Cable collet runout.

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Brad Christy

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Brad,

ER collets typically come in fractional sizes, in 1/64" increments and metric sizes in .5mm increments, and will collapse all the way down to the next nominal size

Thanks. Brad.
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BlackJack Hydros
Model Machine and Precision LLC
 

RaceMechaniX

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Fingers crossed Terry the ER collet style coupler will help. For the FE SAW boats we had to go back to a single piece coupler with saw slits.
The runout of a couple tenths was still too much of the ER collet at 60kRPM+ with a wire drive. There is practically no vibration in the driveline, just a nice whine of the motor.
2a09d0ef-a433-4e13-bbd9-2b38151882d4.JPG
 

Terry Keeley

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Fingers crossed Terry the ER collet style coupler will help. For the FE SAW boats we had to go back to a single piece coupler with saw slits.
The runout of a couple tenths was still too much of the ER collet at 60kRPM+ with a wire drive. There is practically no vibration in the driveline, just a nice whine of the motor.
60K! Wow!

I'm only looking for 1/2 that so hopefully I'll be OK.

Surprised they clamp them on, aren't they out of balance like that? I purposely went with 3 set screws at 120* to keep things balanced.
 

RaceMechaniX

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Yeah, clamping works when the wire diameter and coupler are tightly controlled. We only use one specific manufacturer of wire that is very consistent. The coupler is 100% symmetric about the rotating axis minus machining tolerances, but it's better than any multipiece coupler.
 

Terry Keeley

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Got some Speedmaster collets coming, I'll check them and report my findings.

I'm sure they'll be quite good knowing the quality of the rest of their products.
 

Jim Allen

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I don't think that style does well with cable because it's for a specific shank size, cable is not a specific size and changes under load.

Brad
I must agree with Brad & this explains why any collet used on a cable MUST be split from "end to end". The photos show the simple heat sink fixture that allows the cable's end to first be silver soldered for .125" at its end. Next, the cable is soft soldered, solid, for 1.250" on that same end. The remainder of the photos show the spring steel split collets & their full hard ground seats that give a very high clamping force & concentricity with in .0002" total indicator runout.

Jim Allen
 

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Bill Gibson

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Gotta say that the few that I had that had run out issues were all Aeromarine collets. Not so with Speedmaster or Zippkit collets.
 

brad nichols

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Those EU couplers look heavy and up the rotating mass, Al's run very true and would be lighter for sure.

Brad
 

Terry Keeley

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Here are 3 successive videos of a 21 DD runout at the flywheel, at the collet and at a 0.078 wire, using an Octura Flex-Hex.
Thanks for posting this Bob.

4 - 5 thou is way better than that Aeromarine I had but still ain't great. Wonder what the face of the flywheel is where the collet sits? If that's out just a bit it can translate to a bunch at the end of the collet.

Does it have a register (stub) that fits well into the flywheel?
 

BobBonahoom

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Thanks for posting this Bob.

4 - 5 thou is way better than that Aeromarine I had but still ain't great. Wonder what the face of the flywheel is where the collet sits? If that's out just a bit it can translate to a bunch at the end of the collet.

Does it have a register (stub) that fits well into the flywheel?
It does not have a register/pilot. Also, with a bigger diameter shaft than the 0.078 wire, the problem will get magnified. Maybe its worth facing off the flywheel to see if it can be improved? Has anyone ever tried that? I know if your patient and keep loosening, tightening, measure, repeat, you can sometimes hit a sweet spot where the runout at the shaft goes to 0.001-0.002".
 

BobBonahoom

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The face of that flywheel is pretty good. Only about 0.001", so the extra 0.004 - 0.005 is from the collet I think.
 

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Terry Keeley

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The face of that flywheel is pretty good. Only about 0.001", so the extra 0.004 - 0.005 is from the collet I think.
Yup, that's pretty good, probably mainly the collet that's out.

I'm gonna turn up a mandrel with the taper of the collet built into it, mount the flywheel and true it up that way.
 

Brad Christy

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Terry,

Matching that taper is more difficult than you'd think, and if it's not perfect, you wont like the results. It's far easier and more secure to turn up a mandrel with a straight diameter and use your flywheel collet. Once you lock it down, you can remove the screw and the flywheel will stay in place. You can then turn the entire face square to the centerline.

Thanks. Brad.
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BlackJack HYdros
Model Machine and Precision LLC
 

Bill Brandt

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You fellas are talking way above this retired bankers head and its fun to hear perfectionists discuss things like this but just a couple thoughts;
Aeromarine was the first dealer/distributor i ever started doing business with in 1990. The products have been of great use in the marine hobby at fair prices.
There is always a better widget if you look hard enough, but is it affordable?
In 23 years of racing 1/8 Scale Hydro my son (and I) have surpassed more than 125 race wins in RC Unlimiteds using Aeromarine Square Drive Collets. So they probably do the job.
Because Speedmaster came out with some great collets i also offer them and imho there is nothing better than Speedmaster hardware.

All this being said, most of us can’t do nor understand what you are talking about but why don’t one or more of you offer the service of tweaking a customers collet(s), for a fee? I would certainly promote it.

Great info guys. Just a little above some of us.
 

Terry Keeley

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Did what Brad described and faced off the flywheel. That got the runout at the wire down to about 0.0015" Not bad!

There ya go Bob! A thou runout is excellent, it also verifies that the Octura collets are very good.

I would mark the flywheel, collet and crank somehow so you can re-assemble them in the same position when you need to take off the flywheel. I use a small ball cutter in the dremel and mark where the slot in the collet goes on the inside of the flywheel. I then orient that with the crank pin ATDC.
 
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