Marc,
               I am the only one making redrives at all recently.  Currently teaming up with a partner who has access to all maching gear to make another version.  Why another version?  Well it appears that the ford planetries and g/box parts in the US are now superseded and difficult to source so the cost goes up.  In my search to find an alternative I am now to get a planetry from the GM automatics as there are thousands of them in OZ and naturally reasonably priced.  The ratio is approx. 3:1 which is ideal.
        Planetry sourced, the rest of the redrive is also undergoing a rethink as to cut cost.  Currently just the prop shaft cost $1000 if I take 10 at a time! Singularly the cost is $1500! Looking at getting one cast instead of CNC.  The housing cost me nearly $1200 for a very "pretty" CNC job, so again casting is much cheaper.  A standard planetry is mandatory, as to change the ratio again the cost is horrendous.  Whatever is closest to 3:1 will have to do.
Input shaft will have to be made as I prefer a sold unit over a "pinned" unit.  Again cost, but necessary.
Cushion drive is mainly cast and CNC to finish -- not difficult to set up for CNC and 10 of will not break the bank.
The mounting plate will be cast from Magnesium alloy rather than the 1/2 inch 6061 alloy plate.  Again cost, lightness and strength.

The end result? Cannot tell at this stage but without this progression, there will be no redrives available.  The experimental market is no reason the go into the cost of producing redrives, but the real demand looming is the Agricultural drone crop spraying market.  Here the need is for high power / weight engines (mazda) and therefore a redrive (affordable).  Much legislation involved, but under the experimental banner that all alters.  This market is huge if a drone that can lift up to 500 KG can be made.  Even 200 KG is marketable which is a single rotor mazda.  The "electric" charge cannot compete I feel with the power to weight of the Mazda. 
        Looking at a twin rotor helicopter mazda powered.  Now that will get the natives talking!  Here in Oz a self propelled crop sprayer is way over $500,000.  Then it cannot spray on boggy ground.  Spot spraying is costly, and timing is critical, so drones will come as lifting capacity arrives.  CASA (aust) and the FAA have many regs regarding spraying chemical by air, but as demand increases the rules will be forced to change, I think.  Regardless the market is there which will benefit the experimental aviation sector.  Built on farm, used on farm, even if only to spray plant deficiencies and fungicide , the market is there.
        Hopefully it will all happen, but first a redrive.
Neil.

-----Original Message-----
From: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Friday, October 15, 2021 8:22 AM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Planetary re-drive?

Who is making a 13b fit 3:1 planetary now-a-days? That is since I can’t get a Mistral unit! Need for a 20b.
M

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