Author Topic: 1909 Mercedes Aero Engine  (Read 21357 times)

Online sco

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Re: 1909 Mercedes Aero Engine
« Reply #180 on: May 08, 2019, 10:19:32 PM »
Great work Steve - love the look of the exhaust locking collars!

Simon.
Ars longa, vita brevis.

Offline Jo

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Re: 1909 Mercedes Aero Engine
« Reply #181 on: May 09, 2019, 12:35:34 PM »
Looking good Steve   8)

Are you running on glow plugs or spark ignition? I am coming to that stage fairly soon but the drawings are a bit thin on detail. They do show a contact breaker and distributor but no clues as to how to produce the HT. I could really do with some guidance in that area. The contact breaker is a hall switch but I know it doesn't have the capacity to drive a coil directly so I should very much appreciate your thoughts. In fact, I shall make that a general question for all of my friends here. Someone will know!

The two engines I have seen running have used a distributor and spark plugs. I am planning to use my ignition box I built from Mini Mag   :)

Quote

In the model, the pump is mounted on the end of the crankshaft. The drawing shows two M2 tapped holes in the back but I cannot see what they might be for. They are aligned with the joint line between bush and housing and there is no way of getting a bolt through from the back. Lars, how have you mounted your pump?

I would guess those are clearance holes and you need to tap the crankcase to fix the pump in place, maybe countersunk screws  :thinking: Looking forward to seeing your solution.

Jo
Usus est optimum magister

Offline Jasonb

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Re: 1909 Mercedes Aero Engine
« Reply #182 on: May 09, 2019, 01:20:24 PM »
The hall sensor gets tripped by the 4 magnets, you wire the sensor back to your chosen ignition be it TIM-6, one of Mini-Mags or S/S's box of tricks and the live wire back from the ignition unit goes to the central screw in the distributor which then sends the spark to the relevent plug via one of the 4 screws in the distributor.

Offline Lars

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Re: 1909 Mercedes Aero Engine
« Reply #183 on: May 09, 2019, 01:59:04 PM »
Steve,

Yes of course!  I'll post some pictures this evening when I am home from work. I'll make sure to include some of my failures.

I was very excited when I yesterday finally saw someone building the same engine. To me it has been a quite tough build based on the fragile nature and small size required of bolts etc.
Also I have had to make steel inserts for the plug threads, the aluminum casting thread was ruined following a few assembly/disassembly cycles.   

The waterpunp I mounted with two countersunk M2s or if it was M2.5s, I'll take a picture of my solution on this one as well. This connection between the waterpunp housing and the end of the engine case is not the best, I had very little material to drill/tap in I remember.

Lars


Offline Lars

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Re: 1909 Mercedes Aero Engine
« Reply #184 on: May 10, 2019, 12:30:24 AM »
Steve,
Some more pictures of my build as I promised. I also included some descriptions on my build. I think you are doing a marvelous job on yours, I wish I had been in contect with you earlier!

I'll dig up more photos from the actual machining as well. I broke my phone a year ago (well.. actually it 'fell' very hard to the floor realizing we had made a mistake on the concrete pour on my holiday house I am building this year, so I have to figure out how to retreive some of the pictures from the backup one of these days)

- The block was fairly straight forward. Hard to get a grip on though I thought :). Boring went OK, I also had some chattermarks on the entrance of each bore.

- Crankshaft is press-fit and riveted through all connections. Not sure that is neccessary. Honestly I also put some loctite in there but I doubt very much got wettet in the end in due to that press-fit was fairly tight)
I chose to machine the center bearing surface after pressed togehter (see pic). Machined very slowly it was more of a rub to get the center aligned with the end bearing surfaces.
This is the reason I have a split in two-halfs center bearing, I also wanted to be able to change the bearing

- Pistons and piston rings more or less excectly as your build. When expanding the rings I had a water-bath below when heating the rings, that way when they stress-relaxed and fell of the fixture they got immediately quenched and hardened. Then I just annealed them by feel.

- Bearings etc: I also have pins to locate and fix the bearings & chamfered and drilled them for lubrication, nothing really intereting about those.  For the camshaft I drilled and tapped holes for set-screws to fix those bearings. I did include a spacer between the first cam and the bearing to automatically fix the shaft axially.

- Cylinder liners: Here I did something I regret. I made the liners stick out 0.05" approx from the bottom of the cylinder block. I did this to center the cylinders in the block in a good fashion. The problem I had was the connecting rods interfered and 3 and 9 o'clock and wanted to lift the cylinders so I had to grind the a chamfer into the liners after a press-fitted them. Didnt realise this until I was assembling the engine with pistons. 

- Rocker Arms: I wanted to really make them look slim and like forgings, and I had an idea that they would look unproportionally big (fat) if I machined them out, so I ended up silver-soldering each rocker out of 4 pieces (see pic). Not sure that was worth the effort in the end, but they look ok and works well.

- Carb: Here I made my own casing instead of using the aluminium casting block. I did this just because I thought it looked better in steel.  The carb was somewhat of a pain I thought and ate up some spare drills for those really small longbore holes. Still not sure the carb works 100% as I do not have the engine running well yet.

-Exhausts: Here I silver-soldered two pieces together to get a sharp bend. I may redo these as I think I like plain tubes better,but focus is to get it running good first. The lock nuts were just milled out

- Valves: I made the shaft of the valve in regular steel and the sealing surface is stainless (soldered to the shaft). Then machined. I do have an issue getting them to seal 100%. This is largely (I think) due to my own fumble, as when I had lapped all valves I managed to tip out the assortment box I sued for the valves onto the floor so everything was mixed up. I then re-lapped them but I may have ruined the surfaces. I am currently re-lapping a couple of valves that I know leaks to see the result

- Ignition: I am currently using glow plugs. The idea is to get the settings of the carb worked out with glow and then focus on creating a working spark ignition. I am using regular fuel though, not glow fuel. But O dear do 4 glowplugs require alot of current! Sideproject is going to be creating a stable flow of voltage through regular power outlet transformation.

- Water cooling: Silversoldered tubes on the inlet and outled with a nut connection to the waterpump and future cooler (I have no cooler yet).

Well that is at least a short summary of my approach on this engine, it has been a really fun build so far!
I also include som pictures below (two posts).

Thank you guys and all the best!

Thank you

Offline Lars

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Re: 1909 Mercedes Aero Engine
« Reply #185 on: May 10, 2019, 12:32:02 AM »
more pictures

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #186 on: May 10, 2019, 01:00:19 PM »
Thanks Lars. That's wonderful! I am away for a couple of days but will reply properly on Sunday!

Steve  :)

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #187 on: May 12, 2019, 09:31:58 PM »


I would guess those are clearance holes and you need to tap the crankcase to fix the pump in place, maybe countersunk screws  :thinking: Looking forward to seeing your solution.

Jo
[/quote]

Yes, my initial thought was that they should be for countersunk screws but they are drawn as tapped holes which is a puzzle. Their position doesn't allow for a screw head inside so. If I had thought about it earlier, I would have made the crankshaf a bit longer to allow me to have a heavy flange on the bush into which I could tap holes for the screws in a better position. Too late now! I'm sure something will come to me, probably at four in the morning!

Steve

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #188 on: May 12, 2019, 09:34:46 PM »
The hall sensor gets tripped by the 4 magnets, you wire the sensor back to your chosen ignition be it TIM-6, one of Mini-Mags or S/S's box of tricks and the live wire back from the ignition unit goes to the central screw in the distributor which then sends the spark to the relevent plug via one of the 4 screws in the distributor.

Thanks Jason. The bit which puzzled me was what to put between the Hall switch and the distributor. However, I went to the Doncaster show yesterday and had a chat with the Minimag people. They have sold me a box of tricks which, when fired by the switch will in turn power a coil to give me the HT. I can see a solution clarifying through the fog!

Steve  :) 

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #189 on: May 12, 2019, 09:44:50 PM »
Thank you Lars for taking the trouble to post so many photos and write such a clear explanation. They are most interesting and it is great to see how you have tackled the same problems. Your finish is much better than mine. You obviously have more patience! Your rockers are very nice indeed. On the few engines I have seen in photos they are very heavy and, you are quite correct, they just don't look right.

I did consider machining the centre journal on the crankshaft but couldn't see how to do it with the con rods thrashing around. As you can see, I took the brute force approach and just bent it into line! How did you avoid damage to the rods?

Your exhausts give a neat solution. Bending 8mm tube so tightly for them, as drawn, is going to be hard and the inlet manifold has the same issue. I am pondering them at the moment.

Thank you so much for your pictures. I really look forward to hearing how you get on with running it!

Steve   :cheers:

Offline Lars

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Re: 1909 Mercedes Aero Engine
« Reply #190 on: May 13, 2019, 11:32:37 AM »
Thanks Steve! Not sure at all that my finish is better. Thats the good thing about the 1024 picture limitation, you can't upload hi-res  :ROFL:

When machining the mid bearing surface on the crank I just let the rods slide on the support. Not optimal but with some regular tape as protection on the support I avoided scratching them.

I am curios to see your compression. It is a low compression engine but I still am a little worried on that from my end.

When I started (well tried to) it the first time I did not get it to self-sustain fireing. It fired on a couple of cylinders, which gives me hope, but still have a long way to go.

One thing I have to redo is the glow power, I am having a mains-driven glow driver board made from a friend to secure I have good glow on all 4 plugs for an extended period of time. When starting for the first time the batteries I had soldered together went out too fast.
The other item on the list is to relap some of the valves as I could hear and feel at least one exhaust valve leaking too much

Yes the inlet tubes were done several times.....in the end  I heated, bent until it was deformation hardened, heated, bent, heated bent until I had the shape I wanted.

I'll keep you updated on the progress. I hope to have 10 more hot (short thread, regular thread interfered with the pistons on my build) glow plugs in the mail today. I have scrapped 10 already trying to get my glow power sorted

Lars


Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #191 on: May 22, 2019, 09:17:02 PM »
Thanks Lars. It is always great to hear how other people do things! With respect to compression, I don't know yet as I have not assembled it and lapped the valves. I am leaving the final assembly process to the end so I only get one go at damaging the paintwork. Well, that's the theory!

I have been thinking about bending the exhaust pipes and the inlet manifold. They are 8mm tube bent to quite tight radii which I can't do with my normal bender so I have made up a mandrel pipe bender to see if that will work.



That was a nice job to do and quite satisfying, being made from bits lying around. This one shows it with the first trial bend in place.



It came out quite promising but there was a definite flat on the outer face.





Looking at the bullet on the end of the mandrel, you can see that I had it just a little bit too far back. The full diameter needs to be just a whisker to the right of the centre line of the roller. I adjusted it over and had another go.



That worked well so I started getting cocky and put another bend in at 90



Now spot the deliberate mistake! How on earth do I dismantle it all?



I eventually got it apart and am quite pleased with the results. That is 8mm central heating tube bent to a centre-line radius of 12mm. It is much thinner than the photo suggests as I was lazy with my de-burring after using the tube cutter.



Now I must use it to do some more engine.

Steve   :) 


Offline Vixen

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Re: 1909 Mercedes Aero Engine
« Reply #192 on: May 22, 2019, 09:40:43 PM »
Hi Steve,

That's a neat little pipe bender. Some nice tight bends.

The trick seems to be in positioning the bullet in just the right position to prevent the tube flattening?

Do  you anneal the copper pipe in the bender or before you start?

I need to make one of those for my Mercedes W165 exhaust manifolds.

Mike
It is the journey that matters, not the destination

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #193 on: May 22, 2019, 09:55:23 PM »
Hi Mike!

Glad you like it. Nothing to it really. I have now done precisely three bends so my experience is limited. However, my thoughts at the moment are that the bullet position is important and it needs to support the inside of the tube at the bend point. I started with it too far back so the tube pulled after it had cleared the end, resulting in a flat. The backing block needs to be pushed up quite hard as well so that there is no gap between it and the mandrel giving the tube no room to spread. The tubing I have used as it came but it is already soft. If it were hard, I would anneal it first. My exhaust pipes will be brass but that is quite hard so I will anneal that before I try leaning on it. I will post a report this weekend once I have had a proper go!

Steve  :)

Offline Vixen

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Re: 1909 Mercedes Aero Engine
« Reply #194 on: May 22, 2019, 10:11:09 PM »
Hello Steve,

What brass tube are you proposing to use? Is it the hard, thin wall K+S hobby tube? I will be interested to see how you get on

Best

Mike
It is the journey that matters, not the destination