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May 05, 2004, 06:35 PM
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Thread OP

Where can you get that little rubber grommet for direct drive J250


I lost the little rubber grommet that goes on the shaft of a J250. The prop goes on the grommet. Where can i find this little jewel?

Grant
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May 05, 2004, 06:51 PM
If you are using gws props http://www.allerc.com/ has pushon rubber spacers under accessories. Get the ones for ips motors.
May 05, 2004, 07:27 PM
Registered User
Thread OP
thanks, i found it under motors, prop adapters. It's a set of 12 of different motors.
May 05, 2004, 08:25 PM
Rehab is for quitters
LuckyArmpit's Avatar
Park, I don't screw around with those rubber grommets. I use a 2mm collet adapter. Why? Because with rubber, the prop can actually slip thus robbing you of rpms. 2nd, it aint comin off!!!! I use one on my Scram Blur which has a j250 motor and 4x4 prop. You can get these adapters at Todd's Models and Azaar has 'em at ecubed. Azaar's site is www.ecubedrc.com and Todd's is
www.toddsmodels.com
Some say, "oh, it will add weight"...big deal, the amount it weighs hasn't any effect on my 8 oz. wing.

Dave...
May 05, 2004, 08:34 PM
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Thread OP
Good point Dave,

I think I may have one of those laying around somewhere. I'll give it a try.

Grant
May 05, 2004, 08:57 PM
Registered User
Thread OP
I found my prop adapter, looks like you need to ream out the prop a tad. I was thinking of putting my Razor 300 in my Scram-blur and a 3x3 prop. Unfortunately, this prop has a much smaller hole and will need to be drilled out quite a bit. In fact so much I may not have any hub left. Has anyone tried a 3x3 prop before?

Looking at P-calc with a Speed 300 (P-calc doesn't have a Johnson 250) you get almost 10mph more pitch speed with the 3x3 than the 4x4 but everyone uses the 4x4. Anyone tried the 3x3?

Grant
May 05, 2004, 10:47 PM
Sir Buildsalot
MailOrderGuy's Avatar
Quote:
Originally Posted by Parkflyer
Looking at P-calc with a Speed 300 (P-calc doesn't have a Johnson 250) you get almost 10mph more pitch speed with the 3x3 than the 4x4 but everyone uses the 4x4. Anyone tried the 3x3?

Grant
I fly the J250 on those little 3x3 GWS props, you can expect 5 amps at WOT, less in the air. The 3x2 works well too.
For each of these props I drill it out, then slip it on the J250 shaft using a little Med. CA and I have not had one come off yet.
May 06, 2004, 06:08 AM
Rehab is for quitters
LuckyArmpit's Avatar
I haven't tried a 3x3 prop on my Scram Blur, just the 4x4. I know the 4x4 really zings it pretty good. It draws around 8 amps or so while in the air.
Yep, I had to drill out the hole bigger on the prop but still have hub left.
Forget what size drill to use. I just took out a little at a time with different drill sizes.

Dave...
May 07, 2004, 05:26 AM
Registered User
Thread OP
The 3x3 is a tad smaller than the motor shaft so to get either a prop adapter or even GWS's rubber grommet, you have to drill so much that there's no hub left. I guess the only way is to glue directly to the shaft, but I don't want to glue the prop on my Razor.


Grant
May 07, 2004, 07:14 AM
Crash Master
Gene Bond's Avatar
I just press-fit them onto the shaft w/o any glue, after drilling them out with a #48 drill. The shaft is .078", the #48 is .076"... No problems here.
May 07, 2004, 07:21 AM
Registered User
Thread OP
No kidding Gene? The prop doesn't slip? Hmm... I'll have to give that a try, what motor do you have the 3x3 installed?

Off to Home Depot for a #48 drill.

Grant
May 07, 2004, 09:43 AM
Sir Buildsalot
MailOrderGuy's Avatar
Parkflyer,

I drilled out the hub on the 3x2, then just glued it to the shaft of the J250 with Med CA.

Here is a close up pic:

https://www.rcgroups.com/forums/show...2&postcount=78


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