Machining Disc Blades?

[jlgurr]

My father-in-law and I are building our own tater hiller and have run into a bit of a predicament. The hiller disc we have needs a center hole to fit on the hub we have. The disc is hardened, at least relative to HSS drill bits. What is the best way to anneal and drill or alternate means of making a hole? I've read that at 400 degrees (seems low) the 1080 steel turns to martensite which is brittle. I believe that disqualifies an oxy/acetylene torch cut...

Ideas? Experience?

Thanks,
Jeff

 

[oldtimer 66]

I thought I replied to this. Use a plasma cutter. Depending upon how accurate it needs to be and or finish hand grind to size. You will have the hole in the disk before the part even gets slightly warm. You should be able to put your hand on the part shortly after cutting the hole. Just be a little careful the first time.

 

[Sfrankland]

What size hole do you need? I machine hardened steel with carbide drill bits and carbide end mills. You can you us an end mill in a drill press as long as you are cutting in a downwards direction.

 

[JRP]

Ditto on the plasma cutter. I make templates with plywood such that the tip rubs against the side of the template. To cut a 1" hole I hole saw a 1-3/8" hole in plywood. A quick trip around the hole and a nice 1" hole! Test on some scrap to fine tune the holesaw size.

 

[Jim Timber]

If you're cutting square holes, you can use a cut-off wheel in an angle grinder. Otherwise I'd second the plasma with hole jig. Once you get the template right these crank out quick.

 

[jlgurr]

If you're cutting square holes, you can use a cut-off wheel in an angle grinder. Otherwise I'd second the plasma with hole jig. Once you get the template right these crank out quick.

Hmmmm.... Interesting suggestion there and it's something I can do without farming out (pun intended) the work. The hole can be square, it's just a clearance hole to allow the hub center to protrude through the disc which is solid now.

The plasma cutter sounds like a cleaner although more expensive option. Since we are still in fab mode, it would probably be less expensive to stop now and just purchase the correct hubs and avoid the cost of a plasma cut. The correct hub is $25 while the hub we have on hand is $0.

 

[flusher]

Hmmmm.... Interesting suggestion there and it's something I can do without farming out (pun intended) the work. The hole can be square, it's just a clearance hole to allow the hub center to protrude through the disc which is solid now.

The plasma cutter sounds like a cleaner although more expensive option. Since we are still in fab mode, it would probably be less expensive to stop now and just purchase the correct hubs and avoid the cost of a plasma cut. The correct hub is $25 while the hub we have on hand is $0.

That hiller uses 2 discs--$50 new for hubs. A no brainer.

 

[jlgurr]

Looks like you can buy a handheld plasma cutter for less than a grand at Northern Tool. If I don't tell my wife the correct hubs are only $50 then maybe.... Nah! Better not do that.

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