Tater digger/rock picker

[muddstopper]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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