Author Topic: 1909 Mercedes Aero Engine  (Read 2152 times)

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #30 on: November 29, 2018, 09:50:41 PM »
Thank you Jo and Jason. Plenty of food for thought there. The one that is challenging me is how to put the middle hole in for the cam shaft as I can see it wandering all over the place. The hole will go through the joint line between the casting and the bearing cap and i don't suppose that they will be flush. No doubt it will become obvious in due course.

Steve   :) 

Online steamer

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Re: 1909 Mercedes Aero Engine
« Reply #31 on: November 30, 2018, 12:20:44 AM »
Thank you Jo and Jason. Plenty of food for thought there. The one that is challenging me is how to put the middle hole in for the cam shaft as I can see it wandering all over the place. The hole will go through the joint line between the casting and the bearing cap and i don't suppose that they will be flush. No doubt it will become obvious in due course.

Steve   :)

Drill undersize, and then bore the middle.   Start with a good stiff spotting drill, and it won't wander around.   Boring bar will bring it to size and assure proper position...a drill just makes a hole.

Dave
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Offline Jasonb

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Re: 1909 Mercedes Aero Engine
« Reply #32 on: November 30, 2018, 07:21:20 AM »
Get yourself a long series centre drill, or loctite an 1/8" one in the end of a bit of rod.

Though a small amount of wander won't be so critical as unlike reaming the between ctrs bar won't try and follow the hole.

Offline Jo

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Re: 1909 Mercedes Aero Engine
« Reply #33 on: November 30, 2018, 07:10:03 PM »
The one that is challenging me is how to put the middle hole in for the cam shaft as I can see it wandering all over the place. The hole will go through the joint line between the casting and the bearing cap and i don't suppose that they will be flush.

The cam is in solid metal, the crank on the joint line - Yes highly unlikely the two bits will be flush  :facepalm: Maybe file/grind the two castings as close as you can true then drill undersized and bore a little more off between centres. At least on the crank you have more to play with so can use a larger diameter boring bar to keep it true :)

Jo

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Online Vixen

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Re: 1909 Mercedes Aero Engine
« Reply #34 on: November 30, 2018, 07:36:19 PM »
+1 for ensuring the two castings a truly flat and fit correctly BEFORE you drill and bore the journals. Use some engineers blue to test for flat and fit.

Mike
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Offline Jasonb

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Re: 1909 Mercedes Aero Engine
« Reply #35 on: November 30, 2018, 08:08:45 PM »
Fot the two part crank ctr bearing You could bolt on an over width cap and then mill either side of the cap and the part in the main casting to flush up both sides and bring to final width.

I assume there is a boss cast in for the cam ctr bearing which you should be able to mill the sides of with a small cutter.

You can always but a facing cutter into the between ctrs boring bar to flush things up after pilot drilling.


Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #36 on: November 30, 2018, 08:23:27 PM »
You are quite right, Jo, the camshaft goes through a solid divider in the middle of the crank case. It is in the corner though so it will take a bit of care.

I like the idea of the extended centre drill. I did buy an over-length one but it is just not quite long enough. Lots of good ideas and thoughts here.

Many thanks,

Steve

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #37 on: December 01, 2018, 10:38:04 PM »
Now that I have a crank case, I thought I would have a go at the cylinder blocks. Again, these are most awkward castings to hold!





There are very few good datum faces on the things so I held them by the base flange in the vice and took a skim across the top.



Then turned them upside down and dogged them to the table. This worked out OK but there is very little meat on the base flange so  so I had little room to manoeuvre.



I skimmed them to height across the base and then ran around the periphery to clean to size. Using the wonderful edge finder, I datumned off the corner and drilled the stud holes. Then it was simply a case of boring to depth, or so I thought....





One core was slightly off-set so the casting only just had enough metal to clean. What I didn't realise until later was that I hadn't quite got the casting upright when I skimmed the top and, of course, this compounded the core problem. To clean up properly, I have bored it oversize by 1.5mm and will have to make a thick liner. Not insurmountable but annoying carelessness on my part.





Still, at least the stud holes lined up!



Then the next googly. The dummy core-plug bosses fouled so that I couldn't put the blocks close enough to bolt them both down.



These were removed and I polished the ends with a needle file so that you wouldn't know they were missing.



Well, it is beginning to look like an engine, anyway!



The centres of the blocks need to be in line so that the rocker shaft lines up across the tops. First job was to find a centre line. This was another puzzle due to the difficult shape. However, With the base flange on one parallel and a second underneath a clean part of the water jacket, I scribed an approximate centre line before turning the block over and repeating from the other side giving me two lines quite close together.



At least I can see the problem. One block lies 1.3mm out of line with the other.



Whilst I ponder what to do about it, I have removed the pattern marks.



Five minutes with the Dremel and that is something else ticked off.



I have been out playing trains today and have guests tomorrow but hope to pick the job up again in the week.

Steve   :)

Offline Ye-Ole Steam Dude

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Re: 1909 Mercedes Aero Engine
« Reply #38 on: December 02, 2018, 12:56:15 AM »
Hello Steve,

Looking real good. :ThumbsUp:

Have a great day,
Thomas

Offline Jo

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Re: 1909 Mercedes Aero Engine
« Reply #39 on: December 02, 2018, 09:36:19 AM »
 :thinking: Could you gently file the bottom clamping surface to adjust the angle to pull the top of the cylinder over in line?

I was allowed to fondle my cylinder castings this morning and there seems to be about 5mm top to bottom spare and 2mm on the clamping flange along its length. The width has nothing spare  :ShakeHead:

I know you have been aging your castings for a while Steve, I seem to recall the earlier cylinders did not have the water jacket cast in does yours? I don't think the slightly thicker liners will effect the water jacket  :)

Jo
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Offline Roger B

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Re: 1909 Mercedes Aero Engine
« Reply #40 on: December 02, 2018, 12:13:53 PM »
Excellent progress  :praise2:  :praise2:  and some fun challenges with the castings  :ThumbsUp:  :ThumbsUp:  :wine1:
Best regards

Roger

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #41 on: December 02, 2018, 07:51:34 PM »
Thanks Thomas and Roger. The moral support is always appreciated!

I had been thinking about just filing a slight run across the base but I would rather machine it if I can work out how to hold it.

These castings have the water space cast in and the liners are pressed in to seal. (Wet liners). The thicker liner will be fine and even if it is left a whisker leaning once I have skimmed the base, then that will be of no consequence. I hope to have an evening in the shed this week so we can see how it goes.

Steve  :) 

Offline Jasonb

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Re: 1909 Mercedes Aero Engine
« Reply #42 on: December 02, 2018, 08:15:08 PM »
machine a bit of 1/4 flat with the desired angle which can be done easily by packing in the vice or pack the base of the vice.

Now clamp it down onto your tapered packer as you had it for machining the underside and bores.

Alternative would clamp it down to the mill table with a feeler gauge under one side to give it some tilt. Or pack a solid steel plate with feeler gauge/shim stock to get teh angle an dclamp the head down onto that, less likely to mark the top as it will be supported over whole area.

Agree machining will give a far flatter surface then filing.

Offline Old Bill

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Re: 1909 Mercedes Aero Engine
« Reply #43 on: December 07, 2018, 05:46:41 PM »
Well, I have managed to find a couple of workshop hours this week and took the opportunity to bring the blocks into line. As Jason suggested, I took a piece out of the drawer and machined a run across it using some shim stock under the edge.



Then set it up and checked with the DTI to make sure it was right. (It wasn't!)



After that, it was quite simple.



Success!



Next job is to start putting some holes in the top so I have clamped a datum to the table to allow for quick setting up and movement should it be necessary.





The valve holes are partially cored in so I used a nice new slot drill as a pilot. One of the nicest things I am finding with this job is that I have put away a number of brand new cutters over the years and saved them for 'best'. Well, this is 'best'!



I have also treated myself to some new reamers as I don't have any metric tools. This one turned up on Wednesday, just in time. I am doing something wrong with it though as it 'picked up' in two of the holes despite my best endeavours to keep the flutes clear.



I also managed to mis-read my dials and get one hole 0.010" out of position which is annoying for the sheer carelessness. I should know better by now. Oh well. I shall have to take Jo's advice and treat myself to a DRO.

A few more holes this weekend with a bit of luck.

Steve  :) 

Offline Jo

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Re: 1909 Mercedes Aero Engine
« Reply #44 on: December 07, 2018, 06:13:03 PM »
 :)

A few more holes this weekend with a bit of luck.

 :o

Its the weekend Steve and you are thinking about machining a model engine  :hellno: The weather looks to be  good.... are you not going down to stroke one of your lorries?   :noidea:

Jo
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