I managed to snatch a couple of hours in the shop tonight, Plus, some new toys turned up:

In particular, I needed the 3MT-2MT sleeve, as the one I was using was knackered & allowed about 1mm of vertical slop. Not good when setting tool heights. The new one is as tight as a duck's bum... That red tool is an old one, it's there to show the typical tool size on my lathe, versus the size of thread cutters I bought from RDG. OK, I knew they were going to be small, but aaaaaah, so dinky! That would also be be a pain, as you will see.
So, today I thought I'd try a thread. My first with the proper tool... I've got some rough mystery-steel bar (which has been subject to several lathe-and-mill-related experiments), the end of which was already cut down to somewhere near the diameter I wanted, so it'd only take a few cuts (0.100" off the diameter, as it happened) to bring it to size. Experiments earlier today revealed that taper attachment takes 3/8" Whitworth bolts. The Whitworth tool is the thin one in the picture above.
First job, then, cut down the bar. I have it in the chuck, with the live centre to keep everything in line (no traveling or stationary steady, yet). I've actually got way too much sticking out of the chuck, but I figured I was only going to be taking light cuts, so I'd get away with it. So, the first thing I did was bash my last decent carbide bit against the edge, breaking it. ARGH! Fortunately, I'd sharpened (ish) a HSS bit a while back & got that close to being on centre, so I used that instead. Here's the first 0.010" cut:

The black thing in my hand is the feed engagement lever. My other hand is pointing the infra-red remote control at the camera. Gotta love that remote control... Anyway, a few cuts & measurements were taken, and eventually I had the proper outside diameter (0.370", as measured from the test bolt).
Here we are a bit further along. The chips are a nice silver colour, and the smoke is light, so I'm happy with the speed & depth of cut:

Next up, I need to mount the threading tool. Unfortunately, it's waaay too low in the holder, if placed on the bottom:

Too high if the ali went underneath:

So, I decided to slot the ali block so the tool sat in it & sat at the right height. I must make that QCTP soon... So, over to the mill: The ali is a scrap piece I had, which is already squared off. So I lobbed it in the vice & found the back edge:

With the edge programmed into the DRO, and the width taken (0.940"), it was a simple case of mounting up the cutter, moving to the centre of the block, and touching off:

I chose to cut the slot full-width in one pass, mainly to save time. Fortunately, I have a decent set of metric end mills & collets, so despite the fact I work pretty well exclusively in Imperial, the slot width is 8mm (+ a gnat's c*ck). It needs to be 0.350" deep. The mill, bizarrely, has metric X & Y axes, but an imperial Z-axis. No idea why.
First cut was 0.100" deep, full length. It's in there, somewhere:

This'll find it:

After a few more iterations, and a couple of trips back to the lathe to check the height, and we're done:

Just need to lob it in the lathe, put some packing above (so the screws don't run out of room), and presto. The angle of the photo makes it look high, actually it's almost exactly bob-on:


So, FINALLY, I can cut my thread. This is the second pass, going about 0.010" deep:

I'm cutting with the tool square on to the work for two reasons; neither of them valid: First, because I've got the tailstock in the end of the work, I can't offset the topslide without the tool post fouling the tailstock; and second, I don't currently have an angle gauge, so I couldn't accurately align the tool against the work, having set the angle. Wheras, it's nicely in line, and the tool post clicks into place when used straight, so I know I've got the right angles. It just means I've got to feed slowly & carefully so as not to overload the tool. Several 0.0025" feeds later...:

What that picture doesn't show is the near disaster that happened right at the end. Having taken the cut 0.030" deep, I checked the thread with a bolt. It threaded on, but only just; so clearly another few thou & I'd be there. But, somehow, I managed to bollix up the dials, and whilst i've no idea how deep the cut was that I started taking, it was WAY too deep. Rather than stop, I backed the cross feed out slowly until the chip size seemed reasonable. And left it at that.
The result is OK; it's a bit sloppy at the start of the threads, but much better at the end of the threads:

And it screwed nicely into the taper adapter, yay!


That was all I did tonight. I ran out of time...
BTW, please tell me if I'm over-doing the pictures, or if I'm showing too many of the intermediate steps. As a newbie to the machining world, it's hard to know where to pitch a project like this. I expect for most of you this is like taking a stroll in the park? But me, I'm learning something new every time I stand in front of the machine... So, if I've got it wrong, please let me know so I can improve the write up.
