Author Topic: Greene Automatic Cutoff Steam Engine  (Read 11307 times)

Offline kvom

  • Full Member
  • ****
  • Posts: 2079
Re: Greene Automatic Cutoff Steam Engine
« Reply #165 on: November 08, 2019, 02:12:56 AM »
A bit more on the eccentric strap.  Use a 3/16" endmill to counterbore for the 4 x 2-56 clearance holes that will hold the two halves together.  Then reverse and bring the other half to thickness,  then counterbore that side as well.



Now ready to separate into the two halves next time out.
« Last Edit: November 08, 2019, 10:32:28 AM by kvom »

Offline steam guy willy

  • Full Member
  • ****
  • Posts: 2260
Re: Greene Automatic Cutoff Steam Engine
« Reply #166 on: November 08, 2019, 02:42:53 AM »
Good work there,.. and WOW that looks just like the cast-iron clutch release bearing in my Morris Minor  :lolb: :lolb:

Willy


Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3755
  • Portland, Oregon, USA
Re: Greene Automatic Cutoff Steam Engine
« Reply #167 on: November 08, 2019, 05:40:03 AM »
A bit more on the eccentric strap.  Use a 3/36" endmill to counterbore for the 4 x 2-56 clearance holes that will hold the two halves together.  Then reverse and bring the other half to thickness,  then counterbore that side as well.

So, is a 3/36" end mill the same as a 1/12" end mill? :)
Would that have been a 3/16" by any chance?  Or is there really a 1/12"?  I've not heard of that, but it also seems too small to use as a counter bore for a 2-56 screw.  Just curious!  :D

Nice work on your engine here. I'm enjoying the build!
Kim

Offline kvom

  • Full Member
  • ****
  • Posts: 2079
Re: Greene Automatic Cutoff Steam Engine
« Reply #168 on: November 08, 2019, 10:35:00 AM »
3/16 of course.  Plenty big enough for a socket head 2-56; didn't try a model engineer hex head yet.  I suspect the head will fit but the 1/8" driver might not.

Offline Dennis

  • Full Member
  • ****
  • Posts: 50
Re: Greene Automatic Cutoff Steam Engine
« Reply #169 on: November 08, 2019, 03:02:18 PM »
Hi Kirk, thanks for all the photos and postings.  You have done a lot of work the last few weeks while I have been on the sidelines, nice to be catching up.  I like the way you use the collet block and mill vice, a new approach for me and I am going to use it on the Dickson prototype. 

I noticed the cube you had printed is all non metallic material.  Is that to help control deflection when the metal is deposited?  Too bad it came out hard, I was hoping that process could be used on more of our complicated parts.

Dennis

Offline kvom

  • Full Member
  • ****
  • Posts: 2079
Re: Greene Automatic Cutoff Steam Engine
« Reply #170 on: November 08, 2019, 05:12:29 PM »
Thanks for looking in.

It's printed as stainless steel powder between layers of glue.  Then in the furnace bronze replaces the glue layers.

For small parts I really like collet blocks and a small machinist vise for holding parts, and both can be moved from one machine to another or to/from the surface plate for alignment.

To separate the halves I cut most of the way through using a 1/8" endmill at .025" per pass.



Then cut fully apart with a hacksaw and machined the matching surfaces flat.  To ensure I put the two halves together properly I punched a small dimple in the same end of each.



To move ahead on finishing this part I need to screw them together, but discovered I was down to only 1 2-56 nut.  Ordered some from AME, but in the meantime I'll have to move to something else.



The 3/16 counterbore does allow allows my Wiha nut driver access.

Offline kvom

  • Full Member
  • ****
  • Posts: 2079
Re: Greene Automatic Cutoff Steam Engine
« Reply #171 on: November 08, 2019, 11:58:02 PM »
First eccentric disk started.  I cutoff a 1.5" piece from some 1.5" diameter 1144 round bar.  Then turned a 3/4" boss on one end so that I could then mount it on my lathe's collet chuck.  I then turned a 1" boss 1/4" long in the far end, and turned from there for .343" until that section could fit inside the strap, which is nominally 1.36" in diameter.  After that I used a parting tool to mark off the approximate width of the rib that will fit the strap's internal groove.



Next I reversed the piece in the chuck and turned the outside of the rib to again fit the strap's opening.



From there is was a matter of fettling the width and height of the rib to get a good fit to the strap.  As part of the fitting, I ran a deburring blade along the outer edges of the groove on the strap, and using a parting too to square the bottom of the rib.



After a good little while, success.



I then turned off the temporary collet bosses.  The next op will be machining the collar of the offset hole, which will in turn provide a grip for the lathe chuck to drill and then bore the offset hole to fit the crankshaft.

Offline kvom

  • Full Member
  • ****
  • Posts: 2079
Re: Greene Automatic Cutoff Steam Engine
« Reply #172 on: November 11, 2019, 12:45:03 AM »
Continuing on with the eccentric strap, I mounted it on the CNC mill and machined a 1/4" offset boss that will be the mounting collar on the crankshaft.



Then I drilled a through hole with a 1/2" drill and followed with a 3/4"  Silver-Deming bit.  Offset is .140".



Then bored the hole to a tight sliding fit on the .875" crankshaft.



Plans call for 4 set screws in the collar to retain the eccentric to the crankshaft.  Once I drill and tap those this apart will be finished, and I'll need to make an essentially identical one for the second eccentric strap.

Offline crueby

  • Full Member
  • *****
  • Posts: 9319
  • Rochester NY
Re: Greene Automatic Cutoff Steam Engine
« Reply #173 on: November 11, 2019, 12:50:41 AM »
Great progress.   :popcorn: :popcorn: :popcorn:

Offline Art K

  • Full Member
  • ****
  • Posts: 1205
  • Madison, Wisconsin USA
Re: Greene Automatic Cutoff Steam Engine
« Reply #174 on: November 11, 2019, 02:22:26 AM »
Kirk,
You are making good progress, the way you made the eccentric makes it look easy. Wanted to let you know I was still following along.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline kvom

  • Full Member
  • ****
  • Posts: 2079
Re: Greene Automatic Cutoff Steam Engine
« Reply #175 on: November 13, 2019, 12:43:33 AM »
Thanks for those who look in.  Love to see comments.

My 2-56 nuts arrived in the mail today, so I could continue working on the exhaust eccentric strap.  Since this can't be held easily other than in the vise, it's important to be able to find the center even with the two halved screwed together.  To mount securely in the vise with the split line along the x-axis, I milled small flats that will contact the jaws.



Then for the one that will be touching the fixed jaw, I measured the distance to the split line.  Then when I use an edge finder on that jaw, I can subtract this height to get the Y0 position.  X0 will just be half the distance between the ends of the line.



The strap mounted on the vise before machining the center:



And after:



Since I used the same g-code to mill the center, I half-expected the eccentric disc to fit this strap as well, but the strap appears a few thousand too small to fit snugly.

Offline Craig DeShong

  • Full Member
  • ****
  • Posts: 575
  • Raleigh,NC. USA
    • Lauson small engines
Re: Greene Automatic Cutoff Steam Engine
« Reply #176 on: November 15, 2019, 01:25:39 PM »
Steady progress Kirk, and everything looks Super!.  Following along with  :popcorn: :popcorn: of course!
Craig

Offline kvom

  • Full Member
  • ****
  • Posts: 2079
Re: Greene Automatic Cutoff Steam Engine
« Reply #177 on: November 18, 2019, 11:35:58 PM »
Work took a bit of a holiday as I drove to Kimball TN on Friday morning for some Jeep offroading.  I had some stomach pains that night that didn't respond to antacid, so I went to a local emergency room.  They took a CT scan and diagnosed infected gallbladder.  Rather than having it treated there, I decided I was well enough to pickup up Jeep and trailer and drive back home.  Went straight to the local hospital at 3pm, admitted at 5pm, surgery at 8pm, discharged today at 5pm.  Feeling OK as long as I don't bend at the waist or cough.

Offline crueby

  • Full Member
  • *****
  • Posts: 9319
  • Rochester NY
Re: Greene Automatic Cutoff Steam Engine
« Reply #178 on: November 18, 2019, 11:38:01 PM »
Ouch! Glad it all worked out okay, take it easy till its healed up.

Offline Craig DeShong

  • Full Member
  • ****
  • Posts: 575
  • Raleigh,NC. USA
    • Lauson small engines
Re: Greene Automatic Cutoff Steam Engine
« Reply #179 on: November 18, 2019, 11:47:00 PM »
Ouch! Glad it all worked out okay, take it easy till its healed up.

Agreed, feel better soon !
Craig