Drill Bit Problems

[TomG]

I ordered a 37/64 bit along with my Emporer Kit from CSUSA and the bit drilled a hole way off at the top but then perfect fit at the bottom of the blank. I drilled at about about 2000rpm. Rosewood Burl Blank. Then I tired some soft and hard woods same thing happened.

When I drilled the bottom of the blank with a 15/32 bit from AS no issues.

Did I do something or could the bit be off? Blank is now ruined, hole is larger the diameter of the bushing at the top of the blank.

Tom

 

[TomG]

Just figured it out the damn bit is crooked! I should have realized it when the drill press was almost vibrating off my table. I guess I'll call CSUSA on Monday.

Nice blank from Nolan too!

Tom

 

[btboone]

That's also spinning pretty fast for such a large drill. It may keep more accuracy by slowing down a bit and clearing chips more.

 

[TomG]

Originally posted by btboone
<br />That's also spinning pretty fast for such a large drill. It may keep more accuracy by slowing down a bit and clearing chips more.

I thought that also so I slowed it down twice with the same results.

Tom

 

[Rifleman1776]

Remind them that the defective bit cost you some high quality blanks. Their bits are China made and elsewhere cost 50 cents to $1.00 each. They charge $6 to $10 each for them. You should get quality for that kind of money. I'm a CS customer and like the company but there is no denying they have some quality control issues.
BTW, bad bit or not, that 2000 rpms is too much. I do 90% of my drilling at about 500 rpm.

 

[Mikey]

Be careful about saying that the bits cost $.50 each and are made in china. I have several high quality bits from them that for sure cost more than a buck each. I also buy from Berea hardwoods and they sell USA made bits that often cost as much as what we pay for them. They don't markup much if anything at all because they want us to use their kits. (sell accessories cheap so you buy more of their stuff.)

 

[Tom McMillan]

I've been doing some call blanks with a 41/64 inch bit I got from Hut ($17 plus), and I've also been using a 3/4 inch bit for them. I have my speed at 640 RPM and the 41/64 works great at that speed. I need to get a better 3/4 inch bit and may get it from Hut too as the other drills so well.

 

[Rifleman1776]

Originally posted by Mikey
<br />Be careful about saying that the bits cost $.50 each and are made in china. I have several high quality bits from them that for sure cost more than a buck each. I also buy from Berea hardwoods and they sell USA made bits that often cost as much as what we pay for them. They don't markup much if anything at all because they want us to use their kits. (sell accessories cheap so you buy more of their stuff.)

The ones I have gotten from CS have "CHINA" stamped on them. Anybody can buy China bits at under $1.00 each retail.

 

[Jim in Oakville]

I drill at slower speeds, usually 500 rpm

 

[Fred]

Slower is "usually" much better for drilling. If anything, higher speeds create higher heat and we all know what that does ... (1) warped bits (due to the heat) = irregular holes, (2) CRACKED blanks. Just to list two off the top of my head.

Slow down and let the bit do it's work. Also, try rolling the bit across your saw's table top. IF it is warped you will see it rise and fall as it rolls along. This is assuming you have a table saw! []

 

[KenV]

Vise and runout on the drill press can also cause the overlarge hole at the top and right-on at the bottom. A bit that is off a bit will amplify the problems with a loose vise or sloppy quill.

 

[TomG]

Originally posted by Rifleman1776
<br />Remind them that the defective bit cost you some high quality blanks. Their bits are China made and elsewhere cost 50 cents to $1.00 each. They charge $6 to $10 each for them. You should get quality for that kind of money. I'm a CS customer and like the company but there is no denying they have some quality control issues.
BTW, bad bit or not, that 2000 rpms is too much. I do 90% of my drilling at about 500 rpm.

Thanks for help I tried at at 620rom still crooked hole and there is a slight wobble when I rolled it over my table saw top.

Since you brought it up about speeds, is thier a rule of thumb with wood types and drill speeds?

Tom

 

[hrigg]

I've heard figures from 450 to 900 rpm. My DP only goes down to 620 and the next belt/pulley combo gives me 1100 or so, so all the drilling and milling gets done at 620.

 

[Tom McMillan]

I found some online tables for drill speeds. However, some turned out to be too slow for the woods I was drilling, so I stepped it up some---looks like a bit of trial and error to get the right speed---depends on the type of drill bit you're using and the type of wood you're drilling.

 

[TomG]

CSUSA is going to have a new bit sent out to me after a technician checks the bit prior to shipping.

Could I just buy bits from McMaster if I wanted of the same diameter? I ask in case this happens again I can get a bit the next day.

Tom

 

[Pipes]

The only stuff I have to drill at slow speed is Acryluster . Everything else I drill at HI speed but thats me . But I clear the drill bit a LOT .[] And I drill slow . I use HF bits and a Drill Dr. BUT if I need just one bit I buy it from BB at AS he carries very nice quality bits IMHO .[8D]

 

[bob winegar]

Is it just that the entry hole is elliptical ?

 

[skiprat]

I was always told that 'the harder the material, the slower the speed'
If you want a 'clean smooth' hole in wood, you therefore should use a higher speed. Feed rate is very important too. If you ever use a router, you will know all about relationship between bit speed and feed rate. A router is designed to cut wood at a very high speed but if the feed rate is too slow, you will burn the wood.
If the feed rate is too slow while drilling a hole, it will probably blow the wood.[]
Likewise, when you turn wood, you will often crank the speed up to get a smooth finish.
When drilling plastics, I have found ( and been told ) NOT to use a freshly sharpened bit as it will often 'snag' and crack the plastic.
'Dull bit, high speed, slow feed' Conversely, if you wanted to drill in stainless steel for example, you would have the sharpest bit,lowest speed and steady 'firm' feed rate.
Frequent clearing of the hole goes without having to be said for any material.
There is a trick that people who drill often into plastic sheet do.
If they only have a HSS sharp bit, they will often 'dull' it by a quick touch on a brick or the floor while the machine is coming to a stop.
Another trick for drilling plastic, is to shape the bit differently.
After it has been sharpened, you can grind an angle on the cutting faces. Sorry for being vague on that, but I'm sure you could google instructions on how to grind it. I have seen this angle already ground into the pilot bits of several holesaws.

A bit long winded, sorry. But the point I was trying to make is that you want to 'drill' the hole and not 'screw' the bit through the soft material.

Of course, there are hundreds of ways of doing something. But this works for me.[]

Just found a picture that shows the angle to grind[]

<br />

 

[Rifleman1776]

Skiprat, your comments may be applicable, in a very general way, to a lot of drilling applications. But for specific needs, like drilling end grain into many (maybe most) woods, faster is not necessarily the best technique. In my experience, the slower speeds are more consistent and trouble free. Slower avoids rapid heat build up which can ruin a blank in a blink. Your router comment is not anologous to drilling. Even a high speed router can tear up many woods if you go against the grain or on a cross-grain cut. Thanks, but I'll stick with brad points at slow speed for pen blanks.

 

[PenPal]

Drills and drilling is as subjective as finishes,I mostly only turn slimlines and only use one drill type the Pilot Point DeWalt 7mm
extreme 2. These are made in USA and I get up to 400 plus drillings,retail price 5.60,I never vary the speed from quite fast but rely on the feel when it cuts various timbers,just finished 500 blanks,no blowout,no tracking,I use Corian a lot and these drills suit me very well. Some of our timbers are harder than most,one timber that can easily choke while drilling is Cocobolo.Never used anything under a blank to prevent blowout.
One occasion I was doing a demo at a Working with Wood show,taking no chances fitted a new drill in the Jacobs Chuck in tail stock,needle jaws to hold the blank and burnt a drill,smoke and squealing,the lathe was switched in reverse,very embarrassing.
My feeling is we should use the drill and speed that suits us,same as driving a car or riding a pushbike.
Never look forward to drilling and finishing Ebony and regard it as very hard to find a full black of high quality. Peter

 

[skiprat]

Frank, this reply is not intended to be arguementative or confrontational. We are, after all only discussing holes[B)] I am certainly no authority on drill bits, but I do know some of the principles. The first is that most drilling in any material is more often than not a compromise. The variables are incalcable (sp?)but the types of bits are limited. I honestly have no idea what 'anologous' means, and even struggle to say it. My example of the router bit burning wood was used as this is the most common visible area where burning is seen, but the same principle applies to any steel blade spinning, rubbing, oscillating, etc against a piece of wood. The metal that is touching the wood, but not actually doing any cutting is where lots of heat is generated. The twist drill grinding I showed is for plastics. Up till now, I too have been using brad point bits for drilling end grain, but not for long. I first heard of 'bullet' type bits right here on this site. I guess they are not too common as they apparently cannot be sharpened. A brad point bit is by design made for drilling neat holes across the grain. The two spurs cut like a knife across the grain and then the regular faces dig in and lift out the waste.If the spurs were not there, like on a twist drill, then the the bit will try to lift the wood that is outside the hole. The centre point of course just tries to keep the bit straight. However, when drilling end grain these spurs are pretty useless. In fact all they tend to do is make heat. Because they are now parallel to the grain, they simply don't do anything except push the fibres away and compress them against the sides of the hole and force the main cutting surfaces to work harder. This friction just makes more heat. Even the long point is not as affective any more. The point is not a cutter and because of its length is more prone to 'glance off' or even follow some particularly hard bit of grain in the wood. In effect, I guess that because of the spurs and the point you (we)are actually trying to drill a 7mm diameter hole with only about 4.5mm of cutter edge. In an ideal world, drill bits would have no points, not even twist drills. We could start a hole with a pointed bit, then change it for a flat one I suppose. But that is just a hassle and we live with the compromise.
With regards to speed, my logic says that we want the drill bit in the wood for the least amount of time and to cut a smooth hole as possible before too much heat builds up. Again the compromise. I am surprised at how slow we have to have non-cutting metal against wood or lots of other materials for it to get pretty hot. Another example, one most of us have done; you grab your drill/driver and try to drive in a wood screw into some dense wood but we're too lazy to drill a pilot hole. You get the screw most of the way in before the machine runs out of torque or the driver bit starts to chew up the slots on the screw. You slap the machine in reverse and back out the screw till its hanging out the hole, then grab it. Hot enough to leave little b'b'q lines on your finger tips.[]And that could have been at about 50 revs. But I digress.
Enter, the Bullet! What a cool idea! The point is short so is less prone to wander. The point is a cutter so cuts through the tough grain instead of being steered by it. It has no spurs that are doing nothing. The main cutting edges are pretty flat so they don't try to push the wood out of the way. In fact, I believe that the total cutting edge length is longer than the bit is wide. Thats clever and I can't wait to get some.

Of course I will qualify my statements by saying that this all could be rubbish, but as it makes sense to me, I believe what I've been told by some bright guys and it works for me[8D]

 

[loglugger]

On wood I use my air hose and blow air down along side the bit, that will help keep the bit cool and help got rid of the cuttings. Use safty glass. Have never tryed plistices.
Bob

 

[ahoiberg]

obviously all over the board here, so i'll try to add a different angle on blowouts.

if you just cut the blank longer than need be, doesn't have to be much longer, and drill a little further than the tube will insert (without drilling all the way through the blank), you'll eliminate blowouts almost completely. i found this out the hard way with a few acetate acrylic blanks i tried. maybe this is common knowledge, but maybe it can help someone. once you've drilled, just mark the length of the tube and bandsaw off the extra and whammo, perfect hole without widening or blowout. and if the hole is widened a bit on the top 1/16th of the blank, just glue the tube below that and barrel trim it down.

as far as bits go, if you've got a fastenal store near you, they carry they norsemen drill bits which are really nice. great bits that come super sharp. the price isn't TOO bad considering the quality.

to each his own.