Source for 1/4-28 X 0.078" wire

[BobBonahoom]

Does anyone know where to get a 1/4-28 nitro engine collet for 0.078" wire? Thanks.

 

[John Beardslee]

Bob, I think Glenn gets his from Octura

 

[David Bryant]

I'm curious what size engine you're running?

 

[BobBonahoom]

Thanks John. He did, but Octura doesn't make them any more. I just found one in my junk box that I got from Glenn 10 years ago. Problem solved!

David, we were going to try it on a 21 Nova DD. Not sure if 0.078 is strong enough though. Do you know?

 

[John Beardslee]

I don’t know but Glenn probably does or possibly Mark Sholund. Did you talk to Trudy at Octura to see how many you would have to order to have her make a run of that size? Do they still make the 1/16” size? If so, you could grind one open to .078 I.D.

 

[Charles Perdue]

Bob, when I was playing with the wire drive, I started with the .078 wire but when I was having a problem with them breaking I went to a .093 wire. Later when I found out the real cause of the wire breaking (harmonic vibrations) I never went back and tried the .078 wire. The .093 wire set with a 7 degree arc in the wire is still less drag than with a cable drive and it is bullet proof.

 

[John Beardslee]

Hi Charles
We’re y breaking the wire right next to the collet?
Good to see you checking in here now and then.
Thanks John

 

[Charles Perdue]

It would break on either end, but mostly at the stub shaft.

 

[Brian Spitzer]

Check with SpeedMaster, I think they're offering wire drive collets now for a variety of engines.

 

[ricwally]

Bob, I am running a .078 wire on a RX 21 Novarossi with no issues so far. Jeff Wohlt got a coupler from Octura and also drilled out a smaller one for me. I also saw where Dale was making couplers for Speedmaster. They have a few listed on their site. But, not what you are looking for. It does say that if it isn't listed to give them a call and they will try to accommodate you. Somewhere I saw their initial offering of wire drive couplers.

 

[BobBonahoom]

Bob, I am running a .078 wire on a RX 21 Novarossi with no issues so far. Jeff Wohlt got a coupler from Octura and also drilled out a smaller one for me. I also saw where Dale was making couplers for Speedmaster. They have a few listed on their site. But, not what you are looking for. It does say that if it isn't listed to give them a call and they will try to accommodate you. Somewhere I saw their initial offering of wire drive couplers.

Good info. I am planning to make a couple oilite bearings and put them in the stuff tube, evenly spaced, to stop the harmonics that Charles is talking about. Did you do that also? How long is your 0.078 wire?

 

[Charles Perdue]

Bob, if the wire has a larger arc it is less likely to vibrate BUT then it also makes mounting the engine at more of an angle and this larger arc causes more heat build up in the wire. The wire only needs one oil lite bushing placed about one half the length of the wire. This come out at just below where the stuffing tube exits the hull bottom.

One thing that I did was instead of a round hole thru the oil lite bushing, I put a slot with about .006 side clearance in it aligned to the vertical. This allows you to adjust the strut angle also up and down depth without binding the wire. The side to side support is enough to prevent the harmonics.

An easy way to mount the oil lite bushing is to machine it to fit snugly in the stuffing tube with a shoulder a little larger on one end. The bushing only has to be about 3/8" long. Then file or saw cut a notch on each side of the bushing next to the shoulder. Align these with the vertical slot (up and down). Slide this into the the bottom of the stuffing tube and crimp the stuffing tube on the sides with a set of wire cutters into the notches of the bushing. This works good and can be removed if needed.

 

[ricwally]

Bob, I am running the .078 wire with a 1/8" stub shaft just like on my .12 boat. That way I can stay with the 1/4" ID strut and use Boca SR-144-ZZ bearings. I didn't want the additional size and weigh associated with the larger strut. Especially, hanging off of the back end of the boat. The overall length of the wire and stub shaft is 17 7/8" in my JAE 21 GT. I just use a 1/8" to 3/16" adapter for the 3/16" ID props. Like I said no issues so far. I am not running an intermediate oil lite bushing that Charles suggested. So far I am just using grease instead of oil and no signs of wear or heat anywhere along the wire. Even with grease there is much less resistance than with a cable.

 

[David Bryant]

David, we were going to try it on a 21 Nova DD. Not sure if 0.078 is strong enough though. Do you know?

I see, thanks. No, I could'nt tell you if .078 is strong enough. I have'nt had much experience running wire drives (yet). But I was curious what set-up's people are experimenting with, very intriguing to me.

 

[BobBonahoom]

Bob, if the wire has a larger arc it is less likely to vibrate BUT then it also makes mounting the engine at more of an angle and this larger arc causes more heat build up in the wire. The wire only needs one oil lite bushing placed about one half the length of the wire. This come out at just below where the stuffing tube exits the hull bottom.

One thing that I did was instead of a round hole thru the oil lite bushing, I put a slot with about .006 side clearance in it aligned to the vertical. This allows you to adjust the strut angle also up and down depth without binding the wire. The side to side support is enough to prevent the harmonics.

An easy way to mount the oil lite bushing is to machine it to fit snugly in the stuffing tube with a shoulder a little larger on one end. The bushing only has to be about 3/8" long. Then file or saw cut a notch on each side of the bushing next to the shoulder. Align these with the vertical slot (up and down). Slide this into the the bottom of the stuffing tube and crimp the stuffing tube on the sides with a set of wire cutters into the notches of the bushing. This works good and can be removed if needed.

Charles,
What ID stuff tube did you use with that set up? I was wondering it a larger ID (than what we use with a 3/16" flex shaft) might be a good idea so that the wire never touches the tube.