Author Topic: Double-acting Radial 7 Engine  (Read 7915 times)

Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #90 on: July 03, 2025, 08:27:17 PM »
All seven cylinders have been bored out to size (3/4") and the faceplate was moved back over to the mill. First step is to take 0.058" off the tops of the steam chest bases to get them to the final height. This also flattens out the valve faces, which are never that flat on raw bar stock. So far two done, five more to go. The rotary table was still at  the same angle as when milling the recesses for the bases, and a scribe mark on the rotary table before removing the faceplate ensured that it went back on at the same angle as before. The faceplate will be left there until all the drilling/milling steps are done on the valve faces and bases.

Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #91 on: July 04, 2025, 04:47:23 PM »
Before drilling the steam chest mounting holes in the bases, I wanted to get the chests themselves finished, just to double check hole spacing/wall thicknesses. So, I milled out the centers of the steam chests. Once the first opening was to size, and notes made on handwheel positions/number of turns, the rest went very quickly (that is my version of CNC - Count Number Cranks).

Then laid out the hole positions from the plans, all looks good so I can start drilling the chests and lids. The work stop gives me an indexable start position, so this will go pretty quickly as well.


Offline cnr6400

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Re: Double-acting Radial 7 Engine
« Reply #92 on: July 04, 2025, 08:34:00 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #93 on: July 05, 2025, 03:34:54 PM »
All the holes in the steam chests and covers for mounting them to the cylinder are drilled, then drilled the matching holes in all of the bases were drilled in the same pattern, just needed to establish the starting point in the corner of the bases...

Then turned the rotary table 90 degrees, and have started drilling the mounting holes and exhaust passages into the bases:

When the first cylinder was to that stage, I tapped all the holes (18 of them) in it, and test assembled everything to make sure it was all lining up. It has passed the elfspection:

so will finish up the exhaust passage/mount holes in the other six cylinders. After that, its on to drilling/tapping the flange/gland holes in the steam chests. Also need to tap all the holes in the rest of the cylinders - that will take a few sessions not to wipe out the fingers/wrists. The tapping stand helps a lot, but its still a lot.

Offline cnr6400

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Re: Double-acting Radial 7 Engine
« Reply #94 on: July 05, 2025, 04:36:04 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #95 on: July 05, 2025, 04:55:58 PM »
:ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
Thanks Jeff!

Was just playing around online on the National Archives website, and came across some more neat engine plans from the early 1900's Navy destroyers. A couple great steam pumps along the lines of the Worthington brewery pump and another one that is similar to a simplex feed pump, but has a pump body at each end driven by the same shaft, one for air/condensate, the other for circulating water for cooling. Interesting designs, they are adding to the ever-long project list!  :shrug:

Offline PaulR

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Re: Double-acting Radial 7 Engine
« Reply #96 on: July 05, 2025, 06:20:03 PM »
How will you get the bore in the valve chests parallel to the cylinders? Asking for a friend who's thinking on his next project.  :Lol:

Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #97 on: July 05, 2025, 06:53:06 PM »
How will you get the bore in the valve chests parallel to the cylinders? Asking for a friend who's thinking on his next project.  :Lol:
The steam chests are rectangles, so I'm just going to drill the flat ends of them and put on the glands. The steam chest bases are parallel to the bore since they were milled with the cylinder on the same faceplate as when they were bored. Does that answer the question? Not sure I understand it.

And if your 'friend' wants, they can have a copy of the plans for this engine when its complete (I have been making minor tweaks to them along the way). I also have the more complicated valving setup for the 4-port-reversing version. For that everything is the same outside of the ports/passages and piping.   :cheers:

Offline Roger B

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Re: Double-acting Radial 7 Engine
« Reply #98 on: July 05, 2025, 07:03:40 PM »
As ever struggling to keep up with your build and thoroughly enjoying it  :praise2:  :praise2:  :wine1:
Best regards

Roger

Offline PaulR

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Re: Double-acting Radial 7 Engine
« Reply #99 on: July 05, 2025, 07:16:56 PM »
The steam chest bases are parallel to the bore since they were milled with the cylinder on the same faceplate as when they were bored.
Oops sorry, I missed that step, having trouble keeping up!

Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #100 on: July 05, 2025, 09:07:11 PM »
The steam chest bases are parallel to the bore since they were milled with the cylinder on the same faceplate as when they were bored.
Oops sorry, I missed that step, having trouble keeping up!
No problem! Lots of details in this engine, I've been doing a lot of planning before each step to make sure I haven't milled myself into a corner, okay so far... 

Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #101 on: July 05, 2025, 09:07:28 PM »
As ever struggling to keep up with your build and thoroughly enjoying it  :praise2: :praise2: :wine1:
Great to have you along for the ride!

Offline RonGinger

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Re: Double-acting Radial 7 Engine
« Reply #102 on: July 06, 2025, 02:48:54 AM »
I may have missed something, but why do you have cooling fins on a steam engine? Dont you want them lagged to prevent heat loss?



Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #103 on: July 06, 2025, 03:14:53 AM »
I may have missed something, but why do you have cooling fins on a steam engine? Dont you want them lagged to prevent heat loss?
Hi Ron,
Yeah, did talk about that some posts back. I did that just to make it look a little more like a traditional IC radial, and to see how many people did a double take when it runs with just a little chuffing sound rather than a gas engine roar!  I'll likely only run it on compressed air, so cooling is not a problem.
Chris
 :cheers:

Offline crueby

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Re: Double-acting Radial 7 Engine
« Reply #104 on: July 06, 2025, 02:45:50 PM »
Got the rest of the cylinders drilled for the exhaust passage and pipe flange mounting, then started in on the ports. Got the first one all lined up and drilled starter holes for all three ports, slightly smaller than the finished port width. With this setup, went through and drilled the same holes in the other six cylinders. Seems like a lot, but once its set up and the handwheel advances known, each one only took a few minutes to swap in/drill/swap out.

With the starter holes drilled in all seven (middle port to meet the exhaust passage, end ports down to the level where those passages will be), then set up with a 5/64 end mill and took each one out to dimension, 0.1" tall and 0.15" wide. Again, repeated this operation on each cylinder in turn.

Here is most of the herd so far (last one is on the faceplate still)

Next up is to drill the passages in from the ends of the cylinders to meet the starter holes drilled down from the valve face. So far one cylinder is done.

After the rest of the passages are drilled, last steps on the cylinders will be to mill the short recess to connect the passages to the end of the cylinders, then tap a LOT of holes in all the cylinders. For now, time to head outside and enjoy the weather before it gets up into the 90s this afternoon!

 

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