Author Topic: Alyn Retlas  (Read 3325 times)

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11774
  • Hampshire, england.
Alyn Retlas
« on: July 07, 2015, 11:15:39 AM »
The Alyn Retlas is one of those fascinating engines that I have been unsuccessful to acquire a set of castings for  :( However all is not lost as a very nice man gave me his old set of drawings ;D

However I am confused: The drawings show a 30 tooth and a 15 tooth gear without providing the DP. It shows the outside diameters of these gears at 67.7mm/36mm respectively, so the between centres measurement = 51mm and the engine GA shows that the camshaft is 46 mm horizontally and 12.7mm vertically apart = 47.18 mm between centres :rant:

If I made them 12DP, which I suspect the original design was for, it would require a between centres distance of 51.85mm but those gears are very coarse looking. I could make them 18DP and increase the number of teeth to 40 and 20 which would make it 45mm between centres or 24DP and use 60 and 30 tooth gears giving me 49.7mm between centres. Whatever I do I cannot seem to get a measurement that matches the original drawing distance spacing  :disappointed:.

Thoughts? 12DP gears and expand the centre distance or go for the 18DP and bring them closer  :noidea:

Jo
Usus est optimum magister

Offline Bluechip

  • Full Member
  • ****
  • Posts: 740
  • Derbyshire
Re: Alyn Retlas
« Reply #1 on: July 07, 2015, 11:47:52 AM »

Jo

Not too sure if this fits but .... maybe 12 DP cut to 14DP depth ??

Vincent  Series 'A' timing gears were, from memory, 10/12 DP .. ie 10DP cut to the depth of 12 DP.

Called 'Involute Stub' IIRC

Also, IIRC, this makes the centres seem to be wrong.

You really need that nice Mr. Stevenson, I'm sure he would know why I'm wrong again ....  :)

Dave

 


Offline tangler

  • Full Member
  • ****
  • Posts: 742
  • Christchurch, UK
Re: Alyn Retlas
« Reply #2 on: July 07, 2015, 11:56:39 AM »
Your metric puritanism is really irritating  ;)

Converting your measurements to the imperial units the engine was designed in gives, for the larger gear 32/2.66"=12DP.  PCD of this gear is 2 1/2", PCD of 15 tooth is half this=1 1/4" so centres are at half the respective PCDs =1 1/4" + 5/8" = 1 7/8" = 47.6mm - which seems to be close to the 47.18mm which you have measured/calculated form the drawing GA.  The ODs of these gears (converted to metric) give the figures you've quoted (N+2)/DP.  I'd stick with the design since I'm sure you already have the cutters.

HTH  :)

Rod

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11774
  • Hampshire, england.
Re: Alyn Retlas
« Reply #3 on: July 07, 2015, 12:17:04 PM »
Your metric puritanism is really irritating  ;)

It's my age  :old:


:facepalm: Forgot to take off the depth of tooth on the blank diameters. I have just discovered that the drawing set is incomplete  :toilet_claw:

Jo
Usus est optimum magister

Offline tangler

  • Full Member
  • ****
  • Posts: 742
  • Christchurch, UK
Re: Alyn Retlas
« Reply #4 on: July 07, 2015, 12:21:44 PM »

... I have just discovered that the drawing set is incomplete  :toilet_claw:


That's a shame.  I'm sure we can fill in the gaps; it's a very interesting design.

Rod

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11774
  • Hampshire, england.
Re: Alyn Retlas
« Reply #5 on: July 07, 2015, 12:48:38 PM »
Thanks for the PM Rod, I knew Dave Everrett has a set of castings for this engine. He is the mean  >:(, cruel  :censored: man who one second offerred to sell the casting set then snaffelled them away from us and is now refusing to let them go to a loving home and has told me I will have to wait until he needs a zimmer frame before he will let them go :rant:

Retlas drawings: Looking at the GA. We are missing the Cylinder liner, piston, valves and valve chest details. The base and stand details are only sketches with major dimensions provided  :-\

To quote the drawings :facepalm2: " All dimensions are in inches and are purely for guidance only. I never intended them to all look the same! Obviously certain castings will require more machining than others, so each item gets its own measurement. All that is required is a clean face, once obtained machine no further"

I suspect there was no piston drawing as the words suggest machining the piston to suit a set of commercially available 1 3/4" rings  :stickpoke:

Jo

Usus est optimum magister

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6020
  • Surrey, UK
Re: Alyn Retlas
« Reply #6 on: July 07, 2015, 01:15:46 PM »
Jo check your trig I make it 47.72 in silly metric or 1 7/8" in old money.  Does get confusing when you mix imperial DP with metric sizes. 12DP seems a bit big best count the teeth on some full size horizontal Gardeners which are very similar in a lot of details or get details of the one in Oz

Have you tried playing with MOD gears as its quite likely he just used an odd set that were laying about.

Whatever you decide to go with depth it out with the gears and some paper to set backlash rather than text book measurements then you will get a nice smooth running engine

Leave my mate Dave alone, had it not been for me you would not even have had the enticing details :LittleDevil:

At least he is going to let me have some original Gardener drawings so my version could be made to look like it is supposed to rather than the copy of the Salter engine ;)

J

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11774
  • Hampshire, england.
Re: Alyn Retlas
« Reply #7 on: July 07, 2015, 03:20:45 PM »
Rod has confirmed above that the gears are 12DP.

At least he is going to let me have some original Gardener drawings so my version could be made to look like it is supposed to rather than the copy of the Salter engine ;)

I would prefer that he provided copies of the missing drawing pages. If all else fails I will be forced  to go visit Ron and use my charms to measure up his working model Retlas :shrug:

Jo
Usus est optimum magister

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6020
  • Surrey, UK
Re: Alyn Retlas
« Reply #8 on: July 07, 2015, 05:09:19 PM »
Looking through the info that I have the gears on a half scale engine should be 1.875 apart which is 15/30 at 12DP not what you gave above :headscratch:

But the 1/2" below crankshaft is not correct it should be 5/8" but still the same ctr to ctr length. so the 1 13/16" needs reducing slightly. This may not be possible if you follow the Retlas base casting.

I'm inclined to think the original engine ran 30/60T at 12DP and the model should be 30/60T at 24DP
« Last Edit: July 07, 2015, 05:15:12 PM by Jasonb »

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6020
  • Surrey, UK
Re: Alyn Retlas
« Reply #9 on: July 07, 2015, 05:34:51 PM »
As the pic shows 15/30 is not enough teeth
« Last Edit: July 07, 2015, 06:24:20 PM by Jasonb »

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11774
  • Hampshire, england.
Re: Alyn Retlas
« Reply #10 on: July 07, 2015, 05:55:17 PM »
Counting those it is indeed a 60 and a 30 tooth gear, assuming 24DP that is 3.83" = 47.3mm between shafts.

Guess who has got a full set of 24DP gear cutters  :naughty:

Jo
Usus est optimum magister

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6020
  • Surrey, UK
Re: Alyn Retlas
« Reply #11 on: July 07, 2015, 06:28:37 PM »
Where are you getting all these odd gear sizes from Jo?

I make it 1.875"  (47.62mm) not 47.3mm for 30/60 at 24DP which is the distance I have said all along.

(60/24 + 30/24 ) /2 = (2.5 +1.25) / 2 = 3.75/2 = 1.875"

http://www.hpcgears.com/pdf_c33/23.102-23.107.pdf
« Last Edit: July 07, 2015, 06:34:13 PM by Jasonb »

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 11774
  • Hampshire, england.
Re: Alyn Retlas
« Reply #12 on: July 07, 2015, 06:33:13 PM »
ShopCalc:  :facepalm: I am reading the OD again

The sooner I can stop taking the tablets the better :paranoia:

Jo
Usus est optimum magister

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6020
  • Surrey, UK
Re: Alyn Retlas
« Reply #13 on: July 07, 2015, 06:34:48 PM »
Its not the tablets, its the  :wine1: you wash them down with :ROFL:

Offline Alyn Foundry

  • Full Member
  • ****
  • Posts: 731
  • North Wales, Great Britain.
Re: Alyn Retlas
« Reply #14 on: July 16, 2015, 07:56:44 PM »
Hello again.

I have just read this thread and would like to add a little history.

The Retlas was loosely based upon the Gardner size 1 vertical gas engine. A gentleman named Dion who had taken on the role of archivist for early Gardner engines came across a set of drawings and test sheets but had never seen an actual engine. He made a request in Stationary Engine magazine for anyone with patternmaking experience to contact him with a view to making a replica. Vincent Salter picked up the gauntlet and duly wrote a letter. The reply was so strange at the time, he actually replied saying that he had made no such offer. Then a couple of weeks later replied again saying yes he had but he didn't think anyone would be capable of performing the task. Well, that was a " Red rag " to Vincent who promptly enlarged the photo that had appeared in SE and made patterns in very short order.

We cast most of the parts for the prototype in Aluminium but the cylinder had to be Iron and I had just developed my forced air Propane burner which was so powerful you could drop 10 Lbs of Iron in 20 mins !! In fact it was so hot it melted 1700 deg C furnace batt's after a few runs !!

The gears we used were from a Jap 1 A stationary engine as we were all novices back then. The piston was from a Japanese motor cycle but the engine came together. It finally made it's debut at the very first 1000 Engine rally at Tatton park Knutsford Cheshire.

The flywheel shown in the drawing was later superseded by a much larger and heavier 6 straight spoke, more in keeping with the original.

I also caught the pattern bug and designed the Sphinx around the same time. It was suggested that we offer casting kits and that's how Alyn Foundry was born. The name coming from the Cul de Sac where I had bought my first home and the river that ran nearby.

Many years on a vertical Gardner survivor has turned up in the land down under.

The Retlas was not popular, because of it's size not complexity, but if you need reference to detail all you need to do is take a look at a No 1 Horizontal and turn it through 90 deg !!  ;)

Cheers Graham.