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rickf

AC 720 Pmax tiller tines, how to drill hard steel?

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rickf

Hi

A few of the central tines on my 720 tiller are pretty worn. A few weeks ago, I purchased an Ace Hardware front tine tiller for the briggs 5hp with a reverse cam shaft for $10 - got it home, was about to toss the carcass, but realized the tines looked pretty similar to the Allis ones. Sure enough they're identical (and hardly used!) but they only have two of the three bolt holes. Anyone have any suggestions for drilling hardened steel?

If you have a old Heavy duty 38" tiller or a powermax tiller, you might want to keep your eye out for some of the MTD front tine tillers that used the same tines, 2172511ASM & 2172512ASM are the current part numbers, and seem to be MTD items?

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steve-wis

Buy a good drill, one with high cobalt content. Sharpen it to a 135 deg. point, which is flatter than the standard 118 deg. point. Run it very slow and use a good cutting oil. You should be able to drill them this way. If even this doesn't work, I have taken a torch and heated the spot for the hole red hot and let it cool slowly. This will take most of the heat treatment out of it.

Hope this helps!

Steve

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acfarmer

A conrete/masonry bit will sometimes drill very hard steel,also if you use a small tip you should be able to do a decent job cutting a hole in the tine.

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Kenh

Carbide drill bit. Kind of spendy but will do the job. Just be sure to anchor the part being drilled as the bit will break easier than a HS steel bit.

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rickf

thanks, do you guys recommend a smaller pilot hole first, or just doing it in one shot? I think those holes are maybe 3/8 or 7/16".

At $15 per tine, the 16 tines that were headed to the bin seem worth the effort!

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Ronald Hribar

I would probably drill pilot hole first

easier to locate proper location

I also would recommend Masonry drill

and drill as slow as you can and keep it oiled

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Ronald Hribar

I would probably drill pilot hole first

easier to locate proper location

I also would recommend Masonry drill

and drill as slow as you can and keep it oiled

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Allisgrandson

I see a couple of guys recommended using oil to drill with. If you can, drill outside and run water over the metal as you drill it. This dissipates heat better than using oil and doesn't lubricate the cutting edge as much.

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