trouble drilling

[dozuki]

I have recently started to work with some acrylic and am having a problem with blow outs. It seems like whenever I get near the end of a blank it blows out the last quarter inch or so. Any suggestions would be apreciated. The silver lining is that I am becoming accomplished at the creation of oops band that look prety good if i do say so myself. Thanks for the help

 

[Rifleman1776]

Having had this same experience with my first acrylic very recently, I understand the problem.
See: http://www.penturners.org/forum/topic.asp?TOPIC_ID=11182&SearchTerms=pink,pair
What you do is cut your blank about 1/4", or more, longer than the length of the tube before drilling. Mark your drill bit or set your drill press to go only the exact length of the tube into the blank. That way your bit won't come through and break out the bottom. After drilling, I use my bandsaw and carefully slice off the bottom until the hole is showing then use my pen mill to bring to proper length. Some woods can be equally difficult and the same method must be used. Ditto that for laminates and stabilized.

 

[williampens]

I've also found that using Brad Point bits will help to prevent this problem. I am in the middle of doing 2 El Grande's and lost both of the smaller barrels because my larger bit was a standard tip drill bit. I got smart and made the 1st pass with my smaller brad point bit and then switched over to the correct bit to finish the job. No problems![8D]

 

[dfurlano]

I have never blew out a blank drilling on my lathe.

 

[dozuki]

Excellent ideas. Thanks for the push in the right direction. I knew i could count on you guys. If i ever figure out how to post a photo i'll show you the fruits of my labor.

 

[guts]

paul,are you using any kind of a vice to hold the blanks while drilling ?

 

[ldimick]

One other thing to consider is heat build up. On some woods, and even on some acrylics, you get a lot of heat form the friction of drilling. The heat transforms into either steam (in wood) or expanded trimmings for plastic. The expansion has to go somewhere and so when you get near the end the blank the blank becomes the path of least resistance.

Kind of fun with BOW. DAMHIK. [}]

Anyway, clean out the hole frequently and keep it cool. Keep on eye on your drilled trimmings and that should give you an idea of what's going on.