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    Sprayed-on 3D Printed Pattern Filler

    The strong odor is from the polyester resin base. I stopped using it eons ago for laminate composite work, but its still predominant in the auto filler/putty world because its relatively inexpensive & it works. There are epoxy based systems too, but they get spendy. The fillers are probably...
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    Sprayed-on 3D Printed Pattern Filler

    I really think you would be better off with autobody filler as step-1. It will easily fill the 3DP grooves & conform to any discontinuities in the pattern. A couple coats applied with a flexible rubber applicator (actually playing cards work for modelling work) & rubber block sanded in between...
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    My new project ...Small diesel engine .

    This probably isn't the appropriate post to discuss, but I checked out your YouTube & saw your nice running engine. Is your build documented somewhere? I'd love to see the parts. I was under the impression the Hansen diesel secret sauce was closely guarded information. Men in dark suits might...
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    Diamond Grinding Wheels for a Tool and Cutter Grinder

    I've read about wearing/degrading rapidly & potential chemical reaction at elevated temperatures. Usually the recommendation for steels is CBN. But I'm wondering the same thing for home shop use. Diamond wheels for TCGs are readily available & reasonably priced from typical Asian suppliers. Now...
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    Looking for inspiration

    Nice. Are those 10-32 spark plugs like RCEXL or similar? Is it CDI or coil type ignition system? Is lubrication by premix / blow-by only, or you have some other oiling in the system?
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    COX TWIN 049x2

    That's very cool. Something about multi-cylinder 049's - like a swarm of angry bee's! I've seen a few radials. I'm surprised nobody here on the forum has made a run for Guinness records, like a V12 This site has some other interesting variations, but on different cylinder platforms...
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    Belfair Washington modeling/metal casting club.

    Hi Jim. I'm a long ways from you, but do you folks have a website or newsletters or anything that chats about your projects or activities? There are some guys within a couple hours of me (Calgary, Alberta) who have done some model engine casting in the past & hopefully will again soon, but...
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    Questions regarding drilling small holes, and runout.

    I was always curious about those Cameron's. Can anyone explain what is occurring when spindle/chuck runout is being dialed in? They say the spindle runout is 0.0002" & its a JT0. I think that's a 1.41-deg per side taper, meaning the chuck or collet has a matching angle socket profile, right? The...
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    Ohrndorf 5 Cylinder Radial

    Thanks for catching. Corrected. Where is AI when you need it. OTOH, while re-boring the ID, there WAS inner fear, LOL.
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    Ohrndorf 5 Cylinder Radial

    I made a new shaft with an integral end flange to retain the gear cluster that way. The advantages are it eliminates the bolt & washer business which could come loose one day & runs dangerously close to the back of the ring gear plate as is. The disadvantage is that the shaft is somewhat...
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    Ohrndorf 5 Cylinder Radial

    I never really cared for this washer/screw arrangement but assumed it was necessary for disassembly, but it actually isn’t. The crankshaft can just exit from the rear with its gear still on the shaft & disengage from the idler gears axially. My temporary conclusion was that the steel gear...
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    Ohrndorf 5 Cylinder Radial

    A few more pictures to get caught up to present day. On subsequent running sessions, the engine continued to smoothen out & I could also reliably hand start if still warm. The cylinder flange bolts remained tight & no more valve/piston competition for the same real estate But I had another...
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    Ohrndorf 5 Cylinder Radial

    I made sets of brass head shims from various stock thicknesses just in case.
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    Ohrndorf 5 Cylinder Radial

    So, I commenced measuring all the contributing dimensions (there are many). Rod throw, piston height, cylinder deck height, cam lobe rise, valve clearance… Everything was within a thou of drawings. I did deviate slightly from drawings by decreasing the valve seat width, but net effect actually...
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    Ohrndorf 5 Cylinder Radial

    The exhaust valve indentation on the piston tops was a serious issue to address. My first suspicion was that I had incorrectly placed the ring gear cam plate assembly onto the idler gear cluster off by a tooth. This would have the timing effect of lagging the exhaust valve closing beyond TDC...
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    Ohrndorf 5 Cylinder Radial

    I actually made a tester Teflon gasket for under the cylinder flange earlier but elected to omit them initially. I wasn’t too keen about using Loctite on the threads if it could be avoided. I sourced some 0.002” thick sheet so it wouldn’t affect CR very much. As it turns out, the gaskets did...
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    Ohrndorf 5 Cylinder Radial

    After subsequent runs it was becoming obvious the drill starter had to go. It continued to chew the prop and had more difficulty turning it over as compression improved. I also suspect as the engine began firing, the drill’s gear drive was probably limiting it from free running until I could...
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    Ohrndorf 5 Cylinder Radial

    Remediation. First the easier stuff. Here is my initial makeshift drill starter. It mostly turned the engine over OK to where it would fire, but the prop engagement pegs were mangling the delicate trailing edge root despite my attempts to rubberize it with tubing, heat shrink & electrical tape...
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    Ohrndorf 5 Cylinder Radial

    The #1 piston assembly looked pretty good overall. Lots of lubrication, no shiny wear areas or hot spots. The ring looked like it was just starting to wear in evenly enough around the periphery. A few vertical scratches on the piston here & there but nothing of consequence. However, I noticed a...
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    Ohrndorf 5 Cylinder Radial

    Crankshaft & rods
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