy
« Last Edit: January 20, 2016, 09:24:31 AM by Chipmaster »

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11775
  • Hampshire, england.
Re: Retlas
« Reply #33 on: January 20, 2016, 09:13:40 AM »
 :o There are a lot of very tricky bits to hold for machining in this engine Andy. Nice work.

Jo
Usus est optimum magister

Offline zeeprogrammer

  • Full Member
  • *****
  • Posts: 6320
  • West Chester, PA, USA
Re: Retlas
« Reply #34 on: January 20, 2016, 11:27:28 AM »
Good pics of your operations.
They gave me some ideas that will help.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 527
Re: Retlas
« Reply #35 on: January 20, 2016, 10:18:29 PM »
To determine where to position the cylinder yoke I placed a 1" diameter ground bar between the main bearing housings and a 1.3/4 diameter bar down through the cylinder liner to rest on the 1" bar. It was then a matter of moving the yoke about and taking a series of measurements until I'd got it lined up. I then clamped the cylinder yoke to the base and used a transfer punch to mark the where the holes in the base would be drilled then tapped.

For the main bearings I decided not to make split bearings. I was thinking about the work involved and considering how the plain tube bearings had performed well on my Alyn Foundry Gardner O Type for nearly 20 years. Perhaps for appearance I'll score a split line on the bearings later on.

You may notice that the flywheel and timing gear now have keyways, these were broached by a fellow 'Black Country Live Steamers' member.

Andy

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6020
  • Surrey, UK
Re: Retlas
« Reply #36 on: January 21, 2016, 07:34:24 AM »
You are making quick progress on this one Andy. Quite often I don't unsolder split bearings so also doubt how much they are really needed on our models that don't see much in the way of running time or load. I have also done a couple of hit and miss engines with supplied oilite bearings which are OK if you only need a single flange and cheaper than the raw bronze bar.

J

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 527
Re: Retlas
« Reply #37 on: January 21, 2016, 08:30:38 AM »
Hi Jason,
I am a little further ahead than the pictures suggest and I'm now thinking about the crankshaft. Should I machine it from the solid?  A local profile cutting firm will cut a blank for little cost and I have used that approach before with satisfactory results, but it is a rather slow process - particularly because of stress relieving.
My early efforts at making model engines made me wary of fabricating a crankshaft because a couple of my fabricated cranks failed, one when the engine backfired and the other went banana shape after the heat of silver soldering. These failures did generate some mickey taking at the time so crankshafts became my bÍte noire !

However, I have the exact size of ground EN1A for the shafts and crankpin to hand, all I need is the material for the webs.
When silver soldering, do you start with the shafts, webs and crankpin at the finished size, then simply pin and solder them together?

I have a Bullfinch propane torch so if I silver solder the crank I'd have to get the whole job up to red heat, so I'm concerned it would distort.

Any thoughts or observations.

Andy

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6020
  • Surrey, UK
Re: Retlas
« Reply #38 on: January 21, 2016, 12:33:50 PM »
I've made several from PGMS and have not had problems with them moving more than a couple of thou which can usually be tweaked back without problem.

I cut a good CSK on the outside edge of the pin and inside edge of the shaft which fills with solder and only apply it to these sides which helps with cleanup. Once soldered I pin the joint as I feel all that hammering on a loose joint may distort things but doing it after any gap is filled with solder.

5/8" is the biggest I have done and also only have a Bullfinch torch, with Tenacity No5 I did not have any problems getting the solder to flow, I do it all in one heat.

Galloway Crank http://www.homemodelenginemachinist.com/showpost.php?p=229982&postcount=19

I've also done several from solid, bright flat bar and black bar, as you say its more work but at least you know it should not fail.

Offline Alyn Foundry

  • Full Member
  • ****
  • Posts: 731
  • North Wales, Great Britain.
Re: Retlas
« Reply #39 on: January 21, 2016, 01:35:53 PM »
Hi Andy.

We made lots of crankshafts over the years and learned by mistake which method worked best.

We used ground stock cut and centred at full length for the shaft and used a separate piece for the crank pin. We then cut suitable blocks for the webs that were drilled and reamed to suit the throw.

Now the secret is to use the best flux! Tenacity No 5 is the only one we found to work because you need to get everything hot. Next trick, use a very flat fire brick to ensure your assembly doesn't distort.

To ensure minimal distortion start heating the shafts from either end to get the length expanded. Martin suggested cutting the Silver solder into smallish lumps and placing them on the fluxed joints. This method  worked really well as all you needed to do was heat the area, the solder just melted and ran.

After the assembly had cooled we used to " pickle " it in ordinary household vinegar fo 24 hours, this made excess flux removal very easy.

All that was left was to carefully cut out the section of main shaft between the webs, it would be the last cut that showed a good job! If it jumped you had a banana.  :)  As time progressed we rarely saw a jump, but even a jumper could be rescued, thanks to centring the shaft before soldering it was a simple matter to place between centres and correct the run out.

We never, ever used pinning just relying on the solder to do its job. Funnily enough, the only crank that ever failed was an early attempt at a forging for the RLE. The metal had pocketed in a turn and broke after a few hours of running. Oh, and I also tried 638, without pins that was a disaster too.

Gardner's used solid billet, I remember a conversation I had many years ago with an ex employee who, as an apprentice his job was to drill the plate with 4 holes ready for a senior to slot out the waste material. One member of the Gardner family also developed a crankshaft lathe, of which a couple were rescued by the Anson engine museum.

Kind regards, Graham.


Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11775
  • Hampshire, england.
Re: Retlas
« Reply #40 on: January 21, 2016, 02:26:34 PM »
Oh, and I also tried 638, without pins that was a disaster too.

 :headscratch: Graham I thought you retired long before September 2013.

Jo
Usus est optimum magister

Offline Alyn Foundry

  • Full Member
  • ****
  • Posts: 731
  • North Wales, Great Britain.
Re: Retlas
« Reply #41 on: January 21, 2016, 02:48:38 PM »
Oh, and I also tried 638, without pins that was a disaster too.

 :headscratch: Graham I thought you retired long before September 2013.

Jo

Indeed, yes!

Please note the emphasis on " new formulation "  :)

I'm referring to the first time 638 came out. I was so unimpressed I phoned their technical support people who then told me that it was unsuitable for shock loading. After spending £18.00 on a bottle, a kings ransom back then it was relegated to the shelf. Luckily when we started on the Robinson " X " type it was used to hold the cylinder liner in place.

Kind regards, Graham.

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 527
Re: Retlas
« Reply #42 on: January 21, 2016, 05:15:35 PM »
Thanks for your advice and the benefit of your experience Graham and Jason. Reckon I'll attempt a fabricated crankshaft.
My failed crank was just like your experience Graham, Loctite + pins for my Gardner O Type crank. I'd invited a few friends round to see the 'new' engine, it backired a couple of times and wouldn't run, the valve timing appeared to be miles out. Turned out that was because the shaft on the timing side had sheared the pins and the Loctite gave up. I would have expected the shaft with the flywheel to go but hey ho. I have had great success with glueing in other parts such as cylinder liners with Loctite 638.

Andy

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 527
Re: Retlas
« Reply #43 on: January 28, 2016, 07:47:44 AM »
Further work on the cylinder liner. Copies of the liner and cylinder head plans are included below, followed by pictures of the work in progress. I annotated the plans to highlight the water cooling arrangements.
A guide for drilling the five stud and three water passage holes was made on a rotary table from a piece of aluminium bar about 5/8" thick with a register machined to fit the bore of the liner. At first the holes were all 2 BA tapping size.
After determining the orientation of the cylinder liner the first hole was drilled down through the liner into the cylinder yoke, the blind hole in the cylinder yoke tapped 2 BA then single hole in the liner opened to 2 BA clearance. The first stud was fitted and the guide was used for the other four stud holes (2 BA tapping size) drilled through into the cylinder yoke. All the holes in the liner were opened up to 2 BA clearance size and the fit to the cylinder yoke checked using temporary 2 BA all thread. Plain studs with threaded ends were made up using a Coventry Die Head.
Andy

Offline Chipmaster

  • Full Member
  • ****
  • Posts: 527
Re: Retlas
« Reply #44 on: January 28, 2016, 08:23:10 AM »
The cylinder head then came into play, my first job was to machine the face flat. Unfortunately the diameter of the cylinder head was rather smaller than the liner so it wasn't feasible to machine the edge because the mounting holes would all look too close to the edge. Determining the best position for the head was a compromise between symmetry, appearance and function. Anyway, I used Hafix to glue the head onto the liner turned it upside down and used a very long series 3/16" drill to put the holes for the five studs and three water passages into the head. The cylinder head was held in a four jaw chuck to machine the water outlet and spark plug holes. The original design required the three water passages to be drilled at an angle of 30 degrees from the flat cylinder head face to converge at the bottom of the water outlet hole - quite a challenge!
However the notes that accompany the plans include an update suggesting the cylinder head waterways are easier to produce by drilling sideways through the side of the head to outlet, plugging the holes and filing them flush afterwards. So that's what I did, drilled the outlet hole deeper and finished it with a flat bottomed drill. I accidentally deleted pictures of that operation.
Andy
« Last Edit: February 29, 2016, 04:26:17 AM by Chipmaster »