Orlik PBJ-1H Mitchell

[Bomarc]

Originally Posted by Don Boose

.....As the old Chinese expression goes, "The build of a thousand pieces begins with a single cylinder."

Don

Ah, it is just so Laoshī Boose. I will need to harness all my inner Qi to continue this journey…

And thanks to all for the encouraging words. I’ve been busy cutting the parts of the remaining 27 cylinders. The Orlik diagrams are silent on this, but in assembling the first cylinder, I found that adding small connecting strips were invaluable. So while cutting all the pieces, I attached small connectors to parts I deemed needing them using the paper the instructions are printed on (it seems to be around 20-22lb plain bond). To save my sanity working with the really small parts, I used a technique that others here may find useful (if you’ve seen this before, sorry for the repetition). Below are the bodies of the rocker covers (U15 in the diagram), tiny little buggars they are:



Cut to either side the row of part:



Then glued a connector strip to the back side at each cut edge:




When dry, cut out the strips, and they’re ready to roll with an attached connector of the right width:



Imagine trying to cut and glue a connector after the fact…..ugh! Of course this trick only works with rectilinear parts (that are nicely arranged on the sheet….designers take note). Some odd ball parts like the cylinder bodies required individual attention:



But all the parts are cut and connectors attached so now it’s a matter of roll….glue….shout explicative’s….repeat…….

Mike

[Don Boose]

Some great techniques, Mike!

Looks like we will learn a lot from watching this build.

Don

[Pavel]

I want to warn you that the engines can not fit under the sheeting........
you can see it here Êàðòîííàÿ Àðìèÿ :: Ïðîñìîòð òåìû - B-25J Mitchell 1:33 Orlik 11/08

[Bomarc]

Many thanks for the heads up Pavel! I had wondered if the completed engine would fit in the cowlings, and was planning to to tack two opposing cylinders to the crankcase and compare the overall dimension with the cowing peices. Looking at the photos of the gentleman's build, I see he had to cut off the tops of the rocker covers to get a good fit. I think I'll make my adjustments to the bottom of each cylinder before attaching to the crankcase.

Mike

[Pavel]

good luck! I would follow the bulding, because i've building this model too.
It is very interesting and hard!

Pavel,Russia

[Golden Bear]

Hey, Mike, I was going to jump in with the same advice but see that you already have it. Radial engines also show "creep" in the height of their cylinders as they get built up. I usually trim a little off of the base piece and the sleeve. Then do a test fit as you are planning to see if I need to hack off even more. If you spot glue the cylinders on you can pry them all off for more trimming at the very end if you need to.

One of these babies per model is usually enough for me and you get to enjoy two of them!


Carl

[Bomarc]

Thanks Carl. I had a funny feeling the built up engines might be too big. That why I like this forum so much, lot's of good intel floating around. I plan on "drafting" behind the modeler on that Russian site, although I've no doubt I'll be hitting a few rocks in the water along the way.

Pavel's timing couldn't have been better. I hadn't rolled/glued the lower cylinder pieces yet, so I can just chop them down a bit:



I took off about 1/16" (two lines in the pattern). That's my "guesstimate" to net the error. If it's still not enough after a test fit, I at least won't have to remove as much material for the final fit. For the already assembled first cylinder, I coated the inside with super glue to harden the paper, then I sanded it down on a piece of sandpaper wrapped around a 5/8" dowel:



Here's the rest of the cylinder "tulips" waiting for more pieces:



A little progress....

Mike

[Don Boose]

A lot of progress, Mike. I admire your meticulous approach, which will certainly pay off in the appearance of the engines and the final model. It is a real pleasure to watch such a craftsman and artist at work. Your clearly-written description of each step and the large photos really help visualize and understand what you are doing. The inputs from other premier model builders add much to the build.

Don

[peter taft]

Like the words of the song " Dedication's what you need " , well you certainly have this in abundence here my friend... Nice work on a VERY nice AIRCRAFT - I'll be watching this marvellous build

[Bomarc]

Thanks again encouraging words guys. There a lot of road ahead on this journey.....

Little more progress this morning. Also I finally figured out my wife's camera (Huh? There's an indoor setting?.....Who knew?.....). After completing the basic bodies of the cylinders, I lightly sanded the tops and bottoms in an attempt to control vertical creep:



To the bottom I attached the smaller disc punched earlier as a locator for the bottom cylinder:



In a happy twist of fate, a 5/32" steel punch made a perfect rolling mandrel for the lower tube. It also served as a good alignment jig to join the two parts:





Attaching the upper and lower bodies first made for easier handling of the assembly when attaching the two center parts. Attach both to the front side (no seam) first:



When dry, attach to the back. I hope the value of attaching the connector strip to the bottom of the "V" opening can be seen. Made for a pretty quick (and accurate) assembly:



They're multiplying!!!

Mike