Sometimes it is fun to make your tools ...

[wquiles]

I am working on a diving LED head for a diver in Canada, and I am installing water-tight cable glands. These are threaded Metric 16 x 1.5, and the one in the head was easy since I started with a raw piece of Delrin:

However, the one on the canister's top, already had a cable gland - it used a tapered plumbing fitting. You can see the new cable gland here on top left, and the existing plumbing fitting on the middle. That hole is tapered:

Once I centered the hole, I drill it with the largest drill bit I have (1/2"), which is not large enough since the thread calls for a hole 37/64" in dia:

So what that means is that I need a boring head for the mill. The one to buy of course is the ones made by Criterium, but I have not been able to snag one cheap on Ebay for many months. I recently found this large monster - and I could not resist the cheap price nor the beefy construction - it looks like it could have been hand-made, it is built like a tank and everything is fitted incredibly well. Unfortunately it is designed for 1" boring bars, so I knew I would need an adapter:

So I decided to make an adapter for 1/2" boring bars out of a 1" dia drill rod piece I had around. The hole in the boring bar is "exactly" 1.000 inches, so I had to slightly turn the drill rod for it to fit:

I then drill and bored to get to 1/2" on the other side of the adapter:

I then took a piece of 1/2" drill rod and made my own boring bar:

and gave it the water hardened treatment once the edges look right to me (did everything by eye on the grinder):

Here is the hand-made boring bar and the adapter:

I then drilled and tap the adapter for set screws - I later cut those much shorter:

Here it is ready for use:

and it worked awesome:

and I was able to tap the hole as needed:

Once I finished the tapping, just as I expected, I found that the tapered hole was bigger than the new fitting on the top, so I had to bore it deeper to get to "solid" threads, while still allowing removal if later needed to be replaced:

and this is how it looks now - all possible after making my own boring bar:

Will

 

[precisionworks]

Nicely done

Once you're sure about the position of the boring bar in the adapter, you may want to grind a flat on the BB shank so it always reindexes to the same position - all my BB's either came with a flat or had a flat ground after I got them.

drill it with the largest drill bit I have (1/2"), which is not large enough

A set of Silver & Demming twist drills will see a lot of use over the years. MSC often has their set for around $100 on sale, look at MSC item #63327787

 

[gadget_lover]

That was nicely done. I grind my own tools now and then, but did not think of doing my own boring bars. Probably because I have 4 sets . I seem to spend as much time making tools as anything else.



I was surprised that 1/2 inch was all he had too.

I picked up a cheap S&D drill set at at a sale, and I use them just often enough that I'm glad I have them.

S&D drills have a 1/2 inch shank but the flutes of the drill are larger. I think mine max out at 1.25 inches.

Dan

 

[wquiles]

Yeah, one of these days I will buy an S&D drill set (maybe upcoming Enco or MSC 30+ discount specials?), but for this one time, there was extra satisfaction in making the tool I needed for the job from scratch.