Author Topic: Cretors #6 Oscillating Steam Engine Build  (Read 2375 times)

Offline Dave Otto

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #30 on: January 12, 2025, 08:17:12 PM »
Lots of work in that casting, appears that it all went reasonably ok.

Dave

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #31 on: January 13, 2025, 03:51:05 PM »
There were a number of steps.   :)   The setup was good in theory, as it was successful; but I failed to anticipate the amount of clamping it needed. 
I think I'll make several oil cups next, not many steps to them. 

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #32 on: January 13, 2025, 06:12:49 PM »
The Oil Cups, an “add-on”

As previously mentioned, oil cups were needed (IMHO).  I had a piece of brass 0.350” in diameter and used that for the three cups.  The frame cup utilized the existing 0.350” diameter with the internal part of the cup finished with a 1/4” ball endmill.  The shaft’s bearing cups OD was turned to 1/4" and finished with a 3/16” ball endmill. 
These two pictures show the OD of the large and small oil cups with threaded ends and drilling the oil passage.
<OilCup-1.jpg> <OilCup-2.jpg>
The oil cups are cutoff.  They are finished by spotting and drilling undersized the respective cups with 15/64" and 11/64” for the internal straight wall. 
<OilCup-3.jpg> <OilCup-4.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #33 on: January 13, 2025, 06:14:50 PM »
They are finished with the appropriate ball endmill, 1/4" and 3/16”, to contour the interior.  Depth control is by simple clamp and indicator.
<OilCup-5.jpg> <OilCup-6.jpg>
A funny thing happened on the way to the farm (phrase my grandfather used to say when things veered from the expected).  After making the oil cups, I realized I didn’t check if I had enough space for the pivot’s cup.  After a trip to the shop to check, there is enough space for it and to actually squirt oil in it.
In the pics I’ve seen of the prototype, the crankshaft had a bevel gear on it and a belt was never used on the flywheel.  The shaft was cut long enough to add a pulley I ever use it to power something.

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #34 on: January 18, 2025, 09:22:28 PM »
The Cylinder, #3
The approach to machining the cylinder used both the lathe and mill.  First is the turning of the pivot and then milling of the bore and head surfaces.  To maintain the perpendicularly between the pivot and the bore, I decided to hold the turned pivot in a 5C collet square block.  Since the heads measured roughly the same diameter, they will retain the cast finish.
To setup the lathe, it was indicated on the pivot to be centered and parallel to the lathe bed..  After it was indicated in, a reality check with the circumference of the pivot flange passed with about 6 thousandths variation.  Then it was turned and faced to spec.
<3-Cylinder-1.jpg> <3-Cylinder-2.jpg>
Although I swabbed the bearing surfaces with oil, the first fitting test with the frame resulted in the parts attempting to goad together being both aluminum parts (Prolly the same alloy also).  I immediately stopped and carefully removed the frame.  There was a bit of spot that needed cleaned up.  After the final tenths were removed, it was a fine fit with the frame.
<3-Cylinder-3.jpg>
A tapped hole is needed to attach the spring retainer and was the final operation on the lathe for this part.
<3-Cylinder-4.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #35 on: January 18, 2025, 09:23:42 PM »
On to the surface plate to indicate in the cylinder in the 5C square block.  After examining the casting parting lines and diameters of the flanges, I indicated it square to the 5c block.  Then a reality check of the relative heights of the cylinder head flanges at 90 degrees.  The measurements were within a couple of thousandths.
<3-Cylinder-5.jpg> <3-Cylinder-6.jpg>
On the mill, both head flange surfaces were milled for the correct cylinder length.  Then the bore is bored to spec.  I used a 3” boring head for the rigidity of its 3/4” bar.
Note the 5C square block has a number indicating whether the side is #1 or #2.  It is a gentle reminder to me as to which side I’m working on.
<3-Cylinder-7.jpg> <3-Cylinder-9.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #36 on: January 18, 2025, 09:28:21 PM »
Next is to spot and drill the stream passage.
<3-Cylinder-10.jpg> <3-Cylinder-11.jpg>
While setup with a drill chuck, the head screw holes are spotted/drilled. 
<3-Cylinder-12.jpg> <3-Cylinder-13.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #37 on: January 18, 2025, 09:29:31 PM »
The chuck is swapped to a 3/8” collect and the holes are tapped.  The last operation on this side is to mill the steam passage. 
<3-Cylinder-14.jpg> <3-Cylinder-15.jpg>
The cylinder is flipped 180 degrees and the sequence of operations is repeated on side 2.  The milling stop was good idea, but I checked the bore location with a DTI.
<3-Cylinder-16.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #38 on: January 18, 2025, 09:31:11 PM »
The cylinder is given a rough alignment with a long center drill, then a DTI is used for the final clocking-in.
<3-Cylinder-23.jpg> <3-Cylinder-24.jpg> <3-Cylinder-25.jpg>
Using the center drill, the steam holes are spotted, then drilled to depth.
<3-Cylinder-26.jpg> <3-Cylinder-27.jpg>

Kinda’ iching to assembly this but I need a few more parts.

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #39 on: January 18, 2025, 09:37:21 PM »
The Scr. Cylinder Retaining, #12
I think I’d named this part a bit different, but it is the part that retains the cylinder and captures the spring.  I changed the design material and it was turned from 1” aluminum stock instead of steel.  My thinking is a reduced mass for a part that is screwed into an oscillating part.  It also made more sense to me to simply use a SHCS instead of one piece that needed a thread AND a slot/flat to enable tightening it.  Usually, I strictly stick to the design of the prototype, but this model already is different from the prototype. 
I started by turning the 1/2" section for the spring, boring the 1/4" hole for the screw, and cutting off at +0.010 of the desired length. 
<12-ScrCylinderRetaining-1.jpg> <12-ScrCylinderRetaining-2.jpg> <12-ScrCylinderRetaining-3.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #40 on: January 18, 2025, 09:38:19 PM »
Then it is flipped around and mounted in a 1/2" collect to face as well as to counter-bore for the SHCS head.
<12-ScrCylinderRetaining-4.jpg> <12-ScrCylinderRetaining-5.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #41 on: January 18, 2025, 09:43:03 PM »
The Cylinder Head Bottom, #9
The cylinder heads were turned on the lathe with soft jaws in the scroll chuck.  To turn the soft jaws, a spider or object needs to be inserted between the jaws to preload the scroll.  In this case it is a piece of rod seen in the gap of the soft jaws.  Once the chuck is tightened, the jaw is turned to fit the head.  Both heads are approximately the same diameter and a pieces of paper packing between the jaws and head casting allowed for the slight differences as well as eliminate marks on the casting.  At this time, both heads were fitted to the jaws to ensure there was clearance for both head shapes.
The cylinder head bottom is faced to the specified dimension. 
<9-CylHeadBottom-1.jpg> <9-CylHeadBottom-2.jpg>
As the chuck is holding the casting, it is transferred to the mill to drill the bolt holes.  1-2-3 blocks elevate the chuck to clear the D1-4 pins.  It is indicated in, the DRO set to the required 6 hole pattern, and the holes spotted and drilled.
<9-CylHeadBottom-3.jpg> <9-CylHeadBottom-4.jpg> <9-CylHeadBottom-5.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #42 on: January 18, 2025, 09:45:26 PM »
Rats, at this point I noticed I neglected to the 0.0625 x 1.000” feature to fit the cylinder bore.  So, back the lathe and a bit more turning.
<9-CylHeadBottom-6.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #43 on: January 18, 2025, 09:50:33 PM »
The Cylinder Head Top, #4
With the soft jaws correctly turned previously, the top head has a head start.  The casting is faced and drilled for the piston shaft, then moved to the mill.  As with the bottom head, it is indicated in, spotted, and drilled for the bolt holes.
<4-CylHeadTop-1.jpg > <4-CylHeadTop-2.jpg> <4-CylHeadTop-3.jpg>

Offline rstreift

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Re: Cretors #6 Oscillating Steam Engine Build
« Reply #44 on: January 18, 2025, 09:51:19 PM »
The head is flipped over and checked for alignment.  The recess for the gland nut threads is bored and tapped.
<4-CylHeadTop-4.jpg > <4-CylHeadTop-5.jpg> <4-CylHeadTop-6.jpg >

 

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