Author Topic: 1/4 Scale Cirrus MkI  (Read 21485 times)

Offline cwelkie

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1/4 Scale Cirrus MkI
« on: January 05, 2016, 05:00:28 AM »
Hi everyone,
It has been a while since I've contributed but current circumstances have provided me with the time to catch up on some of the work and photos taken during my build of a set of Zimmerman castings acquired some time back.

In truth, I'd always wanted to build a Chenery Gypsy but haven't yet found a set of castings.  Cutting one out of solid, though possible, is being put off in the hope (however fading) of finding a set of castings one day.

This will be a little different than most build threads.  I wasn't going to bother.  After some time I realized that even if one photo or comment spurs someone on in their endeavours, it will have been worthwhile.  After all, much of what I have learned has come down to what is so freely shared here and who am I to take and not share what I can.

I'll be starting with the crankcase castings even though many of the smaller parts had already been made.  It seems I wanted to get those done before screwing up the courage to cut into these (irreplaceable?) castings.

So, we're off ... please forgive the poor lighting in some shots.

I started with the cylinder deck on the crankcase.  An end mill to start and a fly-cutter to finish to height.  This of course, was after smoothing the bottom surface and determining how much of an allowance to leave so the crankcase / oil-pan flange could be finished.





Once that was done I drilled and tapped the holes for the tappet seal hold-downs.  Then the tappet towers were cut to height, drilled, reamed and countersunk (with a shop-made countersink) for the  o-ring seals.





Small oil drain holes were put in the o-ring cavities before a frightening (for me) undertaking ... rough cutting the cylinder holes with a hole saw.  I've always been uncomfortable with hole saws; they've always seemed so ready to cause grief.  In the end it went well.



Once that done without calamity, a boring head sized the holes.  I then moved on to drilling and tapping the cylinder hold-down bolt pattern.  (yes the cylinder holes are supposed to be unevenly spaced  :))





After all that, I trimmed back the ends to "mark" how far to cut when I got to that.  It was then to finishing the bottom outside edge surfaces.



So far - so good:



The next stage was getting the oil-pan and crankcase lined up for drilling and tapping the flange holes.  The oil-pan was cleaned up with lubed (WD40) wet/dry paper and CA glued to the crankcase for the drilling and such.



The assembly could then be spaced, lined up and mounted to an angle plate to bore the end plate openings.



It was 'round about here that I took "a break" and made a faceplate for my faceplate ... The 12" faceplate supplied with my lathe is just too large and "clunky" for the kind of work I do.  I figured a smaller plate with T-slots would be much more useful.  It index centers onto the large faceplate.  Should look at drilling some more holes so I can mount it to the rotary table ... does it ever end?  ::)



I think I'll leave this post where it is for know.  More to follow ...
All the best to everyone - everywhere!
Charlie



Offline petertha

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Re: 1/4 Scale Cirrus MkI
« Reply #1 on: January 05, 2016, 05:49:35 AM »
Looking forward to your build Charlie. I've always had a soft spot for that engine design. I thought castings were rare as kryptonite though, so the only option was bar stock hogging like Paz did (link). Is someone re-making castings now or you've had them stashed in a vault somewhere? :)
http://homepage2.nifty.com/modelicengine/cirrus%20index.htm

What about the plans, I seem to recall one was featured as a build article in Strictly IC mag but maybe I'm mixing up Zimmerman with Chenery?
-Peter

Offline cwelkie

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Re: 1/4 Scale Cirrus MkI
« Reply #2 on: January 05, 2016, 06:19:52 AM »
Hi Peter - yes SIC ran a series on this engine built by Ron Calona.  I managed to be in the right place at the right time to acquire these castings as I don't think there are currently produced sets.

I too have spent many hours admiring "Paz's" work and shop-made tools.  Another self-taught inspiration for the rest of us ...

I believe someone in Winnipeg was in the process of doing some portion of the Gypsy casting set but have lost track of where that initiative stands today.

It would sure be nice if all of Mr. Chenery's designs ended up being cast again!

Online Jo

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Re: 1/4 Scale Cirrus MkI
« Reply #3 on: January 05, 2016, 07:15:59 AM »
Hi Charlie,

A very nice Gentleman by the name of "Joe" did a set of patterns for the Chenery Gypsy he sold a few sets of castings from these but I understand found it a bit of a hassle. The patterns are now with Kirt at Hemmingway so if you want a set you will have to ask him  ;).

I have a set of both the Chenery Gypsy and the Cirrus castings  ;D And will be following this thread with great interest.

Jo

P.S. Joe also did the Aeronca  :Love: patterns/castings which I also have a set of.
Usus est optimum magister

Online Jo

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Re: 1/4 Scale Cirrus MkI
« Reply #4 on: January 05, 2016, 07:49:52 AM »
It would sure be nice if all of Mr. Chenery's designs ended up being cast again!

I missed that:

Kirt sell the Vee Twin castings and drawings.

A friend "Mike" does the Anzani castings (and a 6 cylinder version  :Love:)

I don't know about a source for the side valve castings.

Jo
Usus est optimum magister

Offline b.lindsey

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Re: 1/4 Scale Cirrus MkI
« Reply #5 on: January 05, 2016, 12:37:21 PM »
This will certainly be one to follow Charlie. Lovely work so far on what appears to be a nice set of castings.

Bill

Offline zeeprogrammer

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Re: 1/4 Scale Cirrus MkI
« Reply #6 on: January 05, 2016, 02:10:31 PM »
I'll be following too.

Excellent start.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Don1966

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Re: 1/4 Scale Cirrus MkI
« Reply #7 on: January 05, 2016, 02:33:38 PM »
Interesting engine, I will be following you also Charlie.

Don

Offline cwelkie

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Re: 1/4 Scale Cirrus MkI
« Reply #8 on: January 05, 2016, 06:05:14 PM »
Thanks all for following along and your kind comments.
Who else but Jo could torment us with virtually every casting set we mention?  :LittleDevil:

Jo - Here are a couple photos of my Aeronca ... no longer in casting form  ;) It was a fun but challenging build for someone of my experience at the time (even now?).





I'm thrilled to hear that the Chenery Gypsy patterns are safe and in good hands.

... back to catching up.

Once the end plate bore was to size I removed the oil pan and used my small shop-made boring head to thin and shape the centre web.  It took awhile to step over a bit at a time but turned out fine in the end.  (Another tool on the perpetual list - a facing/boring head to Graham Meek's design.)



Then it was on to turning it all over, truing it up and doing it one more time.  Here's the result after facing the tappet holes from the inside:



Next it was on to the fiddly job of fitting the oil tray to the oil pan.  I'd dimensioned the tray to the drawings once I was confident of the numbers.  This in involved using an adjustable angle plate to get the draft angle right (on the sides).
Once the tray was ready I proceeded to work the inside of the oil pan so that the tray settled in evenly and at the right height/depth.







Once the tray was in place I could drill and tap the four holes for securing it in place and then put the crankcase back on for drilling and machining the oil dipstick hole.



Now that the easy bits were done (?) it was time to tackle the end covers ... front one first.  I chucked it up using a chuck stop as extra security and it worked out fine in spite of the limited jaw contact area.  It seems I got caught up in the work and didn't take any progressive photos.

I did take one however of the rear cover plate on my new-fangled faceplate ... so much better than the monster beneath!





Looking ahead at coming operations there was a need developing for a number of special (to me) cutters.  These included a couple radius cutters, a 1 1/4" saw, a round-over cutter, valve seat cutter and a couple countersinks.  The block of aluminium is hiding the cylinder head behind the shiny surfaces.  This picture shows that I'd had the rear timing gear cover done by now as well.



I think I'll leave this here for today and continue on with the cylinder head in another post.
Thanks for following along and sharing any comments or suggestions that come to mind.
Cheers
Charlie




Online Tennessee Whiskey

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Re: 1/4 Scale Cirrus MkI
« Reply #9 on: January 05, 2016, 06:21:36 PM »
Geez Charlie,  I'm gobsmacked,  the setups and ops are amazing  :ThumbsUp: :ThumbsUp:

Cletus

Offline Bjorn_B

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Re: 1/4 Scale Cirrus MkI
« Reply #10 on: January 05, 2016, 06:48:33 PM »
This is very very nice! Hats off!

Offline fumopuc

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Re: 1/4 Scale Cirrus MkI
« Reply #11 on: January 05, 2016, 07:06:14 PM »
Hi Charlie, I am following along and try to learn.
Kind Regards
Achim

Offline Dave Otto

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Re: 1/4 Scale Cirrus MkI
« Reply #12 on: January 05, 2016, 07:25:06 PM »
I too have always liked this engine.

I will be enjoying watching yours take shape here on MEM; amazing work so far.

Thanks for sharing,
Dave

Offline Roger B

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Re: 1/4 Scale Cirrus MkI
« Reply #13 on: January 05, 2016, 07:57:46 PM »
A very nice build and I like your setups  :ThumbsUp:  :ThumbsUp:

How big is the Aeronca? Is that a standard servo plug hanging down in the second picture?
Best regards

Roger

Online Jo

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Re: 1/4 Scale Cirrus MkI
« Reply #14 on: January 05, 2016, 08:14:48 PM »
Usus est optimum magister