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Old Nov 11, 2012, 03:08 PM
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glewis's Avatar
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Shaft removal

Now for the tricky part.
With the socket shaft receivers in place, put the bell assembly in the vice.
You need to get everything square so when the pressure is applied the assembly doesn't start to cock on an angle in the vice jaws. Keep positioning stuff until when slight pressure is applied, the whole mess stays straight. This is important to prevent distorting the bell.
Start applying pressure by tightening the vice. The shaft should start to move fairly easy. Press it out from front to back until the shaft is flush with the front bell shaft boss.
Loosen the vice and insert the pin. Press the shaft the rest of the way out, making certain everything is still straight.

Next, preparing the new shaft.
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Old Nov 11, 2012, 03:18 PM
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Threaded shaft preparation

The knurled area of the GWS shaft is in the wrong place for our application and it is too large to fit. You could force it into the soft aluminum, but I would caution against doing that. That being said, here's how I resize the shaft.

First measure the diameter of the original shaft. We will need to cut some of the knurl down so it doesn't distort the aluminum and want it the same size as the original shaft.
Chuck the shaft in the drill and while it spins file the knurl down a bit at a time. Measure carefully, we want a precise fit or the bell will wobble on the shaft.

Keep checking the fit by sliding the bell onto the shaft. You want it to just 'catch' on the knurl as it starts to pass into the bell.

The shaft will be too long at the back at this point, we'll address that later.

Next, installing the new shaft.
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Old Nov 11, 2012, 03:23 PM
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Installing the new shaft

Slide the new shaft into the bell from back to front.
Slip your shaft receiver socket(s) onto the front of the shaft.
Put the mess in the vice and start pressing the shaft into the bell.
Stop when the knurled part is fully seated into the bell boss.

Hang in there, we're almost done.

Next, final assembly
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Old Nov 11, 2012, 04:00 PM
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Final assembly

Now we put the bell assembly back onto the bearing tube. Make sure your tape covering the magnets isn't in your way and preventing the bell from going all the way on.
Measure the shaft protrusion and mark the length.
Remove the bell assembly and chuck the threaded portion in the drill.
Using the cut off disk, spin the bell assembly in the drill and part off the excess shaft. Now while it's still spinning, cut a new E ring groove with the cut off disk.
Remember the tape on the magnets? Now all the grinding dust is stuck to the tape. Carefully remove the tape from the magnets. I like to clean the magnets with the sticky side of the tape to make sure there is no metallic swarf hiding on them.
Slip the bell assembly in, add the spacer and E-ring.
Last thing to do is check the end float of the assembly. You want just a bit of slack. If it's too tight, you will need to press the shaft to the rear just a hair. I've done this by tapping the end of the shaft with a piece of wood. Once satisfied with the end play, install the set screws.

That's it. Done.
Sounds like a lot, but it only takes me 20 or so minutes to install a threaded shaft and it sure makes prop mounting a whole lot easier!

Glenn
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Old Nov 11, 2012, 04:25 PM
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Sopwith Mike's Avatar
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Wow! Hmmm. Not having some of the tools is a bit of a drawback. Perhaps you could run a conversion service

I'll have another look at my options: the threaded shaft is definitely the easiest way to mount the spinner, but...

Glenn, many thanks for your time and effort. I'll consult my club-mate TrevorH; he has quite a well-equipped workshop.

On the constructon front, I got the starboard and port wings to the same stage this afternoon and the wing is starting to look like part of an aeroplane.
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Old Nov 11, 2012, 04:53 PM
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35Mhz's Avatar
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Hmm, why not just thread the existing shaft with a 3mm die?
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Old Nov 11, 2012, 04:54 PM
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The shafts I tried to thread were harder than the die.
Guess you could remove the shaft, anneal, thread then harden.
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Old Nov 11, 2012, 08:27 PM
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Glenn,

Thanks for taking the time to do the prop shaft write up. Very helpful info
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Old Nov 12, 2012, 07:54 AM
The "pro" in procrastination
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Glenn, that's a great write-up. Many thanks!

Steve
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Old Nov 12, 2012, 09:11 AM
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Hope you guys will try it.
The same procedure will work on just about any motor. GWS has 4mm and 2.5mm gearbox shafts too so this wouldn't be limited to just motors with a 3mm shaft.
Of course the listed equipment is just what I recommend.
There are other ways to skin a cat....
Glenn
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Old Nov 13, 2012, 09:07 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
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Where have I got to after all this talk of swapping motor shafts?

I'm still on the wing, which is complete except for the 3/16th soft balsa LE, cutting out and making the ailerons and fixing on the tips. I recall seeing a drawing of one of the H versions (it may have been the prototype) with much rounder tips but all the other drawings I have show the square-cut version.

It's a while since I built as small a model as this and I keep making big-hand mistakes, so far nothing that can't be hidden from casual view. I'm enjoying the journey, and learning a lot from you experienced free-flight converters as you build your own and comment on the other threads.

Mike
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Old Nov 13, 2012, 12:37 PM
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Sorry to clog your thread, once I started the explanation I couldn't stop...
Nice wing. What size wire will you use? Did you consider using an aluminum tube?
Glenn
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Old Nov 13, 2012, 12:56 PM
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Sopwith Mike's Avatar
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Quote:
Originally Posted by glewis View Post
Sorry to clog your thread, once I started the explanation I couldn't stop...
Nice wing. What size wire will you use? Did you consider using an aluminum tube?
Glenn
Hi Glenn,

I'm glad to have such a useful lay-by in the thread! I used the Dubro stuff because I had it in the spares box, no other reason! The wire is just what it comes with: not as hard as piano wire but good enough for a light model with small aerodynamic forces.

I put the LE on since my last post and razor planed and sanded it to shape. Very satisfying!
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Old Nov 13, 2012, 06:19 PM
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Wish I could get the hand of using a razor plane.
I've tried and always make a mess of it. Would like to find a plane that uses a single edge razor blade instead of the dull piece of crap that came in the plane I bought.
Glenn
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Old Nov 13, 2012, 06:33 PM
The "pro" in procrastination
Steve85's Avatar
Canada, ON, Kingston
Joined Mar 2004
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Mike,

Nothing quite like watching the balsa curlicues come out of a razor plane, is there? I think the plane is my favorite tool just for that, and I could probably turn a sheet of balsa into very expensive kindling just fooling around with it!

Regarding size, everything is relative. A 40" span model would be big for my bench, except for the Lancaster which spans 51" and routinely provokes oos and ahs from the family members because it's "so big". Just the same, as Paul Kohlman (Longhorn) has pointed out on another thread, everything on his bench (and mine) seems to be suffering from size creep. Whereas a 28" Guillows model was once a fair-sized model on my bench, I find myself deciding that the CF-100 Canuck I'm mentally designing as a future build will probably need to be bigger than 36" if I want it to look "right"....

Steve
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