hpr ct04 67 inch cat build

[avery]

Was lying in bed lastnight and came up with an idea gonna try it. I'm taking out the flex cables and gonna hard shaft it via a universal don't see a problem as the universal would be similar to the shafts like on mgt4.6 unuless anyone here know of someon who could make me a pair I'm gonna work on building them myself but realy don't have tool for this but feel would be more dependable. It would have stub shaft (3/16) with tube (1/2) longe then longer shaft roughly5 incheas long on end plain other two oposing pins that would slip into tube as th e outdrive shaft comes allway to transon and non water can enter perfect for hard shaft no shaft tube anyone know someone could buid hook me up please

[avery]

Here is picture of shhttp://www.rcplanet.com/Assoc_MGT_8_0_CVA_p/asc25687.htmafts . But not sure of diam will have to check

[graill]

Was lying in bed lastnight and came up with an idea gonna try it. I'm taking out the flex cables and gonna hard shaft it via a universal don't see a problem as the universal would be similar to the shafts like on mgt4.6 unuless anyone here know of someon who could make me a pair I'm gonna work on building them myself but realy don't have tool for this but feel would be more dependable. It would have stub shaft (3/16) with tube (1/2) longe then longer shaft roughly5 incheas long on end plain other two oposing pins that would slip into tube as th e outdrive shaft comes allway to transon and non water can enter perfect for hard shaft no shaft tube anyone know someone could buid hook me up please

The problem your going to run into is the balancing both lateral and rotation at rpm over only1k. You will need purpose built u joints for your application or you will face destruction. When i designed the ujoints for the princess and the arclight i went through a ton of stock and off the shelf varieties both in the us and overseas. The pics you have shown from your link will break quite quickly. I successfuly tried all steel (team losi) to 15 k rpm but the vibration is nasty and the dogs break with alarming ease. Maybe you should try some titanium dogs, i did not as i wasnt going to waste more money on the tooling.

I finally found a company that could tool to my specs and we came up with the design i signed off on early last year. The ujoints themselves utilize titanium alloy needle bearings that will let the ujoints rotate at just over 75k rpm with 5ftlb lateral shear, the operating range for me is 28-35k and at this rpm the lateral shear load rises to 35 ft pound before breakage. the knuckle is a hardened steel alloy piece, and really tiny (grin). the caps are press fit with a 648 sealer. the price of the pair of one ofs was $560.00, i had a set of 8mm and 10 mm made, 8 total, one set for the turbine. The company has them listed now for substantially more along with a performance graph. support bearings are hybrid class 7, mounts are class 5.

I also have a pending patent on orbital ujoints about the size of a dime in diameter that will take 65k rpm with 15 lb lateral shear, but at $1200 a piece i left those just on paper, ones ofs are spendy. Here are some pics of what the princess ran in her last days before i gutted her in an exploded view.

The wear you see on the short 2 inch flexshaft if from the watertight rubber in the rear mount, i needed the small flexshaft to maintain my stinger adjustability. Zero vibration by the way to nearly 40k installed. (no load)

[avery]

Wow so much for that idea I didn't hink it would vibrate that bad my mgr does 40 50 ish I jump her sky high and land hard never broke a cv joint yet 5 yes but never turn that many rpms . Oh well guess I'll either stick with flex or might hard mount shaft and love joy coupling it have you tried that I noticed you put joint near motor I only plan on joint near transom with stub to outdrive

[blackcat26]

Stick with the flex shaft. Tried and proven many times over.

[graill]

Wow so much for that idea I didn't hink it would vibrate that bad my mgr does 40 50 ish I jump her sky high and land hard never broke a cv joint yet 5 yes but never turn that many rpms . Oh well guess I'll either stick with flex or might hard mount shaft and love joy coupling it have you tried that I noticed you put joint near motor I only plan on joint near transom with stub to outdrive

Experimentation is the spice of life, dont let anyone stop you.

[avery]

Oh u right I think somthing like love joy makup could work I'm tossing it around in head but as far as rh cv well if you had to go to titanium I'm going to stay away from there so now options are lovejoy makeup or build gear box with slower motor rpm and increase output shaft but that kinda kills the sound lol . But realy tks for input as it helps

[Gerwin Brommer]

James.

love your work and dedication.
only 1 thing I don't understand.
As shown in the pics : 2 uni-joints.
Why didn't you just put the motor in an angle, so 1 joint could be enough ?
(or was this one just for testing/show how it works, as the other large boat has a motorisation that can't be placed in an angle ? )

[graill]

James.

love your work and dedication.
only 1 thing I don't understand.
As shown in the pics : 2 uni-joints.
Why didn't you just put the motor in an angle, so 1 joint could be enough ?
(or was this one just for testing/show how it works, as the other large boat has a motorisation that can't be placed in an angle ? )

Go ahead and test that one ujoint idea Gerwin......i did, first run almost a year ago didnt go well. (Biggrin)

I need two for a few reasons, pm me if you want to know why. Sorry to hijack your thread Avery.

[graill]

Oh u right I think somthing like love joy makup could work I'm tossing it around in head but as far as rh cv well if you had to go to titanium I'm going to stay away from there so now options are lovejoy makeup or build gear box with slower motor rpm and increase output shaft but that kinda kills the sound lol . But realy tks for input as it helps

I am crazy when it comes to ideas and pushing limits. Blackcat 26's suggestion of sticking to the tried and true flexshaft if this is your first high speed build is very good advice.

[Gerwin Brommer]

I don't think we're hijackers, James.
Avery asked about solid shafts.
Your pics and explanations should be of great help for him ( and us ).

[mm123521]

All:

FYI

U joints MUST run in pairs. The rotational velocity changes, over a complete revolution. The second U joint cancels out this rotational velocity variation.

Also, in order to have the second U joint cancel out the velocity variation, the two U joints MUST be exactly 90 degrees apart. That is: the pin on the second U joint MUST be exactly at 90 degrees to the first.

Otherwise great torsional viabrations occur.

Mark

[Gerwin Brommer]

Just as I expected, that's way too technical for me, LOL !
but great info !

[avery]

Na yal not jump thread it all good I ask. Questions to get input and learn at same time so feel free to input

[avery]

Was wondering what props I should start with the twin lepoard 5692 750 kv any input as I'm about to order motors from ose and props