Mach 3 Turn Problem - any pointers please

[xj5373]

Hi,
I have just come back to a Mach 3 conversion of my Denford Orac after a longish break.
Running a number of the turning wizards and everything seems to work fine (limited testing but I have done some radii as well as plain turning and facing) but when I try screw cutting I have a problem. The G code looks fine and the first pass looks fine, the second pass though misses the work (looks good in Z but inadequate X), the third pass, again looking good in Z takes a deepish cut at the start of the pass but as it progresses towards the chuck there is some X movement and the tool progressively comes out of the job -  like a taper thread. I am not convinced about the pitch either on this pass. I have been stopping the job at this point as there is clearly something amiss.
Critical line of code is G76 X0.192 Z-1 Q1 P0.05 J0.001 L45 H0.005 I26.5 C0.025 B0 T0 which seems ok to me.
I have calibrated the spindle and it is showing 4 pulse per rev which is correct. Can anyone suggest a next step please to diagnose and solve this - where should I start exploring?
Thanks
Ian 

 

[Hood]

You can only use the Index pulse for Mach now, Timing does not work. You will need to change it to 1 slot disc.

Also make sure you use a recent version of Mach as there were changes to the driver for threading.
Lastly you do have a licence I presume as threading does not work in demo.
Hood

[xj5373]

Hello again Hood - Thanks for this. I will change to a 1 slot disc (might take an evening or two - band parctice tonight!) and upgrage to the latest lock down version. I do have a license so should be no problems there. I will report back....
By the way I have done a number of proper 3D machining jobs now with Bobcad CAM and have had a lot of success. It is a bit quirky on the drawing front but generally can do everythig I want - it is a just a cse of finding the appropriate functions. 3D modelling is not as good as Solid Edge but there are often workarounds you can use although I tend to use Solid Edge and import files.

Thanks again
Ian

[xj5373]

Hello again,
Well I have modified the machine to have a single slot and loaded the latest lock down version of Mach 3. It is now 043.022 - was 042.020. I recycled the .xml file and reconfigured input singnals - disabling "timing" and putting the spindle input on "index".  Once I set the input to active low and set the index debounce to 10 (was higher for some reason) I managed to get the "S true" reading something like the set speed. I then ran a spindle auto callibration cycle.
Tried a quick first threading run and it looked a lot better. Pitch looked consistent and passes got progressively deeper, unfortunately toward the end of the program the PC froze - charge pump stopped and lathe stopped.
At that point I decided enough was enough for tonight and came out of the workshop and put the kettle on!
The PC is my wifes old office machine recycled....seemed like a good idea at the time but if it is going to start crashing then maybe I should replace it?
Once again your advice has been great - thanks very much for this. I will give you a further update when I get another chance to test it.
Ultimately I am hoping to get Bobcad CAM to generate code for the lathe.....
Thanks again
Ian
 

[Hood]

I found index debounce of 0 was best for me when I used optos and even 1 would screw the speed up. Suppose it all depends on your setup and what type of opto etc but may be worth trying lower if you do run into issues.

Tried a demo of BobCAD a while back, couldnt work it out as no info at the time, might be now. Asked sales guy when he phoned he said email the iges and he would do a vid showing me how to do it, he sent a screenshot of it but no vid and no explanation. Went with Dolphin CADCAM and like it a lot for the lathe. Well the CADA side is clunky and I dont use it but CAM side I like for Turn.
Hood

[xj5373]

Hi again,

Bit more testing tonight - no PC crashes and I ran the same thread multiple times. Looking pretty good although I am not sure I would trust it with a proper job yet. Ran the TurnDiags plug in and noted nothing untoward as far as I can tell - highest spindle variation 0.41% although I feel the need to run this again with some steel stock in the machine to find out what really happens under load. The ORAC is only a small machine, not a lot of horsepower available and no back gear to help out.

I have two more objectives - get Bobcad CAM talking to the machiine then get the autotoolchanger working!

Ian

[Hood]

Dont use Turn Diagnostics, it is not compatible with later versions of the driver and will likely screw things up for you, disable it or even delete it from the plugins folder.
Hood

[xj5373]

Wow,

This is turning out to be quite a journey - so that is both the Mach 3 Turn manual and Rich's guide out of date. I suppopse in some ways this demonstrates the dynamic nature of Mach 3 but it does make it a bit more challenging to get up and running and eat into your time heliping folk along. I wonder how the manuals are updated - do I know enough to help out?

Ian   

[ftomazz]

Turn is a mess in Mach3.

[Hood]

I wouldnt go as far as say its a mess as it works well for the most part but it is the neglected child. Regarding documentation, the manuals are well out of date but as Mach changes a lot then its hard to update really, having said that Turn specific things have changed very little since the manual was written so it should be more or less relevant today as the day it was written. Rich s' doc was written whilst changes were being done to the parallel port driver as some people had always had problems threading whilst thers never did. Art was redoing the driver and made the Turn Diagnostics plugin to see what was going on, once the driver got changed and finalised the Turn Diagnostics  plugin was no use and could actually cause issues if enabled/used with the later drivers. Really it should be deleted from the download, I will mention it to Brian next time I talk. I have not read Rich s' doc but I thought he would have added that info to it but looks like he has not, I am sure he will read this thread and update the manual if needed.
Hood