Author Topic: Agnes.... 1/16 Scale Pollit & Wigzell Tandem Compound Condensing Engine.  (Read 49649 times)

Offline pgp001

  • Full Member
  • ****
  • Posts: 700
  • West Yorkshire - UK
Just managed to finish the eccentrics to go with the straps, here are a few photo's (I keep forgetting to stop and take photo's so they are a bit random)

Having cut the outer groove to be a good running fit in the straps, the blanks were parted off to width and then drilled and finally bored to size with a single point tool, I did not have a 13/16" reamer.



I then made a fixture that could be slid along the tee slots of the rotary table to give me the offset for machining the cutaways.



The following photo's show it in use.







The same fixture was then used to add the holes for the fixing bolts.



Here they are almost finished.



Phil

Offline Dave Otto

  • Full Member
  • *****
  • Posts: 3830
  • Boise, Idaho USA
    • Photo Bucket
Nice detail, good to see some progress in this interesting engine.

Dave

Offline crueby

  • Full Member
  • *****
  • Posts: 11019
  • Rochester NY
Great parts! And I love the idea for the sliding fixture on the rotary table, gotta make something like that...!

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 4130
  • Portland, Oregon, USA
Those eccentrics are really nice looking!  Like Dave said, nice detail!
The sliding fixture is a pretty cool idea too.
Kim

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 13719
  • Hampshire, england.
Nice to see some progress Phil  :)

Did you position the grub screws where you have so that you can use headed bolts while you set up the timing?

Jo
Enjoyment is more important than achievement.

Offline pgp001

  • Full Member
  • ****
  • Posts: 700
  • West Yorkshire - UK
Grub Screws...........Who mentioned Grub Screws ? .........Not on my engine thankyou.  ;D

Those eccentrics are actually held in place with two hexagon head bolts at 90 to each other, as per full size. The only difference on the model will be the screws will eventually have dimples drilled into the crankshaft once the timing has been established, the full size engine had some gripper pads between the ends of the bolts and the shaft. The bolts are going to be very fiddly to fit and then adjust the timing, so it could get interesting.
Seriously though I may use some grub screws initially until the timing is set, then swap them for the correct bolts later, It is one of my pet hates being able see modern fasteners on something like this, I dont mind if they can be hidden, but certainly not on show.

That fixture was actually a Graham Meek idea, he documented it when explaining how to mill the base and nose radii on small engine cams, so I just modified it a bit to do these eccentrics.

Phil

Offline mike mott

  • Full Member
  • ****
  • Posts: 418
  • Alberta Canada
I really like the look of those eccentrics.

Mike
If you can imagine it you can build it