Author Topic: Elmer's # 13 2X Larger than original ......  (Read 5601 times)

Offline scc

  • Full Member
  • ****
  • Posts: 406
Re: Elmer's # 13 2X Larger than original ......
« Reply #60 on: March 12, 2018, 03:27:09 PM »
BEAUTIFUL work :praise2:         Terry

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 11456
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Elmer's # 13 2X Larger than original ......
« Reply #61 on: March 12, 2018, 04:31:10 PM »
With those nice finishes, I don't blame you for protecting everything. Looks great so far!!!

Bill

Offline toolznthings

  • Full Member
  • ****
  • Posts: 328
Re: Elmer's # 13 2X Larger than original ......
« Reply #62 on: March 13, 2018, 04:31:51 PM »
More assembly ...........

Working the way up with the cylinders, pistons and valve/cylinder head plates. Another set of studs hold these parts to the lower assembly.

Offline toolznthings

  • Full Member
  • ****
  • Posts: 328
Re: Elmer's # 13 2X Larger than original ......
« Reply #63 on: March 13, 2018, 04:44:02 PM »
The last part of the assembly ..........

Added a wood base and name tag to finish up.
To make the engine run since it has no exhaust valve and air is trapped in the cylinders on the up stroke I added a bleeder hole into the cylinders and capped off with two button head socket head screws that are drilled thru 1/8" diameter. Of course this allows a continuous bleed of air from the input air , but causes no problems. It actually adds to the sound of the engines running.

With its size this engine uses a bunch of air, but runs nicely at low speed. Top RPM is about 265. In the video a last minute addition is the gear on the other end of the crankshaft. Item found in my " never know I might need it " drawer.  ;D


Thanks for all the views and comments ! All appreciated ! 
« Last Edit: March 13, 2018, 04:56:30 PM by toolznthings »

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 11456
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Elmer's # 13 2X Larger than original ......
« Reply #64 on: March 13, 2018, 04:47:18 PM »
Is that the right video?  :headscratch: Ah...i see it just got fixed. Nice runner too!!!  Is there no exhaust valve in the design or is it just something you haven't added yet?


Bill
« Last Edit: March 13, 2018, 04:59:16 PM by b.lindsey »

Offline toolznthings

  • Full Member
  • ****
  • Posts: 328
Re: Elmer's # 13 2X Larger than original ......
« Reply #65 on: March 13, 2018, 04:53:17 PM »
Is that the right video?  :headscratch: Ah...i see it just got fixed.

Bill

Fat fingers at the keyboard !  ::)  That's my next build sneak peek just for you !  8)

Offline toolznthings

  • Full Member
  • ****
  • Posts: 328
Re: Elmer's # 13 2X Larger than original ......
« Reply #66 on: March 13, 2018, 05:05:25 PM »
Is that the right video?  :headscratch: Ah...i see it just got fixed. Nice runner too!!!  Is there no exhaust valve in the design or is it just something you haven't added yet?


Bill

Hi Bill,
No exhaust valve. Engine won't run as built from plans without a lot of leakage somewhere. That's why I added the bleeder holes to the cylinders. You can see the button head screws in the video that I have drilled thru.

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 11456
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Elmer's # 13 2X Larger than original ......
« Reply #67 on: March 13, 2018, 05:47:27 PM »
I just pulled the book out and noticed that this is a uniflow design or sorts. Those holes in the sides of the cylinders are supposed to let the pressure out and Elmer must have assumed that with the valve closed there wouldn't be enough compression on the upstroke to offset the pressurized downstroke of the other piston. It would seem your experience proves this wrong unless changing to 2X scale had something to do with it. I should have looked at the plans closer before :)

Bill
« Last Edit: March 13, 2018, 07:04:39 PM by b.lindsey »

Offline bouch

  • Full Member
  • ****
  • Posts: 40
Re: Elmer's # 13 2X Larger than original ......
« Reply #68 on: March 13, 2018, 06:14:47 PM »
The last part of the assembly ..........

Added a wood base and name tag to finish up.
To make the engine run since it has no exhaust valve and air is trapped in the cylinders on the up stroke I added a bleeder hole into the cylinders and capped off with two button head socket head screws that are drilled thru 1/8" diameter. Of course this allows a continuous bleed of air from the input air , but causes no problems. It actually adds to the sound of the engines running.

With its size this engine uses a bunch of air, but runs nicely at low speed. Top RPM is about 265. In the video a last minute addition is the gear on the other end of the crankshaft. Item found in my " never know I might need it " drawer.  ;D


Thanks for all the views and comments ! All appreciated !

Looks and runs great, nice slow speed running.  Reading others comments I'm thinking that the double sizing is the reason you need the bleeders, you didn't make the exhaust holes big enough to let all the air out.

Doubling the size of the cylinders and the stroke more than doubles the volume in the cylinders, it 8 times it.  If my math is right, the original design was about 0.7 cu inches per cylinder.  Double the radius and the length, and now you get about 5.5 cu inches per cylinder.  That's a LOT more air/steam to let out.

But, doubling the size of the exhaust holes only doubles the area allowed for air/steam to escape, so more air/steam is trapped in the cylinders, causing the backpressure.  And to make matters worse, Elmer's design had a slot, while you drilled holes (which I think look much nicer, BTW), so your exhaust port probably isn't even twice his.

Not sure if making larger holes will help (or is even practical).

Thoughts?  Disagreements?

Offline toolznthings

  • Full Member
  • ****
  • Posts: 328
Re: Elmer's # 13 2X Larger than original ......
« Reply #69 on: March 13, 2018, 06:28:46 PM »
The last part of the assembly ..........

Added a wood base and name tag to finish up.
To make the engine run since it has no exhaust valve and air is trapped in the cylinders on the up stroke I added a bleeder hole into the cylinders and capped off with two button head socket head screws that are drilled thru 1/8" diameter. Of course this allows a continuous bleed of air from the input air , but causes no problems. It actually adds to the sound of the engines running.

With its size this engine uses a bunch of air, but runs nicely at low speed. Top RPM is about 265. In the video a last minute addition is the gear on the other end of the crankshaft. Item found in my " never know I might need it " drawer.  ;D


Thanks for all the views and comments ! All appreciated !

Looks and runs great, nice slow speed running.  Reading others comments I'm thinking that the double sizing is the reason you need the bleeders, you didn't make the exhaust holes big enough to let all the air out.

Doubling the size of the cylinders and the stroke more than doubles the volume in the cylinders, it 8 times it.  If my math is right, the original design was about 0.7 cu inches per cylinder.  Double the radius and the length, and now you get about 5.5 cu inches per cylinder.  That's a LOT more air/steam to let out.

But, doubling the size of the exhaust holes only doubles the area allowed for air/steam to escape, so more air/steam is trapped in the cylinders, causing the backpressure.  And to make matters worse, Elmer's design had a slot, while you drilled holes (which I think look much nicer, BTW), so your exhaust port probably isn't even twice his.

Not sure if making larger holes will help (or is even practical).

Thoughts?  Disagreements?

Hi,
The problem is the air trapped on the upstroke. I have a close fit on the pistons and practically no air escapes quick enough to allow the next cycle. Forum member Yogi suggested more free volume above the pistons would probably work also, but a much harder fix since I was way into the build. I'm sure the 2X size didn't help either.

Thanks for the comments !!

Offline yogi

  • Full Member
  • ****
  • Posts: 333
  • Duncannon, PA USA
    • Yogi's Workshop
Re: Elmer's # 13 2X Larger than original ......
« Reply #70 on: March 14, 2018, 04:58:02 AM »
Nice runner Brian!  :ThumbsUp: :ThumbsUp: :ThumbsUp:
The gear wheel adds a nice touch, I like it!

Offline Plani

  • Full Member
  • ****
  • Posts: 59
Re: Elmer's # 13 2X Larger than original ......
« Reply #71 on: March 14, 2018, 05:55:02 AM »
Very nice engine!!
And it's running very smooth  :ThumbsUp: :ThumbsUp: :ThumbsUp:

Plani

Offline Dave Otto

  • Full Member
  • *****
  • Posts: 3138
  • Boise, Idaho USA
    • Photo Bucket
Re: Elmer's # 13 2X Larger than original ......
« Reply #72 on: March 14, 2018, 11:36:58 PM »
Nicely done Brian!
Beautiful engine, and it runs as nice as it looks!

Dave

Offline b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 11456
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Elmer's # 13 2X Larger than original ......
« Reply #73 on: March 14, 2018, 11:48:04 PM »
So now the inevitable question....What's next  ;D

Bill

Offline toolznthings

  • Full Member
  • ****
  • Posts: 328
Re: Elmer's # 13 2X Larger than original ......
« Reply #74 on: March 15, 2018, 12:18:41 AM »
So now the inevitable question....What's next  ;D

Bill

Hi Bill,

Well I got a oscillating engine ready for posting if anyone is interested.  :-\    Kind of a neat redo from a slightly unusual concept.

Thanks for the reply !
Brian