drillbit question

[streetsniper]

I'm trying to drill the touch hole on my first build. I've trashed two bits already. Am I using the wrong kind of bit or is my drill press turning too fast? The pilot went in without a hitch, but the 13/64 turned cherry red and stopped. What am I doing wrong? Billy

 

[TNHillbilly]

First question: where did you buy the bits, what brand, what does the package say....like made in China, HSS?

 

[streetsniper]

Got them at home depot. Blu-mol.

 

[streetsniper]

I think I may have caused some damage to hole. Think I'll order a 5/16 vent liner from totw with the appropriate bit.

 

[TNHillbilly]

I like to use a drop of penetrating oil and fairly low speed the larger I go. I note with the oil, I get a nice spiral, continuous, piece of metal. Perhaps your press has pulleys to change speeds. Maybe some real machinists will comment. I buy my bits from the welding shop. That chain store stuff is pretty much junk IMHO-even the ones marked 'cobalt'

 

[Vaino]

First off I take it that the plug has been removed? Have these new drills been resharpened? A cherry red color possibly is caused by running too fast or if the heel of the drill is rubbing due to improper clearance, the drill won't cut a lick and excessive heat is the result. How fast were you running?. I only use HSS drills which don't have to be sharpened very often if run at a proper speed.....Fred

 

[Zonie]

For a drill in that size range your drill press should be running about 1100 rpm or slower.
On my drill press that would be either the smallest pulley or the next smallest pulley size on the motor. (Or the largest or next to the largest pulley on the drill spindle).

Fast isn't good when drilling steel parts.

Your drill bits should either be High Speed Steel (HSS) or High Speed Cobalt Steel.

Many people think they have to use a lot of pressure when drilling steel and others feel they should go slow and easy.
Both of these actions can break or dull the bit.
Use a firm but not heavy amount of pressure on the handle and when you want to stop release all pressure. Do not let the drill bit run against the steel part with just a little pressure as that will overheat the bit and even the best HSS will dull.

 

[paulvallandigham]

Use a slow speed, and oil on the bit, often, when drilling any steel.

You don't indicate the size of the pilot hole, but when you are planning to drill anything more than 1/8" in steel, plan also to drill the pilot hole out with a larger sized bit, first, before going to the larger drill bit.

I do agree that you need to have any new drill bit sharpened, properly before using it. I used to think drill bits came sharp from the factory, but have found out better since. The same goes for most knives you buy- they also need to be sharpened to be truly sharp.

That drill bit sharpener that was heavily advertised last year on TV works, BTW. Any shop that sharpens knives, and law mower blades can usually also sharpen your drill bits.

Buy the best American made drill bits you can find. The discount stores sell that stuff from China, which destroys out balance of payments, and gives them good American dollars for their worthless paper. The bits are junk. As are most of those tools made in China. If you are only going to be drilling holes in wood, then go ahead and buy the cheap bits. But, for drilling steel, spend the money to get the best.

Check with the commercial desk at your hardware store- where they take care of construction companies, and workers buying tools. They tend to have the good stuff back behind their counters.

 

[TNHillbilly]

And try putting your mikes on some of these bits, then wonder why the tap threads don't hold the screw......then there's the chain store screws..... Wonder how long modern China will hold together?

 

[flashpanner]

I like American made drill bits. Cleveland, Springfield, DoAll, Dewalt(be sure they are the ones from Germany) are good quality tools. Run away fast from the China, Taiwan, etc., manufactured ones. HSS (high speed steel) or cobalt are great. The TiN (gold colored) drills are a sugar coating on a substandard bit substrate. Unless it is on the aforementioned bits, TiN coating is IMO used to help stop BUE (built up edge) or chip sticking.
For cutting fluid, I prefer TapMagic seems to pull heat away better than oil.
Speed? I ran my .0625" bit at 1450rpm, chucked short, and had a center drill starter hole.

 

[Zonie]

flashpanner
The 13/64 drill bit the original post mentioned is a .203 diameter drill.
What speed would you use with a drill that size when drilling mild steel?

 

[flashpanner]

I should have read the whole post with more attention. I'd probably run the 13/64" at around 1200-1300rpm (~65sfm).

 

[Vaino]

I guess I'm a "slowpoke" and would run a 13/64" drill at 700-800rpm in steel and 1200-1300 in wood. The reason for the lower speed in stl is the possibility of hitting a hard spot but also the drills don't need sharpening as often....Fred

 

[bingo1952]

Running a drill too slow can be as damaging as running one too fast. If you go too fast you run the risk of burning the drill. If you go too slow you run the risk of breaking the drill by having it grab too large a bite in the work.

 

[paulvallandigham]

If you run a drill bit slow, then run the feed slow, too. I was taught to simple touch a center punched hole(?) in metal with the drill bit, and then back off to see if the drill bit moves off center. We didn't have " center bits " back then, or at least they were not being used in my shop classes. I have always used pilot holes when drilling any hole that had to be straight, or had to be centered exactly in relation to some other hole to be drilled. And, if the final hole was larger than 1/2" in diameter, we started with a very small bit, then enlarged the hole with at least a 1/4" bit, so that the final bit would have a substantial enough " Pilot " hole to follow, and keep that bit straight. We feed the bits slowly, cleared chips often( like when using a tap or die to thread something ) used lots of oil to cool the bit, and never pushed too hard on the feed, letting the drill do the work. That may sound ethereal to people who have never used a drill, but you do get a feel for it when you have had some experience.

 

[blafen]

I used to buy the cheapos because i could get more bits for the buck, but after numerous breaks and worn out bits i switched to some nice dewalts, very sharp and will cut a consatnt spiral as long as you hold the feed steady, my only complaint is the pilot drill tip makes it difficult to center a bit in the hole from the pilot drill.

 

[Vaino]

When using a small drillbit for a pilot hole, which I always do, 2 things have to be considered. First off, the pilot drill has to be of a dia. that's larger than the web dimension of the larger drill. Secondly, the pilot drill hole should be deeper than the angled cutting lips from the web to the outside corner.This allows the full dia. to engage before running out of pilot hole. Also if a very precise dia. is wanted {the hole normally will be oversize when drilling}, the outside corners of the cutting lips can be rounded on the final size drill, having been preceded by the pilot drill and a .015-.030 undersize drill. The final drill because of the rounded cutting lips will act like a reamer and will produce a "slip fit" hole.Also on brass to eliminate "grabbing", the cutting lips should have a square edge instead of the full rake used for steel. Please excuse this "long winded" post....Fred