Need to drill a hole in a heavy bolt

Metal Shop
1

Not sure if this should go in Metal Shop or Machine Shop category.

I have a large (3/4-7) zinc coated bolt that I need to drill a hole in. It’s a grade 8 hardened bolt, so I’m guessing it’s not something I can just grab a regular drill bit for.

Is there anything I can do (anneal?) that will make this easier? Anyone done this before and have any insight?

TIA!

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@zmetzing or @nicksilva?

I’m thinking no for annealing simply because of that zinc coating. Also, you’ll lose the hardness for the bolt. It will no longer be grade 8.

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3

Use a good HSS or Cobalt drill bit. It will drill pretty easily.

I just did it myself because I didn’t believe it, & yes on a grade 8 3/4 bolt.

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4

Do it on the Bridgeport using V-blocks. Will hold without damaging and better control over drill.

Lots of oil and low speed.

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5

Thanks all! looks like it’ll be easier than I expected.

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It might be worth buying a solid carbide drill bit if you have have trouble drilling the hole.

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I actually need to do the same thing; would this be considered something requiring Bridgeport training even if I wouldn’t be milling in the xy plane? I’ve got milling experience, but haven’t seen a bridgeport class yet that I could make.

-Jim

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I’m not drilling coaxially; I’m basically making carraige bolts that can have padlocks attached to them on the treads. They’re used for attaching equipment with Wingnuts (such as Hi lift jack to a truck).
Similar to this: http://farm4.static.flickr.com/3416/5734122876_8507c323b6_b.jpg

The channel vise sounds like a good idea for something like this.

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I thought a normal drill press wouldn’t be an issue; when someone above suggested the Bridgeport for drilling a hole in a bolt, I figured it might be an issue with the capacity of one of the normal press.

-JIm

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I’m already expecting the hole to take some time. I’m also going for some hard bolts for the purpose (it is a security device after all).
is there a cutting fluid reservoir on the drill press for automatic flow, or should I bring a squirt bottle?

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Use vee blocks. Put them in the vise, smooth jaws only, and then clamp bolt in. Great for round objects.
image

They are on the gray work bench, top shelf, next to Haas.

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