Author Topic: Retlas  (Read 67657 times)

Offline Jasonb

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Re: Retlas
« Reply #165 on: April 07, 2016, 07:31:45 PM »
The problem is that if you put cheese heads on it all those people who don't know what was shown on teh original will all be saying "pity he used cheese head screws". They are not what we would normally use on a model.

Its also interesting that the big end bolts just have plain round heads

Offline Chipmaster

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Re: Retlas
« Reply #166 on: April 07, 2016, 08:18:53 PM »
For the big end bolts, wanting to mimic the original Gardner I bought two 1/4" Whit x 2.3/4" long cap head bolts for 50p from our local fastener stockist, ran a die a bit further down the shank, put them in the lathe and machined the knurling off the cap heads. Much quicker than making the bolts myself and being upside down you can't see the socket in the heads, reckon I'll get away with that  :mischief:. The bolts are a snug fit in the end cap anyway but being able to use an Allen key to hold the bolts might come in handy one day. I machined the bolts down to the core diameter for the last 1/8" so that they could be drilled and have split pins fitted - for appearance rather than function.
Commercially made 1/4 Whit nuts didn't look right at all so I made the big end nuts from some hexagonal mild steel, Whitworth size of course.
J - I will use cheese head screws to hold the scoop next time I re-assemble the engine :ThumbsUp:

Andy
« Last Edit: April 07, 2016, 08:24:01 PM by Chipmaster »

Offline Chipmaster

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Re: Retlas
« Reply #167 on: April 09, 2016, 08:42:34 PM »
A couple of pictures showing the con-rod back in the engine, the oil catcher cup faces the back of the engine. A sight feed lubricator on the outside will feed oil through a tube positioned to drip oil into the cup - sometimes.
Building Retlas 633 by Andy, on Flickr
Building Retlas 634 by Andy, on Flickr
Andy

Offline Chipmaster

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Re: Retlas
« Reply #168 on: May 16, 2016, 06:48:35 AM »
Piston Rings
Using a piece of continuous cast iron bar I decided to make the 1.75" diameter piston rings .09" square. I machined just enough of the cast iron bar to part off the first ring which after cracking open, was heat treated and fitted to the piston. It took me three attempts to machine a ring to the correct fit. I had to anticipate the effect of annealing / heat treatment which slightly increased the dimensions of the ring.

Having arrived at the correct size I finished machining the internal and external diameters of the remaining iron bar and parted off as many embryonic rings as possible. Two rings were fitted to the piston and I have five spares.

Building Retlas 639 by Andy, on Flickr

Building Retlas 640 by Andy, on Flickr

Building Retlas 663 by Andy, on Flickr

Building Retlas 671 by Andy, on Flickr

Building Retlas 673 by Andy, on Flickr

The action of the rings is good and the compression excellent, I assume it will improve still further as the rings bed in.

Andy

Offline Chipmaster

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Re: Retlas
« Reply #169 on: May 16, 2016, 09:03:58 PM »
The main bearing caps of the Gardner Vertical engine (that the Retlas is based on) were cast with integral oil reservoirs /wells. I decided to add rectangular oil wells to my main bearing caps. One of my spare main bearing cap castings was sawn up and milled to produce two wells that were  mounted on the flat tops of the bearing caps, each held by two 6BA countersunk brass screws, a sealant will be used for final assembly. My milling of the recess in one of the wells went a bit wonky because it's impossible to see what's happening with a 3/16" slot drill in my collet chuck. I'll make brass lids that will conceal the errors.

I have a few spare main bearing caps, the foundry man got carried away.
Building Retlas 676 by Andy, on Flickr

Building Retlas 675 by Andy, on Flickr

Building Retlas 681 by Andy, on Flickr

Andy
« Last Edit: May 17, 2016, 06:36:43 AM by Chipmaster »

Online Dave Otto

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Re: Retlas
« Reply #170 on: May 17, 2016, 01:45:27 AM »
You are continuing to make great progress Andy!

The oil well reservoirs on the main caps will add some nice detail to the model.

Dave

Offline Chipmaster

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Re: Retlas
« Reply #171 on: May 17, 2016, 09:11:19 AM »
Valves
The Retlas has three valves, two on the inlet side and one exhaust.

Here are the plans.
212 Retlas Inlet Valve by Andy, on Flickro

209 Retlas Exhaust Valve by Andy, on Flickr

Knowing that it would take me rather a long time to turn small diameter valve stems that were parallel I silver soldered the heads on to two of the valves. Using ground 7/32" and 1/4" mild steel for the stems the valves were made very quickly. The larger inlet valve with varying stem diameters was turned from solid bar. The plans show valves with 45 degree faces operating in 45 degree seats which gave too much contact area in my opinion. I tried one out with the valve face at 45 degrees but couldn't get a good seal so I changed the angle of the valve faces to 50 degrees. This gave a thin contact area and the seal was perfect when ground in.

Larger inlet valve
Building Retlas 646 by Andy, on Flickr
Building Retlas 648 by Andy, on Flickr

Building Retlas 649 by Andy, on Flickr

Machining valve face with a right hand tool and top slide set at 50 degrees.
Building Retlas 641 by Andy, on Flickr

Building Retlas 642 by Andy, on Flickr

Building Retlas 645 by Andy, on Flickr

Valves fitted in their valve chests with temporary springs.
Building Retlas 652 by Andy, on Flickr

I have wound up my own valve springs for other model engines but this design uses conical springs, not essential but they look nice. Sourcing conical valve springs should be easy as I live in Redditch.....

Andy
« Last Edit: November 06, 2018, 10:39:30 PM by Chipmaster »

Online Alyn Foundry

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Re: Retlas
« Reply #172 on: May 27, 2016, 06:41:26 PM »
Hi Andy.

I've been a little busy lately, so, a belated well done and nice progress.

I have just been in contact with a lost friend who now owns this one...........

A case of " here's one I prepared earlier "........... Much earlier, like 25 years ago !!    ;)

Kind regards, Graham.

Offline Chipmaster

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Re: Retlas
« Reply #173 on: June 01, 2016, 11:26:11 AM »
Thanks for that picture of another Retlas Graham, I'm keen to collect as many pictures of Reltas engines as possible.
I would also like to see a video of a Retlas running before I finish my own. Like you I have also had to carry out horticultural jobs that has seriously hampered progress with my Retlas.

I decided to machine the underside of the base so that I could fit an oil tight sump in the future. I haven't been able to find something ready made that's suitable so some sort of soldered brass trough seems likely.

Building Retlas 682 by Andy, on Flickr

There aren't many parts remaining to be made, the valve operating gear comes next, here's a picture of a Retlas that I saw at the Harrogate Exhibition in 2006.
Retlas Valve operating gear by Andy, on Flickr

Starting with the exhaust valve, here's an extract from the plans.
Retlas Valve Operating Lever by Andy, on Flickr

I had to do a fair amount of sawing and filing to arrive at the shape required. The radiused section was formed first by milling away the majority then finishing off on my lathe.
Building Retlas 685 by Andy, on Flickr
Building Retlas 689 by Andy, on Flickr
Building Retlas 690 by Andy, on Flickr
Building Retlas 691 by Andy, on Flickr

Andy
« Last Edit: June 02, 2016, 02:46:06 PM by Chipmaster »

Online Alyn Foundry

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Re: Retlas
« Reply #174 on: June 01, 2016, 05:18:37 PM »
Hi Andy.

Have a look at this........

https://www.dropbox.com/s/9n8drxbyj7gsx70/SAM_0373.AVI?dl=0

This might be the only video to date ?

kind regards, Graham.

Offline Chipmaster

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Re: Retlas
« Reply #175 on: June 01, 2016, 10:14:29 PM »
Thanks for adding that Graham, at last I have seen one running. There's some serious travel on those valve levers  :thinking:

Andy

Offline Chipmaster

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Re: Retlas
« Reply #176 on: June 04, 2016, 09:00:31 AM »
Big end bearing oil feed.
I had a go at positioning the big end oil feed last night.

This is the big end cap showing the route the oil should take.
Building Retlas 627 by Andy, on Flickr

...and here are a couple of pictures of the set up.
Building Retlas 700 by Andy, on Flickr
Building Retlas 701 by Andy, on Flickr

The majority of the oil will miss the cup on the side of the big end cap so I think some sort of sump will be useful.

Andy

Offline Roger B

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Re: Retlas
« Reply #177 on: June 04, 2016, 08:13:53 PM »
What is usually described as a total loss system  :)  :)  ::)
Best regards

Roger

Offline Chipmaster

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Re: Retlas
« Reply #178 on: June 04, 2016, 09:19:53 PM »
Hi Roger  :agree:, I'm hoping it's not a dead loss!
I have connected a drip feed oiler which may look out of proportion but will suffice for initial runs.
Building Retlas 706 by Andy, on Flickr .

The cylinder is also lubricated by a drip feed oiler via a feed through the water jacket. Here is the plan,
205 Retlas Cylinder Lubrication by Andy, on Flickr

I taper reamed the oil hole in the cylinder liner and made a brass fitting with a matching taper. A piece of silicone tube supplemented with Hylosil RTV silicone sealant formed a water tight seal when screwed in from the cylinder casting. These are pictures of my first attempt which failed.
Building Retlas 702 by Andy, on Flickr
the fitting is threaded 1/8 BSP for the connection to a drip feed oiler.
Building Retlas 705 by Andy, on Flickr

This set up is oil and water tight and delivers plenty of oil but I wonder to what extent the oil will be distributed around the entire piston.
Building Retlas 722 by Andy, on Flickr.

I won't fit a non return valve until I've seen how well the cylinder lubrication works.

Andy

Offline Chipmaster

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Re: Retlas
« Reply #179 on: June 12, 2016, 09:47:25 PM »
We're moving house at the end of this month so I have stopped work on the Retlas and started packing up my workshop.
The last time I moved my workshop was 12 years ago when I had a large trailer and plenty of help. At the time I had a Ward 2A capstan lathe, a Colchester Chipmaster lathe, an Archdale vertical miller and a Meddings MF4 pillar drill. I also had a Merryweather Valiant fire pump and several stationary engines that were temporarily housed by friends. The majority of those helpers had now passed on and I sold my trailer last year so I agreed with my wife that I would pay for the machine tools to be moved this time. Fortunately over the last few years I have sold the Ward 2A, Merryweather Valiant and all the stationary engines. However, it was very difficult to find a commercial outfit that would move and store my machine tools between houses, we're only moving 2 miles but I didn't think it would work moving furniture and machinery on the same day, my wife thought the household should come first. So, my machinery is going to be collected 21st June and delivered to our new house 4th July. That will give me time to remove all the vulnerable parts of the machines before they are collected.
Yesterday Saturday 11th June, I hired a self storage unit half way between the houses and my wife and I have moved about a quarter of the heavier stuff so far. All this while we are packing the household effects which includes hundreds of books.
Andy