Engines > From Plans

Unusual Corliss

<< < (2/8) > >>

Caber:
Progress today drilling the valve bores. All the quarter inch stainless stock is seemingly just undersize so rattled in the test drilling reamed to quarter inch. My quarter inch drill however matched the stock so I drilled the holes to 7/64 then ran the quarter drill through very slowly which gives a very nice fit and finish in the bores is excellent. While on this set up I plan to drill the holes for fixing the valve caps.

Caber:
This weekend’s progress was a bit hampered by the installation of a new central heating boiler! What I have achieved is drilling the fixing points for the valve bonnets , all 32 of them and carving out the exhaust valve chest both exercises in learning the circle and array functions of my new DRO.

I also paid another visit to the NMS to look at the Corliss there. I am going to see if I can adapt the MEM design to look more like this engine. One aspect will be mirroring  the design so the valve gear and flywheel will be on the other side, the next task will be to rearrange the slide bar tunnel and connection to the main crank bearing. The final and most challenging  change will be replacing the wrist plate with a second eccentric and valve rod. If anyone who has built the MEM Corliss can tell me what the rotation angle of the valve is when the engine runs that would be a great help to determine the required  eccentric throw as there is no intermediate lever in this design!

Caber:
So I am some 16 hours of workshop time and have now drilled all the holes except cylinder covers into the cylinder block. Touch wood no broken drills or significant errors. The most nerve racking bit is the 20 holes for the steam ports. As these are in the curved surface of the valve guides I decided to create a flat area with a 3/32” end mill then went straight in with 1/16” drill. I used a sensitive drill attachment in a collet with an expensive sharp HSS drill which all went surprisingly well. Now a ton of tapping 6BA for the 1/8” holes and 9 BA for the 1/16” Experimenting on my scrap cast iron it seems I need to go straight in with a bottoming tap as a number 2 bottoms on the 3/16” hole without forming enough of a thread.

Caber:
Another weekend on the Corliss. I made the cylinder covers and as I am looking to get more location for the cross head guide the back end cover is somewhat deeper. The intention is to bury the heads of the bolts to get full contact between the guide and cover. I used the DRO hole circle function but could not realign this after I took the cover off.

I then started work on the cross head trunk guide. This is being made from some 2” scrap steel bar that seems to be cutting quite well but needs support in my lathe.

Caber:
I finished the trunk guide roughing today. Next challenge is to fit it to the cylinder block all fully aligned. After several different ideas I am planning on a couple of stout dowels and clamping them with bolts through the side of the trunk guide. I will start on this tomorrow!

Navigation

[0] Message Index

[#] Next page

[*] Previous page