Another Drilling Question

[dweir]

Okay, Smack me, I am a Noob.

I am having an annoying problem drilling blanks. Seems that the bit likes to "Squeal like a stuck pig". I have a new, sharp, brad-point bit (7mm from Penn State) and no matter what type of wood I am drilling, this hideous squeal comes about midway though the blank. It is so loud, I have to use Hearing Protectors and my dogs run and hide. Any suggestions to quiet this? I am running at a fairly low speed, about 900-1000 rpm. I tried a little Empire (top saver) lube on the bit, It helped a little, but not much. Would parafin (candle wax) help? I have tried other speeds on the drill press, but it makes no difference. Runout is minimal, the bit is square to the table. All other alignments are in spec.

Thanks,
Dave

 

[dweir]

Oh, I forgot.
I have tried other bits, 135 standard, brad point, other manufacturers, etc., but still have the problem with end grain on blanks.

 

[IPD_Mrs]

You can try soap or wax on the bit. From personal experience two things happen when you get squeal. One the inside of your blank is heating up and for a lack of a better word it is brazing the inside. The sides of the bit spin against this and create your squeal. Generally you won't hear the squeal until you are at least 1/3rd of the way in the blank. Typically we drill at about 540rmp.

You can also have this problem if your bit is not true. This is one of the reasons I hate cheap bits. I have gotten more warped bits than I care to count over the years.

Mike

 

[dweir]

I try to avoid the cheap bits. The bits I have received from Penn State seem to be of decent quality. I now realize that pushing the bit in too fast past 1/3 is causing the squeal. I will try going slower through the blank ( I pull out about every 1/3 to 1/2 inch to clear chips), but I will try pulling the bit out, let it spin to cool off and try again. My cheap Delta DP only goes down to 640 rpm. I will try slowing the speed down to see if that helps. I have a bunch of pens to do this weekend (mainly euro and slimline). Folks at work saw some of my pens and now everyone wants me to make them one. I have improved, but still cannot do some of the fancy curves and what not on the lathe (still perfecting my turning skills). But after a CA/HUT/ and a spin through the Beall Woodbuff, people love them. 25 bux a pen too much for a simple slimline?
Once again, thanks for the advice. I am still a noobie on the lathe and will ask a bunch of questions....
Thanks, Thanks, Thanks.....
Dave

 

[JWW]

What Mike said.......

 

[thewishman]

Sounds like you got the right advice. First blank I drilled at 1800 rpms sounded like a banshee - was afraid the neighbors would call the police.

Congrats on selling your pens! That makes things very exciting, though it does cause some pressure when you are making pens to order. Your price sounds good. As you improve your skills, you can raise your prices (if you want to.)

Chris

 

[TBone]

If you have an air compressor, try shooting a shot of air down the hole while the bit is cooling. It may help cool the blank quicker.

 

[R2]

Wouldn't use soap or wax. What about the trouble with glue adhesion?[:0]

 

[stevers]

Agree with Arthur. Mine squeal sometimes too. I tuff through it and move on. Only happens to me on some blanks though.

 

[Rifleman1776]

Since it is with more than one bit, I'm sure your technique is responsible. You have touched on a couple points already. You probably are using too high a speed and not withdrawing frequently enough to clear chips. About 600 rpm is fine for all sizes, do not force and clear chips frequently. I have a sort of 'chicken rule'. Meaning the more expensive or fragile the blank, like a beautiful burl, the slower I advance and the more frequently I withdraw to allow cooling.

 

[dweir]

I took everyone's advice. This morning I drilled 3 Maple blanks using the slowest speed on my Drill Press (620 rpm). I took little bites about 1/4 inch at a time, clearing chips, and had no squeal.

Thanks!

Dave

 

[Paul in OKC]

I agree with the slower speed. Some blanks may sqeal a bit anyway, but most will drill fine there. I probably only 1/8" at a time on most blanks. Seems like pecking through, but have little or no trouble that way. Keeps the bit clean. I know when I have taught new pen turners, I have them do what feels like just touching the wood and pull out. They pull harder than they think on the bit, so this works well.

 

[jwoodwright]

All good advice and don't forget to let drill bit cool between blanks.

Another point is some acryilcs and corian may need a higher speed to clear chips, that is why the drill bit is fluted, clear the chips...
Again, little pressure and clear the bit often on these non-wood blanks.