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Really? The cover has a little latch & should pop right off, especially if its a real Mitutoyo. Now what you see inside might be dismaying (green/white chemical guts & internal corrosion). It pays to have a peek under the hood every year. Batteries are spit cheap these days but the instruments...

Welcome from Calgary! Nice engine! I was up in your neck of the woods recently (Pioneer Museum in Stoney Plain) & there was a nice display of engines like yours popping away among the other activities. Maybe you know already, but there are a few model engineering folks in Edmonton/area who meet...

I was curious about this myself. For mile manufacturers that don't describe them as 'lathe' or 'large angle' is there something more specific that would make them good for this purpose? I bought a few Vallorbe files to try one day when my wallet was on fire. They were spendy but man do they cut...

Very unique & elegant. I like your finishing & photography too.

As Jason says, tappets/followers can have a pronounced effect on both timing duration & valve lift profile on the exact same cam. The theoretical duration usually assumes a tangency follower relationship. But if you have constructed something different, all bets off.

I'm running these AliExpress glow drivers on my 5-cyl radial (one dedicated per plug). So far so good. Specs say 6-24V input. I'm using a spare 3S RC Lipo battery. https://vi.aliexpress.com/item/4000881569350.html?spm=a2g0o.order_list.0.0.39631802yBP5tH&gatewayAdapt=glo2vnm While you are on...

The simplified s & h formulas only apply when Vc & Vd are represented as cylindrical cans. A flat top piston meets this criteria & is easy to calculate. But many combustion chambers are not shaped like simple cylindrical cans in real life, so you have to get a handle on actual volume, either...

(for the simplified cylindrical combustion chamber example only!) if you know CR and stroke (s), h can be determined using h =s/(CR-1). But for a 'non-cylindrical' head it becomes a convergence type solution. Example Vc was measured directly at 0.080 in3. Stroke was iterated until the target...

Using your example which assumes the combustion chamber is perfectly cylindrical, the CR calculates to 21. Bore & Pi drop out of the equation so you can get the same CR value just knowing stroke (s) & clearance (h) using CR=(s+h)/h. But typically combustion chamber is domed or angled or...

Somewhere in my travels I came across an article where someone harvested glow wire from RC plugs & used an AliExpress battery spot welder to join it to his (specialized) housing. I cant recall if it was for a combustion engine, or rocket motor or... Apparently the wire is difficult to source, at...

Terry, what are you using to take those highly magnified pictures? Its a different visual world at that scale!

Way to go Ray. Congrats. You build a unique, running engine in about the same amount of time it takes me to draw the head!

Thanks for your detailed writeup, Terry. Even though I've bookmarked your prior builds regarding rings, I always learn another tidbit or two. Lapping the rings isn't for cosmetics. Smooth sides are important because during combustion the bottom face of the ring must seal against the lower face...

Interesting video

Apparently went kaput just recently https://www.tctmagazine.com/additive-manufacturing-3d-printing-news/latest-additive-manufacturing-3d-printing-news/shapeways-ceases-operations-and-files-for-bankruptcy/

I posted this on the other forum I made an Excel table to generate a stepover routine for an elliptical shape. An ellipse is handy because you can define the A & B lengths independently, resulting in a wide range of aspect ratios to suite the purpose. For example elongated like a bullet or...

Nice spark ignition system, Michael. Sorry for all the questions but this has been on my brain recently. Maybe I missed but what specific CDI unit did you select & what hall sensor was used? I assume the orange part with set screw is your magnet rotor? Is the distributer conductor strip gap-less...

I looked into it when I built my radial. I think the answer is you can broach the shape it but the magic is in making the proper shaped cutter profile which is kind of an exact shape when you get into the details. Depending on the pitch, other tooth compensations enter the relief design...

On the Durabar site, they reference G2 as 'built around ASTM A48 Class 40 gray iron'. Now how exactly that compares to other grades of Class-40 gray iron with even less information is rather cloudy. The ductile irons are a different group designated by prefix 60,65,80,100 series. But I wanted...

Speedy still appears to carry if this is what you are referring to? https://www.speedymetals.com/c-8388-round.aspx This may have discussed before but would Durabar be a bad choice? I was gifted a chunk I was going to use for liners & considered same for rings