best way to drill 5" long hole?

[studioso]

hello,
I have a project brewing in my mind that will require drilling a hole into plastic blanks that will be at least 5" long. keeping in mind that:

-the hole will be blind: only drilled from one side
-the hole will be probably be 1/2" or 3/8".
-the blank will not be rounded.
-I plan to do many of these

I think that drilling on the drill press is out of the question, since mine only has a stroke of 2" and readjusting the height of the table means re-centering the table's lateral movement.
drilling on the lathe seems more reasonable: but the blanks are seldom perfectly square, so it seems to me that to perfectly align the blanks in the 4 jaw chuck that I have I'd need to first square the 4 sides of the blanks.

I'm sure that many of you will have great insights and perhaps can think of other obstacles I might have/ways to do this.

thank you very much

 

[juteck]

This article came up recently, and offers a good way to drill non-square blanks on the lathe. It might be what you're looking to try for lathe drilling.

http://www.davidreedsmith.com/Articles/AuxPenJaws/auxiliary_pen_blank_jaws.htm

 

[randyrls]

Alex; You may have the same problem on the lathe as the stroke on the tail stock ram isn't much more than 2"-3".
I am assuming you will turn down the outside of the blank.

PSI makes a special pen chuck you could use to hold the blank. It doesn't have to be square, only have 4 corners on it.
http://www.pennstateind.com/store/CSCPENCHK.html

Th other "issue" is that most drill bits are not 5" long. Long drill bits are available from Industrial supply houses like MSC, but they are not cheap.

All of that is doable....

 

[Chasper]

hello,
I have a project brewing in my mind that will require drilling a hole into plastic blanks that will be at least 5" long. keeping in mind that:

-the hole will be blind: only drilled from one side
-the hole will be probably be 1/2" or 3/8".
-the blank will not be rounded.
-I plan to do many of these

I think that drilling on the drill press is out of the question, since mine only has a stroke of 2" and readjusting the height of the table means re-centering the table's lateral movement.
drilling on the lathe seems more reasonable: but the blanks are seldom perfectly square, so it seems to me that to perfectly align the blanks in the 4 jaw chuck that I have I'd need to first square the 4 sides of the blanks.

I'm sure that many of you will have great insights and perhaps can think of other obstacles I might have/ways to do this.

thank you very much

Make sure you have at least a 6 inch bit.

I wouldn't be too concerned about moving the drill press table or the tail stock, once the hole is 2-3" deep is isn't going to wander. I can be done as easily on a drill press or lathe, but I would drill a pilot hole first. It is really difficult to clear the shavings on plastic with a very deep hole, especially when the entirely retracted bit does not clear the entry hole. Drill in two or maybe even three steps with increasingly larger bits so there are less chips to remove on the last hole. If you don't get the chips out they will melt together and wallow around the bit making an oversize and out of round hold.

 

[PenMan1]

Alex:
My first instinct would be to look at a Colt 5 Star Pen Maker's Series bit. Depending on the size hole, I have some Colts that are longer than 6 inches. With a 3" quill travel, this bit shoud be sufficient to drill a 5" hole.

It may require moving the DP table up a couple of times, but this is "doable" as long as you are careful with alignment.

On the lathe, the Pen Maker's bit requires very little thinking.

 

[dow]

I drill on the lathe exclusively, and regularly drill in the 4-1/2 - 5 inch range. Hold the blank in a scroll chuck, use a jacobs chuck in the tailstock to hold the bit (like Andy said, the Colt penmakers bits are long enough), be sure to mark the bit with the correct depth, and don't get in a hurry. Clean the hole out often and DON'T let the plastic get hot. Drill about 1/2 inch deep or so and then release the tailstock lock and slide the tailstock over pulling the bit out of the blank. Shoot some wd40 in the hole, slide the bit back in, lock the tailstock and screw the quill in another 1/2 inch. Lather, Rinse, Repeat until you get the depth that you need. The most critical part for me is starting the hole. Oh, and I drill on the slowest speed my lathe will run - 430 RPM on my Rikon.

Hope this helps.

 

[Rick_G]

When drilling something that is not square (antler with a slight curve in it for example) I generally put the drill chuck in the headstock and a live center in the tailstock. Mark the centers at each end or where you want the center of the hole to be. Place the blank up against the live center and move the tailstock forward so the other end is on your drill bit. (I find brad point or starting with a center drill works best) Hold the blank with channel lock pliers and slowly drill your hole. If your headstock and tailstock are aligned properly the hole will be drilled directly at your tailstock point. Stop drilling when you get to the depth you want.

 

[studioso]

thanks for the ideas, rick_G, I think I am too young to hold the blank with a pair of pliers!! I know it's done, I've sen the video, for me it still feels unstable.

when drilling on the lathe, I've seen videos of turners pushing the unlocked tailstock by hand instead of feeding the quill. will that work on any lathe? my excalibur has quite some play when unlocked, so I wonder how much precision I'll get.

 

[Justin_F]

I agree mostly with Dow. I regularly drill 4 to 5 inches on the lathe. Never use a lubricant and only clear every inch or so. Take it slow and I would also start with a center drill - what this dies is to make a precise hole right on center before you continue with the drill bit itself. Just google "center drill". They're cheap and easy to use and you'd be surprised how much "wander" they take out.

 

[dow]

oh yeah, center drill. I knew I had forgetten something. :redface: What Justin said. :biggrin:

 

[Dan26]

I recently made a few stick pens and drilled on the lathe. The holes were 5.5" deep. I started by marking the center with an awl, drilled with a smaller, shorter bit first, then used the long bit. I didn't lock the tailstock just pushed an inch or so, cleared the hole, and repeated. I did use some BLO on the bit. Without it, the bit was getting too hot. As far as how accurate, the pens were less than 1/2" thick and I never hit the hole when I turned them.

If your hole isn't going to be centered on the blank or if the shape is such that the blank won't fit in the chuck, can you cut a blank to chuck up and glue your blank to it then cut it off after drilling? I've never done this but it may work.