Gearhead88
Super User
Cool , I've got Mitutoyo bore gauges from .2" to 6" in a variety of flavours
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Radial engine build
- Thread starter PeterT
- Start date
With my modified tappet guides, rocker box & pushrod tubes nailed down its now rinse & repeat time. 5 cylinders times 2 per + 1 spare (just because) = 11 total. Thought you might be interested in sequential operations all done in one chuck setting so everything is axial. The guides are C544 bronze. The body OD is 6mm, fits 5mm hole in crankcase, 3mm reamed hole for tappets. The cutters are Nikcole, kind of spendy but last forever & I've used them for many aspects on this project. The round profile matched my 1mm section O-ring. Hopefully pics are self explanatory, otherwise just ask.
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So they are different profile inserts for a holder? Are they an ISO standard or something proprietary?
That engine build is coming along very well. Looks awesome!
Yes, many standard widths, square, vee, profile, 2-way cutting, left hand, right hand.... They must have changed the web link but here is some catalog info. I bought a combo shank / insert set many years ago from KBC for like 150 on sale, but they are nutty prices now. Unfortunately I haven't found a clone to these. I can tell you the shank is made from Kryptonite. I wanted to squeeze a bit more depth on my cylinder finning & wanted to take a bit off the shank end that was interfering. The end mill just skipped across & said, nope, not gunna do it.
I've examined the pocket recess & think it could be replicated without too much effort. That would open up new possibilities to shop make holders & take the sting out of the price.
The radial requires (5) gasket seals under each cylinder flange and (2) for the crankcase front & rear. I found some 0.003" thick teflon sheet from Aliexpress. By making a CAD template from MDF I was able to score through & cut the inner/outer shape no problem. But making clean holes for the M3 bolts required a tool because drilling just makes a tattered mess. I didn't want to make a matching plate to kind of die punch it so came up with this. Its ~3mm O1 tool steel but the end is relieved by a ~4mm ball end mill which gives it a sharp peripheral edge. I decided to harden it, I didn't bother tempering. So I just spin it through the template over one of those cutting mats & out comes a clean little confetti dot.
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I debated hardening the rockers because of the axle hole & M2.5 threads & skinny asymmetrical features (potential distortion or cracking). But the hardness of annealed O1 is only a point or so higher than 303 stainless (valve stems) so the thought of wearing the rocker pads I spent to much time on was enough to vote for harden. The tops of the valve stems will preferentially wear, but no problem there.
I didn't take any pics while heating but I was able to focus the torch on the pad segment & just let the heat flow backwards. Once the pad end was carrot red for 10mm or so, in the quench oil it went. So the other 70% will not be fully hardened but that's fine, desirable actually. I buffed off the black & tempered at 450F in my (shop) toaster oven. No noticeable distortion, everything fit nicely.
I didn't take any pics while heating but I was able to focus the torch on the pad segment & just let the heat flow backwards. Once the pad end was carrot red for 10mm or so, in the quench oil it went. So the other 70% will not be fully hardened but that's fine, desirable actually. I buffed off the black & tempered at 450F in my (shop) toaster oven. No noticeable distortion, everything fit nicely.
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My prop arrived from China. Eventually I'll laminate some veneer & make a cool antique profile but this one will do just provide load & blow air on the test stand. Unfortunately I realized the plans assumed a bit thicker prop hub thickness. This one is just under 20mm. So that started a domino effect annoying re-makes. I had to make a thicker drive washer to compensate. That felt a bit overly meaty, so I also drilled some radial lightening holes. But the added thickness then required a matching brass tapered split bushing, so new one of those too. Then a jig & alignment pin to drill the prop screw holes. Well once everything was mounted it was fun to twirl the prop & watch the rockers & pushrods doing their thing.
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Excellent work. The old adage about changing one thing leads to 10 other revisions comes to mind ...
In case you decide to purchase a propeller with a thicker and larger diameter hub, Falcon Propellers does some nice wooden props in a couple styles. (I've no connection, just a satisfied customer.) I'm sure they would provide any dimensions you require knowledge of prior to ordering.
In case you decide to purchase a propeller with a thicker and larger diameter hub, Falcon Propellers does some nice wooden props in a couple styles. (I've no connection, just a satisfied customer.) I'm sure they would provide any dimensions you require knowledge of prior to ordering.
Amazing work as always Peter. You must be nearly ready to make some noise with it.
DPittman
Ultra Member
I don't believe you've mentioned it in a previous post but if you have pardon me.... do you have an end use for this fantastic engine (rc plane) or will you just enjoy it on its' own?
@DPittman Haha, this question comes up a lot. I haven't given a model much thought. I mean I'm capable of constructing something that would suite the engine but I guess the short answer is Scale modelling was never really my 'thing' although I certainly appreciate that facet of the hobby. With somewhat limited play time, I'm more looking forward to the 'next' engine. Maybe inline, maybe Vee, maybe spark ignition. I have some plans & thoughts, but first things first, this radial must run!
Speaking of the package deal, check out this guy. Because building a rotary wasn't enough, he is doing an excellent job on an airframe. That's dedication.
Speaking of the package deal, check out this guy. Because building a rotary wasn't enough, he is doing an excellent job on an airframe. That's dedication.
DPittman
Ultra Member
Wow that is something huh.@DPittman Haha, this question comes up a lot. I haven't given a model much thought. I mean I'm capable of constructing something that would suite the engine but I guess the short answer is Scale modelling was never really my 'thing' although I certainly appreciate that facet of the hobby. With somewhat limited play time, I'm more looking forward to the 'next' engine. Maybe inline, maybe Vee, maybe spark ignition. I have some plans & thoughts, but first things first, this radial must run!
Speaking of the package deal, check out this guy. Because building a rotary wasn't enough, he is doing an excellent job on an airframe. That's dedication.
Maybe you should just build another 2 or 3 of those same engines and hang them on a full size ultralight and we can go flying together.
