Am I doing things right?

Merry Christmas All

Well it’s been a while since I knocked anything up on the lathe so here’s a catch-up of the last few efforts. Snore away, don’t mind me (I’m hoping to be offered some guidance, correction and helpful tips here by anyone with a minute to spare, been lucky so far!).

PART ONE
First item is formed from a 75mm chunk off a 35mm stainless bar someone donated which I figured would make a decent holder for a small toolpost-mounted drill after seeing quite a few variations on the same theme on YouTube and this and other Forums.

I should straight away point out that the best examples I’ve seen are cut as integral tool holders themselves but I don’t have any dovetail cutters to marry blocks of hard stuff to my QCTP and also this item was my first attempt at milling something on the lathe anyway, so dovetailing is well down the learning list and high up the same curve.

Being somewhat wary of milling and having only the faintest clue how to go about it (quite aside from “her” abject refusal to let me buy a dedicated machine!) I decided to hack the bulk of the unwanted SS away with hand grinder and cutting disc first to save the load on the only decent-sized end mill I’d bought so far, from a cheap set of 8 from either Warco or Arc Euro Trade.

Next job, get it square in a spare tool holder and drill an 8mm hole centrally through it in expectation of a miniature 8mm drill chuck shaft coming along later. I used a magnetic clock on the cross slide for that. My Chinese cobalt drill bit was j-u-s-t long enough to poke out the far end, must get some long ones although they seem to be expensive.

That went reasonably well if not very accurately, then it was time to mount the vertical milling slide, base plate and milling slide vise gubbins (bought from Warco with the machine) to the cross slide via the holes vacated by the standard rear toolpost using two 8mm socket screws. That’s when I came across the first problem – this little 4” vise is not really man enough to securely grab anything not flat sided much over an inch in diameter due to its shallow jaws and only just had a decent hold on the outer circumference of the bar, so I pressed on very gingerly with the 12mm end mill (from Banggood) using super light passes and amazingly got some straight cuts. It seemed to take forever to get the face square on to my chuck and take these first very tentative steps into milling but that’s down to my lack of doing that, I suppose, and my fear of breaking something or someone. Also from Banggood is the hex ER32 collet block I used for the end mill. I’ve been happy with everything I’ve had from China so far, it may not be the best finished or most accurate kit although the finish looks great to me, but it’s meeting my meagre needs and even leaner budget.

When it came time to turn the workpiece over and mill the other side it took me even longer before I was satisfied I was getting parallel cuts, but perseverance seems to have paid off. So I now have a graspable tube with a hole through it awaiting a ship from China for the final touch, the drill chuck and arbor. Or the start of further head scratching, more likely.

PART TWO
Being by now a seasoned lathe miller (!) the next job sprang to mind after watching John Mills aka “Doubleboost”, Ade of “Ade’s Workshop” and a few others on Youth Tube turning balls on their lathes and knocking up some great looking contraptions to facilitate this operation. Having only recently been tempted to make some brass handles for my own lathe (much superior to bland standard Chinese efforts as touted by many) from a length of brass hex bar, I got the fancy to create something a bit kinder to my delicate palms and digits and make this Chinese instrument My Own.

Hence the logical progression to my own version (or is it?) starting with exactly the same procedure as that above. This time however I kicked off with 100mm of 50mm diameter aluminium bar to give me space for my idea of a ball turning tool mount. Incidentally for both of these tasks I used my Makita 305mm cut-off saw from Howe Tools (highly recommended machine suppliers, by me at least) to chop the base material. This thing just eats any kind of metal I throw at it very swiftly and efficiently, although it sure creates some tidying up!

Again, first job was to drill a hole through its length. Not as easy as before, however, as this needed to be well off-centre – another first for what’s left of my crucial matter to master. So it was off with the three jaw and on with the four. I’d only used this once before a few months after buying the lathe last November, just to try it out, but had never attempted to line up a job properly with it. Using a square and a clock along its face I got it to run parallel to the bed and got it centre drilled. I immediately understood what “out of balance” means but reducing the spindle speed down to 300 from 500 cured that scary episode.

Using various drills in steps meant no heavy loading that may have moved the piece out of true, so 6, 8, 10, 12, 14 and finally 16mm bores were eventually made right through the aluminium with little fuss but over quite a long period of time. The 6 to 12mm bits were all Cobalt while the two biggies were Blacksmith drills, and I would heartily recommend those too. I used CT90 spray cutting fluid from Screwfix which seems to work well but taught me to work with the window open, however cold it was outside!

With my biggest drill gone it was time to get the boring bar out. This is a scary thing being about 150mm long and a bit spindly. I used it in Banggood’s 3MT 50mm boring bar head stuffed into the tailstock. The first time I hit the ally with it the nose visibly dived about 2mm which got my attention but I quickly realised that if I held firm and entered it slowly it started cutting nicely without the downward bending. I continued taking cuts of 0.5mm until the hole was big enough to clear the fattest part of a 3MT shank at about 23mm.

Time to cut a recess in each end now to take a miniature deep groove ball bearing, one 6805 2RS with a 25mm centre, the other a 6904 2RS with a 20mm bore. Both are 37mm OD, one 9mm wide, t’other 7mm. The enlargement of 20mm depth worth of cut from 16mm drilling diameter to 37mm with the boring tool took forever on each end. Lining up the second one was easier and a good bit quicker with a nice big live centre stuck into the new 37mm recess.

So after what seemed an eternity I had my tubular offset tool holder finished with a bearing recess in each end. I now had to reduce the small end of the 3MT taper on the boring head to a smidgeon under 20mm for about 5mm to allow it to enter the rearmost bearing squarely and snugly, whereas the larger front diameter only has too jam into the face of its own bearing and is pulled in by a 12mm bolt in the back end where a drawbar might usually go.

The novel thing behind my idea (or is it? Let me know folks!) is that here I have a 3MT tool holder that will take not just my ball turner but also anything else with a 3MT spindle that might like to be stuck on the toolpost (incidentally a Banggood BXA 200 wedge type). In this respect I’ve probably made redundant my first effort and could probably rig a 3MT drill chuck to run this same way, or very similarly.

PART THREE
This one came about well after I’d struggled to grab some round bar for machining and figured I needed a better solution next time. Also influenced by a huge deficiency in the 3MT vee block I got cheap from one of the usual UK machinery outlets. It had no holes in its flat faces! So starting out with a chunk of 75mm aluminium bar I knocked up a base plate and drilled a few holes in it to give me this tentacle-waving thing.

This completely solved my problem and also allowed for something bigger and weirder to be grabbed and held in the tailstock.

Someone on here needs to tell me if making things on a lathe FOR the lathe ever stops!?

Happy New Year to machinists everywhere.

Looks good to me Terry, well done!

Couple of observations, not criticisms:

I use CT90 and don't find it obnoxious unless it gets too hot. Probably smoking due to your lump of stainless work-hardening. Depending on the alloy, the machinability of stainless steel varies from 'reasonable' to very difficult. I rarely bother but flood cooling might have made life easier on your job.

Gradually increasing the size of holes with a slightly bigger drill at each step is best avoided because holes made that way are more likely to wander (I think), but more seriously it throws a lot of wear on one small part of each drill's cutting edge. Not good for them. That said, driving a single big drill through a difficult lump of metal might be too much for the machine. In which case, you might have to drill it in steps. I quite like boring holes out, but that 's only an option once you've made a hole wide enough to get the boring bar in!

Dave

Ta for that Dave, welcome observations I appreciate. The CT90 almost pioisoned me, hence the comment! I'm sure any other chemical would have done the same within the confines of my titchy lab, probabaly because I was there for so long in one session. It was a bit disconcerting to see my 150mm boring bar bow its head on first contact, and I nearly gave up there and then.

Dunno if you've done a toolpost dill thing but the one I saw being made by Rollingmetal on YouTube kept seizing. I was hoping not to need any bearings and just grease the shaft heavily. Any thoughts?

CT90 is a tapping oil, you would be better off getting a small quantity of soluble cutting oil and diluting some of it 10% and using it in a squeezy bottle with a long spout.

Thanks for the interest Old Mart. Early on in this adventure someone on Youtube put me off using soluble oil, can't remember why now! CT90 sure seems to work though and doesn't soak everything, I find it very controllable.