Will the epoxy casting technique work long term? I have heard wondrous stories about JB weld but haven't seen it used it that application. A great solution would be a broken piece of an old connector to match the spline, a friend with a welder, and a six pack of beer. (Beer to be applied after the welding).
-----Original Message-----
From: Myles Twete <matwete@comcast.
net>
To: electricboats@yahoogroups.com
Sent: Wed, Dec 16, 2009 4:35 pm
Subject: RE: [Electric Boats] MARS motor shaft to spline coupling?
Not likely…sure, they'll have the keyway coupler, but the spline is the bugaboo.
You won't likely find the whole thing off the shelf and you cannot beat the $15 plus epoxy that my first solution required. That solution applied in this case of a larger, but coarser spline requires a different approach and brings the cost up to a likely $50.
Shipping alone can eat up part of that budget if online purchase with McMaster---a good local bearing shop will have the keyway coupler for under $15.
-mt
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of vectorges@aol.com
Sent: Wednesday, December 16, 2009 12:19 PM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] MARS motor shaft to spline coupling?
A few minutes at McMasterCarr.com will probably come up with a cheaper off the shelf solution. The spline part will be hardest. Do you have access to a marine salvage yard that may have broken parts?
-----Original Message-----
From: Myles Twete <matwete@comcast.net>
To: electricboats@yahoogroups.com
Sent: Wed, Dec 16, 2009 3:00 pm
Subject: RE: [Electric Boats] MARS motor shaft to spline coupling?
o Buy a 7/8" keyed shaft coupler
o Buy or make a short tube that slips over the OD of the coupler
o Weld or JBWeld the tube to the coupler
o Make a a 1 1/8" spline fitting out of the inside part of the tube by "casting" a spline using JBWeld or titanium putty or other strong epoxy
§ Fill the spline part with wax
§ Lube your spline with WD40 or other lube to act as mold release
§ Mix appropriate amount of epoxy and pour into tube end
§ Smoosh the spline into the epoxy, keeping the spline shaft and the coupler coaxial (biggest problem)
§ After cured, use gear puller to remove the new coupler from the spline
§ Voila…coupler made for under $50
o Buy a 7/8" keyed shaft coupler
o Buy a 1 1/8" spline coupler (if available) or spline gear/pinion
o Bore one end of the spline coupler out to the outer diameter of key shaft coupler
o Connect, align and bond (JBWeld) or weld the 2 couplers together.
o Cost: $200 or less I'd guess (mine cost $100 total---(1) 7/8" keyway coupler ($15), (1) used pinion gear w/14-pt spline ($35), plus $50 to grind one end of pinion down to 7/8" to fit in the end of the keyway coupler.
· Expensive, but Best ($500+): Have a machinist make a coupler for you, boring for 7/8" w/keyway on one end and broaching 10-point spline at 1 1/8" on the other.
I used the first approach for my outboard motor (ETEK 7/8" keyway to 14-pt nom. ½" diameter spline coupler) conversion for about a year. In my case, the splines were too narrow and would only last for perhaps 20-hours before self-disintegrating and having to be replaced. After going thru about 3 coupler recasts, I made one out of titanium putty and used it until I discovered the 2nd method above. That new coupler cost me $100 total and has now lasted 5 years or so---I used a lower unit pinion gear for the spline fitting and the pinion gear teeth on the OD were never ground off since they don't interfere in my use as a coupler.
-Myles Twete, Portland, Or.
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of David Goldsmith
Sent: Tuesday, December 15, 2009 8:40 PM
To: electricboats@yahoogroups.com
Subject: [Electric Boats] MARS motor shaft to spline coupling? I've been working on getting my gear box ready to mate up to a MARS
brushless motor set-up. The gear box and flywheel housing will make
mounting the motor through a 1/4" al plate easy enough. The problem
I'm running into is how to mate up the motor to the gearbox input. The
MARS motor has a 7/8 keyed shaft. The gearbox has a 1 1/8" spline
shaft (10 splines.) I've done some searching and can't find a coupling
that will accommodate that spline shaft. Is this something I'll have
to have made custom or what? Any ideas out there?
Thanks,
David
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