Testors/McCoy .049 smoked...

I made this bench-mount weeks ago.. and posted it somewhere.. (I thought..) but not in this thread.





What a mess my bench is..  

Anyway.. I needed a tank-mount/shelf.. and found a bracket that's been kicking-around my work-table for days.. So I decided to put something together. I used my trusty old B & D rotary tool with a cut-off wheel to shorten some screws.. and cut a matching piece of poplar-stock for the tank-shelf.




I'm better-off getting these things out of the way beforehand. I may not test-run the Testors/WenMac engines anytime soon.. but when the day comes.. it's now just a matter of shimming a tank and running a feed-line. The mount is all set to screw-into a post on my deck out back.

I'd like to make bench-mounts for "all" of my engines. Most of them will be beam-mounts. It would be a good Winter-project. I like the idea of "dedicated" mounts.. rather than a universal-mount. I enjoy working with wood.. and making fixtures.  

I made a similar one with poor results.  

Despite being cinched up tightly in a vice the engine vibrated so badly due to the length of the board to the securing point it foamed the fuel.  I think it happened on a Wen or Testors engine like yours.    At first I blamed the engine (bent crank?)  I finally resorted to commercially available mounts.

I posted about it here a year or two.  Rod, Ron, or somebody recognized the problem and set me straight.

Edit add:

This might have been the culprit.



Of course, yours looks a whole lot better screwed together than my hastily constructed example so it may work fine.

Bob

rsv1cox wrote:I made a similar one with poor results.  

Despite being cinched up tightly in a vice the engine vibrated so badly due to the length of the board to the securing point it foamed the fuel.  

Of course, yours looks a whole lot better screwed together than my hastily constructed example so it may work fine.

Bob

In your photo, the mount isn't "centered" in the vise-jaws.. which would amplify the "spring-board" effect. You can see the difference in the jaw-gap on either side. The wood appears rather "thin" as well. A short-arm commercial mount will lessen the effects of vibration.. but if the engine or prop has a bad-enough balance-issue.. it's going to cause problems in a model.

I try to use clear solid-hardwood for a bench-mount if I have it.. and yes; I usually anchor the mount to a deck-post or rail using two long woodscrews.

Back when I was running every new to me engine I built many test stands, some famous, most infamous. Maybe 7-8 altogether. Individual custom stands for everything from Cox to Spitzys. That one probably wasn't the one that caused the vibration problem. Most were built per your example on the spot using 1X2 pine without much consideration.

I think this picture shows the villain under the larger stand, built for either a Cox or tank mounted Wen Mac out of thin T1-11 siding. It vibrated like mad. I think yours will probably do just fine. I couldn't find the thread I posted about it, probably fell off the end of the earth.

A couple of months ago I threw all of them away replaced by commercial stands.



Bob

I hate to bring back an old topic, but just had one question regarding your Testors engines roddie. Do you happen to know the thread pitch for the needle? I just acquired one over these today with the exact same weird tank assembly and all. However, it had no needle with it, which I missed when making the deal. So i am looking for the proper pitch so i can find a correct size screw and make a needle. Any help would be greatly appreciated.

I'm pretty sure it is a UNF 1-72 thread.
I've made new a needle from Brass-stock, it is fairly easy to do using a lathe and the right die for the thread.

Sorry, duplicate...

Thanks for the help. I'll take a peek cause I think I have a screw then. If so, off to the drill press with a file. Poor man's lathe!

It needs to fairly long, as the seat is on the other side of the venturi, but otherwise a screw should work just fine.

I'm sorry Chancey, I don't know what the thread size is.. but I shot a couple macro images of one of my .049 FRV Wen-Mac/Testors engines' needles with my phone-cam. Maybe they can help you find the answer.



"measurements below in inches"

Pretty sure I have that same engine complete. I don’t like them at all, so it’s yours if you want to pay shipping to Canada. It has the needle.

Ron

If he doesn't take it, I'll pay the postage to NC.

Ok. I have since determined by the pictures that the needle is a 1-72 tpi picth thread. I will now look for a screw of the appropriate size and fabricate one. Thank you all for teh help and pictures.

ticomareado wrote:If he doesn't take it, I'll pay the postage to NC.

Where in NC are you? I ask as I am going to be there after Thanksgiving for work.

I PMed you several hours ago.

Unlike Ron, I actually like these engines a lot. They're not the same quality as a Cox engine, but they're great for what they are. Someday I need to design a twin or three engine plane for these engines. If there was a TEF, I'd be a member there, too.

I applaud trying to make a needle for the valve if you're doing it for the fun of it. But if you just want the engine to run, I'd say just press out the needle valve body and press in a Cox NVA. It actually gets you a more accurate needle setting and a smoother run, from my experience. See the thread I did three years ago:

https://www.coxengineforum.com/t8206-follow-the-bouncing-brain


The Mix N' Match Mark

Thanks Mark. This is both for the fun of it as well as just to run. Replacing the needle is not much of an option here as one would need a needle assembly to do this. However, I appreciate your time and link provided.

Here is another picture of my home made one. I made it shorter than the stock and instead included a slot for a screw-driver at the end. It was quite easy to make once I had the correct die for the thread. Always feels good to save an old engine.

That is quite a nice needle there. The joys of having, and knowing how to use a lather. I have always wanted one, but.....

That's just the way Rotomatic starters are made. If you've got a good runner and don't need the nose weight just strip the whole assembly off, drill out a Cox Bee thrust plate, squeeze it on with a plop, plug any rivet hole that might be in the air intake and let her rip. A good one makes a very competitive nostalgia 1/2A F/F engine. A good stripped glow plug model makes for a very light 049 with excellent power to weight ratio.