Author Topic: Two Cylinder Engine  (Read 19650 times)

Offline Roger B

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Re: Two Cylinder Engine
« Reply #180 on: June 20, 2019, 08:04:05 PM »
Another problem  :( I case hardened the camshaft together with a couple of head gasket punches. Whilst I was polishing the camshaft with emery cloth in the lathe it snapped off  :facepalm:

The broken face had the same even grey finish as first time so my piece of free cutting MS was obviously not what I thought it was  :toilet_claw:

I took a selection of pieces of 10 - 12mm diameter steel and parted off 1mm thick discs. The first two I heated to dull red and then quenched. They were clamped to half diameter in the vice and bent. Both failed with brittle fractures. The next sample machined nicely and I tried it first without heat treatment. It bent but cracked, after heat treatment the result was similar. The last sample was not so nice to machine but bent without cracking.

I obviously need to keep my material stock under better control  :headscratch: and learn how to analyse the grinding sparks  :thinking:
Best regards

Roger

Offline Ye-Ole Steam Dude

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Re: Two Cylinder Engine
« Reply #181 on: June 20, 2019, 08:31:22 PM »
Hello Roger,

Sure hate to see that happen to you, it can be frustrating when you get faulty material or mislabeled material.

Have a great day,
Thomas

Offline Roger B

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Re: Two Cylinder Engine
« Reply #182 on: June 24, 2019, 06:47:35 PM »
Thank you Thomas  :ThumbsUp:

Better luck this time  :) I selected a piece of free cutting MS which had a noticeably better finish after milling the cams, very little polishing was required.  After case hardening a little finger pressure was required to reduce the runout to less than 0.05mm and it assembled and turned freely  :whoohoo:
Now I can set the timing and make the pushrods  :)
Best regards

Roger

Offline Admiral_dk

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Re: Two Cylinder Engine
« Reply #183 on: June 24, 2019, 09:51:45 PM »
Nice to see that you have progress again  :cheers:  all the more important as this engine hass to earn it's keep.

That said - I truly know the feeling ; Yeah I finally moved forward - only to realize that this has to be followed by two (or more) steps backward  :???:

Best wishes

Per

Offline fumopuc

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Re: Two Cylinder Engine
« Reply #184 on: June 26, 2019, 09:32:12 PM »
Hi Roger, finally a perfect result. Congratulations. I have to learn these cam lobes milling to.
Kind Regards
Achim

Offline Roger B

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Re: Two Cylinder Engine
« Reply #185 on: July 07, 2019, 07:49:25 PM »
Thank you both  :ThumbsUp:

A little bit more workshop time. I made a head gasket so I could confirm the length of the push rods. They were then cut from 2mm music wire (with side cutters) and then rounded on the bench grinder. The cam timing and sequence was checked and the keyways were cut in the two 40T gears. I put the spark plugs in and was happy to find reasonable compression on no 2 cylinder considering that there are no piston rings and the valves have not been lapped yet  :)

The next step is the inlet and exhaust manifolds. The exhaust need a couple of bends so I tried bending some 6 x 5.1 brass tube with my old Girling former. This was annealed first and then bent by hand around the former. The bends were somewhat flat so I carefully squeezed them back to shape using some aluminium jaws in the vice. Not perfect but should work  ::)
Best regards

Roger

Offline Kim

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Re: Two Cylinder Engine
« Reply #186 on: July 08, 2019, 05:26:46 AM »
Lots of nice progress there, Roger!
2mm seems really small for a push rod - any danger of it bending rather than pushing?

The bends in your brass tube look great!  It can be hard to get those done with the tube coming out anywhere near round, and yours look quite good to me.

Kim

Offline Roger B

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Re: Two Cylinder Engine
« Reply #187 on: July 11, 2019, 06:23:20 PM »
Thank you Kim  :)

The push rods (and most of the valve gear) are copied from my single cylinder vertical engine which will rev to around 10 000rpm so no problem.
Best regards

Roger