What pitch for 1/4" aluminum?

[Paul Saffold]

I'm adding a router table to my table saw extension like the one by John White in FWW. I'm using 1/4" angle for the ledge to support the table (not the plate). For the leveling screws should I go with 1/4 - 20 or 1/4 - 28 in the aluminum? Or does it make any difference? Thanks, Paul

[Bruce Page]

The 1/4-28 UNF will allow somewhat finer adjustments but either will work. I will often use a fine thread in thinner materials for the additional thread strength benefit. You will need a #3 tap drill for the 1/4-28.

[glenn bradley]

I love it when machinists (or those with those skills) chime in on these questions. I always learn something.

[Paul Saffold]

Thanks Bruce. I wasn't sure which was better: more threads or fewer but deeper threads. I stopped at True Value and picked up the tap and bit this AM. It sure is handy having it on the way to work. I've used the taps from Lowes (K.... something) and have had mixed results. I've broken a few but it may be my inexperience.
Yes, Glenn, it's fantastic having members share their knowledge. I've learned so much here on the Creek from the questions others have asked and from the "how-to" threads.
Paul

[ray hampton]

Paul, what is the biggest drill or tap that you broke ?
a drill press or lathe can snap a drill bit quick
1/2 " drill bit is nothing to a drill press

[Paul Saffold]

I've only broken taps. 10-32 and smaller. Yes, I was using cutting oil. Yes, I don't have much experience. And no, I wasn't using a tap in the drill press.;)

[Ronald Blue]

It's very easy to break small taps. Either by to much force or getting a little side force. It pays to back up frequently on small taps to break the chips.

[ray hampton]

If you are drilling a hole with a drill press,the drill bit might break but if you are using a hand drill and the drill bit can not turn your hand will suffer if it are too close to a wall,this is a good reason for using a under - power hand drill

[Harvey Pascoe]

I hate breaking taps so I always do it by hand.

[Bruce Page]

I made this little tapping set in the 70’s. It’s designed to be used with a drill press or mill. The body spins freely on the chucked ¼” dowel so the tap self feeds and is held perpendicular to the work piece being tapped. The interchangeable brass bushings accept everything from 0-80 to 5/16-24. It has saved me a lot of broken taps.