Author Topic: Junkers CLM  (Read 15259 times)

Offline Michael S.

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Re: Junkers CLM
« Reply #45 on: June 03, 2023, 06:31:45 PM »
Hello Roger,
I checked the parts list. It is also just a paper copy. But maybe this will be of use to you.
If you need specific parts to view let me know.

Greetings Michael

Online Roger B

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Re: Junkers CLM
« Reply #46 on: June 18, 2023, 08:15:13 AM »
Thank you Michael  :ThumbsUp: That looks similar to the copy I have. I will let you know if I need any details. I will have to change a few elements of the design to allow for the small scale and for fabrication rather than castings.

On with the crankshaft. I have had to use a variety of tools for turning the crankshaft due to the small size of my lathe and the deep slots between the webs. The full stroke of the crankshaft is 65mm, the same as the centre height of the lathe  ::)

<a href="https://www.youtube.com/watch?v=nBqRCy_7ZXE" target="_blank">http://www.youtube.com/watch?v=nBqRCy_7ZXE</a>

The first section of shaft I turned ended up with a rather poor finish although the earlier cuts looked ok  :( This is not a critical problem as I still have 1 mm left for the finishing cuts. The set up will also be more rigid as the opposite shaft will be held in a collet chuck rather than between centres.

I received a parcel with a huge warning label stating 'Fragile' and 'Open immediately and check for damage'. The contents: 25mm and 35mm cast iron for the cylinder and pistons and aluminium plates for the crankcase  ::)
Best regards

Roger

Offline Michael S.

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Re: Junkers CLM
« Reply #47 on: June 18, 2023, 02:13:44 PM »
Hello Roger,
the crankshaft looks very good. 👍 For me, this is an exciting work process on this type of crankshaft.

And was something broken in the package?

Greetings Michael

Offline RReid

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Re: Junkers CLM
« Reply #48 on: June 18, 2023, 03:06:38 PM »
Crankshaft is coming along well. It's always fun to get small machines to a good job of big jobs! Just take care with that fragile cast iron.  :Lol: :ThumbsUp: :ThumbsUp:
Regards,
Ron

Offline Kim

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Re: Junkers CLM
« Reply #49 on: June 18, 2023, 04:46:31 PM »
Nice work on that one piece crankshaft!  That's a lot of material to remove on that spindly part! Nicely done  :ThumbsUp:

Nice to see that your fragile package arrived with all the CI in tact!

Kim

Online Roger B

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Re: Junkers CLM
« Reply #50 on: June 18, 2023, 08:11:40 PM »
Thank you all  :) Nothing in the package was damaged, it did not pass through the British Postal system or airport baggage handling  ::)

I changed to a DCMT tip and got a much better finish on the shafts, I think the original tip may have been worn or chipped but not visibly. Next I moved over to the Keats angle plate to finish the crankpins. The inlet (shorter stroke) ones were ok with a reasonable finish. Next the exhaust (longer stroke one).
Best regards

Roger

Offline Admiral_dk

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Re: Junkers CLM
« Reply #51 on: June 19, 2023, 10:12:04 PM »
Great to see that you have made progress, while I was on extended Weekend  :ThumbsUp:

A very interesting project  :Love:

Per   :cheers:

Offline cnr6400

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Re: Junkers CLM
« Reply #52 on: June 20, 2023, 12:50:38 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline Zephyrin

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Re: Junkers CLM
« Reply #53 on: June 21, 2023, 10:31:51 AM »
you've embarked on a great and very original project, and the crankshaft is already a feat!
I've found quite a bit of documentation in French on this engine, which seems to have been very popular here in agriculture and industrial locomotives...

https://wikimaginot.eu/V70_glossaire_detail.php?id=1000986
http://vieux.tracteurs.free.fr/pdf/moteur_CLM_type_LC_et_CR.pdf

Offline Admiral_dk

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Re: Junkers CLM
« Reply #54 on: June 21, 2023, 09:45:19 PM »
Thank you very much for the Service Manual Zephyrin  :LittleAngel:  :ThumbsUp:

That explains a lot more than what I've seen so far + much more if I understood French better  :embarassed:

Per               :cheers:

Online Roger B

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Re: Junkers CLM
« Reply #55 on: June 23, 2023, 08:53:39 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: Thank you for those links Zephyrin  :) :) CLM and Peugeot seemed to produce a lot of these engines in smaller sizes, Junkers developed them as the Jumo aircraft engines  and Napier then produced the 18 cylinder Deltic.

There are some interesting features of the design. The two different length strokes seem to give a balance to the engine that I have not really analysed:

<a href="https://www.youtube.com/watch?v=yi2XD8PY5dk" target="_blank">http://www.youtube.com/watch?v=yi2XD8PY5dk</a>

The exhaust crankpin was clocked true and finished to 12mm and then on to the oilways. The 2.5mm dia. 57mm long holes through the shaft were my biggest worry but they were ok. As the stroke on my tailstock is only 40mm there was a lot of sliding in and out to clear the swarf. The only big problem was drilling one of the inlet crankpins, the drill dug in when breaking through but luckily just bent.
Best regards

Roger

Online Roger B

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Re: Junkers CLM
« Reply #56 on: June 23, 2023, 08:56:15 PM »
Reaching some of the holes required a variety of tools and threading for M3 grub screws will also be fun  ::) I think I will have to make a special tap holder for the inlet crankpins  :thinking:
Best regards

Roger

Offline Kim

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Re: Junkers CLM
« Reply #57 on: June 23, 2023, 10:13:48 PM »
Ouch on the bent drill bit, Roger!  Glad it didn't ruin anything!

Were you able to straighten it and use it more? Or did you have multiples of that drill in stock?

Kim

Offline Admiral_dk

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Re: Junkers CLM
« Reply #58 on: June 24, 2023, 09:26:22 AM »
Close call on the Drill Bit  :hellno: - glad it didn't ruin anything   :cheers:

The Crank looks to be very nicely staight and smooth  :ThumbsUp:

Per

Online Roger B

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Re: Junkers CLM
« Reply #59 on: July 06, 2023, 05:46:22 PM »
Thank you both  :)

I broke and then binned the bent drill, too much risk otherwise  ::) I bought 4 originally as I felt they would be 'disposable'. The next step was to tap the ends of all the oilways M3 for sealing grubscrews. As expected I had to make a special tap wrench for a couple of the holes. Finally I drilled the oil holes to the journals. This now defines the orientation and rotation direction for the crankshaft.
 
I have been thinking further about boring the liner. By the time there is a revolving tailstock centre and some means of driving the boring bar there is barely enough space. As it is not actually a single cylinder but two separate cylinders with a space between them I could bore from both ends in the usual way. With careful clocking of the outside of the liner any final errors would be removed by lapping.

The connecting rods have required some thought. Assuming a peak pressure of 80 bar the load per piston is 2500N. The exhaust piston (single) connecting rod is copied from my other diesel and should be ok. For the inlet piston (twin rods) this is 1250N per rod if all is balanced. For the bearings at the top of the rods I am looking at some model RC car units with a dynamic load of 1321N and a static load of 530N, a bit close but we will see what happens. The big end bolts will be M4 in a 6mm wide rod. The proof load is 5100N (8.8) which with 2 bolts per rod is fine. I could reduce to M3 with a proof load of 2920N (8.8) which still has a good factor of safety.
Best regards

Roger

 

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