Author Topic: Squint Scale Curtiss Model K Aero I4  (Read 14019 times)

Offline RReid

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #90 on: November 28, 2023, 06:40:17 PM »
Yesterday afternoon, after getting back from our daughter's, I dropped the cylinders and heads into a solution of OxyClean for a few hours. I'm pretty pleased with the subtle "weathering" this produced. I'm not sure the photos fully capture the difference, but they do look much better to my eye than the "too bright" of before.


Regards,
Ron

Offline cnr6400

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #91 on: November 28, 2023, 08:22:09 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Online Kim

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #92 on: November 28, 2023, 08:37:31 PM »
Yesterday afternoon, after getting back from our daughter's, I dropped the cylinders and heads into a solution of OxyClean for a few hours. I'm pretty pleased with the subtle "weathering" this produced. I'm not sure the photos fully capture the difference, but they do look much better to my eye than the "too bright" of before.
They look great!  And you're eye is the one that's important in this situation!  They do look good and I'm glad you're pleased with them.  :popcorn: :popcorn:

Kim

Offline ddmckee54

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #93 on: November 28, 2023, 09:09:00 PM »
The cylinders do look more age appropriate now.  Now you have to do something about those shiny rockers, and maybe add some oil and grease stains to the sides of the cylinders.  Or you could just wait until you get the engine running and let nature take its' course.

Don

Offline RReid

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #94 on: November 28, 2023, 11:58:57 PM »
Thank you guys, I appreciate the feedback.
Quote
Now you have to do something about those shiny rockers, and maybe add some oil and grease stains to the sides of the cylinders.  Or you could just wait until you get the engine running and let nature take its' course.
As a "brass era" engine, I'm happy to leave the rockers alone and just let nature take it's course, as you suggest, Don. The ali though needed some extra help. :stir:
Regards,
Ron

Offline RReid

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #95 on: December 03, 2023, 02:40:51 AM »
The next task I decided to tackle is what I call the lower crankcase in the drawings, but really is just simply the oil pan, though I'm not planning a wet sump for this engine. Instead I am planning to cut in the windows as shown, to make the lower “works” visible.


I started the end plates by soldering a pair of ¼ x 1” brass bars together. Then the outer radius and the inner rabbet that will accept the wrapper skin  were machined with the help of the rotary table. Flipping the part over allowed me to cut the part free from the bar stock while also bringing it to the designed 0.2” thickness.


Next, after separating the two halves, the notch to clear the bearing carrier was cut in, and the holes for the fixing screws were drilled. These were then used to pilot the tap drilling locations into the upper crankcase.


The skin was cut from 0.032” sheet and formed in the vise and over bits of pipe, first one of a small radius and then a larger one close to open the shape up the final desired curvature. As is often the case, I was too focused on just how to do all this to even think of the camera!

Once formed, the skin was soft soldered to the end plates. A spring clamp held the parts together, and holding the clamp in the vise allowed me to easily apply the torch from the side opposite the solder.




Of course the shape now makes the engine too roly-poly to stand on its own without help, so I made a simple (and temporary) wooden cradle for it.
« Last Edit: December 03, 2023, 02:48:06 AM by RReid »
Regards,
Ron

Offline cnr6400

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #96 on: December 03, 2023, 03:56:53 AM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline Roger B

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #97 on: December 03, 2023, 08:13:00 AM »
Excellent  :praise2:
Best regards

Roger

Offline Admiral_dk

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #98 on: December 03, 2023, 09:08:51 AM »
Very nice fabrication of the 'Sump'  :praise2:

I like your aging of the Cylinders too  :ThumbsUp:

Per         :cheers:           :popcorn:

Offline RReid

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #99 on: December 03, 2023, 03:39:37 PM »
Thank you CNR, Roger, and Per! :cheers: :wine1:
Regards,
Ron

Offline RReid

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #100 on: December 08, 2023, 02:22:31 AM »
A key feature of this engine is the use of a single push/pull rod to actuate both the intake and exhaust valves for each cylinder. The exhaust valve is opened in the normal way by a “bump” on the cam pushing the pushrod and the rocker “up”. On the intake side, the cam has a “flat” that the rod falls into, pulling the rod and the rocker “down”. The downward force comes from an external compression spring mounted in a cage, concentric with and acting upon the rod. The bottom of the spring cage also incorporates a combination rod guide and cam follower guide.

Making up those cages has been the task of past few days. The bases and the uprights were milled and formed from 0.032” sheet brass. The rod/follower guide was turned from 660 bearing bronze. Here they are before and after being silver soldered together. Those things were a bit of a bugger to solder, with the thin brass and the thicker bronze, plus the need to have clamps in place to hold things together,
plus they are fairly small. Made it a bit tricky to get the right heat in the right place. All told, some of the four came out better looking than others, but I think all are plenty serviceable.


Once together as a unit, I held each upside down in the mill vise and used a drill-then-end mill sequence to form a flat bottomed well for the cam follower to ride in.


Here they are loosely assembled. There are not as yet any lower flanges on the push/pull rods for the  springs to bear against, so they are just resting on top of the lower guides for the pics. In keeping with the weathered look of the cylinders, I plan to keep the post-soldering “patina” in place.



Regards,
Ron

Offline Dave Otto

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #101 on: December 09, 2023, 12:33:44 AM »
Nice work Ron!
They look great!

Dave

Offline cnr6400

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #102 on: December 09, 2023, 01:17:49 AM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline RReid

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #103 on: December 09, 2023, 03:24:33 AM »
Thank you, Dave!
Thanks, CNR!
Regards,
Ron

Offline RReid

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Re: Squint Scale Curtiss Model K Aero I4
« Reply #104 on: December 13, 2023, 01:10:41 AM »
One job left undone on the crankcase has been making and attaching the engine mounts. Because they stick out and would complicate things if I wanted to clamp the case in a vise, I deferred them until all the critical crankcase machining was finished. With the spring cages and cam follower guides lined up and installed I believe I've reached that point and so have circled back to finish up those, as well as to cut in the crankcase “windows”. A few other minor finishing jobs like filling the seams with epoxy and some rounding off of a couple of edges are also in the queue. I might even go ahead and give it some paint.

In the view below, two of the intake side mounts have been soldered into place. They are formed of 0.032” and 0.063” sheet brass, silver soldered together. Then they are soft soldered to the crankcase. The larger piece to the left is a combined engine mount and magneto platform. When I put that together I forgot the script and soft soldered it together, so rather than risk having it fall apart with more heating I will attach it using nice fillets of JB Weld. But before I do that I will solder on the three exhaust side mounts, which are shown lined up loosely in front.

Regards,
Ron

 

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