Tool Post Mod

I finally got around to making a new part for the Quick Change tool post on my Hendey Lathe.  To rotate the tool post the top nut must be loosened with a 24mm wrench.  Grabbing the wrench gets old after a while.  So, I wanted to make a new “nut” with a lever attached to it.  This is a popular modification and this isn’t an original idea on my part.

I looked around on eBay for some material to make my part out of and stumbled upon a good deal for some 1215 steel 1.75″x12″ hex stock.  Shipping was free which meant a flat rate envelope which the steel absolutely decimated.  But it is thick steel so the mailman was hard pressed to damage it.


The first task was to turn the hex stock into round stock which is pretty simple with a lathe as you might imagine.  I’ve pointed out the nut I’ll be replacing with my part in the picture below.


Once the stock was round I headed over to the power hacksaw to lop off a 6″ section of it.  The hacksaw made short work of the job once again making me thankful to have it.


The 1.75″ hex stock was turned down to 1.75″ diameter round stock.  The plan I came up with called the part to have a base diameter of 1.49″ so as not to interfere with the part below on the tool post that has a 1.5″ hole in it.  So, I removed some more material from the diameter.


I wanted to angle the side of the part so that the lever wouldn’t hit the other lever that holds to tool in place.  I used my protractor and a gauge block to measure the angle I wanted to match.


To cut the taper, I rotated the compound to 15 degrees and made repeated passes until I was happy with the results.  I ended up with a tapered section 1″ long which would be easy to divide later on.


As this would be replacing a nut I needed to drill and tap a hole.  I measured the male thread on the tool post and found it to be a M16x2.  I didn’t have a tap this size but managed to find a good deal for one on eBay.  Supposedly, it was used but looked brand new.  According to my tap drill chart, the appropriate drill is a 35/64″.  Sadly, I don’t have this size drill bit and decided to use a 9/16″ which is only 1/64″ larger.  I center drilled and then drilled to depth with a 1/4″ and 9/16″ drill bit.  I then tapped the hole by hand on the lathe as I’ve shown before.


Having finished all the steps I can do with the part held in the chuck this way, I parted it off.


I flipped the part over in the chuck, used an indicator to verify it was held square, faced the end of it, and broke the edges.


Finally, I pulled it out and threaded it onto the quick change tool post.  What do ya know, it fits!  If you’re making one of these, at this point you want to tighten the piece down and mark where you want the lever to be.  If you’re lucky it’ll end up there.


To put the lever into it, I needed to use Gill’s mill since mine still isn’t running.  After getting the part correctly positioned (which took much longer than the actual cutting) I made the first cut: a small depression with a 1/2″ end mill.


Next, I drilled and tapped a 3/8″-16 hole.  It’s probably not good practice to make parts that have metric and USS threads.  On the other hand it was good enough for GM for years.  So, no worries.


To make the lever I grabbed a piece of 3/4″ mystery steel.  This was one of the 18″ pieces of steel I picked up at the flea market for $1 a piece so I ahve no idea what it is.  I made the handle section of the lever a little less than 3/4″ and took the shank of it down to 1/2″.  On the very end I cut some 3/8″-16 threads using a die.


I test fit the lever to the “nut” with it still in the lathe and it worked as expected.  I proceeded to break the edges and part the lever off before re-chucking it and cleaning up the end.  From there it was a simple step to put the two pieces together.  I’m quite pleased with the finish I got from my lathe and the mystery steel.


I used my new piece to loosen and tighten the tool post down a couple times.  For some reason, each time it tightened down in a different positon before settling on a position to the left of center that I didn’t want.  At this point I could either remove some material from the base which would rotate the lever around clockwise when tightened or add material to the base which would move it counter clockwise.  I chose to add some material by putting a thin shim under it.  That got the lever where I wanted it and no one will ever know.  Well, besides all of you..but that’s not too many!  Finally, I took the lever off, added a drop of Lock-tite, and reassembled.  Alternatively, I could have milled some flats on the lever but I don’t have the capability to do that.  Besides, this was much quicker.  Finished!


PS – 1215 steel cuts nicely.

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