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trashcan
02-27-2004, 08:50 PM
I just broke two drill bits trying to drill a hole in a .75" ball bearing. I ground a flat spot in it and clamped it in my drill vise and ..viola!! broken bit. This is a project for a puppet stand for my kid so any good advise would be helpful. (Next step is to try to weld the bearings to 1/4" round stock and I don't know if I'm good enough for that yet!?!? Thump On!!

glockdoc
02-27-2004, 09:12 PM
A good ball bearing should be harder than ****. Not sure if there is a drill bit made that will drill one. You might be able to use a torch to heat it up and draw the hardness out of it. How about silver braze or LFB.

Maxwell
02-27-2004, 09:20 PM
Typically you need an EDM process to machine something that hard. Electro-discharge machining that is.

A high quality carbide drill in a very rigid setup MIGHT be able to drill it, but I really have my doubts.

Good Luck

Maxwell

JoeHobart
02-27-2004, 11:24 PM
i have a small set of cobalt bits from HF (the 40$ set) for drilling hardened stuff. Good investment. Slow slow slow on the speed too. How about a die grinder/dremel stone to rough out the hole?

I'm not sure exactly what your planning on doing with it, but do you really need hardened steel, or just a small metal sphere? I wonder if you could just anneal it and get what you need without all the effort. Maybe i don't understand. Are you just trying to seat a 1/4" round to it, and using a hole to align, or is there some reason you cant just jig it up for alignment and weld it on?

pturner
02-27-2004, 11:26 PM
Mcmaster has case hardened (vs through hardening for ball berings) ***** for sale, should be easy to drill if you grind a flat. cost for 3/4" is $15 per 50. Part number is 96455K59

trashcan
02-28-2004, 07:21 AM
heres what I'm trying too achieve...I want to attach the ball bearing to the end of a peice of 1/4" round stock because it is a project going to be used for a 3.5 yr olds puppet stand and I thought that it would be better than just having the ends of the round stock just waiting to poke her little eyes. I also think It would look sharp to have the stand all black with silver ***** on all of the ends. I want to drill a hole in the bearing and slip it over the end of the round stock (JB weld inside the hole?) for asthetic reasons. Reading above I'm wondering about the anealing process but it seems the McMaster way might be my best bet. Please explain the anealment process to me and any other suggestions are greatly appreciated. Thump On!!!

Jimbo
02-28-2004, 01:15 PM
Ball Bearings have to be annealed (heated to a cherry red with a torch) before they can be drilled. After that, it works okay.

david_r
02-28-2004, 01:18 PM
Got a charcoal grill? build a nice hot fire, throw the ***** in, make sure they get good and orange then cover with ash or sand and let it cool slowly. Next day, you should have some very ugly annealed *****. Of course, they aren't going to be nice and shiny any more.

Can't gind a flat and silver solder?

BillC
02-28-2004, 02:05 PM
trashcan,

I'll bet if you look around you will find that somebody sells decorative threaded ***** in the size you need. Probably chromed and everything.

Regards,

mrimpact
02-28-2004, 02:44 PM
Originally posted by david_r
Got a charcoal grill? build a nice hot fire, throw the ***** in, make sure they get good and orange then cover with ash or sand and let it cool slowly. Next day, you should have some very ugly annealed *****. Of course, they aren't going to be nice and shiny any more.

Can't gind a flat and silver solder?

exscuse me sir i noticed something wrong! but trying to heat metal up in a charcoal grill will not work.first of all charcoal is of ofcourse made of wood and doesn't produce a hot enough flame.natural blacksmith coal is "coal" not charcoal! or in other cases stuff called "coke" will heat metal up much cleaner. I tried heating metal up with a blazing oil and trash fire and left a rod in the barrel where it was burning and it would not heat up even after 10 minutes.so go figure.

JoeHobart
02-28-2004, 03:04 PM
Ahh, now i get it.

Has 3/4" stamped *****-> http://www.jansensupply.com/page67.htm

Annealing generally means bring it up to temperature, 'soak it' for a while to let the heat sink in, then cool as slowly as possible. For something so small, you'r looking at 60-80 minutes of heat+soak. The color you want is between cherry and bright red, that will give you about 1400-1500 degrees. Charcoal burns at around 2000 degrees, so david's grill idea will do nicely. Just check it to make sure you dont let it go too far from bright red to orangey during the burn. Note this is color in a a darkened room, it will be harder to tell in sunlight. Just leaving them to cool in the ashes is fine, the longer the cool, the softer the metal (which is the same idea as hardening- the faster the quench, the harder the metal).

I got to be honest tho, if it was me, i would just throw 3 hot tacks on the flat and die grind it purty.

-edit- mrimpact bring up an excellent point. we are talking real charcoal, not the pressed sawdust blocks you buy to cook steaks.

mrimpact
02-28-2004, 04:05 PM
i don't know,all i use to bbq is mesquite wood.

Chipmaker
02-28-2004, 09:10 PM
Charcoal is more than enough to heat up a 3/4" diam steel ball bearing to orange heat. I used to use charcoal before I switched to propane in my foundry furnace. If I put forced air to it I could melt cast iron. I will say that all charcoal is not created equal, but major brands like Kingsford will do the job.

I have used wood in an old woodstove with lots of draft to heat 6" diam steel pipes to orange color for forming a lip as well.

To anneal heat to orange color, place in container filled with sand, cover and allow to cool very slowly. The slower it cools the better.

www.frugalmachinist.com

mrimpact
02-28-2004, 09:23 PM
hah,i'm suprised the carbon monoxide hasn't killed ya yet.hmmf

Broccoli1
02-29-2004, 05:02 PM
trashcan, what about a drawer pull/knob. You could weld a bolt into the round stock and then screw on the knob.

bobad
03-02-2004, 05:56 AM
Most ball bearings are 61-63 Rockwell "C". Most normal High Speed drills run about 65 RC, so you can see it's not a good situation.

A good carbide bit will drill it. I've drilled many for use as gage *****. Use a low RPM and "peck" it. No flat is needed to start the drill if you have a rigid setup.

Cobalt drills will also drill it, but use oil and go slowly.

You can anneal the ball by heating it bright cherry red with a propane or mapp torch. Drop it into a can of lime while still cherry red so it will cool slowly. It will then drill nicely with a common HSS drill.

About "titanium" drills. The gold colored titanium nitride (TiN)coating is mainly for anti-galling and reducing friction. You can TiN coat an inferior drill, and you still have an inferior drill. Always get M2 high speed steel (HSS) or Cobalt drills. TiN coating make them even better, but will not transform an "alloy" or "carbon steel" drill into a good drill.