Building the Skookum in 1/32 - Page 3 - myLargescale.com > Community > Forums


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Unread 12-13-2019, 04:48 AM   #21 (permalink)
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Bill, again you continue to amaze with your team. Now you and Henner have more to Joust about, LOL
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Unread 12-19-2019, 08:45 PM   #22 (permalink)
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Working around putting up Christmas decorations, I was able to get some work done on the Skookum

I took this shot to show how the steam flows into the cylinders. you can see that the outer ports go at an angle to supply steam to the cylinder and how the middle one goes through the block to what will be the exhaust pipe.


Here are the cylinders showing the various holes that have been drilled in them.


The side rods for the chassis need a bolt which has a low profile head for clearance and looks. 1/4" stainless hex is turned to 4-40 for this


I finished up the boilers. Here I am ready to solder the inside of the firebox and boiler mount studs. Although all three boilers are almost exactly the same dimensions, I have them numbered for the best fit.


Here they are after soldering


Two boilers were leak free after the first soldering but one had two leaks and had to be resoldered. This shows the before and after pickling and clean up.


And the finished boilers


The cylinders have covers on the end caps. I turn them out to .050 over the cylinder diameter and bore them out to the diameter. this gives a .025 thickness to the cap material.


I check the bore diameter and depth on each cover.


Before I fully part them off, I round the end off with a file.


Here I am drilling out the valve body which has been milled to accommodate the valve.


So here is a good day's work of milling and drilling.


And a box of parts for final assembly which will probably be after the holidays
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Unread 12-20-2019, 11:06 AM   #23 (permalink)
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How are the rear cylinder end caps held in place in the assembly? Also, how do you produce enough threads in the front cylinder head for the single screw that holds on the front cylinder end cap?
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Unread 12-20-2019, 12:43 PM   #24 (permalink)
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Sean
Thanks for asking
I will take some photos showing the setup
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Unread 12-20-2019, 01:13 PM   #25 (permalink)
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Here is a photo of the front of the high and low pressure cylinders, The LP cylinder had a front piston rod guide which I don't need here because of the crossheads but I duplicated the look. The cyl cap has a stud turned to 10-32 which received the extension an holds the cover in place. the HP cyl cap has a raised portion which equals the cap bolt head height thus giving me enough room to tap it to 0-80 and use the 1/8" long screw to attach the cap.




The rear covers will be held in place by the piston rod gland nut. the two extra holes are for the crosshead guides.
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Unread 12-20-2019, 02:00 PM   #26 (permalink)
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Thank you. And the crosshead guide, how is that mounted? I see the holes on the rear cylinder head.
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Unread 12-20-2019, 03:58 PM   #27 (permalink)
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yes, the cylinder end of the guide goes into the hole in the head. I haven't designed the rear attachment yet. I usually have similar holes drilled into the bracket or sometimes I drill a hole through the guide and attach it with an 0-80 stainless screw.
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Unread 01-08-2020, 05:15 PM   #28 (permalink)
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Here is the crosshead guide on the prototype


And mine


Front attachment


Rear attachment


This bracket holds the crosshead guides and the expansion link. It is cut out on the mill and the tabs for the guides are silver soldered on. Ceramic blocks keep the tabs in place


The blocks for mounting on the frame are soldered on also. I used oversize blocks as they are easier to keep square during the process.


Here they are blasted and ready for paint.


The bracket for the expansion link is curved and irregular so I start with rectangular pieces and drill the holes in the mill. On the lathe, I drill out some 1/4" stock and part it off. I then slide a piece of copper tube through the drilled hole and into the hole in the rectangular piece. this centers my piece and the hole in the tubing acts as a pilot hole for the next operation.


They are then drilled out to 7 mm to accept a 4 x 7 ball bearing. A notch is cut with a 1/8" mill as a registration point for the mounting holes




Finally, the shape is cut out on the band saw using the 1/8" blade


Dennis made these beautiful expansion links on the CNC mill which were exact scale dimensions of the prototype, but unfortunately they didn't produce enough valve travel so he will be making some a little longer. I hadn't considered why the link was so small till after I tried it. The prototype had long narrow valve ports which would have scaled down to under 1/32". I used my standard 1/16" ports which need more travel.


So here are the two chassis in various states of completion. I made a brass block with the dimensions I calculated and drilled two holes at the top and bottom of what will be the link slot to check the valve travel which is now perfect.
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Unread 01-08-2020, 07:11 PM   #29 (permalink)
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Thank's for sharing yet another build!

I liked the idea with an off-center draincock hole entering the cylinder.
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Unread 01-09-2020, 02:06 PM   #30 (permalink)
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So the turned end of the crosshead guides just slip into the holes in the rear cylinder head? Is there anything else holding that joint (loctite) or is it only held in by the single screw to the bracket?
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