The Blackwell axle is a worm drive, 3.75 ratio, no differential.
Definitely needs more torque, probably have to have a good size kv outrunner & big planetary gearhead... I haven't measured the motor rpm currently, double the speed would certainly help. At 4s (15-16v), at the start of vid motor running slower was about 12-13v... speeding it up later in vid to 14-15v makes the motor hot & the Sabertooth timeout inside a minute!
Biggest problem is this soil type is really dense brown clay & it's much too moist making it very sticky... with more teeth, I figured it would just ball up with mud... you see in the pics how it's building up on the tracks? the hoe don't move around much.
With the ripper tooth, one 5amp batt in 40 minutes will rip loose a volume approx. 5ga pail+, it's pretty sweet digging that way... but vertical ripping is kinda rough on the model when it looses contact & causes sudden drops on the boom.
Thanx for vid links Neil, if only it was possible to scale down the same power requirements to operate such tools without a monstrosity behind it! Eliminating the long stick on the JD850 would certainly take out a lot of the wobble.
An idea that came to me last night is to try cutting up a wire brush... how are those bristles held in the wood?
Thanx for the input guys... maybe deeper in the hole the soil will be dryer & will crumble easier.
Here's a vid ripping & digging last night... some of the rocks the size of a hardball or bigger, wouldn't be good for the grinder.
https://www.youtube.com/watch?v=-6FoACSLPdo