[deadlykitten]

hello, this thread shows a method for Z&X offsets declarations, on a lathe that is not equiped with a touch setter; osp300

i believe that something similar can be done also on lathes with osp < 300, so to help measuring tools when the touch setter is missing

... i use a zero setter, right on the chuck face ( attached image : " gauge Z " )
... image 1:
...... actual Z offset is 33.501
...... i push CALL + 50, because 50 is the calibration height for the zero setter (*1)
... image 2:
...... actual Z origin : 143.212
... image 3:
...... after CALL + 50, the offset value changed to -109.839
...... i push SET 143.212 - 109.839 (*2)
... image 4 :
...... final offset = 33.373 ( and it is pretty close to the previous value, which was 33.501, as shown in image 1 )

things would be faster if it would be possible to use CALL + 50 ± VSZOZ, instead of CALL + 50; because it is not possible to input VSZOZ inside the edit field, i have to use SET

a way arround this, would be :
... declaring VSZOZ = 0 before starting this procedure, and, like this, only CALL + 50 would be enough to declare the offset; of course, at the end, VSZOZ has to be restored
... or simply input CALL + 50 ± 143.212 ( i guess you will figure it out, if there should be used "+" or "-" )

for X, it may be possible to put the zero setter on the tailstock ( image " gauge X "); i won't present those steps right now, unless someone really needs this; so just ding for more infos !

if you are going to try it, pls check also the notes below / kindly

(*1)
about the calibration height of the zero setter :
... when the dial indicator, of the zero setter, is at zero, there are still 50mm to it's base
... in reality, this calibration height is not exactly 50; depends on zero setter ( i once determined 49.964 )
... for this method, is enough to consider 50, thus i don't mind declaring an offset which is altered by an error of 0.04
... i use the calibration height with increased accuracy only when i do more sensitive stuff, like hunting pigeons

(*2) this lathe is calibrated, and like this, program Z origin ( VSZOZ ) represents the distance between material face and chuck face

on a non-calibrated lathe, the final step would be SET 143.212 - 109.839 + something, where "something" represents the distance between "chuck face" and " program Z zero reference point "; by Z axis calibration ( achieved by messing with encoder origin ) , this "something" becomes zero, thus the " program Z zero reference point " will be on chuck face Z is not the single axis which can be calibrated; ding for more infos !

[Handi-andi]

Well my thought was to use the 3D taster in a similar manner. Put it in the chuck and then use it to touch off both X & Z in a similar manner to that for using a zero setter on the chuck to set the Z axis. I already use a 3D taster as my master tool on my mill.
Thanks
Andrew

[deadlykitten]

hello again handi, using a 3dtaster on a lathe requires to change the jaws ( or collet, etc), and this is time consuming ... inside a mill is enough to go mdi T6 M6 ( < 5 seconds ); this is why, for lathes, i recomand a zero setter, because is much faster to use it

---

on mills, i use the 3d taster with 2 z offsets :
... z offset 1 : long tongue and short tongue, both of them showing 0 ( for absolute measurements )
... z offset 2 : long tongue showing a random value, after rotating only a few degress ( relative measurement )
of course, is much faster to reach z_offset_2 position, because you don't have to turn the dial all the way towards 0

perhaps you already know that a 3d taster can be used for relative measurement ( like a dial indicator, except that is not ok to slide the 3d taster, thus only for punctual use ), and also for absolute measurement ( when both tongues are showing 0 )

i preffer analogue constructions, because they are more intuitive, the brain being able to estimate more easy the angular movement of the tongue

for fast tir adjustement, there are models with 2 adjustment screws just before the palpator, like shown in attached image; is much faster to align those, comparing to the ones that have 4 screws at the top ... the problem is that an aligned renishaw or 3d taster, may get disaligned durring a tool change sequence; i have met persons that don't wanna waste time to re-aling their probes, so they are always clamping & unclamping by hand, so the toolholder never goes into the magazine; when it is not used, it is being kept inside a box, near the machine ... the way arround is to periodically check swing arm alignment, and also to lower the atc speeds for such toolholders that contain measuring equipment, but even so, is hard to keep a low tir for a long period of time, when the toolholder is subject to shocks .. this is why is needed a fast & consistent tir adjusting procedure, and those models with 2 screws near the palpator are easier&faster to align, compared to those with 4 screws at top

sorry if there is 2 much info / kindly

[Handi-andi]

Hi

True enough if speed is the only consideration. My problem with the zero setter is that whilst for the Z-axis I can attach it to the face of the chuck, I do not have anything suitable to attach it to for the X-axis and the spindle is on a VFD drive and so can not be stopped in the same place each time to say attach it to the side of a chuck jaw, which otherwise would be a possibility. Hence, I was thinking I could just put the 3D taster in the chuck jaws and then use it like a zero setter in the Z-axis and then straight onto the centre line in the X-axis, which would have the benefit of automatically setting all references to the centreline without having to worry about a Master tool etc. I have been pondering various options and have a proximity probe off a milling machine available that I had thought about mounting concentrically on a piece of bar stock so I could throw it in the jaws and automate the process, but annoying I can not get the probe to work, partially because I don't know what voltage it runs at and its not responding at 12v, 24v or 30v DC. Hence I was looking for an alternative, but maybe I should just go down that road and try and get them working, which would make life a piece of cake. I only have one chuck for that lathe at the moment, my other two manual lathes have two or more chucks plus face plates available. Really must get a four jaw for this one but its not a priority, trying to get too offsets working properly with the auto tool changer is at the moment.Thanks for your help, if you have any suggestions for how to mount a zero setter for the X-axis direction on what looks like manual lathe but with CNC controls, it has always been a cnc lathe its not a conversion, I would be interested to hear as I am trying to eliminate one issue at a time thanks

Andrew

[deadlykitten]

hello

I have been pondering various options and have a proximity probe off a milling machine available that I had thought about mounting concentrically

at this moment i can not understand exactly how this prox probe would work

let's say that you manage to make it work : will it work only when the tool will be close to center, like within less than 0.3mm ? or will it start to blink at 5mm ? thus i have no clue how it works, nor what accuracy will it have

maybe I should just go down that road and try and get them working

i guess you will still have to change the jaws, so i guess you will lose same amount of time like when clamping the 3d taster

say attach it to the side of a chuck jaw

this may work only for short tools; for example, i may use tools that are so long, that when the turret is at X+position, their edge is under the od of the chuck; i hope it makes sense

if you have any suggestions for how to mount a zero setter for the X-axis direction

please share a photo with the working area of that lathe, maybe i, or someoneelse, will have an idea ?! as you can see, for X axis i have used the tailstock

spindle is on a VFD drive

by the way, how do you open & close your chuck ? so far i believed that it is a hidraulic type, but if it is a classic/manual type, then simply put your 3dtaster inside a shoulder sleeve, and clamp that sleeve with the shoulder making contact with the jaws face, so to obtain repetability among z axis / kindly

[Handi-andi]

Hi

The probes I have available are proximity ones and they have two sensors in them, they are normally used on milling machines and one sensor is used for the Z-Axis and the other for diameter of a tool, hence on paper they are ideal for use as they already have the necessary non-contact accuracy and repeatably at under 0.1mm.

The fact that a 3D taster works like a dial indicator when the plunger is pressed in was the reason I was thinking about it for the Z-axis, as when used like that it is no different to a zero setter, as you only take it to its zero point, as you would do when coming in from the side. As long as the 3D taster is aligned as you say, then it doesn't matter what position it is in the chuck it would still place the point of the tool on the centreline of the chuck when the taster was showing zero. Hence it would be a very simple and fast way of doing it, albeit one has to ensure that the taster is regularly checked, which is one of the jobs that I need to do when I have an hour to spare as I know the one on the milling machine is out, which lives in its own tool holder in the tool stand.

I did think about using the tailstock and zero setter after you mentioned it, but with the auto tool changer on the cross slide the body of the tailstock doesn't pass over the cross slide far enough to be of any use. The other consideration is that the back tool post, and the front one when the auto changer isn't in place, is a multifix one, back is a chinese copy and front is an original swiss one, and they have multiple positions and so multiple offsets.

Therefore taking on board what you have said and my own views, I am going to trial a 3D probe, which I can plug into the CNC controller. It works in a similar manner to a 3D taster but only requires a light touch to activate it and alter the controller, which in theory allows me to automate tool offsets to the extent that I could get the machine to check them each time I run the machine thus improving overall accuracy if I wish. If it doesn't work for me, then it will either end up on the Bridgeport interact when I switch out the TNC145 for the TNC151B controller as a touch probe, or on either the Swiftcut plasma bed as an edge finder or on my Chester Century milling machine with CNC conversion, so it won't be wasted, assuming I don't break it trialing it. I will let you know how I get on and thanks for the help.

Andrew

[deadlykitten]

As long as the 3D taster is aligned as you say, then it doesn't matter what position it is in the chuck

actually, it might matter .... for example, on a mill, if you take the toolholder out and put it back in, but rotated with 180*,you may find that tir has increased

on the toolholders that clamp the renishaw, and the 3d taster, i have a sign, that indicates the face of the toolholder, in respect to spindle phase

which is one of the jobs that I need to do when I have an hour to spare

look for adjusment screws near the palpator : those types can be aligned in <3minutes

allows me to automate tool offsets to the extent that

so far i believed that you were looking only for a mechanical solution, but if you are up to the task to implement automation, then maybe you should consider some type of automatic tool setter

assuming I don't break it trialing it

just set your feed skip overtravel limits : for example, let's say that your palpator breaks if movement is >5mm : in such a case, implement inside your macro a max overtravel of 4mm

if possible, implement the behaviour to stop your machine, if somehow it is accidentaly touched

to avoid some worries, i would gently sugest to think of a setter that is build in rough manner, so, even if it is distroyed, you could simply craft it again in house; maybe it won't be as sensitive as a dedicated solution, but should be just ok for a lathe ... look, for example, the touch setter on the okuma is 1um precision, but even so, after you measure the tool, you have to input a small corection in order to obtain the desired dimension ... some guys consider that once this "smal corection" becomes too big, it means that machine got decalibrated, thus it is a method to periodically check the machine for missalingments, or calibration loss, etc

i guess that you could do those, being given enough time and reason; just saying ... kindly