Drilling hole through a bar

[Upnorth4]

I building a "mini mill" and would much rather drill through the bar to attach, instead of clamping it to the bar.
The steel that chain bars are made of seems very hard, I tried before and had no success.

What is the best way to drill the holes?

Has anyone annealed the bar to soften it before drilling?

My basic metallurgy knowledge says that heating it to an almost cherry red then wrapping it in a fire blanket to let cool very slowly should soften the metal, after drilling it could be rehardened by heating and quenching, dipping in to a mix of oil and water. I don't think quenching a bar is a good idea though, far to easy to end up with brittle metal, which would cause a lot of problems.

 

[tbow388]

Drill Bit

You need to go ahead and buy a good bit. A good bit (that is meant for hard metal) and a drill press will definitely do it.

I would not heat at all!!

 

[BobL]

A cobalt bit will drill most bars except the bearing in the middle of a a sprocket nose.

A hand held drill is generally too fast, what is needed is slow revs, high pressure and some lube - metal cutting lube works best but even light machine oil is better than nothing.

To drill the bearing in the middle of a a sprocket nose you need a carbide bit, a new masonry bit will work, once again high pressure and slow revs and lube.

 

[bigmoose]

What brand bar are you drilling.I have drilled holes is stihl and gb bars with no problem using regular bits.The trick is sharp bits, regulating drill bit speed and use lots of cutting oil.I have had them work hard on some holes and I have had to spot aneal some bigger holes.

 

[srcarr52]

Carbide ball mill or a center cutting end mill. Check amazon, you should be able to get one shipped to your door for $18 and it will go right through even a sprocket tip center.

Be sure to use a drill press and clamp your piece to the table nicely. Holding the piece by hand will almost guarantee a broken carbide end mill.

 

[betterbuilt]

I was drilling a bar today and I started with a 1/8 inch bit like I usually do and it did like it always does drops through with no problems. I went to a 1/4 inch and it made it through the first half no problem and the second half it got a little hot. I switched the bit a few times and was getting frustrated. I got to thinking about this thread and I grabbed a masonary bit and squirted it with Tap magic and it cut right through. The whole fiasco only took about 20 mins but I can see how frustrating it could be with out a stock pile of bits to try.

The next bar I drill I'll try an end mill. Just to see what I'm missing.

 

[sachsmo]

I rekon you will be missing about 19 minutes 40 seconds.

 

[betterbuilt]

I rekon you will be missing about 19 minutes 40 seconds.

Well, I guess it might be worth it. I will say the concrete bit actually surprised me. I had my doubts that it would do anything. Being that I don't know what I'm looking for when I look at endmill bits. Can someone post a link or a picture of what I would need to buy. Thanks, BB

 

[mtngun]

Well, I guess it might be worth it. I will say the concrete bit actually surprised me. I had my doubts that it would do anything. Being that I don't know what I'm looking for when I look at endmill bits. Can someone post a link or a picture of what I would need to buy. Thanks, BB

2 key words to look for are "centercutting" and "carbide."

Carbide end mills work nicely for drilling bars, but they do chip easily and they are spendy.

I've never tried the hardware store carbide bits for concrete and glass, but suppose they would work.

 

[sachsmo]

 

[sachsmo]

"NEW" 5/16" 4 FL. "BALL-NOSE" CARBIDE END MILL-TiAlN+ | eBay

 

[Timberframed]

Just a thought...what about tapered grindstones and then a reamer?

 

[hamish]

Just a thought...what about tapered grindstones and then a reamer?

Gindstones are too weak, even a silicone carbide stone will be shot trying to grind a thousands of an inch out of a hole.

If its not in the bearing, and you have time on your side and a variable drill press, regular hss drill bits will get the job done (once again if you have time of your side), and end mill or water jet make easy work of it......if you have one.

We all either drill too fast or too slow, and head to watch the signs of sucess, and those of failure. RPM and chip creation are crucial all the better the long spagetti's, of material being removed.

 

[BobL]

2 key words to look for are "centercutting" and "carbide."

Carbide end mills work nicely for drilling bars, but they do chip easily and they are spendy.

I've never tried the hardware store carbide bits for concrete and glass, but suppose they would work.

Yep - they work - If I have one I usually use an old one that has been touched up on a green wheel.

 

[saw dog]

bar drilling

Yep - they work - If I have one I usually use an old one that has been touched up on a green wheel.

A quality masnory bit is what I use, and never have had a problem.

 

[betterbuilt]

Thanks for all the help. I don't have a bar to drill at the moment. Now I at least know what I'm looking for.