Pee Wee Horseshoe back plate

Once again, something words cannot describe. Amazing work with the computer and printer. If these bacome a reality, I would most definately be interested in one as I have a PeeWee without a tank/backplate/needle assy. I cannot wait to see how this turns out. Out of curiousity, would this use a needle from an old postage stamp backplate (.049), or something special?

Not sure how it's going to hold up to heat. Ill print it out of Delrin that I just got.

Here is the final part. On the printer now.

Very impressive!

Can't wait to see the results!

Derlin should hold up pretty good, will be a big plus to have a way to extend flight time
with the Pee Wizzer and perhaps improved air / fuel intake for more power.

Here are pics of the first one off the printer out of PLA to test fit it. I need to enlarge the reed area a few thousands. Also tighten the hole for the NVA as it’s a bit loose. Red looks good on the engine. The little slots on the rear intake came off when removing the support material.

These surfaces will have to be flat with no dings for the reed and case to seal for max fuel / air to
flow up into the combustion chamber.

The seal is on the raised edge next to the reed holder part just as it is on the .049 horseshoe back plate. I know the surface looks porous. There is always high temp RTV to help too. I need to adjust the extrusion ratio higher to fill in some gaps. The reed seal can be polished.

That looks good. I am assuming that all the lines I see on the backside are where the printer had layed out the material? It is neat to see how it works from a different angle. Is that an .049 needle assy?

Looks really good. You may want to open up that venturi hole if you are going with the .049 NVA.

The design looks good. If the sealing surface for the read can be made to work it should run. Did you have one of protoypes for reference or did you design it?

The .020 backplate/carb looks terrific Jason! You may want to consider plotting-out the 2nd or 3rd generation .049-style reed-retainers; neither of which utilize a "circlip".

The latest (3rd generation/"Sure-Start") style .049 horseshoe backplate uses a simple snap-on cap to retain the reed. This may be much easier to draw/print.. than creating that internal "groove" for a circlip.

One thing I have found with the horse shoe backplates is getting access to
unplug the fuel line, could modify as shown and helps to reduce the firewall footprint.

gkamysz wrote:The design looks good. If the sealing surface for the read can be made to work it should run. Did you have one of protoypes for reference or did you design it?

I didn’t have one of the Cox versions. I started from scratch and used an 049 horseshoe backplate to capture features. It uses the .049 horseshoe backplate screws and a postage stamp fine thread NVA. . I need to make some changes and print in PLA again to test fit and then I’ll load nylon. Also have Delrin I can print in.

For the reed surface I was thinking of using a polished aluminum rod end, heat it up and then slightly melt the top surface of the reed seal surface smooth. This should fix any imperfections from 3D printing.

I might need to open up the intake more. It’s at .160” where the NVA is then tapers to .110”. I’ll look at a helicopter backplate and replicate what’s done there.

1/2A Nut wrote:One thing I have found with the horse shoe backplates is getting access to
unplug the fuel line, could modify as shown and helps to reduce the firewall footprint.

I might be able to shorten it by .1”. Won’t leave much for the mounting screw holes. Screw holes are meant for #2 screws.

Fingers crossed it works out well, and you have then available....

Is there a reason why you print in PLA then if good switch to a different material? Is it have anything to do with materials cost? Or does one material print better than the other? Just curious.

NEW222 wrote:Fingers crossed it works out well, and you have then available....

Is there a reason why you print in PLA then if good switch to a different material? Is it have anything to do with materials cost? Or does one material print better than the other? Just curious.

Cost is one thing. Setup for nylon is another. I have to bake nylon overnight in my drier before printing. PLA is cheap and easy to print. Works great for testing the fit. Once it looks good then setup for nylon. I have to print Bob’s axle for the funny car yet out of nylon so I’ll do it all in one print along with some teather car wheels.

Jason i would not shorten it the hose is not that hard with a good pair small long needle nose pliers . The overall look is good , is this with the #25 nozzle on the printer and i don't guess you could slow down the printing to make the surfaces smoother , Dont know just guessing may be a melt down if too slow .. I read were you can get products that will Make the surfaces smooth after print but looked like a PIA to go through for say one surface .

I know what you mean about shortening the bottom. It messes with the look a bit.

I do have a .15mm nozzle but I have never used it. It would take some experimenting and I would need to make a filament precleaner to wipe any dust off the filament as that can jam it up. It doesn’t work with all filaments either. Some increadable detail can be had with this nozzle size and might help with the reed seal area and circlip groove.

https://e3d-online.com/blog/2016/11/07/0-15mm-nozzles/

Will this work to clean the filament .. https://weldingsupply.com/cgi-bin/einstein.pl?PNUM::1:UNDEF:X:007062

Form and function with no reduction in the mounting hole dia.

Here is a helicopter backplate reed area. Many different features than the tank reed area in the .020.

Backplate in carbon fiber ABS. Finer detail than PLA.




With the reed and circlip installed.



The reed spins freely and the circlip is seated in the groove. Need to polish the reed seal area. I’m going to try this backplate. I know it might melt but if it work I’ll continue development.

Ah nice is that more heat resistant?