Elmer’s #5 Geared Engine . . . maybe

Discussion in 'A Work In Progress' started by bmac2, Jun 13, 2018.

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  1. Jun 18, 2018 #21

    stragenmitsuko

    stragenmitsuko

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    might I suggest a curved spoke ( filip duclos ) flywheel .
     
  2. Jun 19, 2018 #22

    nel2lar

    nel2lar

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    Bob
    Very nice work.
    Nelson
     
  3. Jun 19, 2018 #23

    bmac2

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    Thank you Nelson

    Stragenmitsuko I thought about that and I think they look great on my Webster. Yep, this thing started out as “I wanna build a Webster”. I deviated from the plans just a little bit.

    https://www.homemodelenginemachinist.com/threads/water-cooled-webster.23224/

    6040 Finished.JPG

    I didn’t get much done today what with work, eating dinner and having a nap but I did get the flywheel roughed out. Environment Canada has issued a heat warning for the rest of the week so with the shop being in the basement (a nice 19c down there) I hope to get it finished during the week and start on the gear over the weekend.

    0420_Flywheel_01.JPG

    0430_Flywheel_02.JPG
     
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  4. Jun 22, 2018 #24

    bmac2

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    When doing a spoked flywheel I like to map everything out in CAD labeling all the drill points and use the center as zero. From there I create a drill chart showing me the X and Y offsets for each hole.

    0435 Flywheel Drill Layout.jpg
    This is my cheater for setting up the 4” rotary table. It has a .375 shank that fits the holder with a plug that’s a snug fit into the center of the table and a handy .25 reamed hole. It may not be as exact as indexing but it’s very close and real fast to setup.

    0450_Flywheel_04.JPG

    0460_Flywheel_05.JPG
    Then by putting a short piece of drill rod into the hole in the plug and I can use it to align the flywheel blank on the table. Clamping on a small table can be challenging, the setup looks dodgy but it feels very solid. One of the things I like about this setup is that everything is at my “0” mark.

    0470_Flywheel_07.JPG
    0480_Flywheel_09.JPG

    Used a 1/8” end mill to drill out all the end points then milled out to top of the openings. My wife reminded me that I had to go to work in the morning so I returned everything to “Zero”, locked down “X” and “Y” and called it a night.

    0490 Flywheel_10.JPG

    0500 Flywheel_11.JPG
     
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  5. Jun 22, 2018 #25

    bmac2

    bmac2

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    Today it’s 30c outside, but it’s nice and cool in the shop. Without the check list and a DRO there is no way I’d attempt stopping in the middle of this. But thanks to my handy highlighter pen it only took me a minute or two to get back to making chips. Finishing the spokes didn’t take long, just had to set the angle and offset and mill them out.

    0520 Flywheel_12.JPG
    0530 Flywheel_13.JPG

    It came out just like the drawing and it looks good . . . . But Stragenmitsuko had brought up curved spokes and that got me thinking. With a flywheel it’s the mass along the outer diameter that counts. With a spoked flywheel I don’t think the spokes add much so I decided to add a little style by running the mill down the middle of each spoke. I like the look but I’m thinking I might have to add some weight around the rim.

    0540 Flywheel_14.JPG

    I got the notch cut out in the base and I’m calling it a night.

    0550 Base_01.JPG
     
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  6. Jun 22, 2018 #26

    stragenmitsuko

    stragenmitsuko

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    that is an absolutely beautifull flywheel !
     
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  7. Jun 23, 2018 #27

    bmac2

    bmac2

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    Thanks Stragenmitsuko.
    Hay You started it. I’m so close to where I have to think about the gears I would have probably stopped with the stock one.
     
  8. Jun 23, 2018 #28

    Brian Rupnow

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    Very nice work and great documentation.--Brian Rupnow
     
  9. Jun 26, 2018 #29

    bmac2

    bmac2

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    Thank you Brian I’ve been following your Double Oscillator build.
    Somehow I knew you were going to work a pulley onto it.
     
  10. Jun 26, 2018 #30

    bmac2

    bmac2

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    I didn’t get much done on the weekend, our anniversary was Sunday, but did manage to sneak in a few hours on Saturday.

    Knocking out the eccentric was just some simple off set turning in the 4 jaw with a little drilling and reaming.

    0735 IMG_2352.JPG

    And I guess this is where the drawings turn into more of a guide line. I’m fairly confident in my math so I guess the only way to see if this is going work is to just do it.

    0572 Ring_Gear_10.JPG

    The gear arm is as in the original drawing with the offset for the orbiting gear was reduced to .312. The hole for the piston rod screw is drilled for a no.6 because as it turns out I don’t have a no.5 die.

    0560 Gear_Arm_01.JPG

    0570 Gear_Arm_02.JPG

    I need is a 21 tooth gear with a .6155 diameter. That didn’t work out with the gear cutters I have but after trying one in aluminum it fit the ring gear ok(?) so I went ahead and cut one from brass.

    0574 Ring_Gear_10.JPG 0575 Ring_Gear_11.JPG 0576 IMG_2312.JPG

    In the instructions it says “Piston rod screw must be exactly centered between two teeth”. I may look out a bit in the pictures but it’s about as close as I can imagine getting it. The plans call for silver solder here but for now Loctite will have to suffice.

    0580 Gear_Arm_04.JPG 0590 Arm_03.JPG
     
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  11. Jun 27, 2018 #31

    stragenmitsuko

    stragenmitsuko

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    been wondering as I followed this build .
    You've already made the piston and cilinder , right .
    If a smaller ring gear is used , that ought to affect the stroke of the piston .
    Did you adapt the dimensions of the cilinder/ piston also ?

    Pat
     
  12. Jun 28, 2018 #32

    bmac2

    bmac2

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    Hi Pat. Yes the gear arm is .063 shorter than Elmer’s plans so the cylinder and connecting rod need to be 1/8” shorter . . . . . . . unfortunately I forgot about that when I started, and made them straight off the plans. This will leave an extra .063” (1.5mm) between the piston and the heads at dead center but I don’t think it will affect performance. If worst comes to worst I’ll just make a thicker piston to fill the void.
     
  13. Jun 28, 2018 #33

    stragenmitsuko

    stragenmitsuko

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    Bob ,

    I think I understand now .
    The stroke is twice the pitch diam of the internal gear .
    Crank throw and gear arm have to be of equal length , that makes it 4 times .375 from tdc to bdt
    on the original plans wich results to 1.5 inch stroke .
    At tdc the crank centre is on one end of the internal gear , and the con rod on the other end .
    Dividing it exatly by 2 for any angle , wich results in the straight motion .
    Hence the importance of the centrelines passing trough the teeth centres .

    Does that sound about right ?

    Been also looking at my box of internal gears , but all I have are ring gears with odd numbers of teeth .
    45 , 47 and 53 teeth . Those won't work for sure .
     
  14. Jun 29, 2018 #34

    bmac2

    bmac2

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    This thing is hard to explain isn’t it?

    Hang in there for gears. There have to be thousands of dead drills out there.

    Every time I saw someone build on one of these things I’d start messing around in CAD.

    This is what I’m going on. I don’t feel that the size of the ring gear is all that critical. As long as it has an even number of teeth and the orbiting gear is half the size it should work. Then so long as the holes in the gear arm set at half the diameter of the orbiting gear this will put the piston rod screw running along a line with the center of the crank shaft. In this drawing the diameter of the gear could be 2 inches of 2 feet and the geometry stays the same. It would have to fit within the envelope of the engine of course.

    Gear Rotation.jpg

    Sorry, I’m not sure if that even makes sense to me and I wrote it!

    My plan is to make an adaptor ring with an outside diameter the same as the gear called for in the plans and bore a hole into it to fit the gear I’m using. This way most parts are per the drawings.
    You’ll notice that the orbiting gear runs in the opposite direction of the crank shaft.
     
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  15. Jul 2, 2018 #35

    stragenmitsuko

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    Nice cad work , and it makes perfect sense .

    Tell me , what cutter did you use to make the gear ?
    21 tooth gear with a .6155 diameter , I 'de say it's a 0.7 Mod gear .
     
  16. Jul 3, 2018 #36

    bmac2

    bmac2

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    Oh the gear . . . . The math just didn’t work out with the cutters I have. On top of that I couldn’t come up with a way of measuring the ring gear teeth. What I ended up doing was making a couple of gears from aluminum and just trying them. In the end I used a Module 1 PA20 No.3 and a small V file to tweak the teeth a bit. It is going to be noisy but it should work.
     
  17. Jul 3, 2018 #37

    bmac2

    bmac2

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    I got the crank and piston rod screws done, these are straight forward turning made from the drawings. Then slotted them with a Dermal cut off wheel

    0600 IMG_2338.JPG
    0605 IMG_2350.JPG
     
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  18. Jul 3, 2018 #38

    bmac2

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    I’m using a ring around the ring gear for 2 reasons, one it gives me a way to mount the gear and 2 it simplifies things immensely by keeping as many of the dimensions as possible the same as in Elmer’s original drawings. As things normally go I need something 2 in. in diameter and all I have at hand is the 3 ½ in. I used for the flywheel.

    0610a Ring_Gear_01.JPG

    0610b Ring_Gear_02.JPG

    After a bit of scratching lines and procrastinating I faced off the blank, and reamed a .25 hole in the center. Then using a piece of drill rod I aligned the bearing mount on the blank and used a transfer punch to mark the positions of the mounting holes.

    0610c Ring_Gear_03.JPG

    0610d Ring_Gear_04.JPG

    Back on the lathe I took the outside down and started boring it out.


    0610e Ring_Gear_05.JPG
    0610f Ring_Gear_06.JPG
     
  19. Jul 3, 2018 #39

    bmac2

    bmac2

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    That done it was time for some major cleanup. I was ready to hall it out to the bin when my wife spotted it. She thinks she’s found where the “tree rat” (pronounced Squirrel) has been getting under the garden shed and was off to fill in the hole with aluminum shavings.

    0610fa_Flywheel_03.JPG
     
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  20. Jul 3, 2018 #40

    bmac2

    bmac2

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    The gear looks to be MIM (https://en.wikipedia.org/wiki/Metal_injection_molding) and feels very hard with 4 tabs that are not evenly spaced. After some layout I broached 4 shallow notches and parted off the ring. This turned out pretty good and the gear is a firm press fit into the ring.


    0610g Ring_Gear_07.JPG

    0610g Ring_Gear_09.JPG
     
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