stunthanger.com
Building Tips and technical articles. => 1/2 A building. => Topic started by: david beazley on February 25, 2013, 09:53:58 AM
-
I want to test my reed valve Cox engines and want to know if anyone has a test stand design that allows quick change of an engine without unscrewing and screwing the 4 mounting screws.
Suggestions? ??? ??? ???
-
Amen to that request! It is a pain if you want to check several engine/ There must be a better way, I just can't think of one.
Andrew.
-
David, i remember those days! Now if i need to test one for the kids i just tighten it in a vise with hard rubber pads on each side.
-
Ouch! That rates as cruelty to engines!
Andrew.
-
Mould an epoxy impression of the side of the crankcase onto the side of a piece of 5/8 inch maple. Mount an over-center type clamp to press on the other side of the crankcase. As long as your using a tractor prop the engine will stay put with little squeezing of the crankcase. This style of mount was proven over many years at Cox. Cox’s mounts were all machined aluminum.
Randy
-
I just screw several of 'em onto a 2x4 down the basement and clamp the whole thing to a bench in the backyard.
If you want "quick change" an easy way is to make a simualted front end of a plane with four pegs for the bolt holes. Then rubbber band the engine(s) on like the Goldberg Wizard or the Cox PT-19.
-
I use a piece of Baltic birch cut and drilled for reedies bolted to my step ladder/run stand. Use only a couple of bolts to mount instead of all four. Fairly quick engine change-outs this way.
-
For goodness sakes. How long does it take to make a gadget to save the amount of time it takes to unscrew and screw four screws?
??? ;D ::)
George
Edit: The board in the center is my old oil soaked reedy stand. I mount it in a large "C" clamp...it isn't going anywhere.
-
George,
I am not overly fussy, but your mounting system looks dire! I don't really want to copy that. When I get to rebuild time, I usually have at least a dozen motors, sometimes twice that number, to overhaul and check . It IS definitely worth making something quick and smart when you have that number of engines to check. Even using two screws as a minimum , I get pissed off with screwing and unscrewing 50 small screws. The overlocking system sounds good to me and I think I will give it a go. Once done it will last me the rest of my lifetime, so time well spent in making such a mount.
Andrew.
-
At the risk of reinventing the wheel I have built a Quick Change Reedy Engine Test Stand.
I wanted it to be:
Simple (KISS)
Tool Free
Strong
Quick Change
Built with what I had on hand
So this is what I came up with. It is mounted in my bench vise for the pictures but I will mount on a 2X4 so it can be clamped for engine running outsifde. (once the snow melts). It is made out of some 1/8" aluminum plate I had laying around. No measurements were taken other than the 1-1/8" hole to mount the engine. Everything was TLAR. There are 2-3/32 roll pins to locate the back plate mount holes on the mount. They are long enough to locate the 2 clamp plates on the back side. The clamping fasteners are 1/4-20 fasteners, I used wing nuts so I don't need any tools. Pix are pretty self explanitory. Took around a hour to make, half of which was cleaning the work space and finding the materials. Could be constructed of plywood as well as Al.
-
a couple more pix
-
Very clever David,
I would guess that pieces circuit board (G-10 epoxy fiberglass) would work too and would not absorb the fuel residue.
-
Nice David!! If i were into reedies a little more these days i would copy your set-up!!
-
George,
I am not overly fussy, but your mounting system looks dire! I don't really want to copy that. When I get to rebuild time, I usually have at least a dozen motors, sometimes twice that number, to overhaul and check . It IS definitely worth making something quick and smart when you have that number of engines to check. Even using two screws as a minimum , I get pissed off with screwing and unscrewing 50 small screws. The overlocking system sounds good to me and I think I will give it a go. Once done it will last me the rest of my lifetime, so time well spent in making such a mount.
Andrew.
I see your point. I work with one or two at a time. Good luck with your fixture.
George
-
That looks great. I kept running thru this old brain something on that order, but could not come up with anything positive. Guess i am getting old.
Just an update to thank you as pics have been added to my favorites files.
-
Hi George,
Glad we see eye to eye, looking back at my post it was a bit snotty! My apologies for that. Your system is fine for the odd engine. However I have recently been befriended by a young lady, all of 8 years old, who wants to become an engineer! Great! I showed her how to build a Cox reedy from my stock of spares. She then built up another two by herself! It is bitterly cold here in my part of the UK, but she wanted to fire them up, so we used your system and fired them up outside. By the time we had run the last one, we didn't think much of the screw system, hands like blocks of ice! Mind you she was so pleased, that we are going to build a trainer and a Combat Kitten for her two engines. Made an old man feel good! Hope she can learn to fly them in the spring.
Regards,
Andrew.
-
I just screw several of 'em onto a 2x4 down the basement and clamp the whole thing to a bench in the backyard.
If you want "quick change" an easy way is to make a simualted front end of a plane with four pegs for the bolt holes. Then rubbber band the engine(s) on like the Goldberg Wizard or the Cox PT-19.
H^^ I use socket head screws and it make motor mount changes quicker than slotted head screws. #^
-
Ummm, guys, you are overthinking the problem! HB~>
-
Love it Larry!! y1
-
Larry,
Perfect line in lateral thinking. You even get to lubricate the vice threads. I did an overlock cam arrangement because I had one in my scrap box.
. Maybe its time to give up on the Cox reedies, they seem to breed, giving them an overhaul is becoming a major project! Recently I have taken to putting lots of air line oilthrough them. The stuff I have is almost like water, so i use a syringe to inject some into the tank and simply choke it through the engine. I hope this will stop the dread castor freeze up of every moving part!
Don't know if this is a smart move or not, I will let you know next year.
Regards,
Andrew.
-
Larry, I love it too! One time I tried to mount a Fox .049 to a piece of 1X2 pine and clamp to a 6x6 deck support outside my basement shop door. Worked fine for a while until the clamp loosened and the whole thing came off! My first reaction was to catch the spinning engine and board but in a nanosecond I realized the folly in it. The engine hit the cement glow head first and drove the element into the piston. I replaced the glow head and the engine still runs, but that was the impetus for engine clamp. ~^
-
Larry, that mus be some spring tension on the clamp. Looks dangerous to me.
-
It is a medium size clamp, and believe me, the engine doesn't move. The vinyl covers help with the traction and eliminate damage to the crankcase. Also, you may note that the other half of the handle is jammed solid against the vice. :!
-
I am just trying to decide what to fabricate from the ideas here. I have some clamps like Larry R. shows, but I don't really want to start the engine in my basement where my only vise is located. Got a few Cox engines I have built from parts and would like to see what they will do.
BIG Bear
RNMM/AMM
-
Why not? A window fan will help with the fumes. I remember when I first moved back to KCKs and my brother was at the house for a dinner with his family and us. He seen his old O&R .60 side port laying on the bench. Asked me if I had ever ran it. I told him no as there is a hole in the crankcase. He said that is no problem with that engine and started hacking out a peice of hardwood that was on the floor. Next thing I know we are in the basement as the temps were in the teens outside. He fire it up by his method of three drops of fuel in the exhaust and turn it thru. A couple of drops in the intake. Hook up battery and put thumb over hole in the crankcase. Two flips it was running. Only ran for a couple of minutes before we shut it down. Forgot to open basement window and we almost didn't get dinner. Mother and my sister-in-law were a little perturbed to say the least.
-
I just screw several of 'em onto a 2x4 down the basement and clamp the whole thing to a bench in the backyard.
If you want "quick change" an easy way is to make a simualted front end of a plane with four pegs for the bolt holes. Then rubbber band the engine(s) on like the Goldberg Wizard or the Cox PT-19.
I like your idea, Paul. Pegs are the only practical way to locate a firewall mounted engine, with rubber bands to provide tension.