Author Topic: Two Cylinder Engine  (Read 69315 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
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

Offline Roger B

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Re: Two Cylinder Engine
« Reply #188 on: July 19, 2019, 08:08:03 PM »
A little bit more on this one. I started some flanges for the plumbing and then found the jig I had made for the single cylinder engine was incorrect. The milling centre was set at 13mm rather than the radius so I had to make a new one.
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #189 on: July 19, 2019, 08:11:26 PM »
The exhaust bends were then cut to length and the joint was shaped with a selection of round files. After silver soldering it doesn't look too bad. Next step silver solder the flanges.
Best regards

Roger

Offline Kim

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Re: Two Cylinder Engine
« Reply #190 on: July 20, 2019, 12:08:26 AM »
Nice looking flanges & piping work, Roger!
Kim

Offline Craig DeShong

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Re: Two Cylinder Engine
« Reply #191 on: July 27, 2019, 10:05:13 PM »
Following along Roger with all the “ups and downs”.  Still lots of progress.  Look’in good!   :popcorn: :popcorn: :popcorn:
Craig
The destination motivates us toward excellence, the journey entertains us, and along the way we meet so many interesting people.

Offline Roger B

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Re: Two Cylinder Engine
« Reply #192 on: July 28, 2019, 09:54:04 AM »
Thank you both  :ThumbsUp:  :ThumbsUp:

I positioned the various flanges and silver soldered them in place. Luckily the exhaust still fitted  :) Next up was the starter coupling using a 6mm bore sprag clutch like on the single. Rather then using an edge finder to centre the grub screw hole I just used a 150mm ruler balanced on top.
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #193 on: July 28, 2019, 10:08:21 AM »
The carburettor adaptor was next. This is turned offset to give a little more material for the grub screw. The one for the horizontal engine was carefully set up in the 4 jaw independent chuck. This time as I found the same stub of 12mm brass I tried a quick and dirty version with a 2mm shim in the 3 jaw sc chuck. Close enough  :) The engine end was turned and drilled, then the blank was parted off and the hole for the carb was drilled. The finished piece was soft soldered onto on of the previously made pieces.
Best regards

Roger

Offline Roger B

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Re: Two Cylinder Engine
« Reply #194 on: August 26, 2019, 07:02:59 PM »
Back to a bit on this one. As the first runs are in sight I made a pair of engine bearer from 10mm square aluminium bar, similar to those on the single. Then as I was lapping the plunger on the injector test pump it was a good opportunity to lap in the valves and then put it all in the ultrasonic bath together.
The valves were marked with small dot punches on the head and were lapped with 20 micron diamond paste using a  small drill chuck as a handle. The seal was checked by fixing a pipe stub to each port and sucking. A leak is generally obvious. As the inlets are siamised they both had to be checked together.
Best regards

Roger

 

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