Boxford Turret Tool Alignment Please Help!

[A McParticipant @amc18453]

Hello all, thanks in advance for reading the following..

I have access to a friends boxford 160 tcli cnc lathe with the 8 tool turret, i am hoping someone can offer guidance on adjustment of the tools to suit the centre line of the spindle.

so far it appears the drilling tools are perfectly on centre with the spindle, yet the left hand cutting tool and parting tool were both off centre by varying amounts.

I shimmed the parting tool and now the tool is off centre by about .3mm which is fine for me, however i wanted to get the left hand cutting tool bang on center so as to not leave a nib on the work piece particularly when facing off.

i attempted to shim the left handle cutting tool by .82mm (nib measures about 1.64mm diameter) however when trying to bolt the tool down with the shim, the wedge block that retains the tool wont fit flush with the turret, in fact its protruding so much that the bolts are not long enough to tighten the wedge down to the turret!

I suppose grinding the tool shank down is now in order? does anyone recommend an alternative method so i dont have to take material off the tools?

thanks in advance all!

[A McParticipant @amc18453]

[John HaineParticipant @johnhaine32865]

All the tcl160 pictures I could quickly find seem to show that it has Dickson type QC tollhoders, which are adjustable and don't need shimming. On a cnc lathe it's important to get the cutting edges exactly on centre to cut accurate diameter.

[Joseph Noci 1Participant @josephnoci1]

As John said…

Normally you set the master tool with absolute reference for tool zero position, and then the rest of the tools are set relative to master, so when you change tools you have only one referred offset to set. But tool height is God. On a manual lathe you compensate as you measure between cuts, and the cut is always referred to a measured diameter.

On the cnc lathe, you might take a reference with the master tool, and set the diameter offset to that measurement.

Now all the other tools are referred to their position relative to that master. If any of the tool heights are wrong, so will your diameter be..

If the tool clamp does not accomodate a tool, then that tool is too large for the slot – you have no choice but to thin it.

But something is also amiss – normally in those tool turrets the tool body sits against the immovable part of the turret slot. The wedge presses down on the top of the tool body. Shimming would RAISE the tool, pushing the wedge further out. The lowest the tool can go is with no wedge.

Perhaps some close up photos of the turret face and tool inserted?

[A McParticipant @amc18453]

Thanks for the feedback, here is an image of the turret, i cant quite see how this is like a Dickson type QC.

i still cant figure out how the tools are adjusted here, maybe im better off making a wedge to suit the shim i am using?

thanks again.

[Ex contributorParticipant @mgnbuk]

That style of turret is usually designed to suit a particular height of tool – inserted tools should be accurately made to put the insert on the correct height so the tools just required clamping into the turret to be on centre.. The only time shims are usually used iis if, say, a 12mm tool is used in a machine designed for 16mm tooling, where a 4 mm shim would be required. The manual should state what size tooling the turret is designed for, and using this size tool should put it on centre.

When the turret is initially fitted onto the machine, it should be adusted so that a standard tool is correctly on centre, but a bump (i.e running into the chuck) can easily knock the tool disc out of alignment. You can check for this with a dial gauge running against the tool bottom seating faceon the tool disc – this should be parallel to the X axis motion. If the disc has moved, it will show a taper . The rear vertical face should also be parallel to the X axis motion – the whole turret body can be displaced in a bump

You would have consult the machine documentation for how to remedy this. On the industrial machines I used to work with, the disc was usually positioned with a Hirth coupling, located with taper pins. A bump would rotate the halves of the coupling, damaging the pins & causing the disc misalignment. The cure in this case was a strip down, remove the damaged pins & stone the flat surfaces to remove any burrs. The halves of the coupling had a "master" taper pin hole that re-aligned the coupling halves correctly. With this in place, the location pin holes were re-reamed, new pins fitted and, most importantly, the "Master" pin removed before re-assembly.

I don't know how the Boxfrod turret postions, but I doubt it will have a Hirth coupling – for cost reasons if nothing else. Given it is intended for educational use it would be reasonable to assume that collisions would occur & have have a straight forward means to sort out any misalignment – the four central screws could, for example, just be a friction clamp that allows the disc to slip easily & re-alignment as easy as loosening them, clocking the tool seating face parallel with the X axis motion & re-tightening.

I would havce expected the drill / boring bar bores to be out in this case, though. If they are truly on centre (clock the bores with the X axis in the X zero position) that would suggest it is your tool holders that are not accuarte enough WRT to tip height from the tool shank base.

Nigel B.

[A McParticipant @amc18453]

Thanks very much for that well articulated and detailed reply Nigel,

after going away to check some videos on turret alignment, so far all im seeing is that is caters for X and Z axis. correct me in i am wrong here, (hobbyist machinist) the issue I'm having is referring to Y axis (of which there isn't one on this machine) for example,

When making the initial front facing cut, the front face is left with a nib or nipple created by the left hand cutting tool. The diameter of this nib is measuring about 1.64mm.

When parting off I am also getting the nib (I suppose that is to be expected on the rear side of the workpiece) and it measures approx 1.22mm.

maybe the shape of the nib will be of significance? here is a photo from the nib left after facing cut with the left hand tool.

also i checked the shank size for the tooling i have here, its 10mm, i did find a sort of guide on the boxford tcli and it mentions 12mm shank size, but without changing the retaining wedges there is no way i could fit 12mm tooling..

specifications where documented here: https://pdfcoffee.com/160tcli-pc-technical-specification-pdf-free.html

as for the boxford manual, it clearly states 10mm SH for my LHCT and the Parting tool.

regarding the bumping of turret into work piece or chuck, there does appear to be some marking on the front face of the turret as if someone has drilled into a workpiece too far and its made contact. i will continue to investigate the alignment of the turret.

Thanks again

[Joseph Noci 1Participant @josephnoci1]

If the Boxford documentation indicates 12mm shank tooling, then I suspect Nigel is right – the tool plate has rotated somehow. Do the test with the dial gauge as Nigel suggested. When I built my CNC lathe's toolchanger and made the slots so that they can take 16mm tooling shanks. That way I can shim top and bottom of the shank to suit – Not ideal , and no place in a production environment, but I have 12mm and 16mm tooling so I made it work. One only sets up a tool once, references it to the master and I find with 4 tools it does almost all the jobs. For threading I tig welded shims and milled them flat on the shanks of the threading tool – that way they are always aligned, since they are changed more often out to fit cutting tools.

Some pics of my turret with spacers for the photo – mine is reversed to the boxford – the cut is 'up' rather than down…

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