still questions about drilling in hardened steel

C

Cushing H.

Gold Member
Joined
Jun 3, 2019
Messages
2,714
I might have outsmarted myself: I have always thought in terms of drilling rivet/pin holes prior to HT ... but a couple of comments by people saying "sure, you can drill hardened blades" caused me to thing "at least try it." well, now faced with it (this is specifically about the 15n20 blades JT just produced) has me reviewing posts on the web. At least one earlier thread on this forum indicates it is doable with carbide drills (maybe several) ... but quite a few posts elsewhere on the web basically say "dream on". (I was also confused as JT's ordering system allowed for an "I will drill rivet holes myself"). So ... what is the current wisdom out there: should I go get some carbide drills and at least try it ... or should I do as Boye recommends, and take a blow torch and try to anneal the handle (problematic - these are small knives and I really risk also annealing the blade area). Please let me know your thoughts??

JT - if you see this - one of the knives I submitted for your AEBL run did not have rivet holes defined. In that blade, can you take a shot at adding a couple holes (either 1/8 or 1/4" in what seem like appropriate places (not critical, and you likely have a better esthetic for that than I do - if problematic, just let it go and I will anneal that handle before I drill holes)
 
Last edited:
You have several options. As you already mentioned, the solid carbide drill bits will easily drill through hardened steel, but they are brittle. You can anneal the tang by heating it to a dull red 2 or 3 times (keep the blade cool by submerging in water, or a wet rag, etc). Or, you can go buy a carbide tipped masonry bit. They will absolutely cut through hardened steel being carbide tipped. I've done this a handful of times. Buy a few of them, they're cheap enough, sometimes the carbide tip will snap off. Oh BTW, the hole of a carbide tipped masonry bit will be slightly oversized, but I always drill oversized holes anyway.
 
Cushing H. said:
I might have outsmarted myself: I have always thought in terms of drilling rivet/pin holes prior to HT ... but a couple of comments by people saying "sure, you can drill hardened blades" caused me to thing "at least try it." well, now faced with it (this is specifically about the 15n20 blades JT just produced) has me reviewing posts on the web. At least one earlier thread on this forum indicates it is doable with carbide drills (maybe several) ... but quite a few posts elsewhere on the web basically say "dream on". (I was also confused as JT's ordering system allowed for an "I will drill rivet holes myself"). So ... what is the current wisdom out there: should I go get some carbide drills and at least try it ... or should I do as Boye recommends, and take a blow torch and try to anneal the handle (problematic - these are small knives and I really risk also annealing the blade area). Please let me know your thoughts??

JT - if you see this - one of the knives I submitted for your AEBL run did not have rivet holes defined. In that blade, can you take a shot at adding a couple holes (either 1/8 or 1/4" in what seem like appropriate places (not critical, and you likely have a better esthetic for that than I do - if problematic, just let it go and I will anneal that handle before I drill holes)
Click to expand...
"dream on":D
https://www.bladeforums.com/threads/drilling-hardened-steel-easy-cheap-way.1625415/
 
One comment about masonry bits.
Often they are not as sharp as should be for drilling steel.
I been using Strongarm drillbits several years now.
Wayback using them during my locksmith days. They will drill thru Relsom and Maxalloy hard plates.
Be aware, Like masonry bits, slightly oversize.
 
The way to drill hardened knife steel with carbide bits is partly technique, but mostly using the right bits. I use three and four flute carbide bits and drill the holes effortlessly. Speed should be moderately high and use firm downward pressure. Placing an aluminum or micarta backing block behind the blade is very wise. Clamp the blade down rock solid and make sure everything is square. If you have a mini-mill, this is a task they are really good at.
 
With a drill press that doesn’t have excessive play in the chuck it’s pretty simple. I use 2 flute solid carbide bits. I’ve drilled 15-20 holes with the current bit I have. As stated there are some techniques and tips that make it work. I clamp my blades to a 1” aluminum plate. My experience has been that a solid backer is a must. Most of the ones I break are right as the bit punches through the bottom side. I run my drill press around 300 rpm. I use a pecking method and a quality cutting oil. Since clamping to a solid backer I haven’t broken any bits.
 
Most metalworking/machine shops will give you small drops and cut-offs. Ebay is the simplest place to get odd pieces of aluminum. The big shops sell off their shorts and odd cuts. Get at least 3X.25" or whatever size you find. You can use the piece over and over again.

Some of these will last for years in a small shop:
https://www.ebay.com/itm/16LB-SOLID...027965?hash=item521efa23fd:g:AtQAAOSwMxxdGzed

https://www.ebay.com/itm/ALUMINUM-B...561623?hash=item1a7b1baf57:g:108AAOSwEJ1cVwuQ

https://www.ebay.com/itm/3-8-X-8-X-...=1535368707709efa57774289458caf62c9fc45f3fa8c
 
I use Norseman carbide tipped drill bits. The shaft is high speed steel so it's tougher and more forgiving when chucked in a drill press. I use mild steel for a backer, available at Home Depot etc.
 
Stacy E. Apelt - Bladesmith said:
. Ebay is the simplest place to get odd pieces of aluminum
Click to expand...
Boy .. amazing the stuff you can find on ebay. Ill have to try that - but might need to try home depot first (time is somewhat my limiting factor right now).

Silly question: if drilling hardened steel is doable, but problematic, those who do it ... why? Instead of always drilling before HT ?
 
I have gone to drilling post HT for AEB-L since I always get wraps where the holes are drilled. I have been getting small 1/8" carbide paddle bits from Amazon for about $8. If I'm careful they last for a few holes. Once I have a hole I have better luck with masonry bits.
 
[QUOTE="Cushing H., post: 19112817, member: 518872"Silly question: if drilling hardened steel is doable, but problematic, those who do it ... why? Instead of always drilling before HT ?[/QUOTE]
Before HT, I can drill the hole in 5 seconds using a 75 cent drill bit. If I am careful with oil, speed and feed, I may get 50 holes before the bit starts to dull.
Ebay is really good source for bits. Search on Ebay for M35 or M42 (both are high cobalt HSS) and sometimes when you buy lots of 10 or more, the price is as low as 75 cents per bit.
I paid at least $5 for the cheapest of the few carbide bits I own.
the old sailor
 
95% of the time I drill pre HT but there are times when I need to change hole placement or enlarge a hole.
 
The main reasion I offer the “I will drill my own holes” is some blade designs don’t need holes. And some people might want to drill the holes later.

If you have issues getting holes in your blades let me know and I will cut a replacement batch for you. If you cover shipping I will cover everything else. Want you to be happy with your blanks.
 
use a double cut solid carbide burr in a drill press . or a masonry 1/8 drill bit. either one should not cost you very much ,and will do the job.
 
Thank you JT, but this is in no way on you. At the time i sent those profiles in i was still battling CAD programs, and figured “why not try”. I have a pretty reasonable drill press now, and picked up some aluminum backer (per Stacy), so hopefully i will be able to replicate what others have done. Worse comes to worse i anneal the handle. I should be able to give my first go at drilling this weekend.

Thank you again for the offer!
 
Success!!! Finally got my drill press set up (had to spend time stopping condensation from a cold water line that runs above it :( ).

Followed Stacy's advice - moderate speed, aluminum backer, everything well-clamped in place. For yucks, tried a cobalt drill (1/8") first, as some in other posts and forums have said they had luck with that. Did not even touch the steel (in fact the thing kept slipping in the chuck with the force I was applying).

Then tried the carbide (not tip ... full carbide) bit. It took just a little bit to get started on the steel ... but once it did it pretty much just churned its way through. I can see Stacy's point: firm continuous pressure - keep it cutting once it has started. Makes some really interesting sounds though. Thank you all! (if I keep doing this I am going to need to go after some of those inexpensive bits some have mentioned on Ebay).
upload_2019-7-6_11-56-32.png
 
Glad you got holes in your blade.
 
You must log in or register to reply here.
Back
Top