# Starrett 91A tap handle



## Ischgl99 (Jul 31, 2022)

I was inspired by @Ecosta777 and Inheritance Machining YouTube channel to try making a Starrett 91 tap handle.  I elected to do the smallest one to verify the process of making the parts before starting on a larger one.  I made it from 4140 I had on hand.  It was a fun project, but working on small parts made this more challenging then the larger one probably will be.

To start, I turned 1/2" bar stock to 12mm (I do everything in metric), then turned the long handle end down to the correct diameter.  I chose not to taper the handles so that I could easily hole it in my chucks for multiple operations.  I didn't see the need for the taper, but time will tell if that is a mistake.  The original has a radius between the center section and the handles, so I ground a radius cutter for this transition.  My hand grinding skills leave a lot to be desired, so this tool could use a lot of improvement.




Next, I flipped it and did the threaded end.  It was turned to the right size, threaded, and then the hole for the plunger bored into it.





From there, it was brought to the mill where the center section was flattened on both sides making it the thickness of the handles.






Now it was time to start on the hole for the tap.  I located the position on where is should be, drilled a starter hole, and then a 7mm hole for the final size.




The next operation was filing the v groove along the axis of the handle where the tap will be locked into position.  I didn't have a square file, so I tried using a triangular file, that didn't work so well.  I will be cleaning up the profile at some point once I get the correct file.






The next steps will follow in the next post.


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## Ischgl99 (Jul 31, 2022)

The next part is the plunger.  I turned a piece of bar stock by plunging with a diamond turning tool and feeding towards the tailstock.  Once at the right diameter, I removed the live center and cut the end off.  Well, that was the plan, turns out the live center was needed to keep if from bending while cutting the end off.  The next one I made was better LOL.






I didn't get any pictures of the following steps, but I put the plunger in a collet to face off the end, then flipped it around and faced the larger diameter end and put a chamfer on it to match the angle of the drill for the tightening collar shown in a bit.




The plunger needs a vee cut in the end to hold the tap as well as a hole drilled for the roll pin to keep it in the proper orientation.  I used my dividing head to cut the vee since I don't have any collet blocks yet.  I chucked it up, touched off the end and top surfaces, and calculated how deep the cut needed to be.




The next step was making the cross drilled hole.  It needs to be accurate and aligned with the vee cut in the end, so I made a fixture plate by cutting a vee groove in the plate for the plunger to sit in, then installed a roll pin for the vee on the plunger to reference off of.  This made sure the hole was at the proper orientation to the vee.  I touched off the plunger in the vee slot to make sure I was on center when drilling the hole for the roll pin in the fixture.





Once oriented properly, it was clamped down and the table moved to the proper location for the hole.  I used a spotting drill to start, and then finished with a 1.5mm drill.






The tightening collar, not sure what the correct word for that is, was turned to size and the knurled using the knurler I made from the plans on Tom's Techniques page, it worked really well and so much better then a bump knurler.





Next, it was bored and then threaded for an M8x1.25 thread to match the handle.





I forgot to mention earlier, there is a slot in the handle for the roll pin in the plunger to keep it in the proper orientation to align the plunger vee for the tap.  I don't have any starter punches and trying to get that tiny pin in the hole was a PITA.  I ended up making my own starter punch by boring a shallow hole just slightly smaller than the roll pin diameter and it was a breeze putting it in.  You can guess what I am ordering tomorrow!  Here is cutting the slot with a 1/16" end mill and all the finished parts.





The roll pin was inserted into the plunger shown in the next photo, and then it was assembled and tested out.  It is a bit rough in some spots, but looks like it will work just fine, but most of all, a great learning experience.





And a final picture to show scale.


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## Chewy (Aug 2, 2022)

Looks Great!!!  Many happy years using a tool you made.


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## DavidR8 (Aug 2, 2022)

Fantastic work!


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## wachuko (Aug 3, 2022)

Outstanding!!


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## Ischgl99 (Aug 3, 2022)

Thanks guys!  I’m happy with how it came out, and I learned some new work holding tricks, so overall a great project to do.  One of these days I’ll get around to building a bigger version, but first I have a steam engine to finally finish.


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## wachuko (Aug 3, 2022)

Ischgl99 said:


> Thanks guys!  I’m happy with how it came out, and I learned some new work holding tricks, so overall a great project to do.  One of these days I’ll get around to building a bigger version, but first I have a steam engine to finally finish.



And you have a thread for that engine build?


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## Ischgl99 (Aug 3, 2022)

wachuko said:


> And you have a thread for that engine build?


Not yet, I wanted to get a bit further along before starting the thread, but I have been taking pictures of each step


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## riveter (Aug 10, 2022)

That's nice.


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## Ischgl99 (Aug 10, 2022)

riveter said:


> That's nice.


Thank you


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