Tuesday , February 20 2018
Home > Lathe Projects > Shop Tip: EZ Tap Guides

Shop Tip: EZ Tap Guides

by Russ Harman

Girls, boys and all the ships at sea.  Did I include everyone?  OK, here is a super simple project to burn up a Saturday or a couple nights during the week while you are waiting for the Sea Chickens (aka Seattle Seahawks) to return for the playoffs.  Far better than watching run of the mill re-runs on the tube!

There is nothing more frustrating (for me anyway) than to take your time to spot, drill, chamfer and tap a hole, only to stand back and see just how crooked the bolt screwed into it is.  Does anyone know how or why this even happens?  Seems like tapping would be a self-righting operation.   It seems like equal pressure on each side of the tap (regardless of where it is in the hole) would result in a perfectly tapped hole … but we all know it doesn’t seem to work that way.  Another of the mysteries of the world.

I made two sets of these little critters to handle the tap sizes I use 99.9% of the time, #4 to #12 in one set and ¼” to ½” in the second.  Each one is  ¾” dia x ¾” long for small and 1″ dia x 1” long for the large ones.   Check out the pictures.

1 each-small and large

Place a suitable length of stock in the mill and mill a flat along the full length about ½” wide.  Cut each to length and dress up the ends and break the corner on the edges.  WOW!  Just thought of this!  If you want to be really cool and original, mill the round into a hex or octagon shape, maybe a pentagon.  Let your imagination run wild!  Woohoo!!!!

Take each one and touch them to the 1”x42” belt sander (or whatever sander you have handy) with a 320 or 400 grit belt to slick up the flat and render a nice clean brushed look.  Now chuck back in the lathe and carefully drill the proper size clearance hole in each for each tap size.  Now relieve and chamfer the hole.

Then I sat at the engraving machine and engraved the size of eachon the flat milled down the sides. If you don’t have an engraving machine a metal stamp set will work just fine. Then I put a smaller size on the top of the tap guides to help sort them out when in the rack.  The engraving can be easily highlighted by smearing cold blue from the gun bench over the numbers. Once the die has dried go back and touche the surface on the belt sander again to remove all but the die within the engraved or stamped sizes.  An alternative method would be  to use a stone or file with a little emery paper on the file.

A little scrap of pine was grabbed out of the waste can, laid out and drilled for the guides.  One row small, one row large.  After a coat of my favorite tough finish for our kind of work, marine spar varnish, they were dry and ready for the tool box the next day.

Tap Guide Assortment

Usage should be self-evident.  But just in case it isn’t, place a lubricated tap in the hole in the tap guide.  Then place the tap and tap guide over the hole to be tapped and (while pressing firmly down) start the first two or three threads.  After that you should be good to go.

Works good when power tapping with a drill also and the end result is sure worth the little bit of effort!

Guaranteed to make more SWARF to sweep up.  Now get to it!

– Russ About the Author

Editors Note:

Another common type of tap guide is a sometimes called a “tapping block”, which can be seen here.

However, Russ’ design has the advantage of being able to tap in tight places.  Whichever route you choose, you’ll find tap guides to be handy!

And if you don’t feel like making one of your own, they can be purchased in a couple of styles:

Round Tap Guide
(Click image to see current price)
V Tap Guide
(Click image to see current price)


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About Uncle Russ

Retired electrical contractor. Really always wanted to be a machinist so I am self teaching and having a great time.

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