Drilling through steel

[JCLP]

I have a 10lb bar bell weight made of hard solid steel. I need to drill 1/8" holes in it. I have tried HSS drill bits found at my local tool dealer but they don't work. Would anyone have any recommendations on what drill bits to use.
Thanks, JC.

 

[Holzhacker]

Festool bits of course.
Don't know about dumb bells but I can tell you they drill very well through standard american steel I beams

 

[Loren Woirhaye]

Hardened steel eats drill bits like a high school linebacker eats cornflakes.  I drilled a little hanger hole in a Starrett straight edge once and it took forever and messed up several bits.

Later I did some reading and found out you can soften the steel with heat if that's practical.  Probably not for you.  Another way to do it is to grind the hole.  I don't remember details exactly and there's a lot of ways to do it.  You can look up machinest's forums.  I recall a pragmatic solution being to use as abrasive in an oil slurry and maybe something like a diamond glass drilling bit. 

Some years ago I got a piloted milling bit with a 5/8" pilot and a 3/4" cutter diameter for enlarging saw blade arbor holes.  I had a saw with a 3/4" arbor.  I enlarged several holes with it but I didn't understand that using a lot of oil to keep it cool was important and I think I wrecked it modifying a dado set, probably drilling too fast.  I do not think saw plates are  as hard as that Starrett straight edge which took forever to drill a little hole in.

 

[Theshipstore]

I just drilled an 1/8" hole in one of my 5 lb bar bell weights, mine appear to be cast iron and with a slow speed of 250 rpm in my drill press and a 135 degree bit I had no problems
Not sure if a battery drill speed is sufficiently slow enough to accomplish this
Just my  [2cents]

Sal

 

[Slartibartfass]

You need to go sloooooooowwwwwwww with the HSS bit. Use 135 degree bit. Use a punch to mark the spot and thus avoiding the drill from walking away. Tin coated bit more durable. Pause in between not to overheat the drill bit. U want to start shaving the metal away.... Low and slow (like in BBQ)...is the way to go.

 

[Scott B.]

I've been doing a fair amount of drilling metal lately and have found cobalt bits to work well. I've not put them on solid steel yet. I would recommend punching a good start in it though.

 

[Bohdan]

Plenty of cutting oil will make the drill cut cooler and last longer.

 

[Billedis]

I use Bad Dog bits and have never had a problem.  Bill

 

[waho6o9]

https://baddogtools.com/Bad-Dog-Drill-Bits.html

Thanks Billedis

[attachimg=1]

 

[wow]

I use Norseman SuperMagnum bits. Have never found anything better.

 

[Kevin McConville]

I have a 10lb bar bell weight made of hard solid steel. I need to drill 1/8" holes in it. I have tried HSS drill bits found at my local tool dealer but they don't work. Would anyone have any recommendations on what drill bits to use.
Thanks, JC.

The weights will likely not be hardened as their intended purpose does not require hardening and further if they were hardened they could be somewhat more brittle and possibly crack when you drop them or they hit against one another. It would be fair to assume they are simply low carbon mild steel. HSS drills should have no trouble with this, the cutting parameters for HSS drilling in mild steel would be 60 to 110 SFM (Surface Feet per Minute) which is a measure of how fast the cutting steel moves relative to the workpiece. for a 1/8" drill this means that it should spin at somewhere between 1800 and 3300 RPM. Oil will help remove heat from the bit also you should drill for a 5 count and then pull the tool away to let it cool and even dip it in oil or water then keep going. The deeper you go the more you will have to take the tool in and out to cool.  Heat is your main enemy here as the tool heats up it can reach temperatures on the vulnerable cutting edges high enough to soften them and then it's no harder than the workpiece and no cutting will take place.  Relative to cutting mild steel, the various other materials (Cobalt, TiN coated and Carbide .....) are primarily able to withstand higher temperatures before the cutting edges soften and thus they can cut at higher speeds and keep their edges longer.

Good luck - hope this helps

Kevin

 

[JCLP]

Thanks to everyone for their recommendations. I bought some HSS drill bits and some oil, geared down my drill press to 350 rpm and was successful. Thank you all.
JC

 

[Birdhunter]

There is a term I've heard machinist use when drilling into hard materials. It's called "pecker drilling". The drill is inserted a small way into the material and then withdrawn. Then the drill goes a little deeper and then withdrawn, etc, until the desired depth is achieved. This process works best with a drill press.

The process allows the "chips" (drilled out material) to come out of the hole, allows the drill bit to cool off a little, and allows new cutting oil to coat the drill bit.

I use the "pecker drilling" technique to drill into steel and even into wood when I'm using a Forstner bit or a bigger brad point bit.