Jump to content

Drilling 5160, or how to soften it enough?


Recommended Posts

Hi guys, I started on a new knife and have it shaped fairly well and went to drill the holes for the pins and ran into some problems. 

beast-01.jpg

The blade is new 1/4" x 2" 5160 and has just been stock removal.  I drilled a 1/8" pilot hole without any problem in 3 spots with a drill press, but when I went for a 1/4" hole, it got part way through and then just started squealing.  I was useing TIN coated drill bits with some oil.  I went to HomeDepot and got a couple of Cobalt bits, but they wouldn't do anything.  I'm guessing that I hardened it going through with the 1/8" holes.  Would tempering the blade make it soft enough to finish drilling the holes?  Could I just put it in the oven overnight, or go for three one hour tempers at 400F?  I tried using the search, but found everybody saying something different...

TIA

Glenn.

Link to post
Share on other sites

Have you quenched it yet.? If not the oven cycles will not do squat.

Either way, were I trying that I would consider taking it up to decalescence and letting it cool in still air a couple of times to refine the carb8de grain a bit and then take it up until it just starts to show a faint red color and try to hold it there for a minute or two and let it cool again. That part is "over tempering" and will come as close to annealing as simple equipment will get you. You should be able to get your holes finished and then harden as normal, or regarded and then oven temper.

Do as much filing and sanding/polishing as you can before hardening, to about 400 grit. It is easier on you the files and the paper if you get it out of the way before hardening the steel.

 

Link to post
Share on other sites

Have you heat treated the knife yet?  If not,  you might have run into some carbides, or it could have done a little work hardening on you.  Those both suck.  If it isn't heat treated, then you can stick it in the forge for a normalization and that should do the trick.  

Link to post
Share on other sites

Take a look at this. http://www.cashenblades.com/steel/5160.html

http://anvilfire.com/article.php?bodyName=/FAQs/heattreating.htm

I don't do 5160 but have run across the same on other steel. This answer may depend upon if the steel has been hardened or work hardened. Find a masonry carbide tipped bit, in the size you need! Take the bit and re-grind the point to about what a 135* bit point would look like. Absolutely to not get that point over heated, cool often!! While you are changing the angle of the point, you need also to be changing the bevel of the carbide! There is not much to work with on a masonry bit, when it comes to regrinding and reshaping the carbide!

Wrap the blade in a dripping wet rag. This will act as a heat sink.  If you have hardened the knife, the wet rag will keep the heat from transferring! Heat the area at the spot you are drilling, till red with a torch!! If you have only work hardened the steel, you should be able to drill it thru with the modified masonry bit, after it cools.

If you have indeed already hardened the knife you can drill it while the spot is red hot. It will eat the bit up drilling the area while red hot.  If you can wait till it cools, use cutting fluid and let the bit cut. 

Either way the bits are consumables, but the good side to that is there are not all that expensive and you get a $3.00 hole in a hundred dollar knife!!

Your bit was cutting by the picture, till it got hot and then it is done cutting! From there on you are at that point work hardening the steel. Cutting oil and a slow as possible speed is the answer on drilling some of your handle holes!! I hope that helps!!

Edited by C Craft
Link to post
Share on other sites

Sometimes you can get away with drilling from the other side.   It looks like you are 1/2 way through anyway, so drilling from the other side may get you the rest of the way.  Will probably chew up the bit anyway once you get to the center though.   I've been learning how to resharpen drill bits :)

Slow speed on a drill press is the way to go.   And once you get the squeal,  pull back, resharpen the bit and inch it down some more.  That helps sometimes.    Otherwise you are just work hardening the area.  Otherwise, my goto for annealing steel is pretty much get it to non-magnetic, then I leave it in a bucket of wood ash until it cools.  Usually overnight, but a few hours should be ok.  That's helped me in the past with salvaged  car/truck spring  steel.   If your blade is not already hardened that is.  If it is,  you will have to reharden it after doing that though.  I've also have just left blades in the forge overnight to cool with the forge.   That tends to leave more scale though.   The key is to let it cool as slowly as possible (generally).

True Carbide bits are nice, but I can only find them online and are somewhat expensive.    You can also try graduating the bits,  as in, start 1/8", then 3/16", then 1/4".   Sometimes that helps, as you are cutting much less at a time.

My experience with a drill press tells me that you are either cutting or you are not.   If you are, go slow, keep cool and shoot for the curl.  If you are not, then the piece is too hard in that spot, drill bit is dull, or other.    A drill press has a tendency to dull a bit right quick if things just aren't right.   Can happen in seconds.  If it's not cutting on the get go,  do something else.     Slow speed, and heavy pressure has often gotten me through a tough spot, even on thick material.

Side Note:  I like to use center bits for starting holes.   Usually used in lathe operations,  they are way sturdier than a skinny 1/8" bit, so you can apply more pressure on the press.  I like a #4.  Added bonus of adding a countersink.

https://www.amazon.com/Anytime-Tools-CENTER-COUNTERSINK-Tooling/dp/B000N216SU

Good Luck,

-B

Edited by Bruno
Link to post
Share on other sites

All of the above work, but the main lesson here is to use new or newly-sharpened drills, and step-drilling is usually a bad idea on holes less than half an inch diameter.  

Link to post
Share on other sites

My money would be on that first drill bit being dull and it work hardened the surrounding steel.......happens to me as well with leaf spring.

I would like some confirmation, I suspect I've work hardened leaf spring hogging material on a belt grinder.....? 

 

Link to post
Share on other sites

Drilling 5160 can be a pain in the neck to be honest.  I didnt have any luck with HSS or Titanium coated bits, I had to get the Cobalt bits in order to effectively be able to make holes in steel. They work pretty well and in my experience can do about 8-10 holes before they need to be resharpened. 

Link to post
Share on other sites

This tip wont help you where you are now but here is another work around to keep in mind for the future. If you are buying "fully annealed" 5160 from a knife maker supply it should drill like butter when you first get hold of it. If you are going to do stock removal all the way, do your layout and drill your holes before you do any grinding. 5160 is deep hardening and I have had issues with air hardening from forging heat. It sounds like you haven't been that hot with your piece but squealing drill bits can generate a lot of heat in a small space and time. You can pick up a bag of vermiculite for a few bucks at any garden center. Put it in a metal container, bring the area you want to drill up to non-magnetic and let it cool over night buried in vermiculite. Wood ash works too but wood ash will wick moisture out of the surrounding air and can cause hard spots. If you are going to epoxy scales on and don't need a precise, machine fit on the pins you could always punch and drift the holes at forging heat, then grind away any swell this creates in the handle profile.

Link to post
Share on other sites

Thanks for all of the suggestions. I have not hardened the blade yet, and yes I bought it new either from Jantz or new jersey steel Barron. 

I used a cutoff disc on the small grinder to remove the big spots, then a bench grinder to get a rough profile, and finally the 4x36 belt sander with 40 and 80 grit belt to get it to where it is. Also some sanding drums for the tighter spots. 

Link to post
Share on other sites

Well, I finally got a break from the weather and life and got the blade softened yesterday.  I used a new cobalt bit and some Brownell's Do-Drill and got all three holes drilled without any problems.

beast-02.jpg

I've got the scales roughed out and I'm working on getting the blade ground most of the way down and almost ready to heat treat.

beast-03.jpg

Edited by Glenn Larsen
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...