8" & 9" Graupner prop prep

[kloner]

I couldn't find the thread with the guys talking about getting props ready for the stock motors, but this is how kloner preps his. i use a step drill, like the old unibit and i come in from the top just till the top two steps are gone leaving the origional precission 8mm hole untouched so when it touches the prop adapter, it's a nice clean fit. Then since it makes a plastic burn around the edge, i'll take a burring tool and hit the edge real quick to finish the edge.

i"m using a tool like this
http://toolmonger.com/2010/02/04/stepless-step-drill-bits/

http://www.harborfreight.com/1-2-half-inch-six-flute-countersink-93342.html

hobby shops offer these, they work too, just kinda cheap stuff for a bunch of money and are harder to not make contact with the precission hole. You don't want to touch that, i try leaving just a hair bit on to make a tight fit

http://www3.towerhobbies.com/cgi-bin/WTI0001P?I=LXG941&P=8

 

[Dreamweaver]

A drill will generally be oversize...how do the props feel on the motor shafts any freeplay?

There's alot of junk reamers out there...however there is one company that makes a nice one...i've got one at home but not used it yet as i'm still using the 10x5's.

Got mine from Amazon this is it : Great Planes Precision Prop Reamer Metric Shafts GPMQ5007


~Mike

 

[kloner]

that's the point, i didn't touch the origional 8mm hole at the bottom so the fit is perfect

 

[Dreamweaver]

I thought the 8s and 9s were 6mm or something?

 

[kloner]

the very top of the prop is 5mm, middle of the prop is 6mm and the bottom is 8mm. makes it so you don't need adapters on different stuff. Some guys here were talking about using screw drivers, others were using countersinks down to the 8mm......

 

[Tahoe Ed]

Kloner, I got my step drill at Harbor Freight along with a 6 speed drill press for $80. I have the drill press set up to stop on the proper diameter and I can do 10 props in less than 5 minutes. You are right, if you don't mess with the bottom cast hole they fit perfectly.

 

[BerndM]

Hey Kloner,
Those are great shots of your prop hubs. Seeing those causes me to recommend strongly, as I have previously in another post here, that I personally think that Graupner users need to gently sand away the "Made In Germany" raised letters.
Depending on how tight you make your prop nuts, you may only have nut to prop contact with the tiny top edges of those raised letters. Not very much contact area compared to the area you WOULD have if those raised letters were smoothed down.
Maybe I'm being paranoid here BUT I won't risk my nearly $800 investment over something as trivial as this.
It only took me about 3 minutes per prop and now I have 100% contact.