When making my mini tap holders some time ago, there was a discussion about making, versus buying tools over on Western thunder, where I mentioned that I could buy one from Arc for under £10.
I duly bought said tap follower from Arc Euro Trade and what a journey that turned out to be.
When it came the grub screw in the image fitted into the back of the tap follower to retain the spring.
Which in itself was fine aside from the fact that the body of the tap follower was too big to fit in either of my Jacobs chucks and although I could have swapped the chuck out for a collet chuck that would have been a lot of messing about each time I wanted to use the tap follower. My solution was to turn up a threaded pin to replace the grub screw. Which on the face of it is simple, except I couldn’t determine what thread* was in the tap follower as supplied, so I ended up re-tapping it to M10.
That done I gave it a whirl and found that the hole in the body is far too big with too much slop for the guide rods to actually hold the tap straight. Which of course is the whole point of the exercise…
Hopefully you can just make out the gap between the two in the close up below. What should be a close sliding fit is far from it.
As I had already modified it I couldn’t really return it to Arc Euro so I put it in a drawer in disgust and moved on.
Fast forward to a couple of days ago and I had need to tap another hole in the lathe and I just happened to have the length of 8mm stainless rod (which I use for tightening my collet chuck) in my hand when I saw the tap follower in the drawer. I took it out and quickly dismantled it and tested the 8mm rod inside the body of the tap follower. It was a perfect fit. I cut another length from the piece I have in stock, to suite a new double ended guide rod and then turned each end down to a close sliding fit. One end has a point, the other has a 60 degree countersink to accommodate taps with points on the end.
Now I have a tool that does what it was supposed to when I bought it. I cannot blame Arc for the initial problem of the shank not fitting my drill chucks because it does state the shank size on their website but I missed taking note of it.
The poorly fitting guide rods is another matter.
You live and learn and I suspect that in this instance I would have been better making my own tool or buying a better quality example in the first place. At least I have been able to remedy it and I may at some point make up a second shorter version to utilise the spare guide rods.
*Having checked the Arc Euro Trade site as I was typing this to confirm that they do indeed note the shank size, I also noted that all the other measurements although primarily stated in millimetres, are in fact conversions of imperial sizes.
As I don’t possess any imperial taps or dies I was doomed from the start in working out what size the thread might be.