So, today I wanted to finish off the cam lock bit. First job was to tidy up the main bore & open it out to 1.5".
This done, the next job was to off-set the work to cut the actual cam part. This achieved, I also scrounged up some weird turning tool from the bottom of a drawer somewhere. I think it's a left-handed tool to cut to a shoulder, but ignorance is bliss so I gave it a quick whizz on the carbide grinder wheel, just to sharpen it up, lobbed it in the toolpost (fortunately, no faffing required, it went straight in at the right height), and got busy with the cutting:

Yes, I know the tool looks like it's mounted on its side. I took me ages to work out which way up it went...
One thing about this tool, it cuts a
very nice surface on 303 Stainless. The entire piece was now turned around, re-centered, a few touches removed from the main diameter just to get it to run true; then I cut a 20 degree taper. This is where the handle will go, and matches the taper on my current toolpost. After a bit of faffing (including re-setting the piece, as it moved a smidge when the taper was being cut, somehow), everything was ship-shape. A quick file to take the burrs off, and a quick whizz with some oiled-up wet & dry paper made no impact on the machining marks. So I pretended it is a "brush finish" & left it at that...
Next job, drill & tap the hole for the handle. First up, I needed to somehow mount it in the milling machine, at an angle of 20 degrees, straight & true... After some headscratching, some messing about with the sine bar & gauge blocks, and discovering that the only way I could fit it into a V-block & clamp would be if I drilled the wrong side of the piece for the handle.... I suddenly got some inspiration. Having just bought a digital angle gauge, why not simply clamp it between V-blocks in the vice, and manually tip it up until the correct angle appeared. A bit like this:


Simples.... used an end mill to make a small flat, centre drill (at max RPMs) to make a wee guide for the twist drills, drilled 4mm, 6mm, 7.5mm, 8mm & 8.5mm ready for an M10 tap.
Now.... as anyone who has read any of my stuff before will know, tapping is not something I enjoy. I'm still dissolving two taps I broke off... and that was in Aluminium; now I'm tapping in stainless steel! I've also found tapping to be an energy intensive operation, and bloody slow.
So... while I was on holiday, I noticed an auto-reversing TapMatic on eBay. Actually, there were several (of various makes), all going for around the £100 mark; one was on Buy-it-now-or-best-offer, so a cheeky offer of £75 was, to my surprise, accepted promptly

I also bought some spiral point taps, which I believe are better for power use than regular hand taps.
Anyhoo, pop the tapping head on the mill - it uses up all my headroom, I could only just fit everything on!


So, here's how to tap in Stainless: Line everything up. Set speed to 115rpm. Hold quill handle with right hand, use left hand to release quill lock (oh for a working quill spring...). Hold torque lever with left hand. With other left hand, switch mill on, then apply a load of cutting oil. Pull quill handle down until tap engages & starts tapping. Keep gentle downward force on until tap comes out of the other end of the hole; then pull quill up. Tap reverses & drives itself out of the hole. From first pulling the handle down to the tap fully withdrawing - 10 seconds (approx). MILLIONS of times easier than farting around with the tap, tap handles, trying to make it all run true. Yada yada. I am SO going to love this tapping head, even if it is too deep for the mill. I can always use it on the pillar drill instead.
Anyway, that's more or less where I left it. The cam piece is now finished, I have the main holding sleeve & bolt to make, the pistons to make, the body to finish off, and the base to make. Blimmin' eck!
