Another Subsoiler

[SensibleNick]

We only just got the tractor, and we're in a-rush to get our veg-patches sorted.

Having borrowed a 2-share plough from a friend and discovered that a) it was HUGE and b) it needed serious repairing, I've decided to make do with a subsoiler instead. From what I've read, fewer people are ploughing these days anyway. I've got a rototiller, and just need to break up the soil a bit before I get serious on it.

So.. I've got my hands on some 90x90mm square section, and a length of 150mm x 15mm strip.

Hopefully I'll get time to cut the parts this weekend, and get started on my first bit of home-built tractor kit.

Total Length of the blade is 980mm, and the securing pins will be steel (top) and Aluminium (bottom) to allow some sort of shear protection. I might end up using the frame for something else later.

 

[easygo]

Nick,

I like the design. What is the wall thickness of the 90x90mm tube? I would guess that if double up the 150x15mm flat steel you would be happier in the long run. I looked up your tractor an The 15mm thick plate would be bent quite easily by that machine if you happen to hit a rock.
For shear pin you should use some sort of low grade steel bolt. I would guess that the aluminum is not strong enough.
There are engineer type people here and I'm sure they will correct me if I am wrong.

 

[beenthere]

Good idea.

You can also put a chain in between the vertical shaft and your tractor draw bar to pull on the blade below the 3 ph arms.
I find that works better than trying to hold the top back with just the top arm.

 

[SensibleNick]

I like the design. What is the wall thickness of the 90x90mm tube?

6mm Wall thickness.. It's plenty strong enough.

I'd have preferred 20mm plate, but as the stones here are relatively small, and as the 7075-T6 Aluminium pin will shear if the blade is presented with more than 30KN, (The blade itself will buckle if the tip hits head-on with 50KN of force) I'll take my chances on it for now. Given time I might plate the rear surfaces of the blade with 5mm plate.

There are engineer type people here

They're closer than you think

I like the chain idea, but the reason for the holes to allow adjustment is so that the lower arms of the 3-point can be set as close to the ground as possible - reducing the leverage that the knife will have over the tractor.
Using that theory correctly means that there will be no advantage gained from adding a chain.

 

[magicheater]

Are you thinking of mounting anything else to the T shaped piece. Because you made the subsoiler adjustable it leaves room for that option.

 

[Baby Grand]

You can also put a chain in between the vertical shaft and your tractor draw bar to pull on the blade below the 3 ph arms.
I find that works better than trying to hold the top back with just the top arm.

beenthere - that's a great idea. I have been trying to figure out how to mod my KK yellow SS to add a shear pin without having to cut it up too much and never thought about just using a tension loaded "fuse". The top link always looks like it wants to buckle under the compressive load.

-Jim

 

[SensibleNick]

Are you thinking of mounting anything else to the T shaped piece. Because you made the subsoiler adjustable it leaves room for that option.

I'm thinking that maybe a device for humping up rows of earth for potatoes? ...can't remember it's name. I'm fully expecting to weld more tabs to the T-piece as time goes on and use it for a good deal of things.

 

[magicheater]

I'm thinking that maybe a device for humping up rows of earth for potatoes? ...can't remember it's name. I'm fully expecting to weld more tabs to the T-piece as time goes on and use it for a good deal of things.

I believe it is called a hiller. Looking forward to seeing what else you come up with!

 

[easygo]

6mm Wall thickness.. It's plenty strong enough.

I'd have preferred 20mm plate, but as the stones here are relatively small, and as the 7075-T6 Aluminium pin will shear if the blade is presented with more than 30KN, (The blade itself will buckle if the tip hits head-on with 50KN of force) I'll take my chances on it for now. Given time I might plate the rear surfaces of the blade with 5mm plate.

They're closer than you think

I like the chain idea, but the reason for the holes to allow adjustment is so that the lower arms of the 3-point can be set as close to the ground as possible - reducing the leverage that the knife will have over the tractor.
Using that theory correctly means that there will be no advantage gained from adding a chain.

I stand corrected and happy to know that it came from someone who knows the answer for sure. Please post pictures of the building process as well.

I mentioned rocks because in my garden the first crop is always the rocks that surface during the winter. When I put in the garden before the first tilling I removed a about 3000-4000lbs of rocks from a 30x90 foot area. The smaller rocks are picked as they appear.

 

[SensibleNick]

I stand corrected and happy to know that it came from someone who knows the answer for sure. Please post pictures of the building process as well.

I mentioned rocks because in my garden the first crop is always the rocks that surface during the winter. When I put in the garden before the first tilling I removed a about 3000-4000lbs of rocks from a 30x90 foot area. The smaller rocks are picked as they appear.

No worries: I'm a Mechanical Engineer working in an R&D department designing large high-speed packaging systems for one of Europe's larger food packaging companies... It's a breath of fresh air to be playing with something that doesn't have to be lightweight

Today had been intersting: I'm giggling at the moment.... I clearly have a lot to learn about the power my little tractor can put down on the ground.
My original reason for the subsoiler was because I thought my tractor couldn't handle the size of plough I'd borrowed. I stand corrected... and have managed to plough 350sqm today and cultivate/rototill it. The largest stone I encountered was the size of a cricket ball, and I broke my first ever shear-pin on the rototiller.

It's given me a few good ideas for a mix between subsoiler and plough.. Might have to make one during the year before this season comes around again.
Still... The need for this Subsoiler is still there, but less urgent. I'll build it, but may well get a longer piece of square tubing for the bottom of the T so It'll be more useful in other applications.

Thanks for the comments though, I genuinely appreciate someone suggesting that I may need to beef it up: It makes me think again and question my own train of thought - always a good and valuable thing