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Help with a split curl on flat bar


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Unless they've been mistreated: age, rust and dirt doesn't mean clapped out. When someone claims vintage/antique I tell them rust and dirt lowers the value, I don't pay for rust and dirt. Two tests you should do: plug it in and turn it on. Second, hold the drill chuck and try to move it sideways, it should NOT MOVE sideways. A very slight bit of a jiggle is okay but if it rattles it's not good for any sort of precise drilling.

Uh .  . . D, if you're breaking small drill bits you need to refine your skills. You're allowing cuttings to fill the bit's flutes and bind in the hole, you need to retract it and clear the hole more often. The reason more small bits are missing from indexes is because they're much harder to sharpen and easier to dull than larger bits. They're also much easier to lose. 

The reason oil keeps drill bits cooler is because lubricant reduces friction. Cutting oil is NOT a coolant, cooling is a secondary benefit if all you needed was a coolant water would work better. WD40 isn't much better than water, use something heavier, 3in1 is about as light as is much good and it is good drilling small holes say 1/16" and smaller. When you clear the hole put a drop on it before advancing the bit back in so the end is lubed. DO NOT use thick oil unless you're drilling 1/2" and larger, thick oil can stick cuttings in the flutes and bind the bit.

Backing bound bits out stands as THE rule of thumb for getting stuck bits out without damaging them! If the bit is bound by cuttings backing it out lowers the pressure binding the cuttings between flute and hole wall. Just pulling or turning it forward increases the pressure binding it and increases the PROBABILITY you WILL break it. Think you can't break a 1/2" bit with a hand drill? Hmmmm?

A bench top drill sharpener is a good investment, a SHARP bit: cuts cleanly, is less likely to bind breaking through, runs cooler, puts less stress on your drill and YOU. I've had mine for more than 30 years and I know how to sharpen drill bits on the bench grinder. My bench grinder has two wheels, a medium and a fine and I WILL YELL AT YOU for grinding ANYTHING but a cutting bit on it. Lathe bits, fly cutters, etc. are allowed, your axe is NOT.

Anyway, my old bit sharpener is old enough I did a web search to see what's out there. And GLORY BE you can get bench sharpeners that will sharpen split bits! :wub: Drill Doctor DD 750X sharpens split bits and uses diamond abrasive drums so they don't wear out of shape! I did a little looking and they're kind of spendy, lowest price I saw was around $100.

I'm not recommending Drill Doctor but I know they work and well. There are others out there that will handle both type drill bits and most max out at 1/2". Some are powered by your hand drill and sell for as little as the $12 range. Others are guides for your bench grinder. 

A sharp bit is a joy to use. Learning to sharpen the on the bench grinder is as satisfying as learning any useful skill is best it'll improve the quality of your work and save you money for an investment in time and a drill gauge.

Yeah, I know I'm going on again but sharpening bits goes WAY back with me, you can't spend much time in a machine shop without learning to sharpen bits. Even carbide inserts need a touch for certain materials and carbide drill bits are near the bottom in bit my drawer, they're only good for really junky materials say drilling a hole through a poor arc weld and breaking through included slag. They dull and surprisingly easily, just a second of chatter and they're pfft.

Frosty The Lucky

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I need to learn to sharpen my bits. I’ve looked up how to do it several times, just haven’t attempted it yet. I’ll also look for some better oil. I’m quickly getting an education on what is right vs what I thought I knew lol. Looks like I need to scrap my “knowledge” and hit the books. 

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I have an old ("vintage") Black & Decker 7900 drill bit sharpener that I use for the smaller drill bits 3/8ths and smaller. It does a really good job sharpening them. For the larger bits, I sharpen them free hand with the bench grinder. My grandfather showed me how to sharpen bits with the grinder over 60 years ago. It's just easier to use the B&D on the small bits.

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On 5/3/2021 at 6:46 AM, JHCC said:

So, 1:2, 2:3, 3:5, and 5:8 are all really easy to draw and are each quite pleasing to the eye

Wow, stay away for a "bit",,, and you miss a lot.

I actually do the same. and use those ratios to get me in the ball park. Ive sorta evolved a scroll/taper ratio that fits within but not identical to those parameters. It makes me feel good so I favor it in my forgings.

I nearly always do a center punch and pilot hole when drilling, and the size of the pilot is just a bit bigger than the flat at the tip of drill bit. This way the bigger bit starts easier because it doesn't have to overcome that flat spot. Too big of a pilot and the bit has a tendency to grab when starting to cut.

My center punch cross section is square not round. At a yellow heat it seems that it is easier to see, and is more obvious when you brush or knock away the scale. I think i read that in the Ring long ago, and liked the feel of it as well.

I was'nt so fortunate as to have a Grandfather teach me how to sharpen bits, but a good friend did. I still do them by hand.

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I'm considering getting a Drill Doctor, which apparently does a good job of sharpening split point bits, as well as converting regular bits to split points.

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I was taught to use a square center punch for that reason as well, and if it still visible when you done, it a bit more decorative.

David

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JHCC, you can't to wrong with the Drill Doctor.  I've had one for years, use it all the time and highly recommend it.  I have the 500X which will do up to 1/2" bits, split point and dual angles; 118* or 135*.  The next one up is the 750X and tends to run about $40 more than the 500X.  Main advantage of the 750X is for larger bits, 3/4".  On Amazon, they are about $100 and $135 respectively.  I think the 500X is fine for just about 90% of the DIY crowd.

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A note for drilling holes for those who pilot them. First off, the chisel point of regular old drill bits has been working just fine for hundreds of years. If they aren't working for you, don't blame the tool. How well a drill bit works is often about power, your drill motor has to be powerful enough to keep the bit cutting at a steady rate. If your drill press stalls rather than producing two clean curls of cuttings it's not powerful enough for the given diameter bit and you MUST pilot or put  up with poor holes and damaged bits.

Everything has limits, it isn't the tool's fault if they're exceeded and fail.

Piloting holes. The correct size to pilot a drilled hole is 1/3 the diameter of the finished drill dia. I pilot 3/4" and larger, the correct pilot bit for  3/4" drill is 1/4". A lesser dia. increase changes the process from a piloted hole to chasing.

Using less than 2/3 of the cutting edges of a drill bit applies a dangerous amount of pressure and strain on the edges. Dangerous to the drill bit and hole quality, not necessarily to the operator. Though if your shop skills aren't good jamming a bit can endanger YOU, especially your fingers and blood level. 

I have a weak sister drill press, a $69 special from a closeout tool store more than 40 years ago. I can't follow the 1/3d pilot rule, I have go to a 2/3d pilot over 1" holes. It does a fine job drilling silly large holes, I have bits up to 2 1/4" I've used, there are larger ones in the collection I haven't use.

I still kick myself for passing on a really nice if old and rusty Auto feed, Dayton Gearhead, floor drill press with a 2hp. single phase motor but I didn't have 240v in the shop unless I fired up my welder generator. The asking price was $100. <sigh> 

While I've been snagged by wildly flailing evil vampire drill shaving I've never bled at a drill press because I don't drill holes without the material being clamped to the table HARD. Putting something in a drill vise only counts if the vise is clamped down, a piece of metal spinning 120rpm weighing 3lbs, (my old, light weight 0 axis, drill vise) will shatter bones in your hand easily. Clamp it down!

The bit is much more likely to snag on break through if the pilot is too large. 

Chasing a hole is typically done for high precision, NOT placement. (prevention of wander) A good example of a chasing process we're more likely to need is making pivots for say a treadle hammer. You want the pivot pins to be close fitting AND free moving so a porous bronze bushing is a big plus. A drop of oil will saturate the bushing and keep your pivots lubricated and rust free. Good yes?

Thin bronze bushings don't suffer lash well, that's space between either the male or female components of the bearing. You want really close tolerances and smooth, even polished surfaces on the moving part, usually the pin. Matching the pin to the bushing is easy, polish it till it's right.

Getting the female of the joint right is a little trickier, drill bits don't make a very smooth hole, not awful if it's sharp but not really very good. It will make a more true and smooth hole if you hog it rather than chase it to Dia.

Chase the last few thousandths with a mill cutter, they are precision instruments of stock removal, certified to strict tolerances themselves. The flutes are not designed to carry cuttings out of a hole like the flutes in a drill bit. The flutes in a mill cutter are intended to allow cuttings to drop out through the bottom of the hole and by their shape prevent binging. 

Frosty The Lucky.

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My snapping smaller bits with hand drills is probably a little bit (NPI) cuttings clogging the flutes, but is mainly too much speed and not keeping the drill vertical over the hole. The bit binds and snaps. This never happens when I am using a drill press. 
 

I forget who it was earlier in this thread who said “high pressure : lower speed”, but thanks. I tried that yesterday and bits I had thought were dull cut very well. 
 

I also tried hand sharpening a bit. No luck. All I managed to do was make the bit about 1/4” shorter.  I even had a brand new bit to use as a reference. I am buying a Drill Doctor. I usually use cobalt bits, so it would pay for itself in only a few years.

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Sharpening drills is easy peasy once you learn the "wrist flip". When i first started in a machine shop years ago i asked about sharpening the drills. An old guy pointed to the snag grinder, then proceded to teach me how to do it. The trick is to hold it at the proper angle then flip the wrist so that you cut the back side lower than the cutting edge. Easy to show, hard to explain. Also a good sharp stone on the grinder is required. 

Another note is relieve the back of the drill. Get that cutting edge as thin as possible. The relief will help chips get pulled out of the hole, and provide some room so they do not build up and get snagged. Many of the newer larger drills come from the factory with the back side relieved now but not the smaller ones. 

Cutting speed an pressure is dependent on what you are cutting and with what. A carbide drill cuts at a different speed than a HSS and stainless cuts with much more pressure than mild. The trick is to get enough pressure so you have a proper chip but not so much that you burn it up with to much pressure. Deeper cuts require multiple cuts also. Cut about 1/2" pull the drill, blow out the hole, drill and repeat. Never try and take a deep hole in a single cut. 

Heat is what make things hard to work. There is heat build up in 3 places. The tool, the piece you are working, and the chip. If your tool heats up it becomes soft and will not cut, if the piece heats up it work hardens and will not cut, what you want is to get the chip to carry the heat away from the tool and the piece you are working. That goes back to getting a proper chip for the material. 

Do not use to much oil. When hand drilling a couple drops is all that is needed. If it starts to dry out a couple more. Do not flood the area or fill the hole with oil. That will just waste the oil and the oil can bind the chips in the hole. I get cutting oil from work, a quart of oil is still about 1/2 full after a year. The oil does not have to be anything special either. Water can be used but evaporates fast. Just something to lube the hole and drill. 

Pilot holes are not necessary either. I have cut some pretty big hole and the only thing i ever do is maybe use a spot drill on big drills. Just enough to get it centered. 

A lot of new fangled drills are on the market now but a good quality set of old fashioned HSS twist drills will last you a lifetime if you keep them sharp and use them properly. The majority of the drills i have replaced is becuase i have lost them. There really is no need for the specialty drills in the home workshop. Even in the shop at work we mostly use HSS with the occasional carbide or coated drill. Getting into cutting materials other than steel (brass, aluminum, nylon, copper, etc.) is when we start getting into the specialty drills. Also a carbide or coated drill gives a different chip than HSS so you have to watch that. 

You can tell a lot about how your tooling is by how the chip looks. For instance a HSS drill cutting mild should make small chips if it starts pulling a spiral the drill is getting dull. That is a general rule of thumb. 

I posted this on another thread but think it is worth posting here. To get the speed and feed to cut is a simple formula. You do need some info to plug in though. RPM = (FPM x 12 / PI x dia. of tool) . FPM will change with material and tool. Those can be found from the tool manufacture and the material supplier or there are about a dozen books on the market with that info. (RPM x PI x tool dia. / 12) will give you FPM. 

For those who may not know: HSS is high speed steel and FPM is feet per minute. 

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Titanium and other such coated drills become plain HSS after sharpening, correct?

What about mill scale or high carbon steels, HSS works well for those?

Carbide requires a press?

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BillyBones, I dont have a machinist background but i pretty much do as you stated. I pilot most of my holes, from about half inch and up for sure.I use water for lube for under half and a good cutting oil for larger. I dont use auto feed, i am the "auto" feed.  ;)  It doesn't take long to get a good feel of your drill press and proper cutting pressure. When you dont use the auto feed, clamping your material becomes pretty situational, not a hard and fast rule. When you self feed, you can feel the grab begin and backing it off a bit keeps it from binding up. I look at it this way, you are standing there anyway,,, might as well use both hands.  :)  However I strongly recommend clamping everything if you use self feed,, it will bite you and break your bits. HSS is all I use and they will last a lifetime.  

I think if you check,  a 1/4" pilot for a 3/4" bit is within the ball park of "a little bigger than the flat of the tip of the bit". I may use a 7/32", and because i self feed, I can better center the bit in the hole then gently increase the down force as it begins to cut. So close enough for me for a rule of thumb vs shop practice. 

If you sharpen your own drill bits you can change the cutting angle of the bit for different steels, cast, brass, etc, so yes, HSS is all you need. However i often dont do that and adjust for the differences by my self feed control of cutting pressure.

I use my "new" camel back and my "old" industrial post drill(motorized) for my drilling. Both have their nuances and do the job.

You might consider A good next addition to your shop would be any kind of a drill press. A hand drill just doesn't cut it,,, you might say.

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Generally yes grind a coated drill and you have a HSS drill with coating on the secondary edges, sides. However they do make carbide and cobalt TiN coated drills. Those are found in specialty applications like aircraft manufacture. They also cost a pretty penny. 

1030 is a pretty high carbon steel for what i do at my job. However i have cut much harder steels at home on my drill press but i do anneal the material first. So i cannot say yes it will cut it but i can say i have done it annealed. Keep in mind many of the cutting tools you are already using are made of HSS steel, taps, dies, files, etc. Most of the HSS steel you will encounter is of the M-2 or M-50 variety. Cutting steel is all about speed and feed. 

Anvil, what is this auto feed that you speak of? 

Frosty, i am like you, a hand drill is for shootin screws. I aint no good with one either. 

 

 

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I'm going to give my cheap drill press it's maiden run drilling some 5/16ths holes this weekend on a 3/8ths in thick set of tong blanks I've had sitting around forever. I usually just punch them but this seems like a good way to get acquainted with the drill press. This is all dependent upon the vise showing up before then. 

Pnut

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BillyBones, both my camel back and my industrial post drill have auto feed if you want. On the way to town I realized that most modern drill presses probably don't have an auto feed. I drill a lot of holes as a traditional smith. Figure a 10' rail, pickets to code with two tenon's on each picket. Perhaps that's why I can feel my bits start to grab so I can back off on feed to prevent problems. I shouldn't assume that's true for all. My bad. 

And you are correct. Feed and speed are the two prime factors along with sharp and proper angles.

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I have used auto feed drill presses before, i was just joking about who really uses it. Everyone i know does it by feel. 

My drill press is an old Cummins built in 1978. Works great need new belts though. I found a machine shop here that had a big 3 head drill press for sale. But the wife would have hurt me if i spent what they were asking. 

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I've certainly broke my share of drill bits whilst "getting the feel", but hey, that gave me good practice sharpening the dang'd ole thangs!

Lol, that's just a puppy! The patent date on my camelback is 1900! I got a steel on both and two different people rebuilt each for me. The post drill needed  bushings and a thrust bearing. I have about $100 in it and used it as my daily driver for about 15 years. The camelback was also a give away and another good friend and machinist rebuilt it. It needed a journal cap and that's about it. He traded me for cabinet hinges for his house.

There are things I can do with the post vice that I can't do with the other. Lol, if my center punch is a little off on a cap rail, I can tilt the cap a bit, apply a little bit of feed speed and walk the pilot drill to just where I want it! What's the warning on FiF? Don't try this in your own shop just  because you heard it here?  

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The machines i run at work are called Davenport screw machines. Imagine a 5 spindle lathe that indexes to different cutting positions. But i hold tolerances within .0005". One of the machines has a 1906 build date. Proves that old tech is still good tech and if taken care of can last forever. Davenports are now all computer controlled CNC things that just need button pushers.  

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