Norvel/AP .061 prop stud size compared to 5-40 stud

Hi 1/2A,

Thanks for your input.

End Goal is to put a 3-blade spinner on my Scientific P-40 with the AP engine. Preferably, the stock plastic Cox piece with the retaining barrel. I strongly suspect that is my lightest option.

I thought I read the sizes you quoted. I didn't think that the Norvel and AP used different studs, and that is what had me confused!

The appropriate drill bit for 3 mm is 0.010" smaller than for 5-40. The appropriate for 4 mm is a bit bigger. So I just need to pickup a bit for 4 mm and drill/tap appropriately. That is better than retapping the 5-40 hole for 3 mm. Gee, I guess the AP is a better fit than the Norvel in this instance.

Pics to follow!

Yes the Norvel .049 /.061 is not ideal for a good solid re-tap of the Cox 5-40 plastic three blade.
spinner's metal stud.

The 4mm option will surely get you there with a good secure fresh set of threads. Having said that the first
effort should be to tap it to 3mm and see how good the bite is, might as well if it works great. If not no big
deal as the next jump to 4mm will be a good transition for the 4mm tap to cut through.

Which spinner will you use?

Sounds like it would be easier to simply make a stud with two different ends?

About only caveat with using a Cox aluminum prop cone as a prop nut is once threaded, would have to drill a tightening hole cross wise that clears threaded prop mount shaft. Then an Allen wrench or piece of music wire could be used as a bar to tighten cone nut.

I was hoping CoxIntl still had three bladed spinners...but oh the sadness, I will wind up with a two-bladed one:
https://coxengines.ca/cox-.049-plastic-spinner-hub-yellow.html

944_Jim wrote:I was hoping CoxIntl still had three bladed spinners...but oh the sadness, I will wind up with a two-bladed one:
https://coxengines.ca/cox-.049-plastic-spinner-hub-yellow.html

HOLD UP!!! Did somebody say 3 bladed plastic yellow spinner? I was sure I heard something about a 3 bladed plastic yellow spinner! You sir are in luck! Call Matt at EX Engines. He will not have the 3 bladed spinner, YET, but he will shortly. I just sold him several sets of that very thing, shipped them to him yesterday from Omaha Ne. Can't remember how many I sent of the props by themselves, some of the engines I sent came with those also but here are pictures as proof. I wouldn't drag my feet if I were you though, I didn't send them very many. Good Luck!
Scotty68

Awesome! Thanks a bunch. He will be contacted shortly!

944_Jim wrote:Awesome! Thanks a bunch. He will be contacted shortly!

944_Jim, Say I wasn't actually looking for these but while looking for something else I ran across these. You wouldn't happen to be interested in a bright red three bladed spinner? How about a dark red one? I have one of each. : ) I could probably even be persuaded to part with one of them. It is hard to tell from the pictures but one of them is a considerably deeper red than the other. It is also slightly shorter and less pointy, hope that helps. I am still looking through an estate I purchased a week ago, who knows what else I'll run across?
Scotty68


I spoke too soon, upon digging a little deeper, I actually have 3 red ones. 1 dark and two of the sharper bright red ones.

Hi Scotty,

I'm looking for one for my Scientific P-40. Your dark red one may be the ticket!

I checked my current 3-blade spinners, but they are too pointy. I believe they came from the old F-15, Mantis models. I mean, Really Pointy!

I'll attach a picture of what I don't want, but already have, for your comparison in just a bit. I think what I have are more like your bright reds.

Thanks a bunch...more to follow in 15 minutes.

Yeah, the extra pointy ones are kinda weird. Not sure what they would look good on. Here is a better picture for a comparison.



I, as a preference, fly much larger stuff. One of my favorites is a Phoenix Models Cessna 182, it is a 46 sized aircraft and I fly it with a beautifully shiny Saito FA-65 fourstroke. This plane is gorgeous in my opinion but it came from the factory with the longest, sharpest pointiest red spinner you ever saw in your life, and the red didn't even match! That sucker was never even installed on the plane, it was placed directly into file 13 and I never lost a wink of sleep over it. : ) Here are a couple pictures of my Cessna, just in case you were interested. It is even smaller than the rest of my planes but it is just so darned purdy....

Ok, this is the nose of the P-40. If I can a smidge bigger than 1", I should be good on diameter.

My Really Pointy ones (that I don't want on this model) measure 1.095" long by 0.800" diameter.

Actually if you have a visible gap between the cowl and spinner, the slightly smaller diameter may actually work. It doesn't have to be as tight as it was on the real machine. It will still look good even if there is a 1/8" (3mm) gap. You will see this gap in the Cox RTF's. Gap may also be needed for the spring starter, especially if it is the no drag snap starter.

Just FYI, it's easier for me to see the measurement on your calipers if they are actually turned on. Just sayin'. Lol!  Regardless, I think I have what you are looking for. You be the judge. First three pics are of the one that you WON'T want. (the pointy bright red one)





But these...these are of the one that you will want. (the shorter dark red one) And I don't blame you, she's a beaut!

GallopingGhostler wrote:Actually if you have a visible gap between the cowl and spinner, the slightly smaller diameter may actually work. It doesn't have to be as tight as it was on the real machine. It will still look good even if there is a 1/8" (3mm) gap. You will see this gap in the Cox RTF's. Gap may also be needed for the spring starter, especially if it is the no drag snap starter.

Do the Norvels have a spring starter? I am not sure, I've only owned a few but I don't think I've ever seen one on a Norvel. Currently, this is the only one I own. And it's adorable. : )
Scotty68

Scotty, we can take this off the forum.

The battery in my calipers is dying. The display blinks on/off as the "I'm dying" signal. I managed to time the P-40 overhead shot just right. I gave up after 12-13 attempts on the "wrong" spinner. At least I recorded the measurements on a paper.

That is one beautiful model!
What diameter and line length do you swing it on? (YuckYuckYuck!). I have two big ones that came as part of a collection...both have older 72 mHz radios. One is a sweet looking 4' twin. It looks like the old 50 Calliber from Model Airplane News. I'd love to make it CL!

I like the dark one for the P-40. So do you have the prop stud barrel that goes with it? What is the diameter? Length?

I have larger stuff from a collection that I won't use. Maybe we can trade. If you are good on BIG PLANE supplies, then we can figure $omething out.

Thanks a bunch!

944_Jim wrote:Scotty, we can take this off the forum.

That is one beautiful model!
What diameter and line length do you swing it on? (YuckYuckYuck!). I have two big ones that came as part of a collection...both have older 72 mHz radios. One is a sweet looking 4' twin. It looks like the old 50 Calliber from Model Airplane News. I'd love to make it CL!

I like the dark one for the P-40. So do you have the prop stud barrel that goes with it? What is the diameter? Length?

I have larger stuff from a collection that I won't use. Maybe we can trade. If you are good on BIG PLANE supplies, then we can figure $omething out.

Thanks a bunch!

Sure Jim, We can take this off the forum. Just tell me how and I'll follow your lead.
Scotty68

Okay? Maybe you can follow my lead? By "Off the forum" I assume you mean private? Like Private messaging? Or private email?
Scotty68

Scotty68 wrote:Do the Norvels have a spring starter? I am not sure, I've only owned a few but I don't think I've ever seen one on a Norvel.

The spring starter is a Norvel accessory part for use with their accessory tank mount. Here's a photo of my .061 Big Mig for my 36" Sterling Minnie Mambo RC. There is a groove molded in the tank mount, a 1/8" 90 degree bend in the spring end hooks into a hole in the motor mount beam, bolting the engine in place holds the spring in place. Otherwise it works exactly like the Cox snap starters. Here, I have temporarily removed the special Norvel head and put a Cox .049 head on.

Yup, another day where I actually learned something. Will wonders ever cease? That's very cool, I have almost no experience with this little stuff. The only reason I own any of it is because I purchased an estate a week or so back and that gentleman had TONS of stuff, a lot of it small stuff. I bet there were over two hundred Cox engines. If you research my user name on this forum you will see how I got started and some of the engines I acquired thru the estate. I posted pics on this forum in order to find out what they were. (all the different models of them I mean) I have a little more Norvel experience but that is only because I regularly buy them and resell to a guy in Madrid Spain who would probably buy every Norvel on the planet if he could.
Scotty68

My snap starter is GREEN. As in Sullivan Hornet!

I finger-diddle the Cox engines. But the AP and Norvel .074s get the electric finger. They were all placed into service new out of the box. I think the.074s are just about broken in, so they may get the finger soon. The AP is also just about to also. I may install springs on the Norvels, but the cowl on the P-40 is really too tight around crank case for a spring to poke through.

Oh, and Scotty...PM sent. I'll check back in the am. Thanks a bunch!

I don't ever plan to become so intimate with my engines that I would use a term like "finger diddle" but different strokes for different folks. I'm not gonna judge ya! Lol! I actually acquired one of those electric fingers that you're talking about but mine is blue, says "lite machines" on it.
Scotty68

BIG Happy Dance!!

Oh, and Scotty...any kits in that estate stash? Show us the lumber!