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raveney

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Hello All,
Last weekend I machined the sand casted flywheels. There was a fair bit of filing required to clean up the spokes, but the rest of the machining was straight up lathe work using a faceplate to bore the shaft, taper the hub, and cleanup a few spots where the pattern didn't pull cleanly on the inner rim.

Then I fastened each one to an 7/16" arbor and trued up the outer diameter. I had to use the boring bar upside down and run the lathe in reverse to get this to work on my 7X14 mini-lathe but got a very good finish using auto feed at 500 RPM with copious spraying of WD-40. The aluminum that was remelted to cast these is giving a very nice surface finish so far, unlike other extruded melts that I have done which were gummy and smeared.

Then I broached the keyways, primed the centers and set aside to dry. I will polish up right before final assembly as the aluminum seems to scratch easily unlike cast iron.
Faceplate.jpg
arbor.jpg
finished_FW.jpg
 

raveney

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Hello All,

The base casting was de-gated using a table saw by clamping it to a wooden sled and raising the carbide tipped blade in small (0.1") increments. The underside was then machined flat using a 2" fly-cutter after leveling up on the mill. A few passes on the surface plate with wet-dry 150 grit paper gave a good stable part to work with. I then clamped and aligned it on the table using the hold down bosses and a transfer punch. I set some clamps and parallels to allow repeated removal and replacement as the work progressed. This also allowed offsetting so the tooling could access as sides and features as the Grizzly hobbyist lathe has very limited Y travel.
align.jpg

The main standards, valve standards and cylinder pads were then decked, drilled and tapped. I used #10-32 for mains and mounting, #6-32 for cylinder and #4-32 for valve standards. The casting machined very nicely, not gummy at all. The defect cleaned up well where the sand didn't fully pack at the inside corner. There are a few seams that might show up after painting, and will need filling with either JB Weld or body putty. Someone also accidently drilled two 1/16 holes in the wrong spot while laying out the galleys. :rolleyes:
deck_tap.jpg

mains.jpg

galleys.jpg

I enjoy setting the travel stops for removing inside features like these galleys. My mill comes with X-axis ones, but I added the Y-axis ones. One can see the front stop next to the handle. The rear one is mounted on the right of the column. The "stop" rods are removed and stored on the tool rack when not in use. A post below covers some details. I use them frequently


A semi-finished base below. Still need to drill and tap the guide bars, side mill the main standards, minor fettling and restore the pebbly finish. I have a small sand blaster, and have had some success by striking the surface with a stiff wire brush.

Anyone have other tips or tricks?

finished_base.jpg
 
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peterl95124

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someone else has also drill holes in the wrong locations, you can loctite in some aluminum rods or aluminum screws if the holes are threaded, or if they are blind holes cut them 1/16 taller than the hole and peen them in. What I found building my Merlin is that while there's some machining mishap on almost every large piece of aluminum in it, once its all put together no one (not even the builder) notices. There's even some big blunders recovered from by epoxy'ing in a new chunk of aluminum (hobbyist "additive machining" :) !!!). Do obsess about things like bearings and journals, but don't obsess with things that are "as cast" surfaces. great progress, keep up the good work !
 

raveney

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Hello All,
Glad to have you following this project. We all make mistakes, but in this case it was recoverable. I loathe breaking taps in things that I have spent days making. Yesterday I enjoyed some time off work because of the Thanksgiving weekend and puttered on some small parts for the base. Bearing caps and valve standards were patterned using high density foam so they were a little rough, but machined nicely. The casting was done last month, but included some reference photos. Machining foam with accuracy is a bit weird.
foam dowel.jpg
foam profile.jpg
as cast parts.jpg

I reckoned that the bearing dowels were the most important feature so located them, drilled for 10-32 studs while clamped high enough to side mill the finished width and then flipped to cut out the bearing gib/recess. I also milled the square oil reservoirs off camera
index cap.jpg
side mill.jpg


The valve linkage standards were treated similarly. Sand one surface as reference, clamp to rotary table centering on the journal, drill & bore for bearing. Then sweep the corners while rotating the table and side mill the base to finished length. I also radiused the bores and removed some cast boogers under the bored hole inside the recess. Next I finished the width to match the mounting pads on the base. This left one of the recesses too shallow, so I roughed it out lower to match the first one. When I made the patterns I cut a stack of three profiles with the center being whole, and the two outer layers having cut outs. Wasn't considering the depth at the time.

I also cut the lengths while clamped and true so I could later flip, clamp and measure and drill the #4-40 clearance mounting holes
ream bearing.jpg
mill base.jpg
finish width.jpg
restore recess.jpg
 

raveney

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Up next are the guide plates that were cast into the base on the original engine. Because I only have aluminum & brass casting equipment I omitted these from the pattern as aluminum wouldn't wear well under sliding friction. I searched for suitable cast iron remnants, but only came up with a chunk of 1" hot rolled steel as a donor. With a new blade in my bandsaw we were in business. Squared up the stock and milled the locating features on the bottom first.
A36 for guides.jpg

mill bottom guide.jpg

I love using my Florida Flywheelers flea market depth mic for checking dimensions while clamped down. Really appreciate using old tools. :)
I wanted to have the oil dams like the original, so machined them next using an 1/8 end mill. Then I cut the bearing slide areas, and drilled the stud holes. After trial fitting to the cast base I realized that some shimming was needed and added some counterbored mounting holes that will be hidden by the top plates later. This should allow the guide plates to be secured to the base rigidly and the stud/nuts on the top plates to be adjusted for bearing slide wear as I imagined Mr. Muncaster intended.
oil dams.jpg


extra counterbores.jpg
locating and shims.jpg
stoning guides.jpg

I don't have a 1/8 radius bit so just filed the corners using a template
radius corners.jpg

finished base.jpg

Progress so far with the aforementioned parts secured using non traditional socket head cap screws because they are so easily removed. The plan is to make scale taller hex nuts and studs eventually. Plan is to work on the main bearings next so all other dimensions are based on that center line
 

raveney

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1" bearing bronze was sized, drilled and reamed 7/16 which ends up .4385 with my tooling. I then squared surfaces, rounded over corners and milled out the races. Achieved a snug fit by removing and checking insitu. Concentricity and height is dead on (well.... relative to me). Now we have the main reference for all other machining. The last photo shows the ugliness in surface finish left on the base casting just below mains and other areas that were machined. I was thinking of attempting to mix sifted fine sand or blast media in the metal primer and paint again in an attempt to restore the pebble finish. Anyone try this before?
square up bronze stock.jpg
mill out races.jpg
7_16 shaft.jpg
 

raveney

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Hello all,

This weekend I'm attempting to fabricate the cylinder block by TIG welding materials that I had on hand rather than purchasing a billet of cast iron. I had some 1/4 A36 hot roll plate and a piece of 1-1/4 SCH 80 A106 GRB pipe from the dumpster. I bought some silicone bronze filler rod to avoid distortion as much as possible. I sketched it on paper, and the only challenge I see is sealing where the steam enters the cylinder. I think I will be able to tell when I get that far if I get full "penetration" of the passages. If not I'll use a 1/16" electrode to fill any areas that might leak.
raw material.jpg
concept.jpg

Started by rough cutting the plate with the grinder, machined edges and lightly abraded the surface using a flap disc. Then I bored the recesses in the end plates to hold the pipes in alignment. Cut and trued the ends of the cylinders (pipes) and sand blasted all pieces. I have never used silicone bronze tig filler, so I made some test welds to dial in the amperage settings. I used 95 amps with a foot pedal for most of the welding (brazing?). the most difficult spot was the circumferential segment between the cylinders. I was using a gas lens #8 cup and had to stick the electrode out about 1/2" to reach this area :oops:. Here's where I was glad that I chose bronze filler rather than attempting straight welding. I still got some warpage/misalignment of 0.017" on one of the cylinders as witnessed by the taper when I skim-cut the top of each cylinder to receive the base plate and passageway plate. Hopefully this cleans up at the target bore, if not I'll go bigger or sleeve it.
bore recess.jpg
parts for welding.jpg
weld circumference.jpg

It all seems pretty good at the end, and ready to line bore on my "big" lathe (a Harbor Freight 9x20) I will repurpose a 1" boring bar I already made for the Panther Pup and Otto-Langen engine. Just need to sort out a rigid and repeatable support for the cylinder block.

flycut machining.jpg
ready for line boring.jpg
 

peterl95124

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I have used silicon-bronze with my TIG, especially for inside corner fillets as you did, but bronze doesn't penetrate so there won't be any joint where the cylinder butts to the end plate, I would have used a mapp gas torch and silver-braze which penetrates everywhere there's enough heat and flux. There's obviously no strength issue in your build, just a crevice that might rust, but probably not in your life time so probably not a real worry, just a thought.
 

raveney

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Hello again,
this weekend we line bored and honed the fabricated cylinder block. In hindsight my choice of dumpster offcuts of steel pipe was not my brightest. It did not machine well cutting through the red oxide and cleaning up the pitting, but managed to slog through it and ended up with 1.447 bores after lapping. I had a 7/8" boring bar with a 3/16 round HSS cutter that I had to lengthen. I had cross drilled this on a 45 degree to reduce the bending stress in the middle and used leftover diver's lead weights to dampen the chatter. The bit feeds out about 0.004 each 1/8 turn so it was fairly accurate to control the cut. Had to side track and make a batch of tee-nuts for the cross slide to clamp it all down. The 123 block and small angle plate allowed me to just switch bores without realigning it all.
Not the best finish though 😒 A106 Grade B has 0.3% carbon, 0.4% Chrome and 0.4% Nickle so a tad hard to bore with HSS
setup.jpg
boring bar.jpg
lead damping.jpg
before lapping.jpg

A honing/lapping was needed for this, and I wasn't [patient enough to order a nice ACRO lap this size. Let's just make on up I said.... Look at my sketch and one can see why this didn;t work to well. The slotted segments of the barrel are so thick they really resist bending and increasing the barrel OD. Never came across this before with smaller ones. I guess there must be some undercutting (green line) on the store bought ones?
lap drawing.png
lap.jpg

It still ended up doing the job though. Same picture after lapping
after lapping.jpg

Thanks for watching!
Next weekend, I'll drill and machine the steam passageways and tap the end plate holes. I have some 304 SS 3 mm sheet for the valve plate left over from the heat treat oven job.
 

Richard Hed

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Hello again,
this weekend we line bored and honed the fabricated cylinder block. In hindsight my choice of dumpster offcuts of steel pipe was not my brightest. It did not machine well cutting through the red oxide and cleaning up the pitting, but managed to slog through it and ended up with 1.447 bores after lapping. I had a 7/8" boring bar with a 3/16 round HSS cutter that I had to lengthen. I had cross drilled this on a 45 degree to reduce the bending stress in the middle and used leftover diver's lead weights to dampen the chatter. The bit feeds out about 0.004 each 1/8 turn so it was fairly accurate to control the cut. Had to side track and make a batch of tee-nuts for the cross slide to clamp it all down. The 123 block and small angle plate allowed me to just switch bores without realigning it all.
Not the best finish though 😒 A106 Grade B has 0.3% carbon, 0.4% Chrome and 0.4% Nickle so a tad hard to bore with HSS
View attachment 142753 View attachment 142754 View attachment 142755 View attachment 142756
A honing/lapping was needed for this, and I wasn't [patient enough to order a nice ACRO lap this size. Let's just make on up I said.... Look at my sketch and one can see why this didn;t work to well. The slotted segments of the barrel are so thick they really resist bending and increasing the barrel OD. Never came across this before with smaller ones. I guess there must be some undercutting (green line) on the store bought ones?
View attachment 142758 View attachment 142757
It still ended up doing the job though. Same picture after lapping
View attachment 142759
Thanks for watching!
Next weekend, I'll drill and machine the steam passageways and tap the end plate holes. I have some 304 SS 3 mm sheet for the valve plate left over from the heat treat oven job.
They ended up looking good, What is the end diameter? End to end good?
 

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