You definitely enjoy designing. Not sure your experience on fabrication skills but everyone has to start somewhere. Prototyping takes multi-skills, patience, lots of money and the ability to learn from failure more often than not.
Suggestion? Get a used 3pt pto tiller or two as a learning step to your goal. Gives you a working model(s) to learn from for your application and conditions. Your not going to build a one-off tiller cheaper. Then if it doesn’t work like you think it’s more on the electrical motor side than the mechanical tiller side.
Good luck.
Good points, all well taken. And I do follow from what you are saying that I just sort of jumped into the middle of all this without much backgrounder for the reader. Thanks on that. Sometimes I start doing that in design groups, and the folks I work with call it, “Phil Speak,” because I am babbling in terms that are very clear to me, but no one else can understand.
The building part is kind of easy for me. My first “real” job at 15 years old was as a Welder’s Helper in a Farm and Tractor Repair Shop. From there on through various Construction, Engineering, Design and Build, CNC Machine Design, etc. Now I am an EE, but still play mechanical – anyway . . . .
But as far as design on all this . . . There is a little more than just putting an Electric Motor on a PTO Shaft for this . . . Starts with the speeds . . . .
Typical 3 Phase Motor Speeds (60 Hz, US) are
3600 RPM (2 Pole) common
1800 RPM (4 Pole) common
1200 RPM (6 Pole) not so common.
Matching those up to existing equipment is not always so easy. PTO based designs are generally built around an Input of 540 RPM, and you may have noted above that the tiller shaft is in 200 to 250 RPM range. So that means to get the full range with a Variable Speed Drive, you have to add a speed reducer or gear box change up front.
So to avoid all that, the first model(s) I looked at were more like “garden rototillers.” That was where the starting tine layout came from. But those are really lightweight, take multiple passes, and did not look like they stacked or parallel very well.
Going deeper, I would have liked to have found a used existing 3-point hitch type Rototiller “organ donor” as it were – like you are saying -- but what I found was usually at or near full new prices, or kind of beat – here is a sample >>>
This Yanmar 6ft Tiller is in great shape. Tines are all good, just used a month ago in garden. Heavy made and at an affordable price. Delivery available for a fee. Located in Commerce, TX. Contact...
dallas.craigslist.org
And so started with looking at some new ones for comparative anatomy. (
) Below is a list of various standard options . . . . A major limitation on all this is without the tractor in front – you still have to build or create the mobility and transportation part.
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CountyLine Rotary Tiller, 4 ft., RT4CL
$2,099.99
Phil Note: This one is interesting in that it claims it can rotate forward or reverse. I think that also means removing and re-installing the tines? Since the overall tractor platform only goes in one direction? If you can just change the direction of travel, it reverses the “forward / reverse” rotation of the tines relative to the soil, but I do not think a typical PTO + 3 Point would allow that, unless you were to drive the Tractor in Reverse?
At 4 foot wide, this should take 10 to 20 HP?
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CountyLine Rotary Tiller, 5 ft.
$2,099.99
Phil Note: Here you get an extra foot wider, for the same price. But no “forward/reverse” rotation option. So I guess we can assume the “value” of Forward / Reverse is about equal to 1 foot of width?
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CountyLine Rotary Tiller, 6 ft.
$2,399.99
Phil Note: This is interesting in that it appears to just add one foot width to the 5 foot – for $400 – so for base pricing that can sort of infer that and adder of 1 foot = $400.
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Heavy Duty Skid steer 72" Rotary tiller Rototiller Attachment, New
Find many great new & used options and get the best deals for Heavy Duty Skid steer 72" Rotary tiller Rototiller Attachment, New at the best online prices at eBay! Free shipping for many products!
www.ebay.com
US $1,900.00
Phil Notes.
Overall a “like.” This drops down to the price of the 5 foot above – but is no longer PTO based.
Since this is designed to mount onto a skid steer, instead of a 3 point tractor hitch, it also has the most flexibility for mobility. It is a Hydraulic Motor Drive, so there is no gearing involved, but rather just throttled through the motor speed, pump, and/or valves.
On the issues for an Electric Conversion, this means instead of mechanical methods of power linking and speed control – like chains, gears, shafts, etc – we would need to buy a Hydraulic Pump. If one wanted, it could also be Mechanically Driven (Gears or Sprocket/Chain) and the dead end of the shaft is exposed on the open end.
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So that is the sort of the review of “State of the Art,” unless someone / anyone caught something I missed or mis-understood. Any adds or corrections are very welcome.
If that is good, I will do the Equipment Mobility and Travel, next . . . .
