Cretors #1 Horizontal Steam Engine Build

[rstreift]

Thanks.  Nothing is perfect and some of my "oops" is in simply reading the prints. 

[rstreift]

The Slide Valve, #S332-B

As this is the first slide valve I’ve machined, it took some pondering to figure out how to approach it.  I figured the “tab” was sufficiently strong to use to hold the valve to machine the sides and pocket.  The overall dimensions were reasonably uniform, so I knocked off the high spots with a file and used the bottom as a datum to machine the tab.
S332-B-SlideValve-1.jpg, S332-B-SlideValve-2.jpg

With it flipped over, a parallel gave me an offset to indicate the center of the tab to machine the sides and pocket.
Milling off the sliding surface and finishing with a fly cutter, this side is done.
S332-B-SlideValve-3.jpg, S332-B-SlideValve-4.jpg, S332-B-SlideValve-5.jpg

[rstreift]

The print indicated a 45 degree angle for the top of the valve.  Maybe it is to enhance the smooth flow of steam, but other than that I’m not sure why they machined it.  The tilt table is seldom used and I keep a layer of LPS3 on it.  For this small part, I cleaned off only the section I needed to use.  No, it is not rusty. 😊
I screwed up a bit on this on.  For unknown reasons, I had it in my head the angle was 20 degrees and setup the table that way.  When I made the cuts on the first side, I realized this may hit the pocket.  So, I stopped and decided it was fine in this configuration and did the other side the same.
S332-B-SlideValve-6.jpg, S332-B-SlideValve-7.jpg

The third side was an end, so to speak.  I reset the table to 45 degree, lined up the valve, and machined it. 
S332-B-SlideValve-8.jpg, S332-B-SlideValve-9.jpg

The corners have a compound angle that was not specified.  I measured the print and set it up accordingly. 
The last feature was to cut the slot for the valve rod.
S332-B-SlideValve-10.jpg, S332-B-SlideValve-11.jpg

[rstreift]

The Gland Nut, #S332-J

The gland nut for the steam chest is cut from a piece of hex stock.  I drilled the hole and finished the bottom of the hole with a flat ground drill.  It’s then tapped and finished with a bottom tap.
S332-J-GlandNut-1.jpg, S332-J-GlandNut-2.jpg

The external features are turned and cut off.  The curved section was not specified and there is only one, so I shaped it free hand.
S332-J-GlandNut-3.jpg, S332-J-GlandNut-4.jpg

[rstreift]

The Chest Stud & Nut, #S332-K

The chest studs need nuts and I made them first.  They’re from  SS 303 hex stock, drilled/threaded with a 0.10 washer land.
S332-K-ChestStudNut-1.jpg, S332-K-ChestStudNut-2.jpg

The studs are from SS 303 rod with thread relief and rounded ends.
S332-K-ChestStudNut-3.jpg, S332-K-ChestStudNut-4.jpg

The stud lengths were adjusted so that the studs will have 2-3 threads projecting when assembled.
S332-K-ChestStudNut-5.jpg

[rstreift]

The Valve Rod, #S332-C

The valve rod and eccentric strap have a coupler, so I cut and squared off brass bits for both.  The coupler pieces are spec’ed to be silver soldered to their respective shafts, but since Loctite is a fine product; the coupler parts will be threaded and loctite’d to their respective shafts.  While Loctite would be sufficiently strong without the threads; I just preferred to thread it. 
Holding the bit in a square collet, the coupler was drilled/tapped for the rod.  Then turned as per the print. 
S332-C-ValveRod-1.jpg, S332-C-ValveRod-2.jpg

Mounting the round in a 5C square block, the pin hole is drilled/reamed and turned on end to cut the yoke.
S332-C-ValveRod-3.jpg, S332-C-ValveRod-4.jpg

The rod is straight forward as the studs, just a bit longer.  The ends are threaded.  When running the coupler on the rod, I realize that with the thread relief one cannot see the threads.  I reckon that if this engine ever gets enough runtime to wear out the coupler, the future machinist will have to figure this out.
S332-C-ValveRod-5.jpg, S332-C-ValveRod-6.jpg

The assembled valve rod with nuts.
S332-C-ValveRod-7.jpg

[rstreift]

The Eccentric Strap, #S332-D

This part includes the rod and coupler end as well as the casting.  The coupler end blank was just machined while doing the valve rod.  The eccentric’s shaft is threaded and loctite’d to the coupler end the same as the valve rod. While they look similar, this is the eccentric strap’s coupler.
Holding the brass bit in a square collet, the coupler was turned/tapped.  Then to the mill to machine the male feature on the coupler end and drilled/reamed for the connecting pin.
S332-D-EccStrap-1.jpg, S332-D-EccStrap-2.jpg, S332-D-EccStrap-3.jpg

The shaft’s machining starts with a light skim for the correct diameter for a 10-32 external thread, then the thread relief.  A die completes the threaded end.  The second photo is the other end of the shaft.
S332-D-EccStrap-4.jpg, S332-D-EccStrap-5.jpg

The casting is consistent in its dimensions and it is machined on both sides to the required thickness. 
S332-D-EccStrap-6.jpg, S332-D-EccStrap-7.jpg

[rstreift]

Using the bottom of the casting as a reference, a little layout work here will provide lines to use when splitting the casting and milling the cut surfaces to the correct dimensions.  I use the center line for reference to drill/tap the hole for the screws and one of these lines to position the casting in the vice.
S332-D-EccStrap-8.jpg, S332-D-EccStrap-9.jpg

While the original engine was specified to be finished all-over, I’ve decided I’d be happy with as-cast finish on most of the non-machined areas of the parts.  This led me to increase the distance between the screw holes by an 1/8” for a better balanced appearance.  The spindle is centered on the casting and the screw holes are drilled for threading and clearance as well as tapped.
S332-D-EccStrap-10.jpg, S332-D-EccStrap-11.jpg, S332-D-EccStrap-12.jpg

The casting is split on the center line.  Using the laid out lines on each casting, they are milled flat and screwed together.
S332-D-EccStrap-13.jpg, S332-D-EccStrap-14.jpg, S332-D-EccStrap-16.jpg

[rstreift]

The hole for the rod and finishing the boss for the hole is next.  The eccentric strap is fixtured to an angle plate and then mounted on a faceplate.  Counter weight in the form of the three clamps was needed to balance out the casting/angle plate.  Hole is drilled/tapped and the boss is turned down.
S332-D-EccStrap-17.jpg, S332-D-EccStrap-18.jpg, S332-D-EccStrap-19.jpg

The area between the boss and the flat surface of the eccentric strap needed blended and I decided to fixture it on the mill and use a ball nose end mill to blend it.
S332-D-EccStrap-20.jpg, S332-D-EccStrap-21.jpg

I seem to be missing a hole in the middle for the eccentric. 😊  The part is lined up in a small 4-jaw independent chuck on the laid out center lines, I put a prick mark in the middle to give the pointer a place to rest.
S332-D-EccStrap-22.jpg

The angle with respect to the Z-axis is 25 degrees.  The sine bar table is fixed in the tailstock and zero’ed.  Using a sine bar and stack, the compound travel is zero’ed to the sine bar.
S332-D-EccStrap-23, S332-D-EccStrap-24

[rstreift]

The part is drilled/bored out to eliminate the excess metal.  Then the DRO’s axis and the compound are zero’ed so that I can return to the same position. Since I know the diameter of the hole, a little math gives me the target figure on the cross-slide readout to attain about 0.150” less on the spec’ed diameter on the surface of the part.  I needed that surface to indicate the part in when it is flipped over to do the other side.
The method I used is to move the compound to make the cut and return the compound to zero.  Move the cross-slide for the depth of cut and crank the compound to make the cut, then return the compound to zero.  I move the cross-slide for the next depth of cut and crank the compound to make the cut, then return the compound to zero.  I continue repeating until the cross-slide’s readout is on my target figure. 
S332-D-EccStrap-25.jpg, S332-D-EccStrap-26.jpg

The part is flipped and indicated in on the uncut portion of the bored hole.  The same procedure above is used to cut this other half of the “V” shape.
S332-D-EccStrap-27.jpg, S332-D-EccStrap-28.jpg

The last feature is the oil hole. This is not critical and the shaft is used to align the threaded hole parallel to the table.  The screw is in the way and a clamp takes its place.
S332-D-EccStrap-29.jpg, S332-D-EccStrap-30.jpg, S332-D-EccStrap-31.jpg

[rstreift]

The Eccentric, #S332-E

Now to make the mating piece, the eccentric.  The challenge I find in this is to make a mate to the eccentric strap’s “V” shape that is just a bit snug to facilitate wear-in.  I’ll use a two stack of paper shims, after wear-in, the one shim will be removed and the remaining shim can be removed in the event the engine gets run often.
I select a cut-off and face the end for marking.  I need to prick the center and an offset of 1/4”.  With that done, the stock center prick mark is centered in the chuck.
S332-E-Eccentric-1.jpg, S332-E-Eccentric-2.jpg

Since I’m using a different lathe than used for the eccentric strap, I need to set up the angle.  When I made the sine table, I intended it to be held at the headstock end.  Most of the time I use it held on the tailstock side. 
As previous, the travel on the table’s bar is zero’ed and then the stack/sine bar is added and the compound travel is zero’ed on the sine bar.  I do a reality check by measuring the eccentric strap’s angle and find it to be ~73 degrees instead of 65 degrees.  Oops . . . . . .
First, I use the 73 degree locked protractor to the angle I just set on the lathe, it eyeballs the same.  The other lathe is compound is still set and its eyeball’s the same as the protractor.  Apparently, I’m consistently wrong.  I recheck my figures and come up with the same stack.  I recheck the stack and I’m using a 2.00 and 0.113 gage blocks.  Then I see it! 
Through a highly trained “lack of attention to details at a crucial moment”, I see that I have the 2.00 block on its side, thus the stack was actually built with 1.375”+0.113” gage blocks.  So, my actual angle is 72 degrees 39’ minutes.  RATS.  If one goes back to photo #24 of the eccentric strap log, one can easily see it.  I’ll put it here to save you some time. (some of the gage block is hidden by the sine table bar)
S332-D-EccStrap-24-closeup.jpg

Upon reflection, the model will run just fine with the eccentric’s mating angle at 72 degrees 39’ minutes.  I went ahead and cut the eccentric with the same error. 
S332-E-Eccentric-3.jpg, S332-E-Eccentric-4.jpg

The stock is turned down to the finish diameter and scribed with the center and outer edges of the “V” feature.  A groove is cut in the center to the depth of the “V”.
S332-E-Eccentric-5.jpg, S332-E-Eccentric-6.jpg

[rstreift]

On the eccentric strap it was simpler to flip it over to cut the opposite side, here it’s simpler to use a boring bar and reverse to cut the opposite side.  It took a couple of iterations to achieve the fit.
S332-E-Eccentric-7.jpg, S332-E-Eccentric-8.jpg

The fit up has turned out well, time to indicate in the offset and turn the eccentric part.
S332-E-Eccentric-9.jpg, S332-E-Eccentric-10.jpg

The eccentric shaft’s hole is drilled/reamed.  My chucking reamers go to ½” and I need to use a hand reamer.  In this case it was simpler to spin the chuck by hand than move the wrench.
S332-E-Eccentric-11.jpg, S332-E-Eccentric-12.jpg

[rstreift]

The print specifies two set screws at 90 degrees apart.  The eccentric is set in a v-block and is rotated until the indicator sitting on the top of the boss bottoms out.  Lines 90 degrees apart are scribed close to center as it’s the lines I need, not the center.
I use the lines to align the eccentric in the vise for the first set screw hole.
S332-E-Eccentric-13.jpg, S332-E-Eccentric-14.jpg

After the 1st set screw hole is finished, the eccentric is rotated 90 and the second is drilled/tapped.
S332-E-Eccentric-15.jpg, S332-E-Eccentric-16.jpg

The final operation is to turn the cam to its final dimension.
S332-E-Eccentric-17.jpg

[rstreift]

The Connecting Rod, #S331-B

The connecting rod casting has both rod ends and a spigot to hold it.  After some consideration, I decided to use the spigot and turned it to 9/16” so I could use a 5c collet block as well.
S331-B-ConnectiongRod-1.jpg, S331-B-ConnectiongRod-2.jpg

It is mounted in the lathe to turn the outer diameters.  Having played with the casting, I know the part is reasonably symmetrical so I use an adjustable parallel to align to the 5c block edge.
S331-B-ConnectiongRod-3.jpg, S331-B-ConnectiongRod-4.jpg

In the mill, I’m checking that it is parallel to the table and that the jack/clamp does not move it.  Once it is secured, I mill off to 1/2 of the specified thickness plus 0.10 to allow some error; I’ll clean that up at the end. Then repeat for the other side.
S331-B-ConnectiongRod-5.jpg, S331-B-ConnectiongRod-6.jpg, S331-B-ConnectiongRod-7.jpg, S331-B-ConnectiongRod-8.jpg

[rstreift]

Time for some layout work.  The lines to layout are for the outline of the caps and bottom parts.  I marked out the radius for the cap so I can cut off the excess and prolly grind/file it to shape.  Each rod end is prick punched on each of their mating parts to ensure they can be assembled exactly the same way to keep the wear patterns together.   A couple of minutes at the bandsaw and I have two rod ends to machine.
S331-B-ConnectiongRod-9.jpg, S331-B-ConnectiongRod-11.jpg, S331-B-ConnectiongRod-12.jpg

I line up the end on the turned area, find center, and drill/tap the for the cap bolts.  This is different than what I’m used to as the cap needs to have the threads and the rod end needs a clearance hole.
S331-B-ConnectiongRod-13.jpg, S331-B-ConnectiongRod-14.jpg, S331-B-ConnectiongRod-15.jpg

The tapped holes for the rod are drilled/tapped.
S331-B-ConnectiongRod-16.jpg, S331-B-ConnectiongRod-17.jpg