Flex drive question

[ED66677]

Let me first resume the situation...
My Xcyclone (Kyosho Blue Streak copy) runs pretty well with 8XL, cheap 4000Nimh Camelion 12 cells pack, cheap Mystery 80amp ESC, and best result with K42 carbon prop, drive shaft is rigid, 4mm dia. M4 at prop, yeah I know here in France we use metric but still, 3,2mm (or 3,17mm = 1/4") flex are common!

During last runs I notice the hull was not enough "aerial" due to prop angle pointing down so the front tend to "dive" a very little, I first move COG as far as possible in the back but then at startup the nose is lifting like hell!

So I'm thinking about flex drive, in order to have the possibility to adust thrust angle, what do you think?

What material do I need? I allready have an H&M 3,2mm flex with 4mm/M4 shaft, I have the equipement to make a strut from aluminium tube with 4mm ball bearing each end
I see on OSE that there are .130 flex, teflon liner and coupler, but this is 3,3mm not 3,2 or 3,17??? this is confusing me!!!
What's the liner inside diameter?
I don't want to go for 3/16 shaft because it's not metric!:D

[saleens7]

you have a 3.2mm flex, thats very similar (just .02"smaller from a .130) in size to a .130 cable...you should use the teflon liner for .130 cable

http://www.offshoreelectrics.com/products.php?cat=70

(look for it at the bottom of the page)

and the copper tube

http://www.offshoreelectrics.com/products.php?cat=38

(its the 4th item down, chose the 7/32" one.)

that should be what your looking for

[ED66677]

the thing is how will I get this tube in France? it's gonna be bended or twisted before it reaches by workshop if ordered via OSE!!!
the "Octura Coupler Flex Hex 5mm to .130 Cable Short" should be ok for the flex I have and will fit to the 8XL

[saleens7]

you can just order the teflon tube (it can be bent, but it wont be messesed up) and you can try to look around for 7/32" brass (or copper, with that work also??) tube at a local hardware store..

(thats .2188" or 5.5563mm brass tube)

theres a fraction, to decimal, to mm chart right here to help you out

http://www.offshoreelectrics.com/info-pages/conversion-chart.php

[ED66677]

non metric is not a problem for me, it is for most of french people, but I work for an American company for so long... it helps a lot :D so I'm very familiar with inches and your type of screws and threads and other dimension things, but If I go the any shop around here and ask for a 7/32" brass tube they're gonna look at me or don't know if K&S is well distributed in Europe
I think I'll take the risk to have it shipped from OSE
BTW is 7/32 the ID or the OD? I'd rather use 1/4" tube because then I wouldn't need brass tube anymore, teflon liner would come out of the transom via a 1/4" pneumatic bulkhead, have plenty at work!!!

[Rex R]

for K & S tubing sizes refer to outside diameter

[ED66677]

ok then! I'll go for .130 liner and 7/32 brass tube!

[paulwilliams]

ok then! I'll go for .130 liner and 7/32 brass tube!

Ed,

I have some PTFE tube I can send you if you like. I'm in Devon, UK (the bit above Brittany :D ), PM me your address and how long you want it.

Regards,
Paul

[ED66677]

Thanks Paulwilliams,
what size of tube is this?
I don't mind to have to pay for some tubing from OSE, but as many thing in RC model I'm trying to find cheap an reliable alternative to expensive assembly that I can find in France
On some french FE boat forum, I've tried to grab info regarding existing liner and their dimension but that doesn't look consistent, not very clear and not corresponding to what I saw on H&M web site
There's a big RC shop near where I leave, and probably the only one in France that has H&M parts in stock (sometimes and not all)
I don't mind to use any kind of anything that is reliable, the easiest for me was H&M 3,2 flex with 4mm prop shaft, because I can build my own strut with 4mm ball bearing

[paulwilliams]

I used to make flex drives some years ago for UK fast electric racers and I still have a large quantity of flex cable, shafts and liner.

The liner tube I have is for 0.130" cable. The liner is nothing special, simply a PTFE impregnated plastic tube, but you have to buy a minimum quantity of about 30+ meters, so I've still got quite a bit! Fits inside 1/4" (6.35mm) tube, either brass or aluminium.

Paul

[ED66677]

so it's a 1/4" outside diameter and probably around 3,9 to 4mm inside diameter, is this correct?

[Mich. Maniac]

If your not sure order your flex shafts first and have it in hand, I cant measure tubing at all by eye. and just to add flex shafts work just fine in that model, vibrations dont have any affect so far. good luck

[ED66677]

tell you what Mich. I did another test yesterday with the 3,2mm/4mm/M4 H&M flex I had, re-built a tube with 4mmID teflon and 2 bearings, it seems to be much better, the first time I tried it, I probably had a bad coupler so the flex was not spinning correctly, it was strongly vibrating at this time but yesterday I've used a H&M coupler, just holding the motor in my hand and the tube with flex in it in a vise!!!

[Mich. Maniac]

I have noticed.. Off subject here but. I turned my motors by hand and I think my prop shafts are bent. No shallow water run-ins or anything. I use sharpened and balanced props. I just dont know why

[ED66677]

have you got Flex or rigid shaft Mich.?