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Found an old (Davies-Charlton?) diesel airplane engine

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Old 03-19-2016, 12:21 AM
  #26
jef-lemmens
 
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Originally Posted by ffkiwi View Post
You DO need some decent alloy-I don't know what DC were using towards the end of production but the rods wee rubbish and slogged out quite easlly.

ChrisM
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I do agree with Chris that the conrod aluminium is rubbish , I call it chewing gum aluminum , I use 7075 aluminium for conrods , I am now working on a DC Sabre whose conrod also is worn out , I try to measure as accurately as possible , but if there is anyone who knows the exact center distance between the smal and bigend , that would be a great help .



Regards Jef
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Old 03-20-2016, 10:09 AM
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OK Jef-I found one in my spares box-measuring up I make it 17.4mm or 0.685" between centres

ChrisM
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Old 03-20-2016, 10:26 AM
  #28
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OK Jef-I found one in my spares box-measuring up I make it 17.4mm or 0.685" between centres

ChrisM
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OK , thank's Chris for the info

Regards Jef
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Old 09-03-2017, 11:55 PM
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Good evening all, I have two merlins as does my brother-in-law and we need to find some cyliner gaskets to rejuvenate them but to find the gaskets is like trying to find a live Dodo. Can anyone help with some solutions.

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Old 09-04-2017, 12:16 AM
  #30
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Originally Posted by Dayle View Post
Good evening all, I have two merlins as does my brother-in-law and we need to find some cyliner gaskets to rejuvenate them but to find the gaskets is like trying to find a live Dodo. Can anyone help with some solutions.

Dayle
Cut them yourself out of thin card.
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Old 09-04-2017, 02:05 PM
  #31
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Originally Posted by Dayle View Post
Good evening all, I have two merlins as does my brother-in-law and we need to find some cyliner gaskets to rejuvenate them but to find the gaskets is like trying to find a live Dodo. Can anyone help with some solutions.

Dayle
IIRC the originals are red fibre-about 0.8mm thick......and likely to be well and truly extinct by now...! I've just measured the lower OD of a Merlin liner at 7/16"...so one option would be to find some copper tubing of 7/16" ID and make them from this by simply parting off rings from the end of the tube- It goes without saying that you will need a lathe to do this-but it is probably a lot less hassle and will give a better result than trying to cut them by hand from card. The lathe will also allow you the option of making varying thicknesses of gasket, and providing you anneal the stuff, it will remain soft enough to compress slightly as things are tightened up on reassembly and provide the desired seal. Quite a few diesels rely on a copper gasket to seal the crankcase-cylinder joint area-Webras, Taifuns etc-so its hardly a new approach.

Be aware though that tubing is rarely perfectly circular so it pays to true up the outside as well-and I would be inclined to rub down the gasket surfaces on some wet and dry after parting off, to remove and burrs. You wouldn't require much in the way of tubing-only a couple of inches-enough to chuck and a bit more for working area-so you might well be able to pick up a scrap piece gratis from your local plumber or plumbing supply outlet....

Yes-my suggestion requires a bit of effort-and access to a lathe-but you'll only need to do it once-and a half hour of work will produce a lifetimes supply of gaskets. [and the principle can be adapted for backplate gaskets, tank gaskets as well....the only limitation is how thin you can go-it is not really practical to try and part off anything much thinner than about 0.01"-and this will vary depending on the material you're attempting to do it on. A final point-on reflecting-I can't see any reason why you could not use plastic tubing in a similar setup-something like plastic plumbing tubing again-or perhaps aquarium tubing. To make gaskets accurately out of sheet material (metal, paper of plastic) you need dies and punches-and there's a lot of work involved in making these-fine if you're going to produce 100s or 1000s of gaskets-but a problem if you only want one or two gaskets. By 'thin sheet' I'm thinking of material in the 1/32" up range-the 'paper' type gaskets you find on a backplate for example-can be cut quite easily with a compass type circle cutter-but the Merlin cylinder gasket is much much thicker....

ChrisM
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Old 09-04-2017, 09:12 PM
  #32
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Cool

Thank you Chris & Gossie, I set my Qualis 'Junior' lathe alight once the water wheel is generating power and turn out (hopefully) some gaskets of some sort. I know it was a looooong shot trying to find fibre ones. I have just looked at the liner under an eyeglass and because of the slight protrusions just above the intake transfer ports (and inbetween them) the gasket would appear to need to be of 1/2" (0.50" or 12.7mm) I.D and 9/16 (0.5625" or 14.2875mm) O.D. I will try copper and maybe aluminium, not sure about plastic. Anyhow, will advise as to how it goes.

Kind regards

Dayle
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Old 09-04-2017, 09:54 PM
  #33
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Quote:
Originally Posted by Dayle View Post
Thank you Chris & Gossie, I set my Qualis 'Junior' lathe alight once the water wheel is generating power and turn out (hopefully) some gaskets of some sort. I know it was a looooong shot trying to find fibre ones. I have just looked at the liner under an eyeglass and because of the slight protrusions just above the intake transfer ports (and inbetween them) the gasket would appear to need to be of 1/2" (0.50" or 12.7mm) I.D and 9/16 (0.5625" or 14.2875mm) O.D. I will try copper and maybe aluminium, not sure about plastic. Anyhow, will advise as to how it goes.

Kind regards

Dayle
Don't forget Brass, machines nicely and you can easily anneal it with a gas torch.
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Old 09-04-2017, 11:24 PM
  #34
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Quote:
Originally Posted by Dayle View Post
Thank you Chris & Gossie, I set my Qualis 'Junior' lathe alight once the water wheel is generating power and turn out (hopefully) some gaskets of some sort. I know it was a looooong shot trying to find fibre ones. I have just looked at the liner under an eyeglass and because of the slight protrusions just above the intake transfer ports (and inbetween them) the gasket would appear to need to be of 1/2" (0.50" or 12.7mm) I.D and 9/16 (0.5625" or 14.2875mm) O.D. I will try copper and maybe aluminium, not sure about plastic. Anyhow, will advise as to how it goes.

Kind regards

Dayle
Dayle-I wouldn't get too wrapped around the axles over the material-I would suggest that copper, brass (as suggested by qazimoto) aluminium or a suitable plastic-nylon or Delrin-would make a suitable gasket -all you want is something that is a bit compressible to generate a seal-all of the mentioned materials have-and still are-used as gaskets in various engines. I was merely thinking in terms of what would be the easiest way of making several copies of what is-in a sense-an oversized glowplug washer!....hence my initial suggestion of copper tubing as the starting material. but you could make it from whatever stock you have available-solid or tubular. In your shoes i'd probably grab a bit of delrin rod-but that's only coz I have a lot of it in various sizes-and no copper! My experience with Merlins is that the liners vary from smooth to quite roughly machined on the outer surface, depending on when they were produced-so not all have the protrusions you noticed.

ChrisM
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Old 09-05-2017, 12:25 AM
  #35
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Thanks Chris & Gazimoto, a new way of making the gaskets has been suggested to me by an arts & crafts friend, using a disc cutter that they use for thier jewellery. They can be bought in sets with 1/16th or 1mm increments. She said she would try some very thin (0.45mm) copper for me to see how it works. As for the finish on the liners themselves Chris, mine were crafted with a flint adze. A little bit of needle file work will tidy them up.

Kindest regards
Dayle
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Old 09-05-2017, 12:30 PM
  #36
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I use good quality hollow point punches and 1/32 or 1/64 automotive gasket paper. Use a light hammer and tap them on a hard plastic chefs chopping board.
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Old 09-05-2017, 12:33 PM
  #37
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If any one has a good spare rod for a DC Sabre or Spitfire I'lll willingly take it ... need one to complete a restoration.
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Old 09-07-2017, 07:20 PM
  #38
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You might check with motorcycle or gocart shops and see if you can get Klotz brand "Beanol". Modified Caster oil and blends easier. D.H.
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