13/64 drill bit for a 1/4" WL liner

[ZUG]

Drill hole using an undersize drill of about 0.015 - 0.010" then use the 0.208" drill to finish it to size. This will compensate for spindle run-out and drill point grind unevenness .

 

[Eric Krewson]

Good advice!

 

[Zonie]

Zonie, I think these HF bits are miss-marked, the next step up in the set is 7/32, it measures a perfect .2090 and appears to be exactly what I need, even though I have a very good set of calipers and this bit appears to be correct, I am going to buy a #4 bit just to be sure. Picky, picky that is me when it comes to this stuff.

This is exactly why I strongly suggest buying a dial or digital caliper (or a micrometer) to anyone who needs to drill a precision hole.
Long ago I learned not to trust my eyes and what was marked on drill bits. Also on the very small drills, it is just about impossible to clearly see the markings.

Remembering the old, "Measure twice, cut once" adage for carpenters, I think saying, "Measure twice, drill once." could be added for machinists.

 

[Vaino]

When installing a WL liner or any other liner, I first drill w/ an undersized drill and then use the tap drill specified for the liner which produces maximum thread depth. When working as a toolmaker, made a reamer out of a drill by rounding the drill point corners when a smooth, accurately sized hole of an odd ball size was req'd. .....Fred

 

[pooch156]

Go to harbor freight and get a set of bits. HF bits are not great, they are cheap. Pre drill smaller. The final bit will drill to size regardless of the point not being evenly sharpened. I get the one below every few years. The cheaper sets make holes too.

https://www.harborfreight.com/cobalt-drill-bit-set-115-pc-61886.html

Don't trust HF's number drill sizes. Always check them with a micrometer or caliper. I got so frustrated with the complete lack of quality control that I threw the whole set in the trash! Some were actually bent. McMaster-Carr is where I go to for quality bits. Pricey? Not really. Quality? Absolutely! I also have a Starrett tap drill chart hanging on the wall of my shop.

 

[SDSmlf]

1/4" WL liner with tap but no #4 drill bit which is .2090. The closest I have is a 13/64" bit that is .2031. Suppose the 13/64" drill bit is sufficient to use to run a 1/4/32 tap into?

By the tap drill charts I use, the 13/64” drill seems a bit too small for a 1/4-32 tap. A 7/32” (.2187”) tap drill would give you a theoretical 77% of thread.

 

[Eric Krewson]

I bought the correct size bit from Fastenal, the job has been competed.