Lbm

M

Mase

AzB Silver Member
Silver Member
I have a bunch of LBM and am having problems drilling it. I am trying to put a 3/8 hole through a 1" piece of .560 ferrule material.

I center drill it. Drill it with a 1/8" bit, then a 1/4" then 5/16" then 3/8". I am currently turning the lathe at 500rpm but have previously turned it faster.

I just did 7 ferrules and 6 of them cracked. I have never had this problem with any of the other materials I have used.

Any help would be appreciated.
 
My first suggestion is to try it much slower. Slow your lathe down about as slow as you can and be very patient about drilling. Next, you might consider using a minature boring bar on you final couple of cuts.
 
If you must drill, slow it down to about 350 rpms and keep the chips out of the hole. When I drill acrylic, I keep a steady flow of compressed air in the hole. It also serves to reduce the heat. I used to have the same issue with Diamondwood too.
 
If possible, I'd consider live tooling.
Are you peck drilling or plunging?

Frank
 
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LBM is brittle. IT's hard but brittle.
3/8" thru and uncapped without a backing is a breakage waiting to happen imho.
 
All the suggestions so far are good advice to follow. I usually run a little faster than has been suggested myself. I would also drill the full size hole all at once after center drilling. But LBM is too weak not to solid cap in my opinion.
 
Mase said:
I have a bunch of LBM and am having problems drilling it. I am trying to put a 3/8 hole through a 1" piece of .560 ferrule material.

I center drill it. Drill it with a 1/8" bit, then a 1/4" then 5/16" then 3/8". I am currently turning the lathe at 500rpm but have previously turned it faster.

I just did 7 ferrules and 6 of them cracked. I have never had this problem with any of the other materials I have used.

Any help would be appreciated.
Click to expand...
had that problem a couple times before too
i quit drilling them
i bore with my router
1/4" x 1.50" long bit
no problems since then
my problem with lbm is the crap in the material
geezzzzzzzzzzzzzzzzzzzzzzz
 
You'll create less heat by peck drilling a rough 1/4" hole and boring it to size.

I've used 3/8-16 lbm thru ferrules for years with no problems. I don't recommend breaking like a gorilla using this style but I have them on my personal cue and break with it all the time.
 
Another thing to consider, which I'm sure you have, but bears mentioning, what type of chuck are you using? 3-jaw, 6 jaw, and just how much clamping force are you chucking with?

With .09 wall thickness when done, and on brittle material, it's feasible that too much clamping pressure with a 3-jaw could be a culprit too. I'd consider using a delrin collet to spread the pressures a little more evenly. Put a bottom in it and indexing would be alot easier too.

Just a thought.
Frank
 
Push your drill bit in a ways & pull it out. Then feel the bit. If it's hot you are forceing it & you will have to drill a little, pull out & clean both the hole & the bit before drilling a little more. You may have a dull bit too...JER
 
Thanks for all the help. I experimented with something else after hearing from a few of you and it seems to be working. I am centre drilling and then going with the 3/8 bit in stages at 325rpm with water sprayed on it. Seems to be working.

Thanks again.
 
> Good info so far! My questions to the original poster are these.

What kind of drills are you using,carbide or HSS?

High quality drills or 4/1.00?

Untreated/polished or surface coated?

Brand-new or resharpened?

If resharpened,are your flute lengths centered? Is the "web" thinned out?

Once again if reground,relief?

What kind of wheel?

What angle are you using,118 or 135?

Some people may think that any one of these may not make a bit of difference,combine a couple and see how big of a difference it makes.

If I'm step-drilling with a sharp,stiff bit and a non aggressive "peck" style is still cracking them,I'd be reaching for a small boring bar,and questioning my drills as well as the material.

I'm with Chris on this,some materials just cut/drill faster at speed. If your machine will let you,try it at 1000 or so. I don't center-drill ANYTHING at less. Tommy D.
 
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Mase,

How old is your mtrl.?

I bought some LBM from Atlas, maybe 4-5 yrs. ago, maybe longer. I bought enough that I just started running out a yr or so ago. This was before their LBM-2.
The mtrl was pretty hard to begin with but seemed to get harder with age.
Near the end of my supply, it seemed like every ferrule I drilled, cracked before I could get thru it. I step drilled it 1/4 to 5/16".
That's when I restocked with the new improved version of LBM-2.
It was considerably softer, as determined by machining. Totally different chip.

I am not rough in my machining practices by any means but I'm not comfortable with having to baby the mtrl. either. If I'm going to drill it, I'm going to drill it. I'd much rather have it crack in the chuck than on the shaft.

The point being, if you've got some older mtrl., that may be the problem.
Scary thought, huh?
 
i have had the same problem drilling G-9 which is a basically a harder version of LBM.what i found was that i was cracking it with the center drill bit,which was 5/16.if i went all the way in it caused tiny cracks at the material.i started making smaller or actually more shallow center hole and drilling off that.
 
Mase said:
I have a bunch of LBM and am having problems drilling it. I am trying to put a 3/8 hole through a 1" piece of .560 ferrule material.

I center drill it. Drill it with a 1/8" bit, then a 1/4" then 5/16" then 3/8". I am currently turning the lathe at 500rpm but have previously turned it faster.

I just did 7 ferrules and 6 of them cracked. I have never had this problem with any of the other materials I have used.

Any help would be appreciated.
Click to expand...
If you are using a standard twist drill like you would use for wood that is your problem. They clog and build up heat and refuse. Here is a trick. First drill a pilot hole with a bit like this. You can drill the finish hole with this bit as well.
http://www.bcae1.com/images/jpegs/plexibanddbit.jpg

A trick is to take a standard twist bit and grind the tip off so it looks like an end mill and after drilling the pilot hole use it to finish the hole. It will cut the hole similar to the way a boring bit would as well as leave a flat bottomed hole if you are making it capped. You can even grind a relief on the bit down past the tip so it builds up pretty much no heat. In other words the bit is smaller in back of the tip for some length. You also may want to take the bit and snap it off or grind it down so it is as short as it can be and still work.

A third thing you can do is use a router bit as a boring tool to finish a pilot hole. Lots of ways to do it, it is not too hard to get a good result with some practice. Sometimes you can make tools that work better yourself.
 
Make sure your lathe isn't on reverse when drilling. Been there, done that. :)
 
KJ Cues said:
Mase,

How old is your mtrl.?

I bought some LBM from Atlas, maybe 4-5 yrs. ago, maybe longer. I bought enough that I just started running out a yr or so ago. This was before their LBM-2.
The mtrl was pretty hard to begin with but seemed to get harder with age.
Near the end of my supply, it seemed like every ferrule I drilled, cracked before I could get thru it. I step drilled it 1/4 to 5/16".
That's when I restocked with the new improved version of LBM-2.
It was considerably softer, as determined by machining. Totally different chip.

I am not rough in my machining practices by any means but I'm not comfortable with having to baby the mtrl. either. If I'm going to drill it, I'm going to drill it. I'd much rather have it crack in the chuck than on the shaft.

The point being, if you've got some older mtrl., that may be the problem.
Scary thought, huh?
Click to expand...

I got a fairly large quantity about 11/2 years ago. This is the material that I am using. Before that I used the Ivorine 3 and had no problems with it. I do not like the new Ivorine 4 so I went to LBM.
 
Mase said:
I have a bunch of LBM and am having problems drilling it. I am trying to put a 3/8 hole through a 1" piece of .560 ferrule material.

I center drill it. Drill it with a 1/8" bit, then a 1/4" then 5/16" then 3/8". I am currently turning the lathe at 500rpm but have previously turned it faster.

I just did 7 ferrules and 6 of them cracked. I have never had this problem with any of the other materials I have used.

Any help would be appreciated.
Click to expand...

Mase, the 3/8 hole leaves the ferrule wall a little thin. i have never had a capped lbm ferrule cracking. try going with a 5/16 hole and drill with short end mills, the end mill drills so much straighter and cooler this is very important. i also use them on ivory. the heat from the drill bit and wall thickness may be the problem. drill slow do this 2 or 3 times per ferrule. i have use the same end mill for ferrules since 1992 still going strong. hope this helps. Jeff O
 

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