Author Topic: 1909 Mercedes Aero Engine  (Read 19464 times)

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 10237
  • Central Massachusetts, USA
Re: 1909 Mercedes Aero Engine
« Reply #150 on: February 18, 2019, 12:11:53 PM »
Sorry to hear and see this Steve, glad you're not hurt.  Its frustrating, but parts can be replaced...eye's and fingers cant

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13584
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: 1909 Mercedes Aero Engine
« Reply #151 on: February 18, 2019, 12:59:29 PM »
That can be frustrating Steve. Hope today will go better for you.

Bill

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3634
  • Portland, Oregon, USA
Re: 1909 Mercedes Aero Engine
« Reply #152 on: February 18, 2019, 06:04:56 PM »
I feel for you, Steve!  I've done that before and it never feels good.  :'( But you picked an excellent course of action.  Stop for the day and come back later.  You'll feel much better about it in a few days.  But as you say, its just a part of the hobby.  And, as Dave said, parts and equipment are replaceable.

Kim

Offline Old Bill

  • Full Member
  • ****
  • Posts: 100
Re: 1909 Mercedes Aero Engine
« Reply #153 on: February 19, 2019, 09:05:26 AM »
Thanks for your sympathy. What irks the most is that it was entirely avoidable and due only to my carelessness!

Damage repaired and I had enough material in stock for another. As the rods are 72mm long and the material comes in 300mm lengths, I was tempted to buy only one length but discretion being the watchword, I bought two. I was also fortunate to find another good end mill in the drawer so all was not lost and I soon had them all roughed out.



Now it is just a filing job. I turned up some buttons for guidance and away I went.





The fun bit now is the dipper to pick up the oil.





Now to profile the rest and give them some finish. Hopefully, no more excitement for a while!

Steve  :)


Offline Old Bill

  • Full Member
  • ****
  • Posts: 100
Re: 1909 Mercedes Aero Engine
« Reply #154 on: February 20, 2019, 10:20:50 AM »
Started the day by finishing the con rod profiles.



Little end bushes.



Big end bushes.



There is insufficient room inside the crank case for split big-ends so the rods are one-piece and have to be fitted whilst pressing the crankshaft together. This gives the interesting challenge of pressing it together true and straight, correct first time.



Centre bearing bush. This is drawn plain but again, there is no way of retaining it. I reckon there is enough space for flanges on each end so I have made it thus. We shall see whether it fits in a moment!







I found a large bronze bolt in the drawer so I have turned the end bearing from that.



This one carries a thrust face to carry the airscrew axial load. I have deliberately left it over-thickness so I can adjust it on assembly. Interestingly, the plain end protrudes beyond the end of the crank case and into line with the timing gear so the casting may be a bit thin here. I may have to trim the end back but we shall see.





One more bush and then it is time to start on the crank!

Steve   :)


Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 10237
  • Central Massachusetts, USA
Re: 1909 Mercedes Aero Engine
« Reply #155 on: February 20, 2019, 11:05:27 AM »
It's looking great Steve!   

Can't wait to see the crank!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3946
  • Switzerland
Re: 1909 Mercedes Aero Engine
« Reply #156 on: February 20, 2019, 12:53:41 PM »
Looking good  :praise2:  :praise2: I'm glad you recovered quickly from the little mishap  :wine1:
Best regards

Roger

Offline bent

  • Full Member
  • ****
  • Posts: 404
  • Wet side of Washington State, USA
Re: 1909 Mercedes Aero Engine
« Reply #157 on: February 20, 2019, 08:38:38 PM »
"the rods are one-piece and have to be fitted whilst pressing the crankshaft together. This gives the interesting challenge of pressing it together true and straight, correct first time."

!!!  :headscratch: :noidea:

Wow.  Following/lurking with interest.

Offline Old Bill

  • Full Member
  • ****
  • Posts: 100
Re: 1909 Mercedes Aero Engine
« Reply #158 on: April 06, 2019, 10:14:20 PM »
Well, I'm back! Life can rather get in the way some times and this hasn't been helped by my writing off my car. Apart from the car, the only damage was to my pride but that hurts! Anyway time to get back in the shed.

All three bearings in and the bar turns sweetly



I drilled three holes in the centre bush. The two end ones are for oil and the centre to engage with a peg in the crank case to prevent it from rotating.



Now onto the crankshaft. Lay out all the material and then start on squaring up the webs.











The the crank pins. These should be a simple turning job.





Unfortunately, I overcooked them a bit and they were only a firm push fit. Rather than make a complete new set, I decided that I would push them all together with Loctite. If it doesn't work I will have another go, half a thou bigger next time!



The front end of the crankshaft has a 1:10 taper to seat the propellor boss so I set that up by clocking along a piece of silver steel with the topslide set over. It only took a couple of goes to get it perfect.





Then a keyway for the timing gear and propellor boss.



The piece of aluminium on the left is a jig to hold the pin square whilst pressing it into the web. Pressing it all together true is going to be quite a challenge and I need all of the help I can get.







Trying to keep it all true using the angle plate which has a convenient slot to dodge the big end.







Half a crank in the lathe to check the alignment. It was a couple of thou out but a good push with the thm soon brought it into line.



Now the other end.





Another alignment check and adjustment.



The final push





The moment of truth. As expected, it was not perfect but 0.010" out. I took a slightly brutal approach and jut put it back in the press to give it a push!





Actually, this worked although it did take me three hours to get it good enough. It is now within 0.001" eccentric which I think I can live with.



The next problem was that it didn't actually fit in the crank case! Fortunately, there was enough meat to allow me to make some more space.







Bingo!



Just skim the bearings to length and it is all beginning to look promising.



Machine the sump to match.





A crank case with crankshaft which rotates!



That job has been bugging me for a while but I think I have it now. Propellor boss tomorrow and then I can spin it.

Steve  :) 

Offline Ye-Ole Steam Dude

  • Full Member
  • ****
  • Posts: 1424
  • Deep East Texas on Sam Rayburn Lake
Re: 1909 Mercedes Aero Engine
« Reply #159 on: April 06, 2019, 10:42:36 PM »
Hello Steve,

Looking really good  :ThumbsUp:

Have a great day,
Thomas

Offline Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 12537
  • Hampshire, england.
Re: 1909 Mercedes Aero Engine
« Reply #160 on: April 07, 2019, 07:23:57 PM »
Well, I'm back! Life can rather get in the way some times and this hasn't been helped by my writing off my car. Apart from the car, the only damage was to my pride but that hurts!

I was wondering only yesterday if you had done any more on this model Steve. Nice to see the crank together  :)

Shame about the car think positively it means you have an excuse to buy yourself another one  :naughty:  Lets be honest writing off a car like my old Pug is easy I think a scratch in the paint would do it  ::)

Jo
Usus est optimum magister

Offline sco

  • Full Member
  • ****
  • Posts: 1620
  • Location: Northants UK
Re: 1909 Mercedes Aero Engine
« Reply #161 on: April 07, 2019, 07:41:12 PM »
Great work on the crank Steve, filing away all your assembly methods for when I get round to mine!

Simon.
Ars longa, vita brevis.

Offline Old Bill

  • Full Member
  • ****
  • Posts: 100
Re: 1909 Mercedes Aero Engine
« Reply #162 on: April 07, 2019, 09:17:32 PM »
I wouldn't follow me too closely, Simon. More treat it as a way of avoiding some pitfalls!

Yes Jo. I have now had a new car for a week and got a speeding ticket for it in the post yesterday! Not having a good month!

Anyway, back to the engine. The propellor flange is mounted on a taper on the end of the crankshaft. Whilst the tool was set over for the crank, I took the opportunity to turn a bit of silver steel to use as the reamer for the flange.







I hardened the thing out and then just polished the edge with a whetstone.



The flange was just a turning job although getting the tapered hole in the back square to the front face was fun. In the end I machined the front first and then pushed it hard against the chuck whilst I step-drilled it, reamed it and cut the keyway.











It all worked well and I could push it onto the end of the crank. Now I can turn it and I must say that I am very pleased with the outcome. It it smooth and slightly tight with newness rather than binding. A good outcome.

Now, onto the pistons. I decided to do them in pairs, crown to crown.





After doing one end, I reversed the piece and held the new piston in the collet chuck whilst I turned the other end.





Here is a new purchase in the shape of a collet chuck with a base that can be held in the vice. This is my first use of it and I must say that it made life easy.









Two pairs of pistons ready to part off.







Four pistons, machined to length and a reamer through the gudgeon pin holes.





Gudgeon pins next and then I can see if they go up and down!

Steve  :) 


Offline Admiral_dk

  • Full Member
  • ****
  • Posts: 1356
  • Sųften - Denmark
Re: 1909 Mercedes Aero Engine
« Reply #163 on: April 08, 2019, 09:41:14 PM »
Nice progress + I like that you could straighten the crank so it runs as it should - always a potential problem with buildup cranks  :ThumbsUp:  :cheers:

Offline Old Bill

  • Full Member
  • ****
  • Posts: 100
Re: 1909 Mercedes Aero Engine
« Reply #164 on: April 14, 2019, 10:12:24 PM »
Next job was the gudgeon pins. They are silver steel again with bronze inserts in the ends to avoid scoring the bores. I pressed the bronze plugs in the ends and then turn the assemblies to length.







A this point, I found that on tdc, the block was lifted off the crank case! I checked the lengths of the bores and found them to be OK. Then I made a dummy piston on a piece of rod and tried it in the bores. It appears that the liners have all squeezed in a couple of thou at the top. To get over this, I thought I would just taper the top of the piston above the ring so, as a trial, I used some emery paper on the top 2mm of the dummy piston and it did the trick. I then went back and did the same to the working pistons and all was well. Another hurdle overcome!





So I could now get the pistons to the top of the bores. However, the crank would not turn past the 3 o'clock / 9 o'clock position. A look inside revealed that the sides of the rods were touching the crank case and the bottom edges of the bores. That took some carefull work with a needle file to sort out.





It turns!



Now onto the rings. I had never made rings before so I approached this with some trepidation. However, in the end, they turned out to be quite straightforward.





I parted one off as a trial first to check the thickness and then use to sort out a process of breaking and then heat treating them.



Thickness was right first time but I was puzzled about how to split them.



Well, that didn't work!



I found that a cold chisel just gently tapped over a vee did the job nicely.



The heat treatment had been worrying me but I was told just to spring the ring out to the required size and place over a piece of steel before heating to bright red. You will see the ring relax after a few seconds at that temperature so then just let it air cool. Surprisingly, that worked a treat and I was very pleased with the outcome.







It fits! Actually, I had to trim the ends with a needle file to allow the ring to close down sufficiently at the top of the bore but it was all very satisfactory.



I parted off more rings until I had run out of bar and then treated them in the same way.





The crank now turns smoothly with four pistons and four rings fitted. A bit time consuming but very satisfying.



The question now is what am I going to do next? Probably oil filler and breather for a bit of light relief.

Steve  :)