Drill Bit Quality?
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nos ...@nospam.com
I have a few of Silver & Deming drill bits ranging from 5/8" to 1" which I purchased at the local Princess Auto. When drilling 3/16" mild steel they seem to cut alright for a hole or maybe two (using a 1/2", 3/4", 1" sequence for example) but the edges dull quickly and even worse, the flukes(sp) have a tendancy to chip off making resharpening a lengthyand annoying procedure. I have priced out better bits (4 or 5 times as expensive with nothing apparently available in between) but am wondering if they are all that much an improvement. I would expect they are composed of better steel (alloy vs carbon??) and may have other advantages. For a hobbiest, does anyone feel they are worth the extra cost?
Laurie Forbes
"Robert Swinney" judy...@attbi.com
IMO, not worth the difference in price to go to the expensive ones unless you use them a lot. Bits of that size are fairly easy to re-point with a bench grinder; whereas, professional type drill bit sharpeners over 1/2 inch are pretty pricey.
Bob Swinney ...
"Karl Townsend" K...@cmgate.com
Its kinda like buying oats. If you you want good oats, you got to pay what they're worth. If you can use oats that have already been through the horse, they're a little cheaper. <G>
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"Dan Buckman" danbuck...@enter.net
save your money on the bits and get a good drill press.
With a good drill press not only can you eliminate all those steps, But you can ram a bit thru dull or sharp.
radial drill is just another name for a rotary punch.
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J R North jasonrno...@bigfoot.com
The cheapy SD bits are ok; mine work well. The bigger the bit, the more important rpm and machine/workpiece rigidity become. I turn 1/2"-1" bits very slow, with lots of lube.
They like to carve slowly. If you are spinning them fast, not using coolant, or your setup is not rigid, they won't last.
JR Dweller in the cellar
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"Greg O" goo1959S...@email.msn.com
I question your methods of hole drilling.
If you use a pilot hole, keep it small, near the size of the center web.
Also check your RPM, with a 1" hole slower is better unless you have a killer super ridged drill press.
My guess is the combination of a large pilot hole, and my guess is a low end, undersize drill press, is that the bit is chattering and the chatter is breaking the cutting edge off the bit.
Greg ...
Grant Erwin gr...@tinyisland.com
Dan, did you ever put a dial indicator on your drill press table farthest from the column and then put your full downfeed pressure on it? Even fairly solid drill press tables deflect under these conditions. That's why step drilling is mandatory on thick stock unless you just don't care if the hole is straight.
Trevor Jones t.o.jo...@sympatico.ca
These would have been Power Fist Brand? Canada's answer to Harbor Freight's low end line of Chinese tools.
Cheap but still not worth it....
Drills are worth paying the bucks for.If for no other reason than to save yourself the frustration of using the junk.Buy the ones you need , when you need them.Store them well ,and let your descendants worry about who gets them next.They'll last a long time.
Cheers Trevor Jones
"Dan Buckman" danbuck...@enter.net
Um, my drill press is a cincinnati gilbert, yer not going to get much deflection with a 1" drill bit Table is not going to move cause it sits on the ground, press weighs in around 6,000 lb and a good bit of that is in the arm and head, so it's like 3 or 4 thousand pounds you have to push just to counter the force of gravity.
Long ago before I had the neet stuff I just had a horrible freigh (one of their first when they just had a two page tool dispersal flyer) 13" bench top press, Drilled 40 1.25" holes with that in 1" stock, no pilot, not dial indicator either. I did however use a pipe on the quill feed.
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"Robert Swinney" judy...@attbi.com
Dan, Why, you're just the drillin' fool, aren't you!
BS ...
"Ed Huntress" huntr...@optonline.net
Whoa, those are big bits. What's the shank diameter? What's the shank diameter capacity of your drill press?
There are a lot of things that can be going on here. Many smaller drillpresses won't slow down enough to drive a 1" bit. My Walker-Turner probably would croak if I used it to drill 1" holes in steel.
Unless...you use a series of drills, starting with a small one (my drillpress is happy with 1/4" bits in thick steel) and moving up in steps to make that hole. You're probably doing that, because not many drill presses can shove a chisel point that big through solid metal.
Tell us, please, your shank diameter, the type of drill press, your rpm's if you know them, and whether you're drilling in steps, starting with a smaller bit.
Ed Huntress
Wayne Cook way...@pan-tex.net
Don't bet on it. I bet if you put a indicator on the end of the arm you'd see some movement. All that weight is pressing down and flexing the column and the arm. Any pressure downwards will cause it to raise some. I've used a much larger American Holewizard (it weighed in around 14-16k) and I've seen visible deflection of the end of the arm.
There's no such thing as no deflection. Just degree's of it. Big machines tend to deflect less than small machines. But the design of radial drills tends to leave more room for deflection despite the m*** of the machine.
Wayne Cook Shamrock, TX
petey pe...@noospam.org
Your drilling process leaves a clue as to why the drills are chipping.
The SD bits you have may be of lower quality, but you can make them last longer by not drilling in steps. What is causing the chipping is the chatter of the bit as it rides on the edge of the previously drilled hole. If your drill press is not very rigid and powerful and you must drill a pilot hole, drill it no bigger than the web thickness of the finish drill.
Also, back the steel with a piece of aluminum so that the drill does not chatter as it breaks through the steel.
It is up to you to determine if the more expensive drills are worth the extra cost, you give no information as to the manufacture or material of the drills you have. More than likely they are plain HSS which should drill well over a dozen 1" holes in 3/16 mild steel before needing a resharpening.
"Ed Huntress" huntr...@optonline.net
Somehow I missed Laurie's note that she was drilling in steps. So, ignore what I said about that.
Even so, a 1" bit is hard to keep from chattering in any drill press short of the monsters.
Ed Huntress
"Dan Buckman" danbuck...@enter.net
Yea well i see visible deflection in the arm every time i raise or lower it.
You may get some movement out at the end just because of the long arm, The angle will be small enuf as to be unimportant.
There will be such small deflection in the arm it'self as to be irrelivant.
so what deflection you get probably depends on how weezed out your drill is, and the slop between the arm and colom Which still should take most of the weight of the arm before it moves.
I didn't say "no deflection" I said "yer not going to get much deflection with a 1" drill" Since you didn't seam to understand, what I meant was Not much as in not enuf to make step drilling 1" give you any accuracy improvement relivant in light of the big innacuracy inherant with using a twist drill in a radial or other non precision drill .
further more in any of the drilling I do (not to say for anyone else) i have never found the deflection of any drill press used with any drill to cause me any problem. If you need a hole that close use a boaring barr.
I have a suspission that had I said I was getting lots of deflection you would have come in with the counter arguent of how little deflection there was in the drill someone else owned that you once used.
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"farmboy" no....@no.spam
Curiously, just the opposite seems to be said by some in the ongoing "Homemade tool and cutter grinders?" thread. That is, you should throw them out and replace them when dull, since you can't cost-effectively sharpen them well enough in the HSM environment. If so, then do the good ones cut N times better or last N times longer? Seems like a shame to toss expensive drills.
Best, Jude Miller
jim rozen jim_mem...@newsguy.com
What speed are you running them at? A one inch drill running in steel should probably be running at about 60 rpm or so, especially if it is a plain carbon steel drill. Slow things down, and the wear/chipping issues should go away.
Use some cutting fluid as well (sulfurized pipe threading oil) and that will help a good deal.
Jim =================================== please reply to: JRR(zero) at watson dot ibm dot com ===================================
"Ed Huntress" huntr...@optonline.net
Hardly anyone tosses 5/8" to 1" bits, Jude. Those suckers cost too much.
They're also the easier ones to regrind well.
Ed Huntress
nos ...@nospam.com
On Mon, 25 Feb 2002 21:29:13 -0600, "Greg O" Thanks everyone for your replies.....
I gather that going with successively larger bits is not a good idea i.e. better to start with a small pilot followed by the full size bit.
Not sure what is meant by the "center web" however.
Yes on all counts. Am using 210 RPM (slowest available) on a cheapie China 5/8" chuch drill press (Princess Auto special). There is some chattering alright esp as the bit size increases.
I'll try going from a small pilot to the max size but I wonder if my drill press has the jam to handle that big a cut at once.
Laurie Forbes
nos ...@nospam.com
On Mon, 25 Feb 2002 19:34:35 -0800, J R North Yes - that's what I'm finding. As to lube I've tried both WD-40 and engine oil, both in good quantity, and not noticed much difference between the two except the WD-40 produces more smoke.
Laurie Forbes
nos ...@nospam.com
On Tue, 26 Feb 2002 08:52:43 -0700, Trevor Jones Correct on all counts :) Actually I'm not all that displeased with the Power Fist drill press considering that I paid only $188 (Can) for it. It's not really suited for large bits I know but I get there eventually, just with a measure of irritation.
I hear you but I don't wnat to throw good money after bad (if the good bits don't work all that much better than the bad in my less than robust drill press).
Laurie Forbes
nos ...@nospam.com
OK - I'll try that as well.
I mentioned they are Silver and Deming. The only markings are "HSS 1 CHINA". They also have a black coating which come to think of it looks similar to the coatings on a cheap and useless sets of taps & dies I also have :) That's pretty much what I was told at the store so it appears I'm doing something wrong.
Laurie Forbes
"Ed Huntress" huntr...@optonline.net
There is no hss named "hss 1". You have some Chinese junk, probably what they call "M50 equivalent." That's a very cheap, low-performance hss made worse by avoiding any use of tungsten.
Good luck. <g> It should work if you don't get it too hot, and you'll have to accept more-rapid wear than you'd get with good hss. It shouldn't chip, though, unless it was badly heat-treated or you're just beating it up with chattering or grabbing.
Ed Huntress
nos ...@nospam.com
On Tue, 26 Feb 2002 21:06:03 GMT, "Ed Huntress" Actually the "1" was the bit size (I should have been clearer about that).
I don't find that hard to believe - same as my cheap tap/die set I suspect I would not doubt its the chattering/grabbing that's causing most of the problem. I'm still uncertain though if the good quality bits would be more resistant in that respect.
On the topic of steel quality, I recall one can tell, at least to a certain extent, what kind of steel is involved by the type of sparks that come off the grinder. I think I'll compare my cheap drill bits to some known tungsten alloy steel I have.
Laurie Forbes
"Greg O" goo1959S...@email.msn.com
I also have a cheapy drill press with a 3/4 HP motor and often drill holes of the size you discribe. I use a pilot hole of around 1/4", slow speed, make sure the belts are TIGHT, and feed it as hard as you can without beaking the table off the stand! I replaced the factory belts with AX series of belts, much better at power transmission than the A series, cloth wrapped belts that come with the drill press origanially. some swear by the link belts available, I have not tried them.
In your case this should help!
Greg ...
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