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Edwards Five cylinder aircraft engine
- Thread starter Master
- Start date
Its not a square, its an 'O' as in O.S. engines. Which is metric. Discussed here.
https://www.homemodelenginemachinist.com/threads/edwards-radial-5-build.6923/page-2#post-212957
I recall seeing that post before & curious why Edwards elected to go for a purchased part when other things parts are made of higher difficulty. Obviously hardened & ground & partial? hole for the end pads. Well, FWIW I intend on making mine from air or oil hardening drill rod.
https://www.homemodelenginemachinist.com/threads/edwards-radial-5-build.6923/page-2#post-212957
I recall seeing that post before & curious why Edwards elected to go for a purchased part when other things parts are made of higher difficulty. Obviously hardened & ground & partial? hole for the end pads. Well, FWIW I intend on making mine from air or oil hardening drill rod.
Attachments
You are welcome. So the set screw would be accessed under the piston skirt during assembly with an L Allen key? Does it lock against a flat made on the wrist pin? Do you put them in with blue Loctite or something? I’ve seen the method but paranoid if it ever comes out & then inside the crank case.
You appear to be making rapid progress, look forward to some pics one day!
You appear to be making rapid progress, look forward to some pics one day!
I think it goes like this
- cam part is mounted to a chuck, the chuck/adapter plate is mounted to a rotary table. Both the RT center (first) and part (second) must be coaxial & pre-zeroed to quill initially (very important)
- tool up woodruff cutter, back out in either X or Y, it doesn't matter really but it has to be one or the other. Lets say we will infeed X from the side, so Y must be locked to always be zero
- since the cam table is given in terms of angle vs cam lift, one would have to build a machining table that equates lift to equivalent depth of cut, since you will be subtracting material from the machined base ring which becomes the cam end result
- increment the RT to position-1 (0-deg)
- infeed the cutter to depth by moving mill table in X direction
- back out X, increment RT to 2-deg... rinse & repeat... until you complete 360-deg
- now maintaining that setup, change cutter depth up/down to other cam lobe elevation. In other words if you have cut the intake cam profile, then you now reposition the cutter to do the exhaust using the corresponding table values
Now in reality it may be that you cut the zero lift sections (colored bands) by constantly turning the RT once at depth. I cant say. That might be smoother than a bunch of little facets & depnds on how the cutting itself goes. You are going to have to smoothen the facets on the cam rise section anyways.
- cam part is mounted to a chuck, the chuck/adapter plate is mounted to a rotary table. Both the RT center (first) and part (second) must be coaxial & pre-zeroed to quill initially (very important)
- tool up woodruff cutter, back out in either X or Y, it doesn't matter really but it has to be one or the other. Lets say we will infeed X from the side, so Y must be locked to always be zero
- since the cam table is given in terms of angle vs cam lift, one would have to build a machining table that equates lift to equivalent depth of cut, since you will be subtracting material from the machined base ring which becomes the cam end result
- increment the RT to position-1 (0-deg)
- infeed the cutter to depth by moving mill table in X direction
- back out X, increment RT to 2-deg... rinse & repeat... until you complete 360-deg
- now maintaining that setup, change cutter depth up/down to other cam lobe elevation. In other words if you have cut the intake cam profile, then you now reposition the cutter to do the exhaust using the corresponding table values
Now in reality it may be that you cut the zero lift sections (colored bands) by constantly turning the RT once at depth. I cant say. That might be smoother than a bunch of little facets & depnds on how the cutting itself goes. You are going to have to smoothen the facets on the cam rise section anyways.
Attachments
Master, not sure if you saw this build post on another model engine forum. He happens to have CNC capability but still you can get some insight of the components.
http://www.modelenginemaker.com/index.php/topic,8770.0.html
http://www.modelenginemaker.com/index.php/topic,8770.0.html
Good Morning Peter T and Merry Christmas. Thanks for the info. Enjoyed the pictures. I test fit the master rod. It is interesting in assembly. It only goes together one way. Almost got myself in a jam test fitting it. Working on the lower cylinders right now. Bad weather is great for getting quality shop time.
Hi Master. Hmm good question. The naming & function of saws is not clear to me & my own experience sawing in the mill is quite limited.
In KBC catalog they use this naming:
- Plain Slitting Saw (lower teeth count, thickness starts about 1/32" = .032" to 1/8" depending on dia)
- Jeweler Slotting Saw (high teeth count, thin blades starting at 0.008" to about 0.128" depending on dia)
- Screw Slotting Saw (in-between-ish teeth count?, thin blades starting at 0.008" to 0.182" depending on dia)
On my 6061 heads I used a jeweler saw, 3" diameter, 168 teeth.
https://www.kbctools.ca/itemdetail/5-746-565
I'm actually not sure if cutting aluminum over steel is easier, worse or about the same. On one hand, aluminum is softer so one would think a bit more aggressive feed. But OTOH the gummy nature makes it harder to clear chips. I had too much time in the heads by that stage so I elected more conservative shallower depth of cut & more passes. I seem to recall 0.020-0.025" DOC ~ 350-400 rpm, but I can check. Some folks advocate a shallow guide slot, then cut full depth. Personally I would test this theory a bunch of times before the real deal.
Back to your master rod, where the 4 link rod bottom ends pre-installed on the master rod & shimmied in the entire cluster? I haven't gotten that far myself but its got me wondering. I think my crank case has a narrower opening than the Edwards. In my mind I was already thinking I will have to feed the link rods in through the cylinder holes.
In KBC catalog they use this naming:
- Plain Slitting Saw (lower teeth count, thickness starts about 1/32" = .032" to 1/8" depending on dia)
- Jeweler Slotting Saw (high teeth count, thin blades starting at 0.008" to about 0.128" depending on dia)
- Screw Slotting Saw (in-between-ish teeth count?, thin blades starting at 0.008" to 0.182" depending on dia)
On my 6061 heads I used a jeweler saw, 3" diameter, 168 teeth.
https://www.kbctools.ca/itemdetail/5-746-565
I'm actually not sure if cutting aluminum over steel is easier, worse or about the same. On one hand, aluminum is softer so one would think a bit more aggressive feed. But OTOH the gummy nature makes it harder to clear chips. I had too much time in the heads by that stage so I elected more conservative shallower depth of cut & more passes. I seem to recall 0.020-0.025" DOC ~ 350-400 rpm, but I can check. Some folks advocate a shallow guide slot, then cut full depth. Personally I would test this theory a bunch of times before the real deal.
Back to your master rod, where the 4 link rod bottom ends pre-installed on the master rod & shimmied in the entire cluster? I haven't gotten that far myself but its got me wondering. I think my crank case has a narrower opening than the Edwards. In my mind I was already thinking I will have to feed the link rods in through the cylinder holes.
Sorry for late response. I found info on the slitting saw. HMEM article stated .025 thickness. The rods are like a puzzle. Easy when you do it correctly. My method. Install master rod. Slide bearing in, then just insert each con rod through open cylinder and install retaining pin. Last step would be to put in the link retaining plate and horse shoe clip