Pee Wee .020 ?

I remember reading about this , but only thing was that the fix was sand down the inter side (closest to the tank) can't recall the reason why it was made that way  . Found it dam if it wasnt Me that posted to were Andreas post here > https://www.coxengineforum.com/t8552-mylar-stainless-steel-reeds-with-circlip-type-reed-retainer?highlight=circlip

Ken,
How many clips do you need? I may have spares. Today is Hobby Closet "straighten-up" day, so I can look and report later.

I kept this little box which contained replacement vials for old wooden levels. I purchased the vials from a old boss of mine. I repaired a old level I owned and the box was pretty neat. I put all my .020 parts in this box. The box is small about 3"x4". I just found the box and sure enough there was a red .020 tank inside with a copper reed and the skinny clip. So, I took the clip off of the copper reed and installed the thicker clip and it still didn't work with the old copper reed. It was preventing me from being able to turn it. I took the skinny clip in and sure enough , the Mylar star reed passed the suck and blow test. I took it out back and gave it a run, it started up, needled well so I cleaned it up and put it on the shelf. Certainly this will go on a freeflight model.

That is interesting, Ken. I wonder how the larger diameter wire C-clip came about, as it is incompatible with the earlier reed system, too. Perhaps a change to availability of wire diameters through supply chain issues? Back in the day, these engines were produced in very huge quantities, which would make it easy for Leroy Cox to have wire delivered to his specifications.

Also interesting the other thread mentioned by Eric, where the trick was to hone down one side facing the reed, so clearance could be restored. That seems to be the most practical solution to redeem the situation. Now, I know to treat my reeds with utmost respect, because there are no perfect replacements now.

It's unlikely a wire size became unavailable. I only measured a few removed from older PeeWee and one with a mylar reed. They were about .020". I would guess new production went awry. The photos on the site look wrong like the wire size is much too large.

Out of curiosity was the too big round clip from an OEM rebuild kit Ken .

Eric, the clip that wouldn't work was from a newer rebuild kit which was purchased over the past two years. I can see just from looking at the new vs old that the new clip is considerably thicker. If I need to, I can bend my own circlips from the same size music wire. For consistency, I've used springs and cut pieces of coil from the springs leaving enough for a return bend. I've had to make circlips for wrist pins on several occasions and springs work great for this purpose.

Considering where/who packages the rebuild kits, would it be worth addressing this with the vendor? I ask because I recently purchased a short stack of .020 rebuild kits. I guess I need to check them. Of course, the easy answer is re-use the original ones.

Ken,

I looked inside a few .020’s including one with a heli backplate…. The heli plate clip is .023, And the same size is in a newer rebuild kit that I have as well…. The standard PeeWee’s have .019” clips….

An interesting side note, On a couple of known older PeeWee’s the starter spring is .031” dia….. Later is .040

A few years ago, I had issues when rebuilding some .049 Bee's having a circlip-style retainer for their original copper/4-point/star-shape reeds.. which measure .001" thick. The Mylar reeds are .005" thick. This includes an OEM Cox star-shaped Mylar reed.

Out of curiosity, I measured the wire-size of several circlips from parts-engines that I had previously disassembled.. to find slight differences.





If I needed to rebuild an engine with a circlip-style reed-retainer, with a Mylar replacement-reed; I needed to select from my thinnest .028" diameter wire clip-stock.. and possibly have to "shave" .001"/.002" from the "venturi-side" (opposite from the raised center section of wire; I refer to it as the "tang" which bisects the center.. and then terminates.)

I made a simple tool for this, using a hardwood dowel; close to the circlip's diameter. For the .049 engine.. this was a 7/16" or 12mm diameter dowel, which I cut a shallow "slot" on-center.. using a fine-toothed hack-saw blade. This slot was to hold that raised "tang" section of the clip.




Cut the dowel to approximately 2" length, chuck in a VSR electric hand-drill and bear-down squarely on some fine adhesive paper. The clip instantly detaches for checking its thickness.. making the process not too laborious.. As ya'll know; it's well-worth it to get this fit right.