Engines > From Kits/Castings
RLE Last & First
Jasonb:
Continuing with things up at the head end the valves were done in my usual way by putting a small ctr drill hole into some 303 stainless bar so the stock could be supported with the revolving ctr and a DCGT insert used as it can get in nice and close.
A 2mm dia insert was used to form a fillet where the stem meets the head and also to cut the 45deg seat.
While the valves were still part of the bar stock I used that as a handle to give them a quick lap with some 600grit silicon carbide powder and oil.
They were then saw off and held in a collet to face the head and then fitted from the back of the collet so the ctr drill hole on the stem could be turned away.
The rocker arm was cut to my new shape to allow for the inlet valve to be closest to the push rod, the curve allowing it to reach over that to the exhaust.
While I had the CNC going I also did the gocernor latch arm and the cam follower which also had two holes tapped for the latch.
All three parts went back into the manual mill to have the excess holding material milled away
The cam follower was drilled to take a spigot that will be formed on the end of the push rod
The latch arm was thinned down either side for looks more than anything
Lastly the under cut of the latch was machined using a flycutter with a suitably ground HSS bit
The reduced thickness could then be slotted and CSK for screws with enough length to the slot so it's position can be adjusted.
Jasonb:
I decided that I would like a square push rod on my engine rather than the round one shown on the original drawings so a length of 4mm keysteel was ordered. A spigot turned on one end so that the bronze cam follower could be Loctited to it and the other end was drilled and tapped to take a small threaded adjuster. Rather than fiddle about with a small part in the 4 jaw I just drilled a bit of aluminium to the across corners distance of the rod and after sawing a slot down the side used that as a split bush.
The engine was screwed to the machining plate once again and clocked in true before finding it's horizontal ctr line.
I slipped the cam gear and it's pivot into place and touched off on the side of the gear then zeroed the DRO. I could then set my other heights relative to that.
I could then mill off the excess from the cylinder mounting flange and the rocker pivot bracket followed by a 4x4 slot for the rod to run in.
A few M2 tapped holes for the retaining blocks completed the work that needed to be done in that setup.
The two retaining blocks were just suared up from some off cuts of brass, drilled for bolts and a small ctr drilled hole added for a drop of oil to be applied. I knocked the corners off after the photo with a small file so that they looked like cast blocks.
Jasonb:
Another thing I wanted to add to my RLE was a pulley on the non governor side. I will modify the spokes of the cast flywheel to allow one to be fitted but while waiting for those decided to make the pulley.
I have quite a few 5kg cast weights from a multi-gym and although it is not the best cast iron in the world I thought it would do for this job. I piece was cut from one of the weights with my Femi bandsaw and then held in the 4-jaw to get it to the basic shape, here the inside has been turned with a 3degree "draft" to the edge and an insert with 0.8mm radius was used to leave a fillet between the inner edge and what will be the mounting lugs for that cast look.
I then held it the other way round in the 3-jaw and machined off the remaining corners before transfering to the Cuts Nice Curves (CNC) machine to shape the mounting lugs and drill their holes.
I probably should have gone 1mm lower with the profile cut as the "step" that can be seen is the fillet left from using the 0.8mm radius cutter.
It was not a problem as I had intended to go over the inner "cast" surface with the Dremel to texture it a bit so did the remaining fillet at the same time.
I wonder what is hiding in the other bits of that weight :thinking:
http://www.youtube.com/watch?v=YghxCw-0vu8
Jasonb:
The two flywheels arrived at the beginning of the week, they did look a bit rough and had a fair amount of thin flash so the first thing I did was to take a small cross pein hammer and carefully chip the flash off. This shows the one on the right after chipping and the left as delivered.
I then fettled the flywheel, I like to do this before any machining a sit saves marking the finish turned rim if you intend to leave that bright. It was mostly done with files and then a quick tickle with the Dremel equipped with a grinding bit, again one on the right has been fettled. There is a little more to do between the spokes where they meet the hub.
Where possible I like to hold flywheels by the inside face of the rim and get that to run true as it is not a surface that is going to be machined, this is another reason to clean them up first. With the 3-jaw's jaws reversed it fitted easily and was just tapped on the side until it ran with minimal wobble.
My machining sequence was:
Rim OD, Rim Side both these done with CCGT inserts using the holders that make use of the two "spare" corners.
I then changed to a boring bar with 0.8mm corner radius CCGT insert and flattened off the side of the inner rim, this ended up 1.75mm below the side face of the rim.
The hub was then faced, spot drilled, drilled 6mm with a stub length drill, opened out to 9mm and then a boring bar used to take it out to final 10mm dia using the crankshaft material as a plug gauge to get the fit right which is tighter than a nominal 10mm reamer gives.
Lastly change to a brazed tip tool with 1.5mm nose radius, set the topslide to a few degrees and clean up the OD of the hub. Knock off all corners with Lathe file.
To do the other side I changed to the 4-jaw and got the flywheel OD running true before machining Rim side, recessed side, hub face, hub OD.
With two done it was time for a trial fit
Jasonb:
I needed a way to mount the belt pulley described a couple of posts previously so clamped the non governor side flywheel to the mill table and located it's centre and ensured two opposite spokes were along the Y axis. The DRO made quick work of spotting, drilling and tapping the three holes at 120deg spacing and then I went round again with a 3-flute milling cutter to form a counterbore.
Some short lengths of 10mm steel were drilled M3 clearance and then bonded into the counterbores with JBWeld and left to set for 48hrs.
Once set the flywheel went back into the 4-jaw on the lathe to have the three bosses machined to length and also a small step turned that would locate the ID of the pulley.
and with the Pulley in place.
J
PS If you buy one of those Alyn Foundry stickers that can be seen bottom right of the last photo they give you a set of castings free. Stickers are not cheap though:LittleDevil:
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