Messages

11

General Mach Discussion / Re: Newbie: Tool Diameter in Mach problems.

« on: July 14, 2009, 02:53:20 AM »

Yes - Assuming you have set up the tool table correctly, you must then select the tool,( a T command) so that the correct number of tool shows on the screen (or you can just alter the DRO on the screen if you wish), but then you must tell your program to take the diameter into account - see G40, G41 or G42.

You might have difficulty in selecting the right G41 or G42. There was a very good post by Graham Waterworth which described this - if you search his posts.

 Also, just because you select the Tool and say G41, this doesn't mean the tool will move to the correct cutting position immediately. It needs a move prior to the one where you cut, to get the tool onto the right offset.

12

General Mach Discussion / Re: Setting tool offsets

« on: July 14, 2009, 02:45:16 AM »

I also find the tool offset page  too ***. My apologies to whoever designed it.

Yes - your point about changing tools and loosing the relative position is what I was trying to say. You can make your reference point anything, as Hood said.

This is why I use the corner of my cross slide - that never gets taken off the lathe, and is always there to measure to. When you "Home" the lathe, set the "home offsets" on the homing page, so that if you then put in a command G0X0Z0 the table moves so that the corner of the slide is in position X0 Z0. As I say, mine 00 is touching the chuck (Z0) on the centreline of the lathe (X0).

I now set all my tools in the holder and measure their position relative to the front corner of the cross slide. Job done. If I change tools or fittings on the cross slide, the corner of the slide is still there to measure the new tool to.

13

General Mach Discussion / Re: Setting tool offsets

« on: July 13, 2009, 03:33:34 AM »

If you have a tool that you use more often than others, then use that. Other than that  you can use any pointer, or a marker that you wish. It need not be a tool as such.

When setting up my tool table, I used a corner of my cross slide as the marker, because it was easy to measure to and from, to the tips of the tools I put in the holder.

Set your homing with, as Hood says, offset positions, so that when you home the machine, your marker/pointer or tool 0, (whichever you are using) homes to position 0,0 i.e. I assume X0 is on the centreline, I have my Z0 on the chuck. The DRO's should all zero (machine co-ordinates)

Now place the tools in their relevant holder - and it does not need to be all the same holder - and measure with a set of digital calipers, the distance from your marker to the tool tip. This is your tool offset. You can move the table to a more convenient position to do this.

You can test the offsets by putting the tools in, and (as I am sure you know) typing in the tool number, bearing in mind for Mach Turn the Tool number is a four figure number eg. T0202 - (tool number 2 and offset 2) both pairs of numbers must be included. G0X0Z0 should then take the tool tip to your 0.0 position.

You can see why I use a seperate marker. In my case, the corner of the cross slide is always there and I can always measure to it, especially if the tool is one you do not use all that often, and you wish to check the offsets. If you use a tool in a holder as a marker, you have a lot more adding and subtracting to do to get the differences in length and position.

Like you I also have a centre drill holder at the back of the table. I have made holders for all my drills so they just slot into it to a set depth. X offset is always the same, of course, and the z offset brings then point of the drill to the centre of the chuck, just in the little space between the jaws. This makes any depths easy to calculate.

14

General Mach Discussion / Re: 5 phase stepper and Mach 3

« on: July 13, 2009, 03:00:13 AM »

Yes - OK -  our plaster board and plywood still comes in 8ft x 4ft sheets - they call it 2400 x 1200 now. The trouble is some times it is that size, other times it is the old 8 x 4.

We, in UK try to be everything to everybody, I think - but I live and learn, 5 phase motors and 0.2inch pitch - who would have though of that!!!

15

General Mach Discussion / Re: Need help Mach 3 Version R2.63 on MW XP HOME w/SP3

« on: July 13, 2009, 02:52:19 AM »

To get back to the rest of your post - yes, the motors will probably be 200 steps per rev. I would use the drives set to 10 microsteps - which will give 2000 steps per rev.

You seem to be saying that the thread pitch is 18 teeth per inch. This seems an odd figure. My old Acme was 10 revs per inch, my new ball screws are, of course metric at 5mm per rev.

If your pitch is 18 per inch, then your steps per inch work out at 36000. Should be OK for some nice accurate work.

16

General Mach Discussion / Re: x axis loosing current position

« on: July 11, 2009, 05:13:19 AM »

You do not say what the readouts are on the DRO's when this happens. I realise that, unless you watch these all the time, that would be difficult, but if it is 10 inches out in 40 inches, the problem should be quite apparent before the axis changes direction.

If you are in fact, loosing steps, then one would think this would be a regular loss along the axis (and if you mark the job in pencil every foot, you will see that it is 3/4 short each foot). If it is something sudden i.e. Mach has suddenly lost interest in one line and gone onto the next, for no apparent reason, then the DRO's should bear no relation to the program when the move occurs.

It must be one, or the other. If your machine was loosing steps intermittently, then I am sure you would hear or "pick this up" immediately.

I don't know if it is possible for Mach to keep a log of it's movements, I've never heard so.

17

General Mach Discussion / Re: 5 phase stepper and Mach 3

« on: July 11, 2009, 04:55:12 AM »

Mr C -

I,ve not heard of 5 turns to the inch ball screws. I have just fitted some 5mm pitch ball screws on my lathe (the previous set were Acme threads at 10 turns per inch.) The back lash is much reduced with the new ball screws.

Just a check ( and I am sure you will have done it) - are your 5 truns per inch actually that, or are they 5mm pitch ball screws - which will be short 0.4mm each 5 turns. I am afraid some retailers are not as precise as they should be when selling these thongs.

Mind you, I hadn't heard of 5 phase stepper motors either !!!

18

General Mach Discussion / Re: Water cooled spindle motor safety

« on: June 22, 2009, 03:36:55 AM »

Following on from the last post, you could try having a switch which put a signal on the Forward and Reverse switches of the  VFD. This, on my Omron, shows up as a fault, immediately, and the spindle is dead. As soon as the signals are removed, and replaced by only a Forward OR Reverse the spindle starts again

19

General Mach Discussion / Re: tool offset question

« on: June 22, 2009, 03:28:35 AM »

I don't know about the tool offset button.

For the run from here -

Try the set next line button first.. The problem is, Mach has, on a restart to start at a point where it knows what it is, and which axis it is moving. I don't know Mastercam, but if it ignores the G1 (or G0) commands, and merely lists the moves on each line, then Mach will be a bit stuck understanding which axis to move and where.

If you pick a line, with "Set next line" that contains a full instrcution, then pick "Run from Here", Mach should run.

I use the demo version, and this runs the buttons properly, as I say, once you have picked where to start.

20

General Mach Discussion / Re: Can't always zero the X, Y and Z axis in Mach.

« on: June 17, 2009, 03:04:20 PM »

Lindsay - does your machine have "home" switches fitted, and do you "home" your machine at the beginning of each session.

Machine Co-ordinates are used by Mach to keep track of it's position, it includes in it any offsets for programs, tools, etc. It is for mach - and when you look at Machine Co-ordinates, it is difficult (sometimes) to equate them with the program we are running. The only way to alter these Machine Co-ordinates is to "Home" the machine by pressing "RefAllHome" this moves all axis, in turn, to their respective home switch, and then (if "auto zero" is set) it zeros the Machine Co-ordinates.

Machine Co-ordinates are viewed by pressing the "Machine Co-ords" buttong, the surround lights, or underlines, and you are now viewing Machine Co-ordinates.

If you do not have home switches fitted, then you can zero this in any position by pressing the RefAllHome button.

Mach will now keep it's position relative to its last zero mark, in Machine Co-ordinates.

This position will be no use to normal work on the machine, and therefore you should press the Machine Co-ords button. The surround will go out, and the DRO's will now show Program Co-ordinates. These are the ones you want to use when machining.

Jog you machine to the 0.0.0. position of the program and then press ZeroX, ZeroY and ZeroZ. This will zero the Program Co-ords display, and you are then in a position to start your program. An offset has been entered to tell Mach the difference between the two displays.

Provided your program has no G54 - G59P*** commands in it, which changes the "offsets" (i.e. the relationship between the Machine Co-ordinates and the Program Co-ordinates) then your program should run as you expected.