CRANK AND COLLET RUNOUT

[NOVALTD]

To all engine builders. I would like to know what is the general rule of thumb regarding crankshaft runout and collet runout ? For high percision and maximum HP

anything over 0.0005 is NOT acceptable for optimum performance? Is this standard operating procedure? Does anybody make dead on collects? I appreciate it I could hear from Marty,Jack,Jim

Rod, Andy and Mark. Thanks for your help. Dan McCormick- NAMBA 221

 

[Jim Allen]

Crankshafts that are ground between lapped centers should have a total indicator runout of less than .000025". Collet assemblies that are precision ground after hardening can have total indicator runouts of .0002" four inches from the flywheel face providing they are mounted using a precision taper or hub locator. The photos show a flywheel with the .5002"+ OD hub that fits inside the female collet's inside tappered end which has a .5000"- ID hole. Two 6-32 screws secure this piece onto the flywheel's face as the flywheel's hub locates it. Some flywheels have a hardened steel piece shrunk into the aluminum flywheel that is ground for the hub locator. Notice the long length of the split tappered collet that can be used to secure either a shaft or cable. A hardened steel .005" thick thrust washer is used between the clamping nut's inside surface & the hardened, tempered collet. This prevents damage to the clamping nut when very high pressure is applied with the two 5/8" wrenches. This system is used on both nitro & gas engines

The same type of mounting system is used for ball & pin type universals that also have the same .0002"- total indicator runout at the ball.

Jim Allen

 

[anthony_marquart]

Jim,.. I KNEW you were going to comment on this one!

 

[Terry Keeley]

I want everything to be true to less than 0.001" (a thou).

Some of the collets are nowhere near that and need to be trued or tossed! <_<

 

[anthony_marquart]

I would guess that most of them... especially the "offshore" versions,.. are no where close to that.

 

[Tim_Duggan]

Two 3 piece 3/16" collets I got from a well known US based manufacturer were so bad for run-out I couldn't use them. Only thing straight about them was they went "Straight" to the trash can. Needless to say I won't buy another.

 

[RodneyPierce]

LMAO!! Greg, Im pretty sure you hit it spot on. :lol:

 

[Kez]

Two 3 piece 3/16" collets I got from a well known US based manufacturer were so bad for run-out I couldn't use them. Only thing straight about them was they went "Straight" to the trash can. Needless to say I won't buy another.

I have the same experience. I have to buy 4 collets to pick two that have acceptable run out.

Another source of vibration is the flywheel. Small runout in the flywheel (crank, flywheel cone and flywheel combine) tranlates into big vibration problem because of the mass and radius.

 

[Ray Sametz]

Tim did by any chance did the MFG start with A and end in eromarine ?

Greg

I've been buying collets from Aeromarine for years, If I get a bad one, send it back and it's replaced no questions ask. Geez, better yet, pay a machine shop downunder to custom make them for you. See how that works out, probally cost more then the motor itself. :wacko:

 

[Tom Foley]

Crankshafts that are ground between lapped centers should have a total indicator runout of less than .000025". Collet assemblies that are precision ground after hardening can have total indicator runouts of .0002" four inches from the flywheel face providing they are mounted using a precision taper or hub locator. The photos show a flywheel with the .5002"+ OD hub that fits inside the female collet's inside tappered end which has a .5000"- ID hole. Two 6-32 screws secure this piece onto the flywheel's face as the flywheel's hub locates it. Some flywheels have a hardened steel piece shrunk into the aluminum flywheel that is ground for the hub locator. Notice the long length of the split tappered collet that can be used to secure either a shaft or cable. A hardened steel .005" thick thrust washer is used between the clamping nut's inside surface & the hardened, tempered collet. This prevents damage to the clamping nut when very high pressure is applied with the two 5/8" wrenches. This system is used on both nitro & gas engines

The same type of mounting system is used for ball & pin type universals that also have the same .0002"- total indicator runout at the ball.

Jim Allen

Thats probably the only flywheel youll see with a starter rope groove !

 

[moparbarn]

Crankshafts that are ground between lapped centers should have a total indicator runout of less than .000025". Collet assemblies that are precision ground after hardening can have total indicator runouts of .0002" four inches from the flywheel face providing they are mounted using a precision taper or hub locator. The photos show a flywheel with the .5002"+ OD hub that fits inside the female collet's inside tappered end which has a .5000"- ID hole. Two 6-32 screws secure this piece onto the flywheel's face as the flywheel's hub locates it. Some flywheels have a hardened steel piece shrunk into the aluminum flywheel that is ground for the hub locator. Notice the long length of the split tappered collet that can be used to secure either a shaft or cable. A hardened steel .005" thick thrust washer is used between the clamping nut's inside surface & the hardened, tempered collet. This prevents damage to the clamping nut when very high pressure is applied with the two 5/8" wrenches. This system is used on both nitro & gas engines

The same type of mounting system is used for ball & pin type universals that also have the same .0002"- total indicator runout at the ball.

Jim Allen

Thats probably the only flywheel youll see with a starter rope groove !

you're showin' your age, tom :lol: :lol: . see ya in c-town!!

 

[Joe Warren]

Make sure you dont cause the problem by soldering the end of the flex shaft excessivly, I have seen this many times cause a Problem if you suspect shaft run out is excessive? I have also seen a problem if someone has cranked down on a shaft that is out of round & distorted the collet lock....

 

[Ted buckley]

Tim did by any chance did the MFG start with A and end in eromarine ?

Greg

I've been buying collets from Aeromarine for years, If I get a bad one, send it back and it's replaced no questions ask. Geez, better yet, pay a machine shop downunder to custom make them for you. See how that works out, probally cost more then the motor itself. :wacko:

If you get a bad one ? im yet to get a good one

I found out that the octura ones are quite good however

Anyone have a good link for Octura Collets? My Hobby shop never carry's them.

 

[Walt Barney]

Tim did by any chance did the MFG start with A and end in eromarine ?

Greg

I've been buying collets from Aeromarine for years, If I get a bad one, send it back and it's replaced no questions ask. Geez, better yet, pay a machine shop downunder to custom make them for you. See how that works out, probally cost more then the motor itself. :wacko:

If you get a bad one ? im yet to get a good one

I found out that the octura ones are quite good however

Anyone have a good link for Octura Collets? My Hobby shop never carry's them.

Ted,

I carry Octura props and collets.

thanks

walt Barney

Tanks 2 U

Walt's Hobbies

 

[LarryConrad]

Tim did by any chance did the MFG start with A and end in eromarine ?

Greg

I've been buying collets from Aeromarine for years, If I get a bad one, send it back and it's replaced no questions ask. Geez, better yet, pay a machine shop downunder to custom make them for you. See how that works out, probally cost more then the motor itself. :wacko:

If you get a bad one ? im yet to get a good one

I found out that the octura ones are quite good however

Anyone have a good link for Octura Collets? My Hobby shop never carry's them.

Ted,

Your local hobby shops don't carry squat for anything RC, but I think Hub has paint by number sets and kites on sale this week. :lol: