Tater digger/rock picker

muddstopper · Jun 28, 2013

After reading this thread, http://www.tractorbynet.com/forums/build-yourself/282805-potato-digger.html. I decided to see what kind of tater digger I could come up with. I have a old toybuilt horse tiller without and engine I think will be good to experiment with. the tiller tines are 21in wide, so that is the width I plan on making the sifter. To make the sifter shake. I will attach a pulley to where the tines originally attached. This shaft is tapered, but I already know that the brass worm gear and bearings are just pressed on internally, so what I plan to do is just make another shaft, without the taper to put my pulley on. I'll make it a belt drive to the sifter box because of the dirt that will most likely get in it when digging. Since this particular troybuilt doesnt have the pto option, and the tines turn when the wheels turn all the time. I will make some sort of tensioner puller so I can disengage the sifter box when its not digging.

I am not sure how fast the sifter box needs to vibrate, but it seems the tiller worm gear is about 14:1 off the engine. I am just going to do another 2 to 1 reduction in gearing to start with, unless someone has some sort of ideal just how fast the sifter box needs to shake to clean the dirt from the tater and rocks. I think I will use a shaft at the top of the sifter with a cam type offset and connecting rod to make the box shake. Havent got all that figured out yet. I could use a good picture or two of this type of setup if anybody happens to have one.

Thinking is making my head hurt, and its to hot in the shop anyways. Think I will make a run to the metal supply and see what kind of cutoffs I can pickup for this project. Got to find an engine as well, so I guess a trip to the mower shop is in order also.

CliffordK · Jun 28, 2013

I would make the shaft long enough to go to the two sides of the tater digger, then add an eccentric to each side. The two eccentrics would need to be timed, so if you do additional reduction, you would need a chain or gears. Perhaps try it without more reduction.

You could just cut the tines off, and use the shafts from the tiller if you wish.

Or, perhaps a pulley system to another shaft that goes side to side. This then would allow you to build your clutch/belt tensioner.

Does the tiller already have a cutoff for the tilling mechanism? You could add a clutch to the motor, but t wheels should be able to propel the machine without shaking.

muddstopper · Jun 28, 2013

Made a trip to the metal store. $57 later I got a piece of 14 plate bent to my desired dimensions and 40ft of 1/2in hot rolled rod.
Also stopped at the mower shop and got a connecting rod out of a mower engine. I will use it to connect the eccentrics to the shaker box. Its aluminum so might not hold up, but we'll see. They also had a used troybuilt motor mount that I needed since the original one is missing. No used motors, but if I wait they will have sooner or later.

This tiller is one of the older troybuilts and doesnt have the ability to engage or disengage the tiller tines. My newer one does, but I aint messing it up. I think using belts and a tensioner will be the easiest way to activate the shaker box. I will be mounting a jackshaft for the upper pulley and the eccentric and using the connecting rod to connect to the shaker box. Only thing that should see any vibration should just be the sifter itself. Might also see some vibration on the jackshaft, but it shouldnt shake the tiller to pieces. Biggest hurddle right now is figureing out how to connect it all to the tiller. Not many mounting points on the cast tiller housing. Will have to come off the transmission and the rear housing somehow. The rear housing only has 2-5/16 bolts that can be used. Those bolts will hold the hilling attachment so maybe they will hold the digger.

jkis · Jun 28, 2013

on the you tubes and pictures i thought the leading/cutting edge was on and angle with the middle being foremost, would you be able to make the rocks go left or right, to keep them from being under your feet, and it was narrower than the wheels

muddstopper · Jun 28, 2013

jkis said:
on the you tubes and pictures i thought the leading/cutting edge was on and angle with the middle being foremost, would you be able to make the rocks go left or right, to keep them from being under your feet, and it was narrower than the wheels

You are right about the blade being between the wheels and on an angle. I plan on putting bigger wheels on the tiller for pulling power. I have already cut the angle on the edge and welded the cutting edge up with HF-503, 13% manganese rod, to harden the edge and help with wear. I sharpend the cutting edge but left it just a little rounded. I didnt want a knife edge on the blade. I have it laid out ready to weld the rods in place. Not quite ready to fire up the welder tho, still havent decided how I am going to mount the thing

jkis · Jun 30, 2013

when i get stuck, i line up or put, everything closer together, and do something else and look at it as i walk past or have a coffee, until the ideas take place,
cheers stuart

muddstopper · Jun 30, 2013

jkis said:
when i get stuck, i line up or put, everything closer together, and do something else and look at it as i walk past or have a coffee, until the ideas take place,
cheers stuart

Pretty much the same thing I do. Look, think, sleep, dream and then decide. LOL

I decided to take the top of the transmisson off to check out the running gears before going any further. I just rebuilt my other tiller drive and it cost me about $200 for gears, bearings and seals. I didnt want to invest the time and money building this digger only to find out the worm gear was stripped in this one. Gears where good, but oil looked funky so I decided to drain it all out. Thought I had the drain pan under the plug, but succeeded in draining most out on the shop floor. I figured since I had to cleanup the mess, might as well wash the grease off the tiller to.

I have studied my mounting problem and have decided to make a plate to bolt on top of the transmission cover, and run metal all the way to the rear of the tiller where the 2 little 5/16 bolts hold the attachments on. This should take the stress off the rear mount and give me something to weld to. Couldnt find any metal to continue the project, metal shop closed on saturday, so I will work on it some more after the 4th. I am considering buying one of the harborfreight engines to drive it with. They have a 7hp for just over $100. I am not a fan of the chinese knockoffs, but this digger wont really see that much use so unless I run across a good used engine, cheap, I'll go with the knockoff. I should have this thing running with a new engine for around $200.

jkis · Jun 30, 2013

the cheap motors, that i know of around here are doing okay, most important thing is to change the oil when you get it and regular, glad the gears are okay, keen to see the development of this machine
cheers stuart

Baby Grand · Jul 2, 2013

jkis said:
when i get stuck, i line up or put, everything closer together, and do something else and look at it as i walk past or have a coffee, until the ideas take place,
cheers stuart

Yes - stop thinking about it and you'll figure it out!

HarryN · Jul 2, 2013

Well, that's the first "Frankin-Tiller" I've seen - LOL
Look forward to seeing it work!

Millwood · Jul 3, 2013

I just can't bring myself to buy a new Spedo CPP-T spud digger for the 3pt on my Kubota. I noticed the one you are building Muddstopper for the walk behind. Got a couple quick questions. Your screening rods look like 1/2 inch round stock. Any reason so large diameter? Would it make any difference to weld your rods underneath the cutter to prevent spud damage? Overall, I like the concept and design and plan on similar.

OldMcDonald · Jul 3, 2013

Following on from Millwood, I had, and still have, an enormous rock and stone problem all over this place, evn after 10 yrs and several thousand tons of rocks removed. I have also grown many acres of potatoes in my time and have used several different tractor mounted lifters as well as seen many more. I built a stone rake of two sides 18" high, with 1" rebar attached at 12" spacing and 6" inches into the ground. 10 feet long and 2 feet wider than the tractor outside wheels. I had to add a lot of weight but it worked great. I built a pick-up box on similar lines to mudstoppers idea, but rear mounted so I had to reverse into the windrow of stones. I again used 1" rebar, 2" gap between, but ground one end of them flat and sandwiched them between two plates so that there was a smooth top and bottom in use. The rods were 80cms (say two and a half feet) long and fixed at the tractor end too. Solid back and sides to the box.

I think the 1/2" is the minimum I would use for potatoes. On the little information I have found on the net it seems to be a common size. For rocks I would definitely up the size unless you only have potato sized stones to deal with. I take it from your set-up that the blade will be vibrating too. This dramatically reduces the power needed to use the digger.

Millwood · Jul 3, 2013

Well, I guess the 1/2" round stock rods make sense if the attachment is doing double duty as a spud digger and stone picker. Since this is my first crop on my land, I did my 200K ton of rock removal last fall when I ripped it up and amended the soil for growing. Now, my thoughts are in harvesting the spuds.

The process requires removing the dirt from the spuds and back onto the ground. How one does this is open to different designs. The chain method is what I'm used to seeing in large scale agribusiness on Burbank Russets with thick armor skins, but the concept of shaking it off makes more sense to me, since Yukon Gold spuds have a thin skin and rolling up a chain conveyor will tear them up. That's why I was impressed with the design of the Spedo CPP-T, one row harvester. It brings dirt, rock and spuds up, low to the ground in a basket that moves laterally within a rigid frame, front to back to shake off the dirt, then drops them gently back on the ground for manual pickup. That's the design I'm building.

CliffordK · Jul 3, 2013

I wonder if there would be an advantage of making a tater/rock accumulator. Even if you dumped it back on the ground, follow the system with a non-shaking bin that would catch the taters, then when full, you could simply dump into a nice pile, then go again.

If you made it removable, you might be able to even dump it into a bucket or cart.

Millwood · Jul 3, 2013

I thought about an accumulator/catcher, that would be very low profile, to catch the spuds coming out the back, but since my soil is ancient river bed, I still have lots of rocks about the size of golf balls. and I'm afraid the catcher would be a 50/50 split between crop and rock and not worth the effort to build.

I wasn't joking when I previously said I'd done my 200K ton of rock removal when I opened up the ground. 6 were the size of a Volkswagen Beetle and took a crane to lift and remove. Then I removed every other tine on my rock rake to get the next bigger sizes and hauled out 14 dump trailers full, replaced the tines and went again for 21 more trailer loads for the rest. It took two months, plus 475 yards of top soil and manure to fill the ground to level, but it seems the rocks have percolated up from China to replace the ones removed, so for me just shaking the spuds and laying them on the ground with the rocks is my best bet.

CliffordK · Jul 3, 2013

How much abuse will the taters take?

Perhaps if you shook the accumulator too, you'd get a bucket that had spuds on the top, and rocks on the bottom.... solve two problems at once

Except, perhaps the smaller taters would still sink some.

muddstopper · Jul 3, 2013

Been away for a few days. Picked up a 7hp engine at Harbor freight today. On sale for $119. Havent even looked to see what kind of pullies I need. I'll just compare to what is on my other troybilt and pickup what I need. I think I have it figured out. Have to wait till Thurs. for the metal store to open to get what I need. Probably spend most of the wkend working on it. My son and grandkids are coming in tonite to spend the 4th with us. Bringing the new Great Grandbaby with them. Going to have a housefull for a few days. To many women in that crowd, Shop might start looking pretty good after a day or two. LOL Might get something done. Wonder if grandsoninlaw knows how to weld. Wonder if I can talk the crowd into helping split my winter wood. ah em, what about a few of my other projects. Sure hate to waste good help. Got to start planning.

muddstopper · Jul 3, 2013

I will comment on the 1/2in rods and my method for mounting on top. I think it was already touched on, but I plan on this digger doing double duty, picking rocks as well as taters. Might try it on onions to just see if it will work. I am mounting the rods on top mostly because i didnt think of mounting them on the bottom to start with. Oh well. Anyways. I intend to build the ends of the rods up, blending them into the plate using a hardfacing rod. My original thoughts where that digging in hard rocky soil might vibrate the rods lose as they wear if they are mounted on the bottom. Hadnt thought about brusing the taters with the ends of the rods. Might change it, might not, I aint growing hundreds of bushels and we eat them as fast as they grow anyways.

I am spacing the rods on 2in centers. I figure anything smaller than a golfball isnt worth worrying about and a golf ball is 1 3/4 dia and should roll on top of the tines. I am still trying to guess just how far the digger should travel or shake front to back. Probably just make the eccentric with a adjustable pin to adjust stroke. Might just drill a few extra holes in the trailing arms going down to the digger plate as well. Easier to just pull a pin to adjust travel than tear it apart and drill holes later.

I am still trying to figure out a way to catch the rocks and taters as they come off the shaker. From the utube videos, it sets awful close to the ground in the back, dont know how much angle I can get away with to get the rock to catch in a trailer. I will probably just make a small skid to drag behind the digger and let the rocks roll into it and drag it to the edge of the field to empty. Wonder just how much weight the old troybilt will drag.

CliffordK · Jul 4, 2013

Presumably your digging depth is below where most of the taters will be. Otherwise you run the risk of cutting some in half, and missing others. Of course, I guess that is the digging depth of the blade, not necessarily the screen. Tapering the ends of the rods will likely give substantial protection to the taters, and rods too.

Thinking about this more, even if the blade is run at an angle, the depth of soil on top of the blade will remain more or less constant. So, if you're cutting 1" below the taters, they should be fine, even if the blade is set at an angle.

muddstopper · Jul 4, 2013

Struggling with just how deep to make the blade go. I cant seem to get the view I want watching utube. I'm just going to make the attachment arms extra long with plenty of extra holes and do the trial and error method. I'll cut off what i dont need once I get it figured out. I am going to use some small tires in the back with height adjustment to help control cutting depth and lifting the digger up for transporting from shed to field. Going to the machine shop in the morning to get a shaft made to replace the current tiller shaft. The tiller shaft is made with a taper on each end, I'm just going to make a straight shaft to make mounting a pulley easier. The machinist agree to give me a few lessons on running a lathe and mill while he makes it. I own a old monarch lathe but seem to break more than I make.