Author Topic: Greene Automatic Cutoff Steam Engine  (Read 26141 times)

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #195 on: December 03, 2019, 12:49:50 AM »
The piece that was cut away from the yoke supplies the clamping pieces.  First, I located and drilled the mounting holes for 2-56 screws.



Then parted from the main body.



Repeat on the other end, and we're ready for the next stage.



After this I cleaned up the sides of the arc to reduce their thickness, but I didn't take any pics here.

Next op will be to mill a rectangular through pocket in the central arm where a type of ball-joint will be placed.  The eccentric strap is a bit too wide and long to fit inside the yoke, so some fettling will be needed before they can live happily together.

Offline Craig DeShong

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Re: Greene Automatic Cutoff Steam Engine
« Reply #196 on: December 03, 2019, 01:37:19 AM »
Is he posting any of his work?

No.  Unfortunately he shys away from computers which is a shame because his work is exemplary 
Craig

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #197 on: December 03, 2019, 12:29:26 PM »
Just as well, as I'd suffer from the comparison.   :-[

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #198 on: December 04, 2019, 02:50:24 AM »
The inside of the yoke needs to be flat for enough depth that the inner eccentric can rotate.



Continuing on with fitting the smaller half of the eccentric strap to the yoke.  The width was fine, but I had to take a good bit off the outer edge with the belt sander to arrive at this.



Then it was time to drill the pivot holes using the same technique as for the eccentric strap.  Drilling had to be done separately from each side, but my .126" reamer was just long enough to do both holes together.



Moment of truth when we see how well it goes together using some 1/8" drill rod as pivots.



Looking at the video of another build, it down't appear the the pivot ange is very great, much less that these parts can do.

Offline scc

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Re: Greene Automatic Cutoff Steam Engine
« Reply #199 on: December 04, 2019, 10:33:32 PM »
Excellent work and detailed posting,    I'm watching and learning.        :popcorn:     Terry

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #200 on: December 06, 2019, 09:23:42 PM »
The next op is to mill a through rectangular hole in the arm of the yoke.  To minimize filing needed to square the corners, I was hoping a 1/8" endmill would work.  When mounted on the mill, two problems became apparent.



The first was that for the end of the hole, there was still too much of the cast arc in the way.  The second problem was that the spindle would hit the arc before the bottom of the hole was reached.  Solution to the first problem was to mill away the part that was blocking the hole.



Then I found a 3/16" endmill in my supply that is 3" long.  A 1.6" stickout ensured that the spindle would be above the arc when the bottom of the hole was reached.


Offline crueby

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Re: Greene Automatic Cutoff Steam Engine
« Reply #201 on: December 06, 2019, 09:57:38 PM »
Great progress, watching along...   :popcorn:

Online sco

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Re: Greene Automatic Cutoff Steam Engine
« Reply #202 on: December 07, 2019, 09:51:01 AM »
That strap is full of challenges isn't it - you keep overcoming them though!

Keep it up,

Simon.
Ars longa, vita brevis.

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #203 on: December 07, 2019, 11:58:12 AM »
The end is in sight on this one anyway. 

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #204 on: December 11, 2019, 01:46:56 AM »
Some more progress over the last few days.

The arm of the yoke was left long to aid in securing in the vise, and now I reduced it to the specified length.  Then drilled and tapped 8-32 for a screw to secure the ball joint that will live in the "cage".



Then went back to work to finish the other eccentric strap and rod.  The inlet eccentric rod is 8" long and requires 3 12-28 nuts to attach it to the eccentric and a lever.  While the Solidworks model has a model of the nut as a model-scale "heavy" nut, the plans do not show the dimensions.  From the model, I fashioned the 3 nuts from 3/8" drill rod for a 5/16" wrench.  Normal fabrication using a hex collet block.  These are the only 12-28 nuts used on the engine.  Certainly the coarse 12-24 version would have worked as well,  but I had neither tap at the beginning of the build.



If a builder were to use standard regular nuts that use a 7/16" wrench, he will need to take this into account when finishing the eccentric strap.

Rather than pay for a 12-28 die, I created the code to thread mill the rod.  The dimensions in the plans are all given in decimal inches.  For the rod, the drawing specified #12 drill rod, which is .220" diameter.  I ordered this from McMaster, but had I thought about it more closely I've have realized that 7/32" drill rod is .219, and the thread's major diameter is .216.  I would also not habve thought I needed to use the rubberflex collet chuck to hold the rod in the mill.



While this worked OK, there's something about the design of the chuck that prevents it from being opened when positioned flat.  So to do the opposite end, I had to remove it from the mill, install on the lathe, and then  I could extract the rod.  It was at this point I realized the the rod would work with a 7/32 5C collet.   :facepalm:  In any case, here's the rod with its three nuts.



To attach it to the eccentric strap, I needed to machine a rectangular through hole into which one of the nuts could be inserted.  Since my nuts use a 5/16" wrench, I made the height of the hole 11/32".  I were to use the standard nuts from the hardware store, the hole would need to be 15/32.




Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #205 on: December 14, 2019, 03:25:23 AM »
Small progress:  rod end for inlet eccentric rod.

Half inch square bar on CNC mill to profile and drill the cross hole.



Over to Bridgeport to reduce thickness to 3/8".



Then lathe for the boss, and mill to drill and tap.


Offline Craig DeShong

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Re: Greene Automatic Cutoff Steam Engine
« Reply #206 on: December 14, 2019, 10:13:07 PM »
This is some rather tedious work, but you seem to be solidly working your way through it all.  I wish my friend who is building one of these were posting because you’ve both seemed to Have settled on the same approach.  He’s working a little slower than you so your progress is out ahead now.  It all looks great !!
Craig

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #207 on: December 14, 2019, 11:42:27 PM »
Craig,

As of this moment, I'm planning to drive to Cabin Fever and then spend 2 days in Washington DC.  If your Apex friend would be interested in hosting a shop visit, it's not far out of my route home.  Probably Wednesday Jan. 22.

My part-o-the-day for Saturday is a bracket that attaches to the inner bearing standard and supports the rod that activates the exhaust.  I couldn't actually find a drawing for this part, and have emailed Dennis.  However, since I do have the Solidworks part file, I didn't need a drawing. 

The profile of the part fit neatly into the bounds of a 1.5" circle, so I cut off a 2" piece of 1144 rod, faced it and mounted in the CNC mill vise between two v-blocks.  The profile was cut with a 1/2" endmill for the roughing pass, and this removed all extra material from the stock.  Then a facing pass op was done with the same endmill to form the 1/32" deep boss.



The finishing pass with a 1/8" endmill followed, and then the bearing hole was drilled.  The thickness of the part is 1/2".



I drilled the mounting holes on the Bridgeport before parting off from the stock.  3-48 body drill, .104".



Then milled out a slot to allow a nut driver to tighten the bottom mounting screw.  Two more ops needed:  an oil hole on the top, and machining the boss on the other side.  A brass or bronze bearing will be machined to fit the hole.


Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #208 on: December 18, 2019, 02:13:41 AM »
I finished the bracket by machining the boss on the opposite side, and then drilling a 1/16" oil hole.



The next parts targeted today are the two pulley that will connect the crankshaft to the governor.  Both are 1144 Stressproof from rod.  The smaller governor pulley is 1.125" in diameter with a 1/4" wide slot for the belt.  It's secured to a shaft by two 3-48 set screws.  Simple turning job with the shaft reamed .188".



The larger crankshaft pulley will be turned from 2" rod, and will the project for the next session.

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #209 on: December 19, 2019, 11:41:59 PM »
The crankshaft pulley was today's task, a relatively simple turning job.  Stock is 1" cutoff of 2" round bar 1144 Stressproof.  Op 1 is to face the stock, then drill and bore center to sliding fit on .875" crankshaft.



Next op to to turn OD to 1.875".



Turn the collar to 1.125" OD, .345" width.



Now the collar can be gripped with a 5C collet and collet chuck, so facing to get the correct thickness of the pulley.



I marked off the width of the belt slot using a very thin grooving bit.



Then a regular parting tool cuts the belt groove.



All that remained was to move the the Bridgeport and drill/tap two 3-48 holes in the collar for set screws.