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Making the Venturi and NVA Reamer made from a bit of the same 1.56mm piano wire i used to make the needles. make sure there's an airtight fit between the NVA and the venturi. Dremel used to make up some needles @11degrees. Silver soldering makes me nervous no matter how many...

Hi all, after procrastinating for months and clearly overthinking the problem of how to make the crankshaft for a twin diesel I/C engine, I decided I needed to be making some swarf over Christmas to decompress from work. After poring over the MotorBoys plans for a while I ended up on Adrian's...

Thanks Peter. Any recommendation on the fit? Also, any tips on keeping everything aligned while pressing together? -Patrick

Thanks Peter, so the sequence would be get an on-size 7/32 (5.56) mm pin such as below, ream an on-size 5.5mm hole and open up a bit with a 5.5mm diamond reamer as you suggest above? Any tips on how to gauge the fit?

LOVING this thread. Thanks for all the replies. Right now im leaning more towards the pressed pin assembly (possibly with a splash of loctite for good measure). My main reasoning is that it would: 1) allow me to make one-piece conrods and fit before assembly. If I were silver soldering, I'd be...

Hi Farsider. Glad it helped and thanks for letting me know. Patrick

Actually, depending on the scale you might need a compressor can pump a bit more volume. The Grasshopper seems a lot bigger than the small Elmers wobblers

Hi, Reabo, I have built a couple of Elmer's wobblers (a #25 and an H-Twin were my first ever engines! when I was starting out) I ran them on air and it worked great. In the end I was lucky enough to get my hands on an airbrush compressor which was absolutely ideal for the task as it was near...

Thanks for all the advice. Im wary about silver soldering because of heat distortion and the need for cleanup/machining at the end. I think braising might be the same. The engine i'm thinking about is 5cc so the crank parts will be very small. Id' be worried braising as I might also melt...

Thanks Pete. I will be watching your build with keen interest especially when it comes to assembling the crankshafts. PS: I love RD250/350s... scary to ride though. If you want to be impressed what someone can do with machines of that era using only modest model engineering equipment you HAVE...

Love the idea. I was thinking of something similar a while back, These engines are a proven design, are absolutely ubiquitous the world over and clones/copies abound. Watching with keen interest. P

Hey Pete thanks for the reply. That sounds like the way forward. Do you have any builds that show an example of doing this? I am worried about getting the press fit right and making sure everything remains true. Also id be nervous that the assembly falls apart at 13K RPM. But I'm here to learn...

Hi, after completing 5 single-cylinder compression ignition engines that run nicely. I thought its high time to get a twin under my belt. I had a look around and they seem pretty rare! I was looking at the FigTree Pocket twin (plans by Ron Chernich from the Motor Boys plan book) but haven'y made...

Thanks Tug, I just looked up the Old Warden events that look great. Maybe I’ll try to get to the July one. I’ll DM you if I’m going! Patrick

Hi Billit, yeah I’ll have a go at those when I get round to making the 3rd one and report back. I need to carve out some time to learn how to make those cutters. Patrick

Had a bit more shed time yesterday and completed Viper #2. This one seems to run a fraction stronger than the other one but only by a fraction. Here is a video of her running after a few breaking in runs (propeller on the right way this time I hope :-) ). I have a solution for a finger-guard...

Thanks yet again for all the good advice guys. I'l certainly get tuition and use a commercial engine until I well and truly know what I'm doing! Patrick

Hey Norman. I have just done the same. Might be good to share construction notes when we're underway building them. Im still 'clearing the bench ' on my Nalon Vioper project but then I'll turn my attention to the Quorn. Patrick

Beautiful planes Tug! I think I'll take it one step at a time and have reached out to my local model flying club for membership and to see if there's someone there who can show me the ropes/lines (excuse the pun). I bought the flight streak off eBay with engine for £85 as a bit of an impulse...