Subject: Making your own steel coupling.
From: paul lamar
Date: 6/26/2017, 2:15 PM
To: A10-Me-Earthlink



I have an idea for you Scott.

There is a water jet company in 1500 Airway Circle, New Smyrna Beach
FL. 32168 | 386-424-7333 <tel:386-424-7333


I have some drawings of a steel coupling that can be made out of
water jet cut steel parts.

Then you will need to find a local tig welder to weld it up.

I have some of the parts. The inner plate that bolts to the counter
weight and the outer ring cut from six inch tubing.

$50 plus mailing.

Use part of Tracy's torque isolator to adapt this to Tracy's PSRU
input shaft. Drill out the rivets and bolt it to the steel output
front plate.

Paul Lamar

Very interesting!  I can query the water jet shop, and will order
these parts if the  shop can make the rest.  No problem with the
welder.

How thick is the metal?

Do you intend for an outer ring to be cut into the small curved
shapes, or make these from scratch?  I guess  they can be flat
instead of curved?

I also assume the 1.78” is the height of each component, so the
total thickness would be about 2”?  I will study my redrive to look
for areas of potential interference.

Please ignore the curved questions of my last post, sorry. Some of
the latter images didn’t display the first time.  I see the
connecting elements are square.

Thanks!

Scott Gettings

.050 to .150. Some of the stuff is  .083. You make it out of what
you can find :-) The six inch tubing is about .150 wall.

The total thickness is about 1.8 inches. Nothing about this is
critical. One inches would work if your not shooting for 500 HP.

Ignore those square pictures. The latest are triangular or wedge
shaped. The square ones bottom out corner to corner. We discovered
that when we built the TTC coupling.

If I get a little more interest in this I wall make a tool that
bends the wedges in a hydraulic press. Saves a bit of welding. I have
built tools like that in the past. That would pay off as the same
design can be used in new gear boxes. We already used one of these
that was similar in a 3 rotor.

I have not heard back from Kevin so if Kevin finds an NC shop that
can make them out of billet at reasonable cost that would be more
accurate.

In any event once this is welded up it would be wise to balance it
between parallel bars. If your gear box is off the engine please
tell me the diameter of the input spline adapter Tracy is using. The
one with all the rivets. That will control the diameter of the
forward plate.

Paul Lamar



Paul,

My welder can assemble these small steel parts, but is not highly
confident of the  precise alignment and balance of the end product.
It looks like some other options are evolving, so I’ll keep  this
one on hold.

My gearbox is on the engine, but if you need the exact shaft
diameter soon, I will be happy to pull the it and measure the shaft.

Other measurements that might be helpful: distance from front edge
of flex plate gear to rear of engine block:  1 5/16” distance from
front of Tracy’s adapter plate to engine block (the total “open”
area between the engine and adapter):  3 1/8” distance from front of
Tracy’s adapter plate to rear face of his riveted spline adapter:
1 1/4” the front of the spline adapter appears very close to the
rear edge of the flex plate ring gear.

It appears that the total thickness of a new coupler (for Tracy’s
RD) would need to be the exact distance from the rear face of the
bolted area of the flex plate to the rear of its ring gear, which is
the plane of the front of the riveted part of the spline adapter.
This would maintain the dimensions for the thrust bearings.  A
coupler that is more thick than this would move the rest of the RD to
the rear, requiring alteration of the existing spacers (the 3 1/8”
distance).  A thinner coupler could be managed with thrust bearing
washers.

Scott Gettings

I just happened to have one. The OD of the part in question is
6.188. The long part that sticks away from the engine 1.158 long.

The idea is to turn it around and put the long part inside the
coupling. We worked this out years ago :-) 3D's 5 and six show this
config.

That Ford part raw weighs 3 pounds. There is unnecessary meat on
both sides that I can be cut off if you send me yours. That will give
you plenty of room and save a bit of weight. Some of the spline part
can be cut off as well. 1.25 inches of spline would be plenty.

Jean is down the road from you in Pompano Beach and he might do it
for you. He has a lathe and a mill. He will need one sooner or later
:-)

Here are a few pictures.

Paul Lamar


Scott, I'll check the dimensions on my RV4. It still has Tracy's
coupling so I will need to change that anyway. I was going to use it
to flight test my new gear box design.

Here are a couple of pictures about what my coupling  looks like
now.

Here is what it might cost if you had the coupling NC Milled In US
dollars from the Internet.

Setup/Programming - 40

Fixturing - 60

Engineering Services - 40

Machining Time Per Part - 60

Inspection/Deburr - 40

Test Part Machining - 60

BS Time - 40

Let me know what you are leaning towards so I won't have to take the
gear box off my RV4  just yet :-)

Paul Lamar



Paul

i just drove to Fort Lauderdale and see the waterjet cutter 92000
psi and they can cut up to 8" thick so is not a problem.They will
give me a quotation by the end of the day for 1 prototype and
different quantity, they can cut also the rubber block cushion. JEAN
PRUDHOMME


Thanks Jean. That thickness and pressure is amazing.

Paul Lamar


I revised the drawing and design the stencil template for water jet
cutter., See attached file for each of them plus the file as solid
parts in aluminum. The back plate to suit the ford plate as 1.860 Dia
where spline shaft attaches.

I will get one sample as soon i get the quotation from them.

JEAN PRUDHOMME

Looks good Jean.

BTW you can simply weld the short piece of 6 inch diameter steel
tubing to the flex plate directly for the steel version. Fill in the
half moon holes with scraps of steel.

In my new gear box design the input shaft is 1.5 inch OD hollow
tubing so that does away with that 2.5 pound Ford powdered metal part
Tracy used. Won't work with Tracy';s box of course. The reason for
this is the connection to the coupling is stronger and so is the
connection to the sun gear. One can use extended point set screws in
both cases.

I found another one of those cut down Ford parts if some one wants
one. $50 plus mailing cost.

One other thing. Here are the motor cycle origins of this coupler
idea. Attached pictures.

Paul Lamar


Paul

I got a quote for the water jet cutter , for the 4 aluminum part it
is $86.84  beside the rubber parts which wont be much.

Could you give me the part number for the 1" thick rubber pad, i
look at it and they have different kind.

I am leaving for Canada this Saturday and i will get the aluminum
bar to get it cut before i go.

I did send them the template on the required format.

I let you know how it came up after done.


JEAN PRUDHOMME

Good work Jean.

Lowest cost way of building a coupling.

Will you be in touch by email while your up in Canada?

Here is the Macmaster Carr part numbers for the silicon rubber
blocks.


https://www.mcmaster.com/#silicone-sheets/=188lmv4


Paul Lamar



This looks like a very exciting and inexpensive option.  I'm very interested in participating!

So the aluminum should handle the repetitive stress is over time?

Would the only other modification needed for those of us with Tracy's RD be to remove the current isolator/plate and have the spline adapter machined to the correct length?  I'm not sure what would maintain the spline adapter and the attached 1/2 of the coupling in the necessary position since the flex plate and spline adapter would no longer be bolted together.

Scott Gettings

You better catch up with Jean before he goes to Canada for the Summer :-)

He is one smart guy, talented  and a hard worker. I think he has completed something
like 3 or 4 LongEzs and flown them.  As far as I can tell he is the only one using Rhino.

Let me know if you want one of these spline adapters. I have two.

Paul Lamar


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