12.5 mm bit

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ed4copies

ed4copies

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I would like some feedback on this bit.

Mine ate my first attempt at a plastic blank. I put it aside and went back to my old bits.

Today, I got an e-mail from a member trying to drill cats and blowing them up (has NEVER happened before), turns out to be the same bit.

I BELIEVE the flutes are cutting aggressively and ANY vibration is leading to "breakage".

Has anyone used this bit succcessfully in plastics???

Thanks in advance!!
 
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I've also made some Jr.s using acrylic and that bit. I drill at 500 rpm clearing every 1/8" and I don't drill all the way through. I make my blanks a little long and trim on the bandsaw after drilling.
 
Yep, same here. I was drilling some Texas ebony and blew up the first 3 tries. It will always happen as the bit was cutting through the bottom end of the blank it would try to lift the blank and SNAP goes the blank. I tried drilling fast and drilling slow and it was still hit and miss. So, now I do like Rick, I cut long and do not drill all the way through then I cut off the bottom end on the mater saw (very carefully).
 
Ed actually come to think of it I did have one half of a Acrylic Acetate #02 - Doodles crack on me as I went through the blank. I do not remember which end it was, but I think the nib.

Here is what I think is happening. When drilling on a drill press using a drilling vise, we might have it too tight in the vice and thus compressing the blank as we drill. Once you drill through the end of the blank the stability in the material is no longer there and it colapses under the stress.

Anyway just some thoughts on it.

Mike
 
It used to happen quite often. I haven't had the problem when I drill similar to Rick's method. The only additional step is that when I clear every 1/8", I also cool the bit and acrylic with water and occasionally use spray silicone drylube. Without the cooling, the acrylic shavings are almost soft enough to form a doughball.

I've had trouble with several CSU bits vibrating significantly more than others, but just assumed it was me and my drillpress.
 
The CATS materials are the easiest to work synthetics I have encountered. I have drilled a lot of blanks with a 12.5mm bit and can't recall any problems with it in any material. I did modify it to be a split point with the drill doctor and I sharpen it frequently. I also never allow the bit to create an exit wound in the blank.

That said, I'll probably blow up the next dozen that I drill with it. ;)
 
Ed, sometimes the design of the flutes and the cutting angle of the tip can effect the way different materials cut.
I had a problem with some drillinig and sent an email to Sandvik-Dormer in the UK. they replied within hours with information, including where I could buy the suggested bit at a location closest to my address!
I think there are bits designed for "plastics" so it might be worth a try to email them.
To me, Micah's suggestion seems the most sensible to follow shoul you not find a satisfactory bit.
 
Thanks to everyone, and I hope more will respond.

The one I blew up was enlarging a hole in the first acrylic Eagle attempted. The 12.5 mm bit was BRAND NEW. Touched the material with the flutes and splinters all over the room.

Needless to say, Eagle had a lot of time in that blank, so I was very distressed that I had broken it. Since then, I tried a couple others and again, felt the bit was at least a contributing factor.

However, today's e-mail about drilling the cats reminded me of this problem, so I want to know if I should just be warning people that MY experience with that bit has NOT been favorable.

So, thank you to ALL who respond (yeah, even you, Cav!!)
 
Originally posted by MLKWoodWorking

Ed actually come to think of it I did have one half of a Acrylic Acetate #02 - Doodles crack on me as I went through the blank. I do not remember which end it was, but I think the nib.

Here is what I think is happening. When drilling on a drill press using a drilling vise, we might have it too tight in the vice and thus compressing the blank as we drill. Once you drill through the end of the blank the stability in the material is no longer there and it colapses under the stress.

Anyway just some thoughts on it.

Mike
Click to expand...
Shouldn't happen, your making a circular hole, strongest structure and the force would be applied equally, part of the problem is not clearing the bit, the materail can't go up and certainly can't go down so it starts to push out and wants to crack the blank.
 
Ed, there are several things you can try. First is to dull the drill bit. I know this is controversial, but people that drill plastic sheet do it all the time. It tends to stop the drill bit 'grabbing' or 'pulling' its way through the material. Next you can Google 'drilling in plastic' There are some easy ways to sharpen a bit specifically for plastic. Another method I use is to increase the speed of the drill but decrease the feed speed. This way seems to get a nice clean hole, but you need to take your time to prevent heat build up. It is not the cutting edge of a bit that causes heat, it's the sides of the bit and the waste between the bit and the sides of the material.

I really try to avoid drilling 'pilot' holes. Just about all of my blow ups have been done that way.

If I have a 'tricky' hole to drill, then I will most definately do it on the lathe. My drill press has a lot of slop ( backlash ) between the quill and the handle. If the bit bites, then it will take up the slack and nose dive into your ( or Eagles ) blank and wreck it. Even if it doesn't bite, it often will vibrate and drill hexagonal holes!!!

Even if you only have a three jaw chuck on your lathe, you can drill an almost perfectly centered hole in a square blank. ;)

Yet another method I have used on complex glue-ups is to liberally coat the outside of the blank with CA and saw dust to make a hard shell that hopefully will hold it together while drilling.
 
Originally posted by wdcav1952

Ed, thank you for your premature thank you. :D My suggestion would be to send your difficult blanks to me to drill. We veteran turners are always happy to help a newbie. :D:D:D:D:D:D;)
Click to expand...

Happy to hear it. I have a couple hundred to do before April 1. Watch your mailbox!!!!

oh, They're pretty easy, only a couple are from Eagle. And there's a few (dozen) tru-stone, some of the metal blanks Dawn has made for me - as I say, nothing challenging!! Mostly just 5/8" acrylics that I want to make into Jr. Gents!!!

Turnaround time - 3-4 days is no problem.

Thanks!!!!:D:D:D:D:D
 
Ed,where is your 12.5 bit from,and what brand?
A good resharpening will help the csusa bit.
And even if it's a Norseman bit,while a very good bit,I will
second Skiprat's suggestions on a different sharpening
technique.
Also,is your vise clamped firmly to the drill press table?

I have had to "dub" or flat a 0° rake across the cutting edge
face of several drills to prevent them from hogging in
and blowing up plastics.
This helps slow the "self-feed" tendencies of a sloppy drill press quill.

Check this article,down to page 2,see picture "K" for an example.(The whole article is long,but a good read);).
http://www.newmantools.com/machines/drillpoint.html

Hope this helps in some small way.
 
Hey Johnny,

Is this a service you would offer your customers.
I happen to be the guy who blew up tho 2 "cat" blanks. (both halves no doubt)

I think it is the bit. Like one member comented it almost seems as if they are pulling the blank up too hard, which would lead you to think the rake angle is too aggressive???

I would love to try getting that changed before I ruin any more of those awesome blanks.

Let me know,
Steve

PS, got the dead center today...I will soon be trying the mandrel less method.

Originally posted by johnnycnc

Ed,where is your 12.5 bit from,and what brand?
A good resharpening will help the csusa bit.
And even if it's a Norseman bit,while a very good bit,I will
second Skiprat's suggestions on a different sharpening
technique.
Also,is your vise clamped firmly to the drill press table?

I have had to "dub" or flat a 0° rake across the cutting edge
face of several drills to prevent them from hogging in
and blowing up plastics.
This helps slow the "self-feed" tendencies of a sloppy drill press quill.

Check this article,down to page 2,see picture "K" for an example.(The whole article is long,but a good read);).
http://www.newmantools.com/machines/drillpoint.html

Hope this helps in some small way.
Click to expand...
 
Hey Ed,

Thanks for posting this.

I see a couple of tricks I am going to try.

1. I am going to try a pilot hole first.
2. I am going to stop short and cut the end off.
3. I am going to slow my DP down to 500 rpm.
4. I am going to try to get the angle changed on my bit.

Thanks again,
Steve
 
Steve,I'd be glad to help you.
Sorry about the blanks,those are too nice.
I'll pm you.
Originally posted by follow3

Hey Johnny,

Is this a service you would offer your customers.
I happen to be the guy who blew up tho 2 "cat" blanks. (both halves no doubt)

I think it is the bit. Like one member comented it almost seems as if they are pulling the blank up too hard, which would lead you to think the rake angle is too aggressive???

I would love to try getting that changed before I ruin any more of those awesome blanks.

Let me know,
Steve
Click to expand...
 
Originally posted by ed4copies

Originally posted by wdcav1952

Ed, thank you for your premature thank you. :D My suggestion would be to send your difficult blanks to me to drill. We veteran turners are always happy to help a newbie. :D:D:D:D:D:D;)
Click to expand...

Happy to hear it. I have a couple hundred to do before April 1. Watch your mailbox!!!!

oh, They're pretty easy, only a couple are from Eagle. And there's a few (dozen) tru-stone, some of the metal blanks Dawn has made for me - as I say, nothing challenging!! Mostly just 5/8" acrylics that I want to make into Jr. Gents!!!

Turnaround time - 3-4 days is no problem.

Thanks!!!!:D:D:D:D:D
Click to expand...

Ed, my computer crashed so I didn't read this post.
 
All CS bits I have used require sharpening before use. I use a Drill Doctor and put a split point on them. Yes, the 12.5mm has given problems with some delicate woods. In that case, I use an over-length blank, drill just past the tube length then bandsaw to spec.
No sympathy from here with plastics blowing up. They should. ;)[}:)]
 
I'm really glad to see Johnny (an expert, IMO) chime in to help Steve. I did not have a GOOD answer.

I do want to reassert, however, that the one I blew out (Eagle's), I had predrilled and it was being held in a beall collet, on the lathe. The conditions were as optimized as I could dream up.

Eagle and I have had SEVERAL LENGTHY discussions about this, since. We both believe the pre-drilled hole was a DISADVANTAGE in this instance. The flutes grabbed, there was nothing under the brad point, so no "straight hole guide".

I believe I would have been better off WITHOUT the pre-drill.

REMEMBER, I'M SO SMART I BLEW UP THE BLANK!!!! YOUR OPINION CAN'T BE ANY WORSE!!! Feel free to tell me I'm all wet (except Cav, he will be busy drilling for a couple weeks now - as a dentist, this should be right up his alley!!) I still have more blanks that I will have to drill!!!
 
Originally posted by ed4copies

The flutes grabbed, there was nothing under the brad point, so no "straight hole guide".
Click to expand...

Ed, didn't you know that brad point bits are the spawn of the devil??????[}:)]

The only time I've ever had problems blowing up blanks of any kind was when I used brad point bits. I quite using them a long time ago.
 
Originally posted by gerryr

Originally posted by ed4copies

The flutes grabbed, there was nothing under the brad point, so no "straight hole guide".
Click to expand...

Ed, didn't you know that brad point bits are the spawn of the devil??????[}:)]

The only time I've ever had problems blowing up blanks of any kind was when I used brad point bits. I quite using them a long time ago.
Click to expand...

Brad points are the berries. For pens, I use twist in only two sizes and that is because my brad points sets don't have those two. Pre-drilling (e.g. guide) holes are a no-no with brad points. We are all guessing as to the cause of this blow-out but the pre-drilling could be the culprit. In this case, we have a plastic that was a glued up segmented blank. That may mean different density materials were used. A grab was probably the cause. And, such a recurrence might be unavoidable when dealing with plastic glue-ups. Woods are more 'cuttable'. Turning plastics is more of a machining operation. qualify: that's IMHO.
 
Ed,
I have had poor luck with pre-drilling.
As to why,I will say that a drill cutting solid material
uses a combination of different cutting actions.
The point area does more extruding than cutting.
The outer portion has a more aggresive action.
This all balances itself out in how we are use to feeling a drill cut.
When you remove a portion from the center of a hole,by pre-drilling,
you remove the part that is more difficult,and requires more pressure to drill.
This leaves the outer edges of the drill to cut agressively,as is their nature,
and it will hog into your blank much quicker than drilling solid.
I think this will explain why things happen the way they do,
or at least can happen,as it did with your Eagle blank.
just my 2 cents worth,hope this helps.:)
 
Let's take the easy part first. I don't know what your problem is. I have a couple of ideas; but they are essentially guesses although I would agree with Rudy that the bit size per se has nothing to do with it.

Twist drills are pretty much taken for granted by most folks, yet their geometry is very complicated and if you get it wrong, they don't work very well. The average home mechanic runs down to Home Depot or Ace and buys the same 1/4" drill bit regardless of whether he is drilling a 1/16" piece of sheet metal, a 1/4" thick piece of steel angle, a 1/2" thick piece of oak shelving, a 2" block of Plexiglas or a chunk of lead. Well, it doesn't make much sense that the same twist drill would do a good job on all of these various materials and the fact is that it doesn't. Fact, also, is that most folks don't understand that you need different types of twist drills for different materials. Sadly, getting a twist drill that is optimized for a particular drilling task can be difficult and expensive so most folks just buy your standard compromise hardware store bit and do the best they can.

I don't claim to be an expert on twist drill geometry; but have done some reading on the subject. For a drill bit to do its best work the point angle, lip clearance angle, rake angle, heel clearance, flute angle and a whole slew of other parameters must be correctly adjusted for the material being drilled. As an example, here is an article that discusses some of the issues related to twist drill geometry.

http://www.newmantools.com/machines/drillpoint.html

I suspect there is no single(one size fits all) explanation for your problem, Ed; but do believe you need to explore the possibility of getting some drill bits that are custom sharpened for your particular application rather than just using an off-the-shelf bit. For folks who are drilling relatively mundane blanks, maybe the standard bits are OK and the risk of blowing up an occasional blank is not a concern. But where drilling expensive or rare blanks is concerned an effort probably needs to be made to acquire drill bits better suited to the application.

Were it me, I would engage in some conversations with professional drill sharpeners and maybe even try to contact the guy who wrote the article I linked to. An Internet search of "twist drill geometry" will provide you with a large number of resources that should help you resolve your problem.




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Dallas, TX................................In Their Memory
 
When I bore a larger hole I will put the blank in cut to size but I will use a piece of another blank that was cut off. I put it below the one that I am drilling. It obviously cannot be bigger than the pen blank. The two are pressed together and put in my vise. Then I drill and usually have a successful hole.
 
Originally posted by Rifleman1776

In this case, we have a plastic that was a glued up segmented blank. That may mean different density materials were used. A grab was probably the cause. And, such a recurrence might be unavoidable when dealing with plastic glue-ups.
Click to expand...

I think you need to get some glasses or at least take more time reading. Where did Ed say this was a glue-up?
 
Originally posted by gerryr

Originally posted by Rifleman1776

In this case, we have a plastic that was a glued up segmented blank. That may mean different density materials were used. A grab was probably the cause. And, such a recurrence might be unavoidable when dealing with plastic glue-ups.
Click to expand...

I think you need to get some glasses or at least take more time reading. Where did Ed say this was a glue-up?
Click to expand...

I said it is an Eagle blank. This particular Eagle blank was his first acrylic, other than those he made from Dawn's black acrylic -which went fine but they were drilled with one of my tried and true Harbor Freight bits (IIRC), where I like to go to visit and buy things I don't need, but with the price of gas I don't get there as often as I once did cause the Durango is a real gas hog, but it pulls the trailer well and the trailer has been sitting since our last show in December so I should probably check the tires........(yes, Karl, that was for you):D:D:D:D

One of his cross ovals. So, while there was SOME glue present, it was not structurally significant, since the blank blew up long before I got that far.
 
Originally posted by gerryr

Originally posted by Rifleman1776

In this case, we have a plastic that was a glued up segmented blank. That may mean different density materials were used. A grab was probably the cause. And, such a recurrence might be unavoidable when dealing with plastic glue-ups.
Click to expand...

I think you need to get some glasses or at least take more time reading. Where did Ed say this was a glue-up?
Click to expand...

Because that is what Eagle does. He cuts up pieces into incredibly tiny and complex shapes then glues them together to make pens that cannot be believed. Below one if his more well-known pens, the Cathedral.

Edit: Sorry, photo didn't 'take', at least on my 'puter.

2008222162920_Eagle's%20Cathedral%20Pen.jpg
 
I know it might seem counter-intuitive but I got the trick from my dad, who's been a machinist for many decades. When you use large diameter bits that are not brad points... dull them :) Most twist bits are way too aggressive and will pull themselves forward with a little bit too much enthusiasm. I had the problem with a 27/64 (I think) and after taking the sharp leading edge very lightly to a disc sander, it stopped destroying my acrylic and punky wood blanks.
 
Welcome to IAP Olivier. Would have sent you a PM, but you did not leave an address.

I believe your father is correct. That is the next thing I plan to try!
 
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