Model Engine Maker

Engines => From Plans => Topic started by: kvom on April 16, 2019, 07:49:51 PM

Title: Greene Automatic Cutoff Steam Engine
Post by: kvom on April 16, 2019, 07:49:51 PM
I will be picking up a set of castings at NAMES for this engine.  The origins are from Historic Models and Reproductions from whom I got the castings for the Joy engine.  The plans and castings are now owned by Downriver Tools.  From their website:

Quote
- Improved Green Automatic Cut-Off Engine

This horizontal steam engine castings and drawings kit is based on the original automatic steam cut-off engine design by Nobel Green in 1838. The model has a 1 1/2 inch bore, 3 inch stroke and the flywheel is 11 ˝ inches diameter.

This engine, built by the Providence Steam Engine Company in Providence, Rhode Island, incorporated variable steam cut-off several years before George Corliss patented his famous variable cut-off Corliss valve gear.  Our model is based on a 150 HP, 17 inch bore and 36 inch stroke Improved Green Automatic cut-Off Engine that has been restored and preserved by the New England Wireless and Steam Museum in East Greenwhich, RI.

Green’s engine design used what has been known as a detachable valve-gear.  The detachable valve-gear varies the steam cut-off point by using the engine governor to raise or lower trip points that operate levers to open the steam inlet valves.  The higher the trip point, the longer the steam inlet valve stays open allowing more steam into the engine’s cylinder.   The detachable valve gear was designed by Frederick Sickels and patented in 1841.  Sickels was only interested in the marine applications of his valve gear and sold the rights to use his patent on land based engines to the Providence Steam Engine company.  Then, when George Corliss introduced his variable cut-off valve gear in the late 1840’s, the Providence Steam Engine Company sued Corliss for patent infringement.

The court battle between George Corliss and the Providence Steam Engine Company raged on for over 10 years and became a landmark court case over what can and cannot be patented.  In the course of the court battle, Corliss won an injunction preventing the Providence Steam Engine Company from building and selling the Green designed engine.  The court case was finally settled in Corliss’ favor and Corliss’ original patent was extended by the US patent office on the basis that the law suits had prevented Corliss from benefiting from his patent.

In 1869, the Corliss valve gear patents finally expired and the Providence Steam Engine Company began producing the Green engine again.  The Green Engine was given some minor upgrades and changes and then introduced as the “Improved” Green Automatic Cut-Off Engine even though it was basically the same engine Noble Green designed in 1838. 

Specifications:

Scale: 1 inch = 1 foot (1:12)
Cylinder: 1-1/2 inch bore x 3 inches stroke
Flywheel: 11-1/2 inches diameter
Overall size: 22-1/2 inches x 12 inches x 12 inches high

I suspect this will prove a good challenge.  The photo below is from their website and represents the only example I've seen running (twice at NAMES).  I don't know the builder's name, but he likes to surface grind as much of the parts as possible.  Mine will look a bit different color wise, and probably not as finely built.  I purchased the plans a year ago so I've had some time to get an idea where the problems will be.
Title: Re: Green Automatic Cutoff Steam Engine
Post by: crueby on April 16, 2019, 08:03:02 PM
That should be a very interesting model.... Gotta go check the popcorn kernel supply...
Title: Re: Green Automatic Cutoff Steam Engine
Post by: fumopuc on April 28, 2019, 07:53:56 PM

[/size]
Hi Kirk, here a model build from bar stock of one of our German forum member.

http://www.dampfundmehr.de/HP/green/im_bau/green_0.htm
Title: Re: Green Automatic Cutoff Steam Engine
Post by: crueby on April 28, 2019, 09:12:33 PM


Hi Kirk, here a model build from bar stock of one of our German forum member.

http://www.dampfundmehr.de/HP/green/im_bau/green_0.htm (http://www.dampfundmehr.de/HP/green/im_bau/green_0.htm)

That is a beautiful model! One bit I have never seen before is a part on the crankshaft next to the eccentric and the governor belt takeoff - looks to be hinged over to the base casting, and wobbles back and forth - some sort of oil pump? You can see it in one of the photos, and partway through the video at timestamp 1:15. Any idea what it is?
Title: Re: Green Automatic Cutoff Steam Engine
Post by: Admiral_dk on April 28, 2019, 09:19:01 PM
I might be mistaken, but look later in the video where you see the bottom two valves controlled by an axel that only oscillates a few degrees back and forth ....  :old:
Title: Re: Green Automatic Cutoff Steam Engine
Post by: crueby on April 28, 2019, 09:24:54 PM
I might be mistaken, but look later in the video where you see the bottom two valves controlled by an axel that only oscillates a few degrees back and forth ....  :old:


Aha! Thats it, that second eccentric drives  that axle in a small back and forth rotation. Clever!


Thanks!
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 02, 2019, 04:04:32 PM
I picked up the castings at NAMES.  Here they are laid out on the shop floor with a 12" rule for comparison (penny might have not been indicative):

(https://pbase.com/kvom/image/169134021/large.jpg)

A test fit shows that the flywheel can be mounted on my 10EE lathe, but it's unlikely I can use it to turn the rim, given that the crossfeed is limited.  I plan on doing it with an endmill on the CNC mill.
Title: Re: Green Automatic Cutoff Steam Engine
Post by: Jasonb on May 02, 2019, 04:18:06 PM
Look a nice set of castings.

I would have thought you only need about 3/4" cross feed movement at the most to do the rim. Upside down boring bar mounted on the side of the toolpost facing you usually reaches out far enough to do face & side, run in reverse.

bdM-g6Wsc1Y
Title: Re: Green Automatic Cutoff Steam Engine
Post by: kvom on May 02, 2019, 04:34:55 PM
With the Joy engine 10" flywheels I was at the utmost to turn, and these are 11".  I probably need to make a custom tool holder.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 10, 2019, 02:02:41 AM
I have been studying the Solidworks model I got from Dennis Howe.  These are more informative than looking at individual drawings.  I spent the day assigning contrasting colors to the parts in order to see how they fit together more easily.  A zillion parts in this one.  A majority of the nuts are 3-48.

The operation of the exhaust valve is interesting as noted in a previous post.  Driven by an eccentric, the strap is connected to a pivoting part whose motion rocks the long exhaust rod *(second pic).  At the other end an oscillating linkage drives the "grate" valve, shown in the third.  Both halves of the valve have matching through slots that when matched together open the cylinder to the exhaust,  The use of multiple slots allows evacuation of more exhaust for an engine that might run a high speed.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on May 10, 2019, 02:05:54 AM
Now that is some clever engineering in that engine! I can see why the 3D model made it much clearer, the individual parts would be meaningless. The gimbals on the eccentric follower is pretty neat!
 :popcorn: :popcorn: :popcorn:
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: jeff l on May 10, 2019, 03:38:06 AM
Just to clarify Downriver tools does not own Historic Models and Reproductions , they merely have the engines on their website to help sales .
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 10, 2019, 01:22:11 PM
Thanks for clarifying Jeff.

I have scheduled a 2 day trip June 4-5 via Boston  to visit the NE Wire and Steam museum where an original engine has been restored.  I have an expiring SW airlines credit that will pay for most of the airfare.  I haven't been back to Boston since I spent 6 months contracting there 20+ years ago.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: jeff l on May 10, 2019, 01:29:22 PM
 Kirk ,The New England Wireless and Steam museum is on my must see list i hope to make the trip soon . I see from the photo of castings that you are missing the governor stand , castings arrived yesterday so I will get this casting out to you .Jeff
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: RonGinger on May 10, 2019, 05:03:52 PM
The New England Wireless and Steam Museum is well worth the visit. They have a couple big annual events, the SteamUp  is usually the first weekend in October. That day the big vertical boiler is fired up and several of the big steam engines are run.

Be sure to check ahead to see if they will be open when you want to visit- its a rather small place and not always open. The founder, who was almost always there, died a few months ago and I am not sure what the opening schedule will be.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 10, 2019, 07:04:53 PM
I just checked the website to see that they're not open every day.  Sent a message asking to visit the day I'm in MA.  If not I'll probably just head to Newport for the afternoon.  I have an airline credit that is use it or lose it, si I'll be doing the trip regardless. 
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 15, 2019, 12:10:41 AM
June 6 is volunteer workday at the museum, so I extended my trip by one day to participate.

Yesterday I decided to start the build by attacking the flywheel casting.  It's a big bugger: almost 12" diameter and probably over 20 pounds.  There's no real way to mount it on my lathe to start, so I started by reducing the lump of iron on the wheel's axis.  (These were needed in the mold to keep the wheel portion from cooling too rapidly).  Here's the setup using 123 blocks to raise it enough to clear the other lump.  Removed enough so that the remainder is inside the rim.

(https://pbase.com/kvom/image/169197695/large.jpg)

Back at it today.

Turned it over to mill the other "lump".  Now the rim can rest on the table, and the clamping is somewhat more secure.

(https://pbase.com/kvom/image/169197696/large.jpg)

Next the inside of the rim is machined to remove the draft.  This surface will be used to secure the wheel on the lathe via the 4-jaw chuck.  I was nervous about clamping too hard on the spokes, so this operation was done with many passes of 5 thou stepover.

(https://pbase.com/kvom/image/169197697/large.jpg)

Final operation on the mill was to face the side of the rim.  This gives a straight edge needed to ensure that the wheel is straight when mounted on the lathe.

(https://pbase.com/kvom/image/169197698/large.jpg)

Now for mounting on the lathe using my large 8" 4-jaw chuck, with the jaws on the inner rim.  Turning the lathe on a low speed allow verification that the inside face of the rim is close as possible to running true.  Then I centered the wheel using the inner rim as a guide.  Note that all of the machining done on the chuck side will be modified later.  Once centered, I used my 1/2" boring bar to turn the inner rim, and then faced the side of the rim and the hub.  The length of the hub was faced to close to the final size.

(https://pbase.com/kvom/image/169197699/large.jpg)

Next I turned the hub using a cutoff tool, then drilled the center 1/2" and bored to 0.855".

(https://pbase.com/kvom/image/169197700/large.jpg)

Final op for the day was to ream the center hole with the .875" reamer, which I had as this was the size of the axles on the Kozo loco.

(https://pbase.com/kvom/image/169197701/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 15, 2019, 12:13:07 AM
The face of the rim is now the reference surface for further ops, as is the center bore.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on May 15, 2019, 12:14:50 AM
Off to a great start, thats quite a big wheel.


 :popcorn: :popcorn: :popcorn:
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: jeff l on May 15, 2019, 03:58:28 AM
Kirk , You didn't waste any time getting this project started , good job .
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 15, 2019, 10:54:24 PM
Not as long in the shop today, but some progress.  I moved the wheel from the lathe and mounted on the CNC mill table with the reference rim face down.  Centered on the bore, and then milled half of the outer rim.  Second op was to face the side of the rim to make it parallel to the reference  face.

(https://pbase.com/kvom/image/169200890/large.jpg)

Next session I will carefully move the clamps one at a time so as not to disturb zero position, then then mill the hub.  Once that is done, flip and mill the other half of the outer rim.  Surface finish looks decent, but I'll try to polish it once back on the lathe.

Turning the rim on the lathe using an upside down boring bar would have been easier, but my lathe has always refused to run in reverse.

Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on May 15, 2019, 10:58:45 PM
Very nice!

One suggestion I would make is before removing a clamp, add another one out on the rim on the same side as the one you are moving - I have had things shift slightly when moving them one at a time like you mention.

 :popcorn: :popcorn: :popcorn:
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: b.lindsey on May 16, 2019, 06:57:30 PM
Off to a great start Kirk. It's a big un but at least the other castings should be easier to hold.  Will be following along.

Bill
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 16, 2019, 07:06:37 PM
Finished the milling.

(https://pbase.com/kvom/image/169206505/large.jpg)

Slight mismatch on the rim that should be fixable later on.  Once I can get a 7/8" axle secure in the hole I could use the mill as a lathe to true it up.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 16, 2019, 11:05:28 PM
Next up are the castings for the main journals.  As the bottom surface seems the most level, I sawed off the excess of the pour and face milled.

(https://pbase.com/kvom/image/169207050/large.jpg)

Then the top surface was milled to be parallel to the bottom.

(https://pbase.com/kvom/image/169207051/large.jpg)

Then  one face was milled to provide a flat for a parallel.

(https://pbase.com/kvom/image/169207052/large.jpg)

Then the entire side could be milled flat.

(https://pbase.com/kvom/image/169207053/large.jpg)

Then it was reversed to mill the opposite side.  Dodging hot chips is not fun.

Next time in the shop I'll do the other one the same way.  My intention is to eventually machine the holes for the bearings on both pieces together.  I'll see if that's possible in the end.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Dave Otto on May 16, 2019, 11:24:18 PM
It seems that the sides of the bearing castings would look better if they had been left as cast; Is there a reason that they need to be milled flat?

Dave
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 17, 2019, 12:18:11 AM
I'm too dumb to do anything but follow the drawings and 3D model.  The other three builds of which I'm aware also made the sides flat and parallel.  There was a lot of extra metal in the casting vs. the drawings, with more to come off on all 4 machined surfaces.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Dave Otto on May 17, 2019, 12:43:34 AM
Makes since, I was just wondering.

Thanks,
Dave
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 18, 2019, 03:48:20 PM
Machining the tops of the bosses for the mounting screws.  Took about .160" off using precision Mark I eyeball.

(https://pbase.com/kvom/image/169213455/large.jpg)

Piece measures 3.818" tall vs. 3.54" in model.  I will remove metal from the tops of both at the same time.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 19, 2019, 03:26:08 AM
After machining the 2nd journal to the same state as the first, I clamped them together to perform the next ops on each simultaneously.

(https://pbase.com/kvom/image/169214600/large.jpg)

These ops were as follows:

1) Machine top surface to bring part height to 3.55".

2) Machine the sides to give a strip .15" high.  This removes the case surface and provides references for determining the center line of the parts.

3) Mill the center slot .75" deep to widen it to 1.374".  The bearing cap will subsequently sit on the resulting ledges, which in turn will be on the horizontal centerline of the bearing.

For the next shop session I need to further machine the side strips so that the two top surfaces are .463" across.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: sco on May 19, 2019, 11:51:42 AM
Kirk,

The starting point with the flywheel a few posts back where you started to machine the flywheel on the mill before it went on the lathe - was that using a rotary table to turn the flywheel or CNC?

The Lane and Bodley has a very similar sized flywheel (might even be the same casting) which I have hanging over me - it's way to big to fit on my lathe so was wondering about at least rough machining the rim on the mill.

Simon.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 19, 2019, 02:34:07 PM
CNC mill initially to machine the inner rim.  This allowed mounting with the 4-jaw.  A rotary table would work as well or better as long as there is a means to clamp it centered. 

Before any of that I manually milled off most of the outside area where the iron was poured so that it would clear the ways.

I am considering a fixture to mount the wheel on the mill spindle in order to get a good finish on the outer rim.  That will need to wait until the center keyway is broached.  The fixture will start with a 1" round rod turned to 7/8" leaving a collar on one end;  diameter reduced to .75" on the other.  Keyway milled on the 7/8 diameter portion.  Then the wheel is put on with keystock and resting on the collar, while the 3/4 portion is clamped into a R8 collet on the mill spindle.  Then with a lathe tool clamped in the mill vise, very fine cuts taken until the rim is smooth.  I doubt more than 10 thou needs to be removed.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Jasonb on May 19, 2019, 04:06:26 PM
Do the drawings show such a thick rim? Seems this engine along with many similar US engines tended to have a much thinner section to the rim which would be nice to reproduce, you could even add dummy bolt flanges and a joint line to get the look of a two part flywheel.

(https://newsm.org/wp-content/uploads/2016/01/greene.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 19, 2019, 10:26:56 PM
The drawing shows a very thin rim, and the 3D model shows it as .16".  However, all three model builds I've seen pics for leave the cast rim quite thick.  While accuracy is nice, I suspect that having more weight on the rim helps in allowing the model to run slowly.  I don't intend to take off more than is needed for a good finish.

I'd guess that the original builders opted for thinner rims to make casting them easier (and probably less expensive).
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Art K on May 19, 2019, 10:32:05 PM
Kirk,
I didn't even see that you got this casting at the show. I must have been to busy or... I did finally meet Jeff & his wife while I was packing up on Sunday. He gave me a few of his business cards & I will post them at shows. You are making good progress and coming up with good workarounds for machines to small for the job.
Art
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: jeff l on May 19, 2019, 10:46:58 PM
The L&B and the Green automatic share the same flywheel ,and can be machined to a thin rim but I agree with Kirk I would leave it a little thicker .
I have in the works a pattern for a two piece flywheel for both of these engines , most people who bought or inquired about the castings asked why the flywheel wasn't a two piece one , trying to make every builder happy here .
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 20, 2019, 12:53:07 AM
Milled the outside edge to bring the top surface width to spec.  Then roughed the bearing cap castings to square the sides and bottom.  Also took a slight edge off the rounded ends in order to be able to obtain a center line with an edge finder.

(https://pbase.com/kvom/image/169219153/large.jpg)

Further machining of the caps will require accuracy as they fit closely to the journals as shown here:

(https://pbase.com/kvom/image/169218949/medium.jpg)

Here the bottom of the cap is to meet the internal ledge while the slots in the cap meets the top of the journal.   
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 20, 2019, 06:43:00 PM
Worked on the first bearing cap for a couple of hours this morning to get a fit to the journal:

(https://pbase.com/kvom/image/169222643/large.jpg)

Comparison with start point:

(https://pbase.com/kvom/image/169222644/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: sco on May 20, 2019, 09:50:21 PM
The L&B and the Green automatic share the same flywheel ,and can be machined to a thin rime but I agree with Kirk I would leave it a little thicker .
I have in the works a pattern for a two piece flywheel for both of these engines , most people who bought or inquired about the castings asked why the flywheel wasn't a two piece one , trying to make every builder happy here .

Thanks for confirming that Jeff.  Personally I was going to go for a thin rim as per the engine in the museum;

Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on May 20, 2019, 09:56:41 PM
That bearing cap is a great fit, watching along!
 :popcorn: :popcorn: :popcorn:
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 20, 2019, 11:24:06 PM
I worked on the second one this afternoon, and the fit at the end is not as good.  A bit more fettling needed. 

My MSC order came in the the bushing and broach needed for the flywheel and crank disk.  Also a bunch of drill rod for future use.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 22, 2019, 11:11:28 PM
I gave the 7/8x3/16" broach a trial run on a piece of 3/8" thick CI through which I bored a 7/8" hole.  My #3 arbor press was able to handle that, but not the 1.25" thick hub of the flywheel.  One issue is that handle hits the wheel on the down stroke, and as it doesn't ratchet, I can only apply maximum pressure on a relatively short range of motion.

So I'll have to use the hydraulic shop press, which is currently employed as a rack for round stock and is blocked with a bunch of other stuff.  That will wait for next week, as I have an out of state trip for offroading to get ready for tomorrow.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 29, 2019, 11:55:13 PM
Finally got back in the shop after the long weekend.  I needed to use a press to broach the flywheel hub for a key.  3/16" B broach.

(https://pbase.com/kvom/image/169270578/large.jpg)

(https://pbase.com/kvom/image/169270579/medium.jpg)

Then milled the semi-circle in the journals for the main bearings.

(https://pbase.com/kvom/image/169270580/large.jpg)

Afterwards, since the journal was in the vise, I decided to swap the inserts in my face mill and take .01" off the sides.  Much better finish.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 30, 2019, 11:24:39 PM
A bit more progress on the journal assembly. 

Machined the bearing space into the caps.

(https://pbase.com/kvom/image/169277912/large.jpg)

(https://pbase.com/kvom/image/169277913/large.jpg)

Next job is to drill the mounting holes for #6 screws into the journals.  Normal chucks are obstructed by the sides,  but luckily I had this tiny one.  However its maximum size is 1/8".  So I first drilled through using a drill bit of that size.  The hole locations were found using the Mark I precision eyeball to center in the boss.

(https://pbase.com/kvom/image/169277914/large.jpg)

Then I reversed the piece to enlarge the holes from the bottom.

(https://pbase.com/kvom/image/169277915/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on May 31, 2019, 08:32:11 PM
Continuing along, I face milled both the journals and caps to within .02" of the specified 1.3" width.  I'm not sure if I want to mill them together when attached.  At present this looks good enough as the width is not a critical dimension.   Then drilled and tapped the tops of the journals for 8-32 screws.  For the caps, I drilled from the bottom after using surface plate and 123 blocks to set the caps vertical.

(https://pbase.com/kvom/image/169285296/large.jpg)

Then reversed to spot face the holes in the tops.

(https://pbase.com/kvom/image/169285297/large.jpg)

Since a #8 washer diameter is 3/8", I used a 7/16" endmill for this operation.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Tennessee Whiskey on May 31, 2019, 09:42:07 PM
I’m silently following along  8)

Cletus
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 02, 2019, 01:29:11 AM
Thanks Eric.

Today's job was to make a start on the main bearings.  The plans call for split bearings but I can't see a need for this in a model that won't run much.  So the bearings will be one piece aside from a collar than will be added to one end of each.  I start with a 5" length of 1.875" hex brass and chuck so that 3.5" are exposed.

(https://pbase.com/kvom/image/169293081/large.jpg)

Center drill and turn down to 1.245" using the journals to test for fit.

(https://pbase.com/kvom/image/169293082/large.jpg)

Drill .5x3.5".

(https://pbase.com/kvom/image/169293083/large.jpg)

Part off two pieces 1.5" long each, then drill 3/4" and bore to .846".  Then ream .875".

(https://pbase.com/kvom/image/169293085/large.jpg)

I found that my 7/8" drill rod was a tight fit, so bored to .877".  For the second bearing I skipped reaming.

(https://pbase.com/kvom/image/169293086/large.jpg)

Then for the acid test.  Assembled journals, bearings, caps and shaft on surface place, and was very happy to find that the shaft turn smoothly and that the bearing are snug even without the caps being screwed down.

(https://pbase.com/kvom/image/169293087/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on June 02, 2019, 01:32:59 AM
Excellent - watching along from the peanut gallery (and popcorn gallery, ... )
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 02, 2019, 06:34:17 PM
No peanuts!  Some onlookers may be allergic.   :ShakeHead:

Next casting up is the crank disk, which attaches the conrod to the driveshaft.  There's a lot of extra iron vs. the final dimensions (e.g., diameter 5" vs. 4.5, .88" thick vs. .54.). 

(https://pbase.com/kvom/image/169295619/large.jpg)

I clamped to the BP table first to machine away the extra "tabs" on the edge, and then to make an attempt to find the center.  Then drilled and reamed 1/2" hole.

(https://pbase.com/kvom/image/169295620/large.jpg)

The final center hole will obviously be 7/8".  My goal here is to have the edge of the recessed area on the conrod side "wobble" as little as possible when running, assuming that it is left "natural".  It's pretty hard to get the center exact for this, even assuming that the edge of the area can be made round.  So my plan is to rough turn the rim using a 1/2" rod as a mandrel, then use the 4 jaw on the rim and adjust until the recess runs as true as possible.  Then I'll drill and ream the center hole while still in the chuck.  We shall see.

In any case, the 1/2" mandrel has been attached with Loctite 620 and is curing.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on June 02, 2019, 06:47:39 PM
 :popcorn: :popcorn: :popcorn:
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: bouch on June 03, 2019, 02:49:42 AM
Hi there,

I just found this topic, and I'm following along.  Looks like a great project.

You, and others, might be interested in seeing what the Greene at New England Wireless and Steam looks like while running.  Here's a video from the last time I was there, the "Yankee Steam Up" from 2017.

05T-rOdp3gst=657s

The Greene starts at about the 5:20 mark...
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on June 03, 2019, 03:01:39 AM
Great video! Thanks for sharing!
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 03, 2019, 12:02:31 PM
I'm leaving for Boston early tomorrow and will be at the Steam museum Thursday morning.  I did a consulting gig in Boston in 1998-99 and haven't been back since.  Planning to visit MFA (Fine Arts museum) tomorrow and Isabella Gardner museum on Wednesday.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Dennis on June 03, 2019, 06:21:19 PM
Hi Kirk,
I just got around to checking on the Green Engine build thread you told me you started.  I am impressed with the work you have done so far and did not expect nearly as much progress.  It is looking great.  Thank you for posting your work it will be great to follow along.

A few notes as I read through all the postings so far:

1. The photo you first posted is an engine built by John Ugo.  John and I worked together to develop the model after visiting the NEWS museum like you are doing this week.  John's engine was the prototype for the kit.  There is a video on You-Tube of another finished model running.  This one lives in Ill.  The Green Engine kit was completed shortly before Jeff took over Historic Models so there are only a few out there. 

I chose to build the Green Engine after seeing it run at NEWS and because the engine played a significant role in the history of steam power and patent law here in the United States.  Nathan Green was the main Challenger to John Corliss' domination the stationary steam engine market.  John Corliss was an excellent engineer but some people believe Green may have been the better engineer of the two.  Green originally worked for Corliss before moving on to start his own business and the two spent many years fighting court battles over patent writes and infringement.  The court battles boiled down to a question of what can be patented and had a large impact on our patent laws of today.  A very interesting story if you are into that sort of thing.

2. Simon asked about machining the flywheel with a rotary table on his mill.  Yes, that is a good way to get around a lathe that is not big enough.  I used that approach on the large Gothic Beam engine with it's 18 inch dia. flywheel.  You have to take light cuts and your arm gets tired cranking the rotary table but it will work.  As Jeff mentioned, the flywheel on the Green Engine is the same casting as the flywheel on the L&B Corliss.
 
    The rim is quite thick with enough metal to turn the inside and outside surfaces round.  I was probably overly concerned about distortion when I made that pattern,  but that was my lack of experience showing through.  On the original engine in the Grand Rapids Museum, the flywheel is hollowed out and there is metal in the model casting to do that.  The hollowed out rims were typical on large engines with these very large flywheels. 

3.  Jeff, the two piece flywheel is great news.  It will add another level of accuracy to the model.  I will look forward to seeing it.

4. Kurt, the assemblies with contrasting colors are really nice.  An excellent idea and thank you for sharing them.  The exhaust mechanism from crankshaft to sliding exhaust valve is quite complicated and your color assemblies make the working much easier to understand. 

5. Comparing the Green Engine Kit to the L&B Corliss Kit, the machining is about the same with the Green Engine having a few more complicated sub assemblies like the exhaust valve and it's driving mechanisms.  That exhaust eccentric with its wobbling yoke tends to confuse people.  Once the Green Engine is assembled, it will run quite well however it is more challenging to get everything adjusted correctly.  The sub assemblies like the exhaust mechanism and the trip levers for the inlet valves require some careful work and a lot of patience. 

Thanks again for posting your work Kurt, now that I see how far along you are, I will try to stay more current.  Hope you have a good time in New England.
Dennis
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 03, 2019, 10:27:15 PM
The result of the first ops on the crank disk with a 1/2" aluminum arbor glued in.  The finish on the rim and face is not as good as I expected, but I suspect there was some flexing of the arbor under the pressure of the tool.

(https://pbase.com/kvom/image/169302942/large.jpg)

After cutting off the arbor, I mounted the crank in my 8" 4-jaw chuck and faced the conrod side.  Here the finish is very good somewhat confirming my suspicion about the arbor.  In any case, the disk is still oversize in thickness (.75 vs. .54 inches) and diameter (4.9 vs 4.5).  I adjusted the jaws until the inner rim ran as true as I could get, but there's still a minor wobble.  Since I need to remove around .21" of thickness, the pocket may disappear, in which case I can machine it on the CNC mill.

(https://pbase.com/kvom/image/169302943/large.jpg)

It's ready to drill the center hole, but I decided to leave the setup as is until I get back from the trip.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Jasonb on June 04, 2019, 07:03:07 AM
What was the reason for mounting it on the aluminium arbor? with nearly 3/8" of excess thickness surely it would have been easy to hold in the 4-jaw from the start and machine enough of the outer rim, face and bore all to finished size in one setting. Then simply reverse and machine to finished thickness.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 07, 2019, 12:24:15 PM
Jason,  I wasn't confident about the 4-jaw holding it securely given the draft angle on the raw rim and a good bit of flashing on the edges.

My visit to the museum in Warwick was great.  The work team there was in the process of finishing a redo of all of the steam piping to their engines, and fired up the small boiler to check their work.  After a period of warm up, they ran 4 of them including the Fitchburg and the Corliss, as well as two smaller ones.  I was told that the Greene is more difficult to run as they suspect the timing of one of the exhaust valves is off.

I was interested in whether the Greene had been painted originally.  The current frame and flywheel are a light bluish grey, but I was show that in a spot where the paint is flaking that there appears to be a dark brown color, and scraping that reveals cast iron.

One thing that impressed me on these original engines is the large number of oil cups and lubricators, seemingly every possible moving part got oil.

The museum has its annual steam-up the first Saturday in October, and it attracts hundreds of visitors.  I was told that there are tables for running model engines on both air and steam.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Art K on June 07, 2019, 05:46:52 PM
Kirk,
Great progress on the Green & it sounds like you had a good trip to Boston. Still following along.
Art
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 11, 2019, 03:06:01 AM
I had left the crank disk in the lathe before my trip. So I was able to face down both sides to target dimensions:  1/2" thick with a .040" boss on the non-conrod side.  This eliminated the recess on that side and close to the rest on the conrod side.

The next step was just to drill/bore/ream the center 7/8".  Then I used my arbor press to broach it for a 3/16" key.  This was at the limit of hand power for me; any thicker I'd have needed to to use the hydraulic press.  Finally, drill and tapped 3 holes for 4-40 set screws at an angle from the back.  These will lock the disk on the crankshaft;  however, I didn't have any 4-40 set screws.

(https://pbase.com/kvom/image/169338979/large.jpg)

Now I needed to turn the rim down to 4.5" diameter, so I made a mandred from a piece of 7/8 drill rod.  I machined a slot 3/16" wide and .095" deep, then glued in some 3/16" square brass as a key.  The end was drilled and tapped 1/2-13.

(https://pbase.com/kvom/image/169338978/medium.jpg)

Now I could mount the crank disk on the lath with a 5C collet and turn the rim.

(https://pbase.com/kvom/image/169338977/large.jpg)

Next I used the mandrel to mount the flywheel.  This allows facing the rim, and subsequently truing the inside rim plus removing marks made by the 4-jaw chuck.  After a good deal of adjustment on with the lathe and the tool, I found a setup that will allow turning the rim across half its width.  Hopefully when I reverse the wheel I can turn the other side at the same DRO position and not have too obvious a center line.

(https://pbase.com/kvom/image/169339001/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on June 11, 2019, 03:20:00 AM
 :popcorn: :popcorn: :popcorn:

Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 14, 2019, 01:29:45 AM
I pulled a back muscle Tuesday and it wasn't until this afternoon that I felt like having a go at the other half of the rim.  This didn't go well as it revealed some faults in the iron, as shown in the following 3 pictures.

(https://pbase.com/kvom/image/169356604/large.jpg)

(https://pbase.com/kvom/image/169356605/large.jpg)

(https://pbase.com/kvom/image/169356606/large.jpg)

I could continue turning down the rim, as it ought to be a lot thinner, but I'm wondering what alternatives there are for patching holes like these.

So I've abandoned the flywheel again and set about finishing the crank disk.  First op was to install aluminum jaws on the CNC mill vise and cut  them to hold the disk securely.  Then I drilled the hole for the crank pin with a 15/32 bit for a 3" throw, and reamed .499 for a press fit of the crank pin.  Finally formed the central pocket with a 1/4" endmill.

(https://pbase.com/kvom/image/169356607/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Jo on June 14, 2019, 07:22:18 AM
I could continue turning down the rim, as it ought to be a lot thinner, but I'm wondering what alternatives there are for patching holes like these.

I would contact the original casting supplier and tell them about the holes - they should send you a replacement flywheel casting.

If it was a legacy casting set which is no longer available the options would be to fit a new rim to the existing centre which would allow for a shiny rim (but there will be a difference in the colour of the Iron between old and new :facepalm2: )  or fill it with something and have a painted rim.

Jo
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Ye-Ole Steam Dude on June 14, 2019, 11:01:47 AM
Hello Kirk,

JB-Weld will do a good job of filling in the bad spots and will machine down OK. Like Jo stated it will be a difference in color but if you plan to paint the flywheel it will not be visible.

Have a great day,
Thomas
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: jeff l on June 14, 2019, 12:27:18 PM
Kirk , Let me know how you would like to proceed with the flywheel, I can send you a replacement if you find that you want one . Sorry about the flaws that you found these things are out of my control .Jeff
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 14, 2019, 12:41:28 PM
Jeff, what's the status of the 2-piece wheel?  Since this is a very long term project I could just wait for it.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: jeff l on June 14, 2019, 12:52:04 PM
Hi Kirk , The two piece flywheel project would be a 6 month wait . Jeff
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Dennis on June 14, 2019, 03:00:53 PM
Hi Kirk, 
Sorry for the porosity in the flywheel rim.  The porosity looks like inclusions, did you see any sand or slag when you hit the holes?  What ever the cause, it is something I will be glad to take care of.  If you don't want to wait for Jeff's new two piece flywheel, I can send you the flywheel from the Green engine kit I saved for myself when we sold the business to Jeff.  Save the flywheel you have and bring it back to me next NAMES show. 

I have been able to save some castings using a tig welder with flashing from other castings as filler, then heat treating at a higher temperature than you would normally use for annealing.  On ground surfaces, these patches were not visible but they probably would be on a polished surface.  There is definatly enough metal left on the rim to remachine after heat treating and the center bore should shrink enough in heat treating to let us ream it to the correct size.  We have never tried this on a flywheel so it would be an interesting experiment.

Dennis


Dennis
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 14, 2019, 07:17:37 PM
At the rate I'm going, 6 months for a new casting, be it one or two piece, is not an issue.  Since it's essentially done other than the grub screws and final sizing, the wheel as is can be used for any testing that might be needed. 

There was some porosity  on the bottom of one of the journals, but that's insignificant and invisible.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 14, 2019, 11:48:09 PM
The next castings to be started are the two feet that support the cylinder.   Here's the 3D SW rendering:

(https://pbase.com/kvom/image/169359662/medium.jpg)

There's a lot of extra iron on all sides of the raw castings, so lots of chips to me made.   The important dimensions to be observed are:

- Height, since I was precise on the journal and bearing height, I want the cylinder bore to line up with the crank centerline.

- length of the top surface so that it matches the cylinder width.

Start with this:

(https://pbase.com/kvom/image/169359687/large.jpg)

Then on the bridgeport remove the pour hole remnant.  4 flute carbide at 1800 rpm and .100" DOC worked well and quickly.

(https://pbase.com/kvom/image/169359688/large.jpg)

(https://pbase.com/kvom/image/169359689/large.jpg)

Then use face mill on CNC mill to flatten the bottom.

(https://pbase.com/kvom/image/169359690/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Art K on June 15, 2019, 02:20:10 AM
Kirk,
To bad about the flywheel, but it sounds like you can work around that. I hope your back is feeling better. I pulled a deltoid muscle and felt it in the center of my back. It was fine during the day but when I tried to sleep the dull ache drove me to visit the doctor. He gave me some pain med's and I laid off the machines at the YMCA gym.
Art
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 17, 2019, 03:57:20 AM
Some more machining on the feet.

Second op with bottom against fixed jaw, it's a matter of lining up the part by eye  to machine the first side.

(https://pbase.com/kvom/image/169369746/large.jpg)

Now I can use parallels to position for the opposite side.

(https://pbase.com/kvom/image/169369747/large.jpg)

Next, machine the top until the length of the surface is as close to 2.3" as I can determine with a steel rule and .01 divisions.

(https://pbase.com/kvom/image/169369748/large.jpg)

Afterwards, reverse and machine the bottom in order to obtain a height of .875".

Finally, machine the sides equally to obtain a thickness of 1".  While not critical, I was happy to hit it.

(https://pbase.com/kvom/image/169369749/large.jpg)

On the second I overshot by .002", so maybe the first was just luck.

Then over to the Bridgeport to mill down the bosses for the mounting screws.

(https://pbase.com/kvom/image/169369750/large.jpg)

That was all I had time for as I intended to watch the US Open golf tourney.  Those annoying burrs probably need to be ground off with the Dremel as using a file will be awkward.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 18, 2019, 12:28:52 AM
Machining finished on the feet:

(https://pbase.com/kvom/image/169372442/large.jpg)

Can't put it off forever, so made a start on the cylinder.  The bottom surface of the casting is the flattest, so used that as reference to machine the top.

(https://pbase.com/kvom/image/169372443/large.jpg)

Then turned over to face mill the base.  Turns out I over cut by 15 thou, but hopefully that won't matter.  Next time in shop we'll try to square the other 4 faces.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on June 18, 2019, 12:47:09 AM
         :popcornsmall:
  :popcorn: :popcorn: :popcorn:

 
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 18, 2019, 10:03:56 PM
Today I continued on the roughing of the cylinder.  First I used a long endmill on the Bridgeport to trim as close as possible the detritus sticking out from the body of the casting. 

(https://pbase.com/kvom/image/169375286/large.jpg)

Then the rest of the available time was in face milling the ends.  Since the back edge of the top face is quite straight, I used that as a reference to mount the cylinder vertically.

(https://pbase.com/kvom/image/169375287/large.jpg)

Then machined both ends removing .01" at a time until all the cast surface was gone.  Tedious but all I had to do was click a couple of buttons for each pass.  Next time in the shop I'll do the sides.  The result of milling the ends is that the cylinder's length is 4.904 vs. the 4.875 called for, 29 thou to work with.  :whoohoo:

My main concern with the cylinder is the bore.  It's a half inch longer than the Joy engine where I had taper in the bore until I bought an adjustable chucking reamer.  Other than that, there's 5 pockets to machine to size and a ton of holes.

(https://pbase.com/kvom/image/169375349/medium.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Dennis on June 19, 2019, 02:54:11 PM
Good work Kirk, and thank you for the extra work to share your build with everyone watching along. 

The cylinder block and all the parts that bolt to it make up about 2/3 of the work in building the Green engine. 

Dennis
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 19, 2019, 10:46:14 PM
Another hiccup on the way to Greeneville.  Looks like an air bubble in the cast, revealed when squaring the back side. 

(https://pbase.com/kvom/image/169379539/large.jpg)

This  looks to be possible to work around.  The core to the admission valves looks ok.  This gap is somewhat wider than the holes on both top and back.  Since nothing is attached to the back other than the exhaust valve plate at the bottom, I could cover this with a third plate so seal it.  The hole in the top is also larger than it appears, and is partially in the area where the steam inlet pipe would be.  Once again it should be possible to seal it, probably by a bridge between the two top valve chest covers.

I'm going to suspend work on this pending advice from Dennis and Jeff.

Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 20, 2019, 01:18:20 AM
In the meantime I played with the SW model of the cylinder to see if I could use the honed hydraulic cylinder tube I used for the Muncaster.

It seems that if I turn down the OD to 1.625 (1/16" wall), I could use this as a cylinder liner.  Any larger I'd need to change the bolt circle for the rear cylinder cover.  If that can work, then the issue of bore taper goes away.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: jeff l on June 20, 2019, 01:50:15 AM
Hi Kirk , I have no problem with replacing the cylinder casting .Jeff
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Ye-Ole Steam Dude on June 20, 2019, 02:02:52 AM
Hello Kirk,

Sure hate to see the bad luck you are having with some of the castings. I see how much work you have put into these pieces. None the less your project is coming along nicely  :ThumbsUp:

Have a great day,
Thomas
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 20, 2019, 01:11:36 PM
Thanks Jeff.  New casting seems to be the better option.  I will use this one to experiment on using the hydraulic tube as a cylinder lining.


Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 20, 2019, 11:26:13 PM
Trying to make lemonade from a lemon, I mounted the cylinder block in the 4-jaw and adjusted by eye until the center of the cast bore was as close as I could get it.  The good news is that even  with the hole a bit off-center in one direction, the lathe doesn't shake at 500 rpm.   :D  The block measures straight on both sides to .004 over 4 inches.  I don't know if there is a way to adjust that, but the deviation shouldn't be significant .

(https://pbase.com/kvom/image/169384019/large.jpg)

As cast, the bore looks to be about 1-3/16" in diameter.  My current plan is to mill it larger on the CNC mill from both directions;  this will remove the flashing from the inside and provide a round surface for precise centering when back on the lathe.  Then I'll bore to 1.5" and test for taper.  If .002" or less over the length then no need for the hydraulic tube as a liner.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Jasonb on June 21, 2019, 07:15:33 AM
is there any reason you are not just boring it as you have it now? Usual practice is to bung up the hole so you have something to mark out the ctr on and then set that point to run true. A bit of hardwood driven into the hole and filed flush will do or you can just hot glue or cyno a piece of 1/8" scrap plate to the end.

I would set it up so that the base clocks true and then bore, also take a skim off the end of the cylinder at the same setting ( crank shaft end) as those are the two critical faces, any differences between those and the bore won't be in line with the cross head guide.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 21, 2019, 02:27:44 PM
The hole itself isn't very round, and there is a lot of flashing inside.  It's also not precisely centered.

A skim facing cut would be part of my plan.  I just noticed that as currently mounted the wrong end is outside of the chuck.  The block is symmetric in that the valve mechanism can be attached on either side (as was the case with the original). The crosshead guide casting works only one way however.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Jasonb on June 21, 2019, 03:01:56 PM
The hole itself isn't very round, and there is a lot of flashing inside.  It's also not precisely centered.

That is why you plug or cover the cored hole so you get a decent surface that you can accurately mark ctr on, then punch and finally clock the punch mark true.

Something like this where the core was rough, I hot glued a bit a aluminium over the end and marked out on that using the height gauge. This setup with faceplate and angle plate will also set your casting bottom true to the lathe axis and therefore your bore will be parallel to that.

(https://img.photobucket.com/albums/v156/jasonballamy/Hit%20n%20Miss/Robinson%20X-Type/DSC02293_zpsqstmrb8n.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 22, 2019, 08:29:02 PM
Despite the good advice from Jason, I decided to pursue my original plan and machine the rough bore before finishing by boring on the lathe.

The block is just under 5" long, and I don't have any carbide endmills with 2.5" flute length, but I did find this HSS one lurking in a drawer (from a bulk lot I bought at a sale years ago and never used).  .75" diameter and 4" flute length.

(https://pbase.com/kvom/image/169391881/large.jpg)

Unfortunately, I found that the center of the core is in the wrong location, approximately 1/4" higher than the design location.  You can see the ledge created after the first pass at a diameter of 1.55" needed to encompass the entire core wall.

(https://pbase.com/kvom/image/169391882/large.jpg)

Then in milling the other end it was even more out, indicating that the core is at an angle to base of the casting that I used as the initial reference surface when squaring the block.  For the replacement block, perhaps a thin rod through the code could serve as a "level", or at least to check against the bottom face.

Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Dennis on June 24, 2019, 01:49:02 PM
Good morning Kirk,

You are finding a lot of problems with the Green engine castings.  I have been bragging for years about the quality of castings from the foundry that made these castings but I am sure embarrassed by the flywheel and cylinder block you have.  I can understand that we should see an occasional inclusion or void but I can't figure out how the core could be put in at an angle.  I have always tried to leave a lot of extra metal in cylinder bores to allow for things like this thinking a few extra passes with the boring bar are better than loosing all the work already in the part.

Whatever the cause, I will replace the cylinder casting or send one to Jeff if he has already sent a casting to you, and appologize again for the problems you are encountering on this model.

Dennis



Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 25, 2019, 01:07:07 AM
Thanks Dennis. 

The location of the bore was partially my bad as I used the dimension from the top surface rather than the bottom to locate the center.  The latter is what should be used to make the piston rod at the correct height.  That said, I think using the hydraulic tube as a liner will work out well, and boring to 1.625 will cover the core position.

Since I had the current casting to experiment with, I drilled one of the exhaust cross holes using a 5/8 endmill.  The exhaust core "appeared" as expected, so that is OK.  The edges are at a bit of an angle to the base surface, once again indicating that the core isn't perfectly parallel to the base.  That should not be an issue.

I'll wait for you and Dennis to decide on the replacement, either your original one or one of his new ones.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 25, 2019, 01:12:30 AM
For the next part to attack, I've been looking at the brackets for the exhaust valves (images attached).  There are two castings for these, and the brackets themselves are mirrors of each other.

In reality, I expect these are easier to make from bar stock than the castings, and I'm tempted to order to a piece of 1.75" round grey iron to avoid the hassles of squaring the castings.  The overall size of each is approx 1.5x1x2 inches.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 25, 2019, 10:43:43 PM
I decided to make the brackets from grey iron rod, which I ordered from MSC.  So today's project is a small part of the assembly, the crosshead for the valve bracket.  Here's a 3D view:

(https://pbase.com/kvom/image/169406248/medium.jpg)

The radius on the top and bottom is .250, so the parts are made from 1/2" diameter rod.  I chose brass as the wll ride on iron guides.  The length of the part is .65".  First step is to drill on the lathe 0.7" deep with a #47 drill for 3-48 tapping.  Both ends of the rod are used, one part on each end.  Then move to the manual mill with a collet block to drill the cross hole 0.110".

(https://pbase.com/kvom/image/169406243/large.jpg)

Next position vertically to mill a 3/16" slot and then the sides to reduce the width to 0.3".

(https://pbase.com/kvom/image/169406245/large.jpg)

Back to the lathe to part off, face, and tap.

(https://pbase.com/kvom/image/169406246/large.jpg)

Finished.

(https://pbase.com/kvom/image/169406247/large.jpg)

Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 29, 2019, 03:39:37 PM
Latest attempt at parts is the sliding exhaust valve grid.  That's the green part of the exhaust valve assembly:

(https://pbase.com/kvom/image/169419683/medium.jpg)

The design of this part has some non-obvious features.  One is the two cross slots;  these are needed so that both are exposed to the cylinder's exhaust port regardless of the grid's position, as the port is only .8" wide.  The other is the width of the grid openings, which is .07".  This is constrained by the distance that the exhaust eccentric motion can move.  On the real engine there are many more thin slits.

An issue with making the part as drawn is that it requires the slits to be 1/4" deep, and in two cases be contingent with the wall of the cross slots.  All of my 3/16" end mills have a flute length of 3/16" and a 1/8" diameter shaft.  So I modified the part to have a pocket within the cross slots, moved the slits outward and within the pocket, and machine the slits from the bottom to a depth of .15" max.

I cut off a 5" piece of 5/8" drill rod and secured in the square collet block with 2.5" exposed (making two parts from one piece of stock).  The part itself is 2.05" long.  Use of the vise stop means I have to establish the part zeroes only once.

(https://pbase.com/kvom/image/169419615/large.jpg)

The cross slots and pockets are machined with the same 1/4" carbide endmill.

(https://pbase.com/kvom/image/169419616/large.jpg)

Then the collect block is turned 90 degrees and the bottom half of the stock is machined away using the side flutes of the same endmill.  Then after a further 90 degree turn the slits are machined.

(https://pbase.com/kvom/image/169419617/large.jpg)

Then the stock is reversed in the collet and the second part made the same way.  Then both are cut away on the lathe with a parting tool.

It appears there is a slight bowing in the part, and when laid on a ground surface light can be seen through the center.  Stresses relieved during the machining are a likely cause.  I will see if stoning or surface grinding can flatten the bottom, since that's crucial to a  good seal with the fixed grid.  Otherwise I might remake from some 1144 stressproof steel.

The fixed and sliding valves need to live in a 5/8" hole in the cylinder block.  I had to order a 15.5mm drill and 5/8" reamer to machine these holes.  The fixed grid is attached firmly to the bottom of the hole with screws, and the sliding grid needs to move freely, so I am hoping that the reamed hole allows this without too much trouble.  As long as the seal between the two grids is good, there is no issue with some clearance between the sliding grid and the hole.

I have the intention to make the valve brackets from bar stock rather than the castings and hence ordered some 1.75" grey iron rod from MSC.  The box arrived yesterday, but no iron inside (box looked to have been damaged in transit and resealed).  Did a chat session with MSC last night to get rod re-ordered.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Art K on June 29, 2019, 10:44:14 PM
Kirk,
You are making good progress despite unfortunate casting setbacks. At least you had the one to practice on. At work we've had boxes come in very busted up & missing contents, which were later found and returned.
Art
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on June 29, 2019, 11:11:39 PM
Thats quite a complex valve setup, very interesting.  The 1144 would be a good choice, gets rid of the warping.


 :popcorn: :popcorn: :popcorn:
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 30, 2019, 12:16:25 AM
I was intending to start work on the lower fixed grid, which I'll make from brass.  Not having any 5/8" round, I'll start with 3/4" hex and turn down to about .65". then heat in a 500 degree oven for a hour or so before turning to .625" and machining.  We'll see if we get warpage then.

I had to help with some family house moving that took up most of the day.

Since with the valves installed one can't see them working, I have in mind a test fixture.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on June 30, 2019, 12:25:26 AM
Doing the stress relieving bake for brass works out quite well, sometimes there is still a very slight bend, but no where near as bad as untreated pieces. Still, it can be worth leaving the final surface several thou tall then taking it down in a final truing pass when all cuts are made. On the 1144, I have not been able to detect any movement in the pieces I have cut.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on June 30, 2019, 02:36:23 AM
I have plenty of brass rod to make the trial, so nothing lost in trying.   :shrug:
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Captain Jerry on June 30, 2019, 07:38:14 PM
Hi Kirk,


I have been watching this closely without having anything to say since I have absolutely no experience with castings.  My main interest is the valve mechanism.  I have doped out much of the Green design for cutoff but had never given much thought to the exhaust, assuming wrongly that it was like the Corliss design. Then when I saw that it was some kind of reciprocating mechanism, I was thinking spool valve but it had not occurred to me that it could be a slide valve.


Your work on the slides is nice. The slots are perfect. What sort of spotting bit do you use to locate them.  I am guessing that the fixed part of the valve will be much like the movable part and that you will use a relieving slot to reduce the depth as you have done on the moving part. It seems like a bit of clearance for the slide would be much preferred to a tight fit and that you could lapp the two faces together to assure a good seal.


All in all, this is a very interesting project and your documentation is much appreciated.


Jerry
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 01, 2019, 01:06:59 AM
Jerry,

The entire piece is done on my CNC mill.  I discovered that when only milling the slots, the endmill only pushed up a thin layer into the pocket.  So I altered the program to use the endmill to chain drill the  slots and extra .020" deep before profiling them.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 01, 2019, 01:19:23 AM
While my brass rod for the fixed valves was in the 500 degree oven, I used this setup to attempt to flatten the sliding valves.

(https://pbase.com/kvom/image/169431276/large.jpg)

My height gauge was used to level the work on the v-block, and I took passes .002" at a time.  Seems a lot better but still can see a bit of light when laid on a ground surface.

I also made a start on the four little rod ends (tan color in the sw image) that are made from 1/4" square brass rod.  One of each pair needs to be tapped 3-48 left handed so that the connecting rod acts as a turnbuckle.  I ordered a LH tap on Amazon, and it should be here in a couple of days.

Once the brass rod had cooled, I turned it down slowly until it fit my "ring gauge" that I made from some aluminum rod using the drill and reamer I got last week.

(https://pbase.com/kvom/image/169431277/large.jpg)

I'll make the parts next time out and see if I get any warpage.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 01, 2019, 11:50:30 PM
Started on the fixed exhaust grid, which is secured to the bottom of the through hole by three 3-48 screws.  The relief slots on the bottom are oriented to the side of the cylinder block that open into the exhaust core.

(https://pbase.com/kvom/image/169434834/large.jpg)

The slits on the sliding edge:

(https://pbase.com/kvom/image/169434835/large.jpg)

I left about .02" to be removed on the flat after determining that the piece did have some bowing.  After parting off the valve, I put it back in a 550 degree oven for another hour+.  Next time out I'll shave the remaining as I did with the sliding grid and see how flat I can get it.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 02, 2019, 11:32:04 PM
The connecting rod between the exhaust crosshead and the swing arm that drives it is designed to allow fine adjustment of the sliding drid position.  As seen in the model picture, it is a length of .099 diameter rod threaded 3-48 on one end and 3-48LH on the other.  A fixed nut between the two thread allows expansion of the length of the rod when turned by a small wrench.  To make this I first had to order a LH 3-48 tap from Amazon; this arrived today.  I previously made the 4 rod ends, so first I tapped two of them RH and the other two LH.

Not having a LH die, I spent most of the afternoon generating g-code for thread milling 3-48 threads.  My CAM program generates the code easily, but I have to tweak the parameter to get the proper minor diameter, and I do this by sneaking up on it until the generated thread will screw into a tapped hole.  Nuts are looser.  Once I had the depth correct, I could easily generate code for LH threads as well.

Here is the result.

(https://pbase.com/kvom/image/169438187/large.jpg)

The plans specify soldering the nut, but I think Loctite will work just a well.  I needed to drill out the threads of the nut with a .097 drill, which produces a sliding fit.  To hold these small nuts for drilling, I laid them on a flat surface and placed a a small drill chuck over it, then tightened.  The jaws of the chuck naturally aligned the nut.  The chuck has a 1/2" straight arbor that's easily mounted on the lathe/
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 06, 2019, 12:04:13 AM
My cast iron chunk arrived yesterday, so today I had a chance to work on it a bit.  The parts involved are the rear caps for the exhaust valves, and are colored in turquoise on the SW diagram.  After cutting the 12" long piece of 1/75" round grey iron into twp 6" pieces. I mounted one piece in the Monarch.  Faced the ends, and then turned a .625" boss .25" long on each end.

(https://pbase.com/kvom/image/169454080/large.jpg)

Then back to the bandsaw to slice off each end.

(https://pbase.com/kvom/image/169454081/large.jpg)

Then using a 5C collet and square collet block, the rest of the machining was straightforward.

(https://pbase.com/kvom/image/169454082/large.jpg)

The 5" piece left from cutting I cut into two 2.5" pieces; these will be used for the exhaust brackets.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Dennis on July 06, 2019, 04:33:05 PM
Hi Kirk,

Still following along, the valves are looking very good.  I like the revisions you made on the exhaust valves.  Also good planning on the machining process.

Dennis
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 08, 2019, 12:06:18 AM
Started on the first exhaust bracket, starting with a 2.5" piece of 1.75" grey cast iron rod.  On the lathe, I turned down 2" in order to remove the mill scale, then drilled and reamed the center hole .501" diameter and 1.75" deep.  After reversing in the lathe, the remaining 1/2" was turned to 1.125" diameter.  The workpiece was then mounted in a square collet block using a 1.125" 5C collet.

On the CHC mill, work zeros for all 3 axes were set at the end of the work on the centerline.  This allowed a consistent setup with a vise stop in that I needed to mill 4 sides 2 ops each with varying depths of cut.  I just set target depth as the dimension from center needed on each op.  Each side was machined at full depth with a 3/8" 4-flute carbide endmill at .050" stepover.  After doing each of the ops, I had this result:

(https://pbase.com/kvom/image/169465658/large.jpg)

Then I used the Bridgeport to cut back the edge of the hole by 1" on each side as per the plans.

(https://pbase.com/kvom/image/169465659/large.jpg)

There are several more ops to go before the part is released from the collet to work on the other end.

The second bracket is identical except that the last two CNC ops are done on opposite sides yielding a mirror image part.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 08, 2019, 05:48:13 PM
My euphoria was short lived.  Some measurements are showing that the inner portion of the bracket is narrower than drawn by a significant amount:  .608" vs. .625".  Normally these aren't critical dimensions, but here there is a bearing at the narrow end, and the tapped holes for the bearing cap won't work as drawn.  I can make them closer together and may do so, but before starting on the second bracket I wanted to investigate where the error arose.

After turning and drilling the second blank, I made some shallow flats on opposite sides on the CNC mill, and was not able to get the proper  distance between top and bottom.  It appears that the issue arises because the work is not perfectly parallel to all 4 sides of the collet block when held on one end by the collet with 2" sticking out.  So rather than cutting with the work horizontal in the vise, I believe I'll need to do so with it vertical and not using the block. 

The Red Cross wants my blood this afternoon, so any further work will have to wait.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 11, 2019, 01:48:26 AM
Today I had only a couple of hours in the shop, so since I'd already done the CAM work for this small part it was a good time to start in it.  This swing arm fastens to the end of the rod that is oscillated by an eccentric on the crankshaft.  It also attaches to the rod end of the exhaust valve crosshead and provides the impetus to move the sliding grate back and forth.  The angle at which it is attached to the oscillating rod determines the throw of the grate, and hence is a major means of tuning the valve motion. 

(https://pbase.com/kvom/image/169480207/medium.jpg)

The part is small enough to be enclosed in a 1" circle, so I machined its profile in the end of a piece of steel that I believe is an 1144 offcut from when it was used for the Joy engine valve rods.  In any case it machines very nicely.

(https://pbase.com/kvom/image/169480203/large.jpg)

Then at the Bridgeport, cut the 3/8" slot 1/2" deep.

(https://pbase.com/kvom/image/169480204/large.jpg)

Then mount on the lathe with the 4-jaw chuck using the spot drill mark to center a wiggler held in the tailstock.  Once centered, a parting tool rounds the inner end of the slot.

(https://pbase.com/kvom/image/169480205/large.jpg)

Then reverse the work in the collet and being the other end up to the same stage.

(https://pbase.com/kvom/image/169480206/large.jpg)

Next time in the shop I'll part these off, then mill soft jaws to hold the parts for finishing the other sides.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 12, 2019, 12:00:27 AM
So I was mistaken about the name of this part.  I read it as "device" mainly because the font used in Solidworks made the cl combo read as d.  In reality it was clevice which is actually clevis misspelled.  I didn't want to call it a device so just called it a swing arm.  Now that that's out of the way, let's finish it up.

I machined a soft jaw pocket matching the outer profile .3" deep, and after parting each clevis off the parent stock I was able to machine the opposite side.

(https://pbase.com/kvom/image/169483916/large.jpg)

After drilling the hole for the control rod, we're finished for now.  These will need a set screw or two to attach to the rod.  The cad model shows a through hole implying two on opposite sides, but it seems to me that with the clevis in place on the engine the inner screw could be hard to access.  So I'm leaving these undrilled for now.

Here's the clevis shown in relation to the other completed parts.

(https://pbase.com/kvom/image/169483917/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 12, 2019, 10:48:15 PM
Now that I have an endmill with 2" flute length, it's back to try again;  this time milling the two main profiles top down.  Starting with 2.5" length of 1.75" round grey iron with reamed .501" hole 1.7" deep in the center.  I turned the bottom  down to 1.125" and milled a soft jaw pocket to match.

The first profile just defines the bottom mounting face of the bracket. Milled 1.9" deep.

(https://pbase.com/kvom/image/169486141/large.jpg)

Not the greatest surface finish, so on the second profile I did two passes with a .005" roughing clearance on the first pass.  Then the second profile, also with a roughing and finishing pass.

(https://pbase.com/kvom/image/169486142/large.jpg)

The other bracket is the same but with the second profile mirrored around the Y axis.

(https://pbase.com/kvom/image/169486143/large.jpg)

Next ops will be to finish the bottom;  hopefully I'll finish both parts entirely next time in the shop.

Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 13, 2019, 11:17:01 PM
More progress on the brackets.  I used the CNC mill to finish the inside (relative to the cylinder block).  The following photo shows how the bracket for the cylinder cover side would be mounted.

(https://pbase.com/kvom/image/169491612/large.jpg)

The onto the Bridgeport to drill and tap holes for the bearing cap, to be made next.

(https://pbase.com/kvom/image/169491613/large.jpg)

Then mill the edges of the hole and drill and oil hole.

(https://pbase.com/kvom/image/169491614/large.jpg)

I was very happy to get to this point without screwing up.

(https://pbase.com/kvom/image/169491615/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 19, 2019, 12:48:09 AM
Having discovered the misspelling of clevis in SW, I saw that there are 4 more needed.  The overall dimensions are identical other than the fact that they are connected to rod ends of different diameter, hence the hole on the small end is larger.

I had ordered some 1144 stressproof rods from McMaster, and the steel I made the exhaust clevises from is not that.  The finish on these is a lot better.  I cleaned up CAM for the first ops, but otherwise pretty similar to the prior parts.

(https://pbase.com/kvom/image/169518421/large.jpg)

With 4 of them to do, this time I'm letting the computer cut the slots.

(https://pbase.com/kvom/image/169518422/large.jpg)

So here they are waiting for the next ops.  I'm looking to make a fixture for turning the barrel versus messing with the 4 jaw to center it.

(https://pbase.com/kvom/image/169518423/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on July 19, 2019, 01:01:40 AM
Great work, following along...
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 20, 2019, 10:06:42 PM
Thanks for looking in Chris.

Today's goal was to finish the 4 clevises, which when we left them were still attached to the ends of the 1" rods.  The first order of business was to drill and tap for 3-48 grub screws

(https://pbase.com/kvom/image/169525462/large.jpg)

(https://pbase.com/kvom/image/169525461/large.jpg)

Since I've not machined over or removed the soft jaws on the CNC mill's vise, I can re-use the profile pocket as long as I can recover the XY zeros.  My mill doesn't have working limit switches;  if it did I could have recorded the machine coords.  In this case I had the finished exhaust clevises, so I placed one in the pocket and used this pointed wiggler.

(https://pbase.com/kvom/image/169525463/large.jpg)

By jogging until the head was smooth to the barrell all around, I can expect accuracy of better than .002 in either direction.  Then I parted off the 4 clevis ends leaving ~5/8" of extra rod.  Then placed the clevis into the soft jaws, I could mill a 1/2" boss centered on the large end of the clevis.

(https://pbase.com/kvom/image/169525464/large.jpg)

Then I could mount the part on the lathe using a 1/2" collet.  This allowed me to this form the inside diameter:

(https://pbase.com/kvom/image/169525465/large.jpg)

And then to drill and ream for a 3/16" rod.

(https://pbase.com/kvom/image/169525466/large.jpg)

Then it was back the mill to use the soft jaws and mill away the remaining material and finish the "back" of each clevis.  The four are now done other then some buffing/deburring.  Todays' sessions was nearly 5 hours, longer than my usual.  If I had to make a few hundred of these I'd need to find more efficient methods.

(https://pbase.com/kvom/image/169525467/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 29, 2019, 04:06:58 AM
After a mini-vacation in Las Vegas, I was back in the shop today to start on the bearing brackets that support the two parallel rods on which the 4 clevises made previously are attached.  One pair of clevises activates the input valves and the other two attach the dash pots.

Starting with 6" length of 1" diameter stressproof rod, I milled 4 sides of the rod to obtain a rectangular bar .75" wide and .5" thick.  The CNC mill then machined the profiles of the 4 parts .22" deep.

(https://pbase.com/kvom/image/169565092/large.jpg)

Then on the Bridgeport  I milled away the bottom stock to free the parts.

(https://pbase.com/kvom/image/169565093/large.jpg)

Still a few manual ops tomorrow to complete these.  So far about 95% of the original bar is chips.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 30, 2019, 12:18:15 AM
In order to drill the center mounting hole vertically through a bracket and its cap, the two must be aligned precisely.  Here's the method I came up with.

First, align as closely as possible by eye and clamp together in the small machinist vise.  Then face mill to ensure that the two sides of both parts are parallel.

(https://pbase.com/kvom/image/169568195/large.jpg)

Then ream the two bearing holes 5/16.

(https://pbase.com/kvom/image/169568196/large.jpg)

After this, I used my new sonic cleaner to remove any oil or dirt.  I then cut 4 pieces of 5/16" drill rod to serve as alignment fixtures while the two parts are fastened together with Gorilla Glue (cyanoacrylate).

(https://pbase.com/kvom/image/169568197/large.jpg)

Next time out I'll drill the center holes for 3-48 body screws and 1/16 oil holes for the bearings.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on July 30, 2019, 11:55:27 PM
These brackets are proving trickier all the time.  After the glue cured overnight, I went about drilling the holes.  The smaller bracket went OK, but here the drill wandered.   :(

(https://pbase.com/kvom/image/169572185/large.jpg)

It's possible I didn't make the spotting drill hole large enough.  The camera color came out a bit weird, but the sonic cleaner leaves the steel with a greyish patina that comes off with a light rub of 1000 paper.  The steel seems to want to rust when cleaned though.

I don't want to cut another piece of stressproof right now and will wait until I have some other parts that can use the same size.

As consolation I spent the rest of the afternoon making the rod ends for the rods that suspend the dash pots.  Each pair has one 3-48 RH and one LH, so that turning the rod can adjust the height of the pots.

(https://pbase.com/kvom/image/169572186/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: Craig DeShong on July 31, 2019, 09:47:33 PM
Hi Kirk,  just getting caught up on this build.  Was sorry to see the problems you were having with the cylinder casting, sort of reminicent of the head problems I had with the Frisco build.  Hope you get a replacement casting you can work with.  The Clevises look terrific.  Great work here.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: steam guy willy on July 31, 2019, 11:58:17 PM
Hi Craig, Following along, and that is an interesting rule you have,,divided into 50ths..! i have seen  8ths 16ths  and 10ths and 100ths but never 50ths..?? is there a special reason for this ? 

willy
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 01, 2019, 03:12:17 AM
The rule is one of many I have picked up over many shows.  I could never find a rule when I was looking, so now with 20 or so scattered over the shop I can usually lay my hands on one.  No idea why the maker of this one chose 32nds.

Today I made the dash pot connecting rods.  Cut the two rods to length on the lathe using DRO to measure and my $90 Hardinge collet to hold it while I parted them.  Then thread milled the two ends of each.  After drilling out the threads of two 3-48 nuts, I glued them onto the rods.

(https://pbase.com/kvom/image/169575860/large.jpg)

The rod ends needed to be bought to 3/16 thickness.  With a clevis one one end, here's the assemblies:

(https://pbase.com/kvom/image/169575861/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 02, 2019, 12:40:30 AM
Continuing on with the inlet, this shows the parts involved:

(https://pbase.com/kvom/image/169580931/medium.jpg)

The clevis mounts on a rod that oscillates as directed by the eccentric and cutoff mechanisms.  The small end is connected to a sort of die block that sides vertically in a slot in the blue part, which serves as a crosshead.  This in turn connects to the valve via the valve stem.  The stem is 1/8" in diameter and has .8" of 5-40 thread .  For timing, the angle of the clevis on the rod determines the total stroke of the valve.  Once set, the 3 nuts on the stem adjust the proper position the of the valve.

To keep everything aligned, the valve slides in a groove and also is constrained by the steam chest cover.

My shop job for the day was to make the simple valve stems, with .8" of thread on one end and .2" on the other.  Decided to thread mill these as my mill was already set up.  Probably silly as I spent over an hour developing the code to cut the long thread.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 02, 2019, 11:42:43 PM
For the slider block, mill the profiles in some 1144 steel.

(https://pbase.com/kvom/image/169584129/large.jpg)

To remove the bottom waste, this is one of my favorite methods.  Better finish the  from the tip of an endmill.

(https://pbase.com/kvom/image/169584130/large.jpg)

Drill and tap the hole for the valve stem.

(https://pbase.com/kvom/image/169584131/large.jpg)

With valve stem attached.

(https://pbase.com/kvom/image/169584132/large.jpg)

Machine profiles of the die block on the end of some 75" bronze rod.

(https://pbase.com/kvom/image/169584133/large.jpg)

After separating from the stock and fettling for fit, assembly of clevis, slider, and die block.

(https://pbase.com/kvom/image/169584134/large.jpg)
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 03, 2019, 06:28:12 PM
Today's work will be to start on the dashpot canister.  Here's a transparent view.

(https://pbase.com/kvom/image/169586993/medium.jpg)

The dashpot cylinder slides within the cavity, and is attached by a rod to the inlet mechanism. At cutoff, the cylinder pulls the valve shut.  On a full size engine, there's a close fit, and when the cylinder is raised a vacuum forms in the canister.  This plus the weight of the cylinder provides the force needed to close the valve.  In this model, a spring is used, so the fit of the cylinder is not as critical.

There are two castings provided for the canisters, but for me it's much easier to make them from round 1144 rod.  The two flanges fit within a 1.5" circle, and I have some 1.5" stock.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 04, 2019, 02:31:57 AM
Start with some 1.5" rod in the lathe, face, and skim turn to get the initial diameter which is used to set the DRO.

(https://pbase.com/kvom/image/169589114/large.jpg)

Then turn down to .850" diameter for a length of .675.

(https://pbase.com/kvom/image/169589115/large.jpg)

Drill a centerline hole .144" (#27) through (1" depth) here.  Then use .5" endmill in the tailstock to rough out the cylinder bore, and finish with boring bar; final diameter .575".

(https://pbase.com/kvom/image/169589116/large.jpg)

Using a parting tool, machine inner diameter to .75".

(https://pbase.com/kvom/image/169589117/large.jpg)

Then part off.  The canister is not difficult to chuck for the remaining ops, so I turned a 5/8" aluminum bar to a close fit to the canister bore and glued it in.  Subsequent ops will use a 5/8" collet and collet block to hold the piece.  At the end a blast from a torch will free the plug.

(https://pbase.com/kvom/image/169589118/large.jpg)

Next shop session I'll finish these and start on the pots.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: crueby on August 04, 2019, 03:09:51 AM
Great work, following along.   :popcorn:
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 06, 2019, 10:55:56 PM
I had a couple of days of frustration trying to finish the first canister.  The aluminum plus glued into the bore didn't hold properly, and the piece rotated ruining it while machining the base.  I tried Loctite instead of glue and that also failed.  I probably would have succeeded with a miniscule DOC.  So one of them was ruined, and I tried to come up with a way to hold it securely to mill out the bottom profile.  Eventually did this:

(https://pbase.com/kvom/image/169600324/large.jpg)

Three pieces of 3/16" square brass glued to the tips of chuck jaws fit into the recessed diameter and allowed a very firm hold.

For the pistons, I turned some 3/4" brass rod down to 5/8".  Then drilled and tapped one end 5-40, and parted off a 1" length.  The opposite end was drilled for a cross pin (to attach the rod end), two 3-48 set screws, and a pocket.

(https://pbase.com/kvom/image/169600322/large.jpg)

The bottom end was then turned to fit the canister with a nice sliding fit.  The top end was similarly turned down, and a grooving tool used form the bands.

(https://pbase.com/kvom/image/169600326/large.jpg)

(https://pbase.com/kvom/image/169600327/large.jpg)

The partial assembly to the rod:

(https://pbase.com/kvom/image/169600323/large.jpg)

Now I need to make another canister.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 10, 2019, 09:42:23 PM
I came up with a better sequence of ops for the canister.  After the manual turning and boring, the flange is machined on the CNC mill.

(https://pbase.com/kvom/image/169617339/large.jpg)

Then back to the lathe to groove the cylinder relief, and finally part off.  To clean up the bottom the lathe chuck gave a good enough hold so that facing with small DOC gave no problems.

Now I could finish the piston the same way as the first, turning to get a good sliding fit.

(https://pbase.com/kvom/image/169617340/large.jpg)

With these done, my next part to attack is the slide shelf.

(https://pbase.com/kvom/image/169617342/medium.jpg)

The overall dimensions are 2.5"x1"x.8".  To make a start, I cut down a 2.5" length of stressproof into a block slightly larger in the other two dimensions.

(https://pbase.com/kvom/image/169617341/large.jpg)

Most of the ops on this part will be manual on the Bridgeport.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 12, 2019, 01:50:50 AM
Today I reduced the block to the required dimensions on all three axes, then cut the three reliefs.

(https://pbase.com/kvom/image/169620892/large.jpg)

Then on to the CNC  mill where the large front pocket was milled .6" deep.  I used a 3/8" roughing mill followed by a 1/4" finishing pass.  Then spot drilled and drilled the 5 holes needed on this face.

(https://pbase.com/kvom/image/169620893/large.jpg)

Next time I'll finish with drilling in the top and the smaller pocket from the rear.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 13, 2019, 08:45:15 PM
I finished up the shelf yesterday, mostly drilling and tapping.

(https://pbase.com/kvom/image/169626654/large.jpg)

I was intending to continue with the slide.  But rather than continue to carve flat sheet from round bar, I decided to order some 1/8 and 1/4 inch sheet A1 tool steel from MSC for these flat parts.  In the interim, I attacked the small part shown in red here:

(https://pbase.com/kvom/image/169626644/large.jpg)

The view here is the bottom of the cutoff assembly.  The shelf is a light brown and the slide is grey.  The input from the governor is a rod that activates a cammed vertical motion of the rod that is attached to our red piece.  As the rod moves vertically, so does the part that engages its slot.  This part in turn is attached to the tappets via holes in the slide.  As the slide moves back and forth the tappets remain at a constant height as long as the slot has a good sliding fit that inhibits any vertical movement.

The dimensions of this "slide bracket"  fit within a 1/2" bounding circle, so I could mill the sides on the end of a piece of 1/2" drill rod.

(https://pbase.com/kvom/image/169626641/large.jpg)

Then reorient the collet block to mill the slot.  I used a 3/32" endmill, slightly smaller than the called for .10" slot width;  but a good fit with its partner is more critical than the dimension.

(https://pbase.com/kvom/image/169626642/large.jpg)

Then part of on the lathe and bring the cut off side to dimension.

(https://pbase.com/kvom/image/169626643/large.jpg)

Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 16, 2019, 02:21:47 AM
Made the simple slide today.  It took a bit of work, but finally got a good sliding fit with the previous part.

(https://pbase.com/kvom/image/169637417/large.jpg)

I found a piece of 2" diameter steel rod in the shop, and am pretty sure it is left over 1144 from when I made the Joy engine conrods.  In any case I cut off a few inches, faced both ends, and machined the profiles for the input valve bracket replacement for the one ruined by a wandering drill bit.

(https://pbase.com/kvom/image/169637418/large.jpg)

To free it from the stock, I needed to part it off.  Doing this in a single deep groove is tough, and I was getting a lot of chatter and complaining from the lathe.  Solution is to cut a groove 1.5 time the width  of the parting tool, and go alternately a short depth from each side.  Tomorrow I'll machine off the backing material and hope to have better luck finishing it.
Title: Re: Greene Automatic Cutoff Steam Engine
Post by: kvom on August 19, 2019, 12:38:42 AM
I got the bracket and clamp separated from the root stock and glued up, but am waiting for a new #37 drill bit before proceeding. 

(https://pbase.com/kvom/image/169649255/large.jpg)

In the meantime I attacked the "trips";  these are the two parts that stand proud of the slide and activate the valves as the slide goes from side to side.  Their height above the slide is controlled by the governor.  Above a certain height the mating catch cannot slide over its trip, and no cutoff occurs.   To begin I chucked a piece of 3/8" drill rod, faced the end, and drilled/tapped for 3-48.  Then turned down to .187" for a length of .675" according to plans.

(https://pbase.com/kvom/image/169649256/large.jpg)

Checked the fit with the reamed holes in the slide.  The left the lathe setup to cut the same diameter on the other end of the stock.

(https://pbase.com/kvom/image/169649257/large.jpg)

Next part off and over to the CNC mill to machine the ends to a 1/4" square.

(https://pbase.com/kvom/image/169649258/large.jpg)

Test to check fit with the slots on the slide.

(https://pbase.com/kvom/image/169649259/large.jpg)

After facing to final length, the 20 degree angle is machined onto the top surface.  On the prototype engine, this face is slightly concave.

(https://pbase.com/kvom/image/169649260/large.jpg)

On the drawing, a threaded boss at the end is shown.  I prefer to use a screw or some threaded rod and a nut for simplicity.

(https://pbase.com/kvom/image/169649261/large.jpg)

I also used 3/16" as the diameter of the slide holes, thus allowing the work to be held with a 3/16" collet.