Author Topic: 1909 Mercedes Aero Engine  (Read 4605 times)

Offline Roger B

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Re: 1909 Mercedes Aero Engine
« Reply #75 on: January 09, 2019, 09:04:15 AM »
Thank you  :ThumbsUp:

I have made my valves from stainless steel screws or bolts.
Best regards

Roger

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #76 on: January 13, 2019, 09:08:24 AM »
I now have eight valves. Glad it isn't a V-12!



I need some valve springs next. I did find a supplier on line but would get caught out by the minimum order charge of 50- which seems a bit steep so I shall be making them. Fortunately, Father gave me a spring winder kit for Christmas so that is the next exercise.



A workshop day beckons.

Steve   :) 

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #77 on: January 13, 2019, 09:29:48 PM »
Well, I have had a pleasant weekend, making up my spring winder. The drawings are accurate and pretty good. A couple of missing dimensions but nothing serious. The only bit I hate doing is the knurling as it is so hard on the lathe. Fortunately, the bulk of it was in aluminium and I got away with it.



The pinch plate is tapered and can be indexed to set the pitch of the spring. I followed the drawings and made up an arbour with the end machined at an angle. The plate was bolted onto the end and just turned. All very satisfactory.







Time for a trial with the lathe set at lowest speed and me gripping the tool tightly.



It does need practice to use to set the tension and get the mandrel diameter right but I had a few goes to start with.



The last hour of the day was spent making up the valve springs themselves. It is nice to be able to get a couple of tight coils at the ends to grind flat.



Job is done and the tool can go in the drawer ready for the next time!

Those springs represent quite an investment of time and effort but I have reached the conclusion that making tools and jigs is never time wasted and they are much more satisfying to use than a lash-up.

Spring caps next.

Steve   :)


Offline stevehuckss396

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Re: 1909 Mercedes Aero Engine
« Reply #78 on: January 13, 2019, 11:58:21 PM »
Nice work! I have made springs myself so I can appreciate what you went through to get them made.
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Jo

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Re: 1909 Mercedes Aero Engine
« Reply #79 on: January 14, 2019, 08:27:55 AM »
I am sure I am missing something here Steve  :headscratch:

How does that actually work? Does the tapered disc rub against the mandrel to give the pitch? I guess the plastic disc is used for friction but how does that achieve the spring :noidea:

Jo

Usus est optimum magister

Offline Ramon

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Re: 1909 Mercedes Aero Engine
« Reply #80 on: January 14, 2019, 10:06:51 AM »
That's a very quick but nicely made tool Steve with what looks to be some very consistent results  :ThumbsUp:

What significance do the numbered radial marks on the plate have?

Tug
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(a very apt phrase - thanks to a well meaning MEM friend)

Offline dieselpilot

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Re: 1909 Mercedes Aero Engine
« Reply #81 on: January 14, 2019, 02:35:23 PM »
You can even buy these ready. http://www.flexbar.com/shop/pc/UNIVERSAL-SPRING-WINDER-p3773.htm I couldn't find a video of one being used though. The circular wedge seems to set the coil pitch and sounds like it can be adjusted during winding. I just don't understand how carriage feed comes into play. I've wound springs simply using a tensioner and carriage feed, with some hand feeding to make the closed ends.

Online steamer

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Re: 1909 Mercedes Aero Engine
« Reply #82 on: January 14, 2019, 03:03:58 PM »
I just ordered one of those diesel,  ..ill let you know what I think, but the price was right.

Dave
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Damned ijjit!

Online Vixen

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Re: 1909 Mercedes Aero Engine
« Reply #83 on: January 14, 2019, 03:47:36 PM »
What is the opinion of the spring pressure required to close the valve. Obviously, too low a spring pressure will lead to problems at higher speeds, whereas too high a spring load will just beat up the valve gear to no performance benefit.
So what is the ideal range of spring pressure?
You can lower the spring rate by increasing to number of turns, or by increasing the coil diameter or by using thinner wire. But you need to know what spring rate you need to achieve

Mike
It is the journey that matters, not the destination

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #84 on: January 14, 2019, 08:59:43 PM »
How does that actually work?

Jo
Hi Jo.

The knurled thumbwheel tightens the polythene disc onto the wire to set the tension. The tapered disc sets the pitch by controlling the distance between the coils. I put a cross hole in the mandrel to trap the wire and then wound it two turns by hand holding the tool just off the surface. This gave me the closed end. I then put the side of the disc against the first coil and ran the lathe for 7 turns (A bit of tape on the chuck helps here!). Finally, I pulled the tool off the surface and wound it another 2 1/2 turns to get the closed end coils before backing it off half a turn and then cutting the wire at the cross hole with the Dremel. I'm sorry the photo doesn't quite show the position of the tool during the wind but I ran out of hands trying to take the picture! Is that clearer?

I must say that it did take a bit of practice. I spent 14 hours making the tool and then a further hour practicing and making the final components. Now I have to find somewhere to keep it for the next time!

Steve   :)

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #85 on: January 14, 2019, 09:03:59 PM »

What significance do the numbered radial marks on the plate have?

Tug
Hi Tug.

The numbers are the thickness of the disc at that point in millimetres and run from 1 to 5. By slackening off the dome nut, the disc can be rotated to the required thickness. These springs were made with the minimum 1mm gaps so if I want to make anything smaller, I think I will have to make a thinner disc. To be honest, it could usefully be case-hardened as the edge is showing some signs of distress where the mandrel rotated against it.

Steve   :)

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #86 on: January 14, 2019, 09:11:44 PM »
You can even buy these ready.

Thanks for the link. I didn't find the ready-made variety and had to resort to making my own although the design was mentioned in the Model Engineer many years ago.

The carriage feed doesn't come into this process as the pitch is set entirely by the disc thickness. I did toy with the idea of a tensioner in the toolpost but this kit did make an acceptable Christmas present selection for Dad to get!

Steve   :)

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #87 on: January 14, 2019, 09:15:32 PM »
What is the opinion of the spring pressure required to close the valve.
Mike

Hi Mike.

I don't have any feel for the spring pressure required to close the valves. The drawing just quotes an OD, wire size and length without specifying the pitch. This will be a suck-it-and-see exercise. Fortunately, I only want it to run and do not intend to fly it or even fine tune it for maximum power. My ideal is smooth, low speed running!

Steve   :)

Offline Jo

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Re: 1909 Mercedes Aero Engine
« Reply #88 on: January 14, 2019, 09:26:35 PM »
Thanks Steve, I think I understand  :thinking: As usual I am looking for something less obvious  :facepalm:

Jo
Usus est optimum magister

Offline dieselpilot

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Re: 1909 Mercedes Aero Engine
« Reply #89 on: January 14, 2019, 10:24:00 PM »
Oh boy, yeah it should have been apparent from the knurl that this tool is hand held.