Author Topic: Retlas  (Read 52880 times)

Offline Chipmaster

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Re: Retlas
« Reply #15 on: January 13, 2016, 08:55:12 PM »
The flywheel was my first task. I had just finished machining the two flywheels for my Economy engine which are the same size as the Retlas flywheel so I was in the mood.
The casting was ugly but I felt that it was viable - at least the problem was too much rather than too little metal. If I couldn't get a good result using my lathe then I could use a die grinder to get into the space between the spokes.
The misshaped rough looking hub was hard going and took quite a time to get beneath the skin but as the job progressed the machined areas cleaned up perfectly well so I had confidence in the integrity of the casting. I had to plug one shallow blow hole in the rim and because of a few other blemishes the finished diameter had to be slightly undersize, not a problem. The spokes still need some fettling and a little filler to deal with the shallow pitting here and there . When spinning on the lathe the flywheel inner rim also runs perfectly true - phew!
Andy

Offline zeeprogrammer

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Re: Retlas
« Reply #16 on: January 13, 2016, 10:21:20 PM »
 :popcorn:

to be followed by

 :DrinkPint:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Jasonb

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Re: Retlas
« Reply #17 on: January 14, 2016, 07:33:21 AM »
And when you curl up you toes they will be lost forever LOL

Stuart

And  :mischief: in years to come they will look at your engine built from the unobtanium drawings and say that's wrong, that's also wrong its not to the original Retlas drawings by Vincent :ShakeHead:

Jo

Stuart, I'm not the only one who has them there are other hit & miss / gas engine collectors who do.

Jo Why whould they say it does not look like a Retlas when it will be a Gardener Vertical not something based on a Gardener with little references.

Andy that wheel turned out a lot better than the external appearance suggested :)
« Last Edit: January 14, 2016, 07:37:05 AM by Jasonb »

Offline Jo

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Re: Retlas
« Reply #18 on: January 14, 2016, 07:42:43 AM »
Stuart, I'm not the only one who has them there are other hit & miss / gas engine collectors who do.

In which case and looking at the date of this engine they are no longer subject to copyright and can be shared and enjoyed, shared and enjoyed  8) Unless of course someone is being mean and just teasing the forum members  >:(

Jo
Usus est optimum magister

Offline Jasonb

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Re: Retlas
« Reply #19 on: January 14, 2016, 07:55:12 AM »
As I said the person who shared them with me said they were for my eyes only so I will not be going against that.

Offline Chipmaster

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Re: Retlas
« Reply #20 on: January 14, 2016, 10:24:02 AM »
Well I'll interrupt the banter and slip in a bit more about the model. :)
I removed the flash from the base casting by filing and set it up for milling the underside flat. The casting was pretty true in each direction and didn't need much machining. Two 1/2" holes were drilled through the thin (1/16") skin left intact where the crank webs will go, very useful for holding the casting down. The skin was knocked out later on simply by smashing it with a hammer. My milling machine had just enough travel to enable the sides and edges of the casting to be machined in one sitting. An extract from the plans is included to show the style of the main bearings, I also marked out and milled the registers for the bearing caps.
Andy



Offline Chipmaster

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Re: Retlas
« Reply #21 on: January 15, 2016, 06:52:07 PM »
My next job was to fit the main bearing caps. I had thicker caps cast so that I could form oil wells in each cap later on using a milling machine to get rid of the excess. I forgot to take pictures of the caps being milled so this instalment starts with pictures of the caps glued to the base ready to be drilled and tapped for 1/4" Whit studs.
The assembly was then put back on the milling machine and the caps and base milled to the correct widths and gap between the housings for the crank.

With my equipment the only way I could bore out the main bearing housings to 1" was to make a 'between centres' boring bar and fix the base to the cross slide of my Colchester Chipmaster. The Retlas base is almost as long as the cross slide so the top slide had to be removed. A sandwich of 16 + 3mm bright drawn mild steel almost brought the casting up to the required height. As you can see in the pictures I used two of the 5/16 UNC rear toolpost mounting holes and the two top slide bolt holes to attach the steel supports with cap head screws. The engine base was in turn bolted down to the steel supports taking care that this set up didn't distort the cross slide, it shouldn't because the base was dead flat, but a Chipmaster cross slide isn't heavily built.
The split line of the main bearings is specified 1/16" below the centre line of the crankshaft. With a 1/8" diameter rod in the chuck and a piece of cigarette paper the base was shimmed up equally front and rear until I was happy with the height. The milled timing side of casting was then clocked to ensure the crank would be at a right angle to that face / datum.
That left me to get the cross slide in the correct fore and aft position then locked by tightening the appropriate gib strip adjustment screws.
The boring bar was 5/8" diameter and I simply advanced the cutting tool with light tapping and measuring the position with a micrometer plus an internal mic as the final reaming size was approached. The bores were finished off with a 1" machine reamer.
Andy
« Last Edit: January 16, 2016, 07:53:40 AM by Chipmaster »

Offline Jo

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Re: Retlas
« Reply #22 on: January 15, 2016, 07:12:36 PM »
 :thinking: Sounds like you need a bigger milling machine, nice power quill feed topped off with an automatic boring and facing head  :naughty:

Its a big old engine isn't it. I will have to decide how much smaller mine will be  ;)

Jo

P.S. I can't see any DRO scales on your chipmaster  :ShakeHead:
Usus est optimum magister

Offline Jasonb

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Re: Retlas
« Reply #23 on: January 15, 2016, 07:49:14 PM »
Comming along well and the oil box on the top is the way to go for authenticity ;)

I have resorted to the between ctrs bar on more than one occasion and its a nice solid setup.

Did you tap all the way the stud holes or plunge with a 1/4" bit to the bottom of the rebate and then start tapping? I've only done that sort of stepped bearing cap before where the stud is outside the rebate.

Offline Chipmaster

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Re: Retlas
« Reply #24 on: January 15, 2016, 08:16:40 PM »
:thinking: Sounds like you need a bigger milling machine, nice power quill feed topped off with an automatic boring and facing head  :naughty:

Its a big old engine isn't it. I will have to decide how much smaller mine will be  ;)

Jo

P.S. I can't see any DRO scales on your chipmaster  :ShakeHead:

Bigger milling machine, try telling that to the memsahib !

DRO .... I'm old skool

Andy

Offline Chipmaster

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Re: Retlas
« Reply #25 on: January 15, 2016, 08:41:45 PM »
Hi Jason, The plans showed the stud in the rebate, I omitted to include an extract from the main bearing plans in a previous posting, I'm using my iPad this evening so I'll correct that when I'm using my pc tomorrow.
As you suspected I used the 1/4" Whit tapping drill to drill down the full depth of the studs through the caps and base casting. Opened up the caps to 1/4" plus about a 1/16" more into the base holes. With the caps still in place I then tapped the holes in the base. Consequently the deep clearance holes in the caps ensured the threads were true. The glue probably wouldn't have held the caps in place if I'd tapped all the way through.

Andy

Offline Chipmaster

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Re: Retlas
« Reply #26 on: January 16, 2016, 07:55:29 AM »
Retlas main bearing drawing shows the studs in the Rebate.

Offline Alyn Foundry

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Re: Retlas
« Reply #27 on: January 16, 2016, 07:03:29 PM »
Hi Andy.

Great progress.........

I built more than one or two Retlas engines over the years, my Le Blonde RP has a massive saddle so I actually drilled and tapped it just for the purpose of inline boring the engine bed casting. I have four screws in the holes so they don't fill up with swarf.  ;)

Looking forward to the yoke casting !!  ;)   With a big lathe it's child's play.

Re the main bearing caps...... It became apparent, much later in time that Gardner had just made them the same as the horizontal engine. Vincent being a National Gas engine owner made them recessed, in fact the picture he used was a rather smaller version of the one Jo posted. It still amazes me to this day how close he got to the original, with such little detail to go on !!

Kind regards, Graham.

Offline Chipmaster

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Re: Retlas
« Reply #28 on: January 17, 2016, 09:01:25 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

Offline Chipmaster

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Re: Retlas
« Reply #29 on: January 17, 2016, 09:27:58 PM »
It was necessary to bore / open out the water jacket to ensure that there would be a route for water to flow up through the passages to be drilled up through the cylinder liner.


Andy
« Last Edit: January 18, 2016, 09:57:04 AM by Chipmaster »