Aerator Tine

nomad · Jun 24, 2004

I just finished making some simple toolings for a core plug curved aerator tine. See attached picture. But I just realized there is a design error in that tine. "Blue" line shows the curveness of the tine (actually, not a curve exactly, but a slightly sharp bent at the middle.) It's almost straight. "Red" and "Yellow" curves show alternative shapes to give you idea on how the curveness of the tine should have been. It should have been a spline (as the tine rotates as well as moves linearly.) Now, engineers or those who trust in their minds with mathematic-vision-in-born, tell us what path the tine follows that will determine the tine shape.
Your views will be converted, by me, to a function
which later will be discretized to inserted into CCam system
which will produce my new tine toolings
which will be produce more efficient tines for your aerators
which will reduce your oil consumption.

Or, there is no error in the original tine?
Who have core plug aerators with curved tines?

Villengineer · Jun 24, 2004

I don't know this for a fact, but I would guess that the tine you have was a compromise between what would have been ideal and what was acceptable. It's quite common for ideal designs to hit the cutting room floor due to cost, manufacturing difficulty, and/or supply chain issues. They may already have the "best" design, but have decided that the difference wasn't enough to justify the burden, whatever it may have been. Of course it's also possible that somebody looked at a straight tine and said, ya know a slight curve might be better and they just started putting a shallow bend in them. The question that really needs to answered is does the ideal tine have enough benefit to even warrant the time, effort, money, etc..? I can't answer that question.

jimgerken · Jun 24, 2004

I don't think it makes any difference what shape it is. Either it is going to shear soil sideways on its way INTO the ground, or it is going to shear on its way OUT. I will give this some more thought.

jimgerken · Jun 24, 2004

...Unless you can make it flexible!

Keith_TN65 · Jun 24, 2004

I'm with Jim. If you make it to go in to the soil correctly, it will not leave the soil correctly.

Darren · Jun 24, 2004

I happen to have an aerator spoon sitting on my desk. It's 8.5" long and the curvature of the 5.25" in-soil section matches the red line. The remainder which contains the connection is straight. The spoon tapers from a tip opening with a cross sectional dia. of .625 to .875 at the section for ejection of the soil plug.

nomad · Jun 25, 2004

"Ideal" tine (with proper spline shape) isn't difficult to be "machined" - Anyway, a die tool is necessary to give the shape of bent section at the middle. All that will be done is to change of the shape of this small die. No extra tooling, no extra machining, no extra cost. Probably, as you said, someone suggested "it would be better if we gave a curveness to that straight tine" and the tine manufacturer gave a simple curveness without studying much on it. If they studied a little more, the correct spline function that would determine the curveness of the tine would be obtained. This tine shape problem may seem to be a small problem, but I am estimating rougly that because of wrong tine shapes tractors are consuming about 3-5% oil more when they are pulling their aerators.

nomad · Jun 25, 2004

( I happen to have an aerator spoon sitting on my desk. It's 8.5" long and the curvature of the 5.25" in-soil section matches the red line. The remainder which contains the connection is straight. The spoon tapers from a tip opening with a cross sectional dia. of .625 to .875 at the section for ejection of the soil plug. )

You have a digital camera? Could you please take picture of your tine for us? Thanks.

nomad · Jun 25, 2004

( I'm with Jim. If you make it to go in to the soil correctly, it will not leave the soil correctly. )

I didn't understand Jim and you. Could you please make it clear? Thanks.

Junkman · Jun 25, 2004

If the tine enters the ground at a 10 degree tilt to the north, as you move away from North, that tine would have to rotate direction by 180 degrees pointing South, so not to come out of the ground without a "tearing" effect. To give you a demonstration of this, take a long straight bladed screwdriver and insert it into the ground at a slight angle. Then using the handle, move it forward so the handle is at the same angle going in the direction that the core aerator would be moving. You will note that there is a "slit" torn in the ground. The only way that this could be avoided is if you had a aerator that was set down on the surface like a cookie cutter and depressed into the soil. Then the "cookie cutter" would have to be pulled straight up and reinserted the same way in another location till the entire area was "cored". Nomads, hope that this explanation helps you to understand the action of a core aerator as it is rolled over the surface of the ground.