Bi-metal hole saws

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Protactical

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Aug 24, 2003
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A local shop has bi-metal hole saws. I would like to dril some 1"+ holes in 3/16" steel, for karambits, and other styles. Probably in O1. Will these saws work? I will probably eventualy get carbide hole saws, but for the moment these are what I have access to.

If the bi-metal won't work, what is the next best bet: Lots of holes and a sanding drum? I also have one of those electric fret saws I have about 6 dozen metal blades, will these cut O1?
 
you can buy one and try? the drywall ones wont work.i have the best luck getting a hole that big by starting with a 1/8 drill bit then a 1/4 then a 5/8 then a 1" keep it cool with a cutting fluid so you dont air harden. i am sure a full time kerambit man will chime in. good luck.
 
What Laurence said. I haven't made any karambits, however I have made hundreds of Bird and Trout knives with the pinkey hole in the top. I start by Forging the hole and ifnish up with different sized stones in a Dremil!
 
Been down this road. It won't work. A standard bi-metal will be wrecked. What you need is a carbide tipped hole saw. These cut through steel and carbon fiber like a hot knife through butter. Definitely worth the extra bucks.

Hugh
 
I've used standard bimetal holesaws to cut dozens of 2-1/2" holes in 3/4" mild steel and a few 1-1/4" holes in 3/8" 18-8 stainless.

It works just fine if you use a drill press, set the speed correctly (find a drill speed table for the material you plan on sawing), clamp the work securly, use cutting oil (motor oil works in a pinch), use plenty of feed pressure, and raise the saw every 1/8" or so to clear out the chips.

Remember to anneal the metal.
 
If you want a clean, smooth hole and very fast cutting, go for an annular cutter. Try one and you'll be amazed at how easy large holes can be made. Rota-broach is one of the brand names that come to mind, but you can get these cutters in just about any industrial supply catalog, in just about any size. In fact, since I started using annulars in my shop, I haven't touched a silver & demings bit at all.
 
I start with a 1/4" hole ans enlarge it with carbide tile cutters in a Roto-zip tool. It works great, but tends to eat the cutters (breakage) if you are not careful.
 
Most bi metal hole saws are for sheet metal, they don't work well in my experience. What I have done ealier on is drill 1/8" holes in the 1" circle for the finger ring. Then, cut the little metal in between with a dremel and cut off disc. You can also mill the hole, that seems to work best and most accurately. You first drill, step by step. first say a 3/4" hole, the up from there and then up from there. If you have a string enough drill press (standing with proper tork), you can then use a 1" cobalt drill bit and that will finish the hole. If not, and you have access to a mill...step up in drill sized to the largest your press can handle and then finish it off with the mill, very, very slowly ! Tracing the circle with a mill ain't easy, so do it slow. Then smooth it with a dremel at 120 grit sanding drum and progress to desired grit (220 - 400 ?) by hand. Good luck bro, those 1" hole are a bitch !:D ....RDT
 
I rarely double-post, but seriously try the annular cutters. You will really love the way they work! Don't struggle, go annular! Woohoo!
 
I put a 1" hole in an 0-1 blade with a bimetal hole saw, it worked fine, except the hole was a little rough. Only used it once, but it seemed to hold up fine.
Kyle Fuglesten
 
I went to my local Ind Supply, and I didn't get the usual blank looks. They had both carbide hole saws, and carbide anular cutters! They didn't have the brand JH mentioned, but they had some serious looking cutters. At about 5 times the cost, and with no know way of attaching it without owning a magnet drill, I settled on the carbide hole saw. But if this style sells for me, I may track down the ACs.

Thanks for all the useable info.

By the way, what is the best hole size for a Karambit? I tried my index finger in a 1" hole, and am now leaning to 1.125". Any suggestions?
 
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