Adapters for GWS Hyper Drive Props - RC Groups
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Jul 13, 2003, 07:41 PM
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Adapters for GWS Hyper Drive Props

I've been asked for advice by several people on how to adapt GWS Hyper Drive props to the 3mm gear shafts on the GWS IPS and EPS gearboxes. I've used several methods. The first two involved stuffing an appropriate size and length of fuel tubing -- or one of the GWS black rubber adapter inserts -- into the hole in the prop hub, and then screwing this onto the threaded gear shaft. Start with a nut screwed down to the end of the threads, then a washer, then the prop with insert, then another washer and nut. Tighten down and you're good to go. It's a bit tedious, but it works.

More recently I found that one of my old MP Jet 3mm prop adapters (photo below) would work. This is a very robust collet-type adapter in which I have great confidence. The best part is that it is a perfect fit for the EP8040 and EP9050 HD props. The 5mm shaft hole and the size of the nut impression in these HD props are both perfect for the MP Jet prop adapter. Unfortunately, the 10x6, 11x7 and 12x8 HD props inexplicably have 4mm holes and nut impressions. So they require modification.

First, you have to shorten the gear shaft so that the prop adapter fits up close to the spur gear. The point to cut on the gear shaft is close to where the threads end. But don't cut it too short! Second, ream out the shaft hole from 4mm to 5mm. Believe it or not, I found a 5mm drill at a Big Lots store (what are the odds!). If you have the MP Jet long prop adapter, that's the only modification you need to make to the prop. Just push the adapter onto the shortened gear shaft; slip the rear collar, reamed out prop and front washer onto the adapter; and add the nut and tighten it down.

If you have the short prop adapter as I did, there's an additional step, as the short adapter threaded shaft is not long enough to extend past the front of the prop hub for the nut to grab. I heated up a soldering iron and used a 5mm bolt to pull a 5mm nut -- heated by contact with the soldering iron -- down into the hub. The heated nut melted the plastic enough to expand the existing 4mm nut impression to fit the 5mm nut. After it cooled, I inserted a 5mm nylon insert stop nut in the newly expanded nut impression on the front of the hub, slipped my MP Jet prop adapter into the back of the prop and lightly screwed it into the stop nut. Finally, I firmly pushed the prop adapter onto the shortened gearbox shaft, held the spur gear in one hand and the prop in the other and screwed the prop/prop adapter assembly down tight. The collet clamped down hard on the gearbox shaft, and the stop nut grabbed hold of the adapter shaft and locked it in place.

The whole process of using a soldering iron to heat a 5mm bolt to enlarge the nut impression sounds like a pain. But it's really not that difficult, and the reward is a solid prop adapter that isn't going anywhere unless you want it to. So once all of your props are modified, you can quickly swap props by simply grabbing the spur gear, twisting the prop off and twisting another one back on. I like this a lot! But if you don't want to go through this process, be sure to order the long prop adapter, and carry around a 5mm wrench to loosen the nut to change props. The 3mm MP Jet prop adapter is a very tight fit on the 3mm IPS/EPS gear shaft, so I believe that one of the 3.2mm adapters from Graupner and others will also work.

NOTE: MKH discovered that the set screw-type 3.2mm adapters do not work on the 3mm gear shafts. Does someone have a 3.2mm collet-type to try?
Last edited by Dave Hederich; Jul 13, 2003 at 10:23 PM.
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Jul 13, 2003, 10:06 PM
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I was not able to perform a search just now, however I remember GWS4CEO saying in another thread that new HD props will have a hub with different size holes (like APC SF props?) I believe it was in a PJS 300 thread. - Brian
Jul 13, 2003, 10:19 PM
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Re: Adapters for GWS Hyper Drive Props

Originally posted by Dave Hederich
The whole process of using a soldering iron to heat a 5mm bolt to enlarge the nut impression sounds like a pain. But it's really not that difficult, and the reward is a solid prop adapter that isn't going anywhere unless you want it to. So once all of your props are modified, you can quickly swap props by simply grabbing the spur gear, twisting the prop off and twisting another one back on. I like this a lot!
That sounds pretty cool Dave. Minimal hardware is always a good thing, and the motor torque is always working to keep the prop on tight, instead of working against it, so no worries about it loosening in flight. Nice idea!
Jul 13, 2003, 10:25 PM
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OK, I found the quote I was thinking about, it was in a Razor thread.

GWS4CEO said:

"In order to let HD props to be fitted into more application at a simplized method, I already make the center of hub with step for 3, 4, 5mm. Hope this will be OK? The mode started this modification a few weeks ago!

Sorry, I forgot to say!"

Would an adapter still be necessary with the newer style hub? - Brian
Jul 13, 2003, 11:06 PM
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Originally posted by mbcone
Would an adapter still be necessary with the newer style hub? - Brian
If I understand this correctly, the newer HD props will have a 3mm bore, with steps for 4mm and 5mm to help us bore them out for larger shafts. If this is correct, we'll be able to mount HD props right to the 3mm IPS and EPS100/300 shafts, with no mods or adapters. I'm not sure what this will mean as to what size nuts we will be able to use. The 3mm shaft nuts won't hold the HD props I now have, as they have a hex recess for a larger nut. Guess we'll have to see one to know for sure.
Jul 14, 2003, 09:08 AM
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Right, you'd need stepped hex recesses as well as stepped shaft holes, and that might end up taking too much meat (strength) out of the hub. I hope that whoever gets one of the first of the new HD props with a stepped shaft hole can explain to us all exactly how it looks, or, better yet, post a close-up photo.
Jul 14, 2003, 12:53 PM
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Given the large number of prop shaft diameters and the several hole/adapter schemes used by the prop mfgrs., I've fallen back on my collection of aluminum tubing, hard nylon tubing, all sorts of small washers and metric nuts. I try to shim the prop without changing its' original hole configuration so that it is usable on the next motor. (which always has a different sized prop shaft) I do agree that the MP collet adapter is an excellent and reliable part. Sometimes it's the best solution.

Jul 19, 2003, 02:19 PM
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MooseFlyR's Avatar
I have had good luck with using the fuel tubing and larger washers method with one difference:

I use 2 pieces of fuel tubing that about fit the nut opening (not the shaft opening)and just a tiny bit longer than the nut opening's depth. I put a washer, then tubing, prop, tubing, washer & nut. This uses the nut openings to center the shaft.The slight compression of the tubing when tightened seats it all fine. Works great on the 4mm HD props where tubing to take up that 1mm difference in the shaft hole is tough to do.

Hope that all made sense. Those HD props are great! Wish they came in more sizes.

BTW... I have also taken to using these 3mm nylon locknuts instead. Lighter, and don't walk in my pusher applications.
Tower Hobbies, Horizon and many LHS carry them for RC Cars.

Dave, thanks for all the HD testing. Plan any on the PJS300 motors? (nudge, nudge)

Last edited by MooseFlyR; Jul 19, 2003 at 02:22 PM.
Jul 19, 2003, 03:26 PM
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Looooeeee!'s Avatar
The matter of the 4mm shafts on the PJS motors, the Axi's and even my tapestreamer conversions begs for a simple solution to prop mounting. I like Ital's little adapter with the counter-sunk bolts, but what about the popsicle sticks some folks were using directly on the shafts of their PJS 300's? I've found a way to mount my thin "e" APC's on my tapestreamer's shaft. I'm using a 5/8" long chunk of saltwater aquarium silicone air-line, which has a nominal I.D. of about 1/8". I just use the tubing like a large Gunther prop adapter, you have to really press the prop home using this stuff. After its pressed in place it will take a 20lb. pull to get it to remove again.

Jul 19, 2003, 11:14 PM
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MooseFlyR's Avatar
Yes, 4mm PJS shafts & 4mm HD holes. I really like the thin prop saver idea here. I'm going to try a 10x6 HD on my new PJS300 for my Carbon Falcon with 2S Etec 1200's. No hole spacing needed, and the shaft is short so no cutting off to be effective. Wish they made a 9x7 HD for this maybe. For larger prop holes, I'll have to look into the tubing thing. It's a pusher, so it would be even better there. Both ways light & simple. Great idea Looee, thanks.
Last edited by MooseFlyR; Jul 20, 2003 at 01:17 PM.
Jul 19, 2003, 11:24 PM
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>> Plan any on the PJS300 motors?

Bob, I've been fighting the urge to buy a brushless motor like crazy until I burn up all of my brushed motors. But I haven't had a brushed motor burn out in months, and I still have a drawer full. I've pretty much decided that the PJS300 will be my first brushless. I don't know how much longer I can resist the urge.

Looee, your tubing idea sounds reasonable. I think I'd be inclined to go with a prop saver on a brushless, though. It's one thing to hurt a cheap can motor and replace it with another cheap can motor. But the cost of brushless motors, and the promise of long running lives as long as you can avoid physical damage to the motor, leads me to think that a prop saver will result in less wear and tear on the motor over time. I would think that a combination of a prop saver along with some version of the GWS rubber spinner would go a long way toward reducing potentially damaging shocks to the motor from the inevitable hard landings.

MooseFlyR, the 10-inch HD prop has a pitch of 6, not 8. The 12-inch HD prop has a pitch of 8.
Jul 20, 2003, 08:38 AM
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Where can I get more info on the thin prop saver?


- RD
Jul 20, 2003, 12:20 PM
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MooseFlyR's Avatar
RD: This thread is where folks are making them from "popsickle sticks"

Dave: Oops! Typo. Been messing with a 10x8 CAM folder on an IPS Dual A ratio and must have had 8 on the brain. Just ordered some 12x8 HD's for my slowstick as well. (previous post edited)

This is my first brushless as well for the same reasons. Should be a perfect solution to my Carbon Falcon's IPS powerplant. M100's, 280's, Duals all too heavy.

Last edited by MooseFlyR; Jul 20, 2003 at 01:18 PM.
Jul 23, 2003, 05:41 PM
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I am using a GWS prop saver with a piece of tubing from a Pentel Hybrid Gel Roller pen to increase the shaft diameter from 3 to 4 mm (I am using the larger props). I just clipped a portion off the plastic tube that holds the ink. - Brian
Jul 23, 2003, 06:00 PM

3MM Shaft Adaptors

Try this web-site for 3mm prop shaft adaptors:

Even though they are located in Japan, I was able to get my order at a reasonable cost to the New York area within a week.

Don (FlyWoody3)

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