Drilling

[srs64]

Try to make this short but my day event were nice I hit a few bumps, drilling 7mm blanks tight tube fit no problems 3/8 on the other hand top end has wobbling and to loose to use and the exit on bottom tight.

Using new bits also

And on acrylics had 2 blow out on bottom?


Any ideas

Sherman

 

[nightowl]

I have to slow my progression down when using bigger bits and clean it out more often during the drilling process.

 

[mikespenturningz]

Even new bits can be dull. I would sharpen my bit if it were doing this.

 

[bjbear76]

you can drill the blank with a 7mm bit first, then follow with the 3/8 bit. That will tend to keep the drilling centered and there's less material to clear when you do the final drilling. And drill slowly.

 

[srs64]

Will give all this a try!
Wasted some good blanks already!

Sherman

 

[Paul in OKC]

If you are not using a piece of wood under the balnk when drilling, try that. It can keep the bottom from blowing out.

 

[Jim Burr]

Good points so far. I noticed you said you were blowing out the bottoms. It's a good idea to NEVER drill through an acrylic blank. They will bust 95 out of 100 times. Drill long and the cut to length. You still get 2 blanks for a Sierra so it's well worth it!

 

[ctubbs]

Very rare, but some bits do come fresh with a slight bend. Lay the bit on a flat surface, place a light source on one side and look from the other side as the bit is slowly rolled. If the end comes off the surface or a gap forms under the middle, the bit is bent and will never drill a true hole. Send it back to the supplier for replacement if new. As always,YMMV.

Charles

 

[siturner]

Make sure your drill press table is level. Check it...even if your bubble is off a little. It makes a difference on the back end.

 

[walshjp17]

Make sure your drill press table is level. Check it...even if your bubble is off a little. It makes a difference on the back end.

Which is why I now drill exclusively on the lathe.

 

[randyrls]

And on acrylics had 2 blow out on bottom?

Sherman; I always use the cut long, drill short and cut to length technique on acrylics. There is a page in the IAP Wiki that goes into more detail.

 

[siturner]

Never tried it...next time I drill I'll give it a try

 

[kooster]

Also, using good quality, higher end bits makes all the difference in the world. Well worth the little extra you spend in the long run, especially if you're literally wasting blanks. I invested in a set of Colt bits. Best investment (after my lathe) I ever made.
Just a thought !!!

 

[John Den]

My way with metal and acrylic

This method is particularly relevant for drill acrylic blanks. as well as metal.

1. I drill on my metal lathe.
2. Very small start with a center drill.
3. #40 pilot drill to its maximum depth 0.1" at a time( 2 turns of the tailstock handle) This pilot drill clears the way for the non-cutting, central chisel edge of the 7mm drill bit and also guides the 7mm drill bit concentrically for its first part of its journey.
4. Then withdraw and clean off swarf.
5. Cool with denatured alcohol keeping the bit cool enough to touch.
6. Drill through with 7mm drill de-swarfing after each 0.2" cooling as before. (watch the drill shank before it enters the blank and if all is well no wobble will be apparent.
7. Hole is absolutely concentric and viewing through the headstock shows no "wobble" at all!

Regards,
John

 

[Adillo303]

Plus 1 on drilling on the lathe.

Do you use the pen blank chuck?

Since I got my 1642, i leave the turn crafter 12 set up for drilling and polishing.

 

[Carl Fisher]

The most common reasons I've found for a drilled hole to be larger on one side than the other (applies to both lathe and drill press) include: runout on the DP or misaligned centers on the lathe, bent drill bit, drill point ground slightly off center, grain pattern causing the bit to wobble. I'm sure I missed a few, but those are the more common.