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Old Apr 04, 2007, 11:39 AM
gpw
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Vt, the GWS DD3x3 just slips on the shaft , with a little drilling ... The 4x2 requires some type of prop adapter .. we use the type that clamps on the shaft when you tighten the prop (collet) .. standard stuff ...but you still might have to drill...depending on what you get ...
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Old Apr 04, 2007, 03:27 PM
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GPW Thanks!

Will try 3x3 first.
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Old Apr 05, 2007, 03:07 PM
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OK, 'nother question from a couple pages back. I understand the increase Throttle to gain altitude vs Elevator to change angle of attac, but not "Number two is to use the joystick to "Prop up" the low wing when it's coming toward you. " What does this mean?

Also, I just got my 3x3 props from FoamFly, and they are a really tight fit to the j250 shaft (like not going to go at all) What do you guys drill with? 5/64? any tips on how to hold it?
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Old Apr 05, 2007, 05:15 PM
gpw
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Spring , when the plane is coming towards you , move the stick in the direction of the low wing , this is assuming you are facing the plane , some noobs fly over their shoulder .looking at their plane behind them ...
You need to drill out the prop carefully , a little from each side does it ...I just tried out a couple of likely sized drill bits till I got a snug fit ...exact size anyone ???
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Old Apr 05, 2007, 05:46 PM
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If the shaft size is a true 2mm, then it's .079" -- assuming an interference fit of 2 thous (not sure on this for plastic to steel) you'd want a hole about .077.

A number 47 drill is .078, and a number 48 is .076.

You might try a number 48 first, and if it's still too tight try the number 47.

--Steve
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Old Apr 05, 2007, 05:53 PM
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Stopped by the local Dollar Store before checking the supermarket for GPWs coffee straws.

In the craft section found these babies, 11-1/2" long and 1/8" OD. Must be a hunnert an fifty in the pack. Good color selection, too. A dollar six with tax.

They call them "Craft Straws".

The length is pretty handy -- almost makes it all the way down the Trainer One without a splice.
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Old Apr 05, 2007, 05:55 PM
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Though Jameco discontinued them, you can still get the DCM-189 version of the J250 at Balsa Products. $2.50 ea.
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Old Apr 05, 2007, 06:03 PM
gpw
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...and they cover all your color schemes/paintjobs ... Nice straws!!!
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Old Apr 05, 2007, 06:16 PM
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Re drilling the prop hole.
I'm assuming you don't have a drill press.

Because there's aready a close pilot hole, the drill bit should follow it without a problem. Drilling from both sides is good where no pilot exists, evening out a difference at the center, but I think it might be better to drill straight through to follow the pilot better, and make a more uniform hole.

Main problem is using an electric hand drill for this -- overkill and may melt the plastic and possibly break the bit if it grabs and you're pushing.

I'd use a pin vice to drill it slowly by hand, or failing that, clamp the drill bit in a vice vertically with about 3/4" showing and carefully turn the propellor down onto the bit -- using a light touch and being careful not to bend or force it. Just ;et the pilot hole guide it and use just the fingertips once it's started. Back it off once or twice to clear the chips. Back it off if you feel extra resistance.

Very long paragraph for a simple operation.
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Old Apr 05, 2007, 09:18 PM
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Just for fun, a couple days ago, I tried drilling out a prop from an ancient rubberband model. went right to 5/64, and it fit the 250 quite snug, unfortunately, it was a degree or so off true (only a couple of degrees!) and made the motor really vibrate at low speeds, so no joy. I like the idea of coming in from both side, also in the prior case, should have started with smaller bits and worked up. My drill press is also an antique radial (remember AMT in the back of Pop Sci?) and I don't think it's up to precision work. I think I'll try feeding the prop on the bit by hand from each end to insure i don't get sideways.

gpw, thanks for the explanation, I have found myself turning slightly while plane is coming toward me to insure i'm not backwards. I'll have to try the low wing method as soon as the snow melts (2"today!) and wind dies down (40mph with gusts to mach ?). I really enjoyed the Michigan summer last week, looks like an early winter though . . . .
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Old Apr 05, 2007, 09:45 PM
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A drill press that's not set square can force a hole to some degree, also if the work is clamped off center. Usually you can adjust a drill press to square, unless the quill has wear problems that you can't take up. A drill press that isn't set square is worse than no drill press at all.

Also important to check the condition of the drill bit. A dulled or mis-sharpened bit can pull to one side. A new high quality bit may make a difference. Plastic is tough to do accurate work in, particularly with power.

But probably being an ancient rubber power prop, the real problem might have just been the original hole was off center -- which wouldn't show up at low rpm, but did with the multi thousands when drilled out for the electric. Since you say you should have step drilled, the pilot hole must have been considerably smaller than what you worked up to -- reaming the new electric prop a small amount should be a lot easier.

5/64" is .078 -- pretty much the same thing as a #47 drill. Easier to find if that is not too loose a fit on this particular shaft.
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Old Apr 06, 2007, 06:14 AM
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Drilling 3x3s

I drill with a 5/64 in my drill press...but when I'm in a hurry, I do it freehand (hold prop in one hand, drill in the other) and it still seems to work OK most of the time; if you drill slowly with a nice clean drill (one that's never been used on anything but props, NOT the one your kid used to try to drill through a stainless bolt!) it does follow the already-drill hole. Then again, I also order the 3x3s in packs of 10 so that mistakes don't cost me a day of flying.

As for prop adapters for the non 3x3s, I've had great luck with these:

http://www.foamfly.com/product.php?p...&cat=23&page=1

They're cheap enough to be almost disposable, and if there's no oil anywhere on the shaft, etc., you can get away without glue (at least on a 4x2.5, for instance), so it's easy to trasnfer to a new motor/prop. I shove one end into the prop, and then press prop-and-adapter both onto the shaft, and it seems to work pretty well.

--Spike
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Old Apr 06, 2007, 06:49 AM
gpw
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We've got a pin vise and an old chuck in the toolbox and we usually have to perform this function carefully at the flying field...a decision made because the 3x3 also fits the 12mm motors...
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Old Apr 06, 2007, 05:30 PM
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I like those adapters -- simple, thanks for the tip, Spike.

GPW,

I will be getting a J250 and props, but at present I have a donated used 180 (I think motor) -- it's labeled a Standard FP-180-k. and an old prop that looks to be 4.25 by I don't know what pitch.

I have a 6 cell 600 mah NimH pack, and a 10 amp ESC. The motor is pulling about 4 amps static with the prop.

I have only an older donated used 8 channel Hitec receiver (lost my smaller 3 channel Hitec rcvr in a plane in a tree) which is a little heavy and overkill (no I don't have a 8 ch TX -- so it's a little wasted on me). One small servo of 9 grams, one gws "park" servo of 18 grams.

AUW with this odds and ends setup and airframe would be a shade under 10 ounces. I know it is supposed to be in the 7 oz range. I know I should have a smaller servo, receiver, and probably a lighter pack, but funds are extremely limited for this.

At this weight and setup do you think it will be okay to try out? I'd really love to try it this weekend if the wind is calm.

If so, I'll mount the gear as is. If not I could wait for the J250 3x3 props, and a smaller servo. The receiver I'll have to live with, unless the wingd blows my other plane out of the tree.

I don't think waiting will reduce the weight much -- maybe 9 grams for the servo -- don't know about the weight of the motor -- could even increase weight.
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Old Apr 07, 2007, 06:58 AM
gpw
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Try it out ... the T-1 has alot of LIFT ... make sure it's balanced...
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