Messages

11

General Mach Discussion / Re: Fixtures, Offsets, Origins & Suchlike

« on: March 04, 2010, 06:57:32 AM »

Thanks all for the quick replies.

Phil, you have explained things in a way that makes the most sense to me. I cannot read gcode as if it were english thus I prefer to stick to cad/cam where possible rather than writing everything from stratch. For simple 2D stuff i've been experimenting with a program called CAM BAM which I quite like however for more complicated and 3d parts I have occasional access to stuff like mastercam when I'm able to blag a few hours of time on the computer at my mates machine shop.

So am I right in thinking that the point I specify as the origin in my cam package will be equal to x0y0 on the machine (in work coorinates) thus if I generated a hole toolpath and set my origin to be the centre then wherever i zero'd my machine would be where that hole would be drilled ?

How would go you about finding the centre of the wheel? Would you have to put a tool in the chuck that had the same diameter as the hole and then jog down & zero the axes or is there another / better/easier/more accurate way of doing this ?

12

General Mach Discussion / Fixtures, Offsets, Origins & Suchlike

« on: March 03, 2010, 07:07:21 PM »

How does one go about machining a pre existing component rather than just a flat sheet of metal?

This is a concept i'm still struggling to get my head around as the majoity of my cnc experience so far has been on a horribly oversimplified educational system.

To give an example: - say I bought a cheap plastic injection moulded wheel from my local DIY store with a round hole in the centre with plenty of plastic around the edge of it. Now lets say I wanted to machine a hex into the centre so I could drive the wheel from a motor/gearbox with a corresponding shape on the output shaft. I've got the wheel and stuck it in the vice of my machine, and I've got gcode for the hex shape. Now how on earth do I tell mach 3 how to machine my hex in the right place so that the centre of the hex is in the centre of the wheel ?

As a second example, immagine i have a machined a simple shape from a thick piece of steel and I then want to drill holes through the piece at 90 degrees. So I remove the part and flip it round so what was the side is now on the top. I've loaded up my new gcode program but again, how do I ensure it starts cutting the holes in the right place ?

This is something I really need to understand as much of the work I want to do will involve machining things on multiple sides and/or machining onto pre made parts.

13

G-Code, CAD, and CAM discussions / Re: Mastercam to Mach Problems

« on: March 03, 2010, 06:36:34 PM »

I've had another play and it seems there are two settings; Distance mode and IJ Mode. My distance mode is set to absolute and my IJ mode is set to incremental - with these settings everyting works. Setting IJ mode to absolute stopped it working. I'm not sure what IJ mode is or does but maybe that doesnt matter so long as it works. 

14

General Mach Discussion / Re: Weird Stretched Screen Problem

« on: March 01, 2010, 08:15:10 PM »

Cheers Phil! Think that's solved it. I did look under general config previously was looking for screen resolution setting like a drop down menu or something. Totally missed the auto enlarge checkbox until i went back to look for it specifically.

Thanks again!

15

General Mach Discussion / Weird Stretched Screen Problem

« on: March 01, 2010, 12:49:03 PM »

I recently installed a new copy of mach 3 on a new computer (winxp) and then copied my profiles and screens over from a backup. However I have a problem whereby when I load my backed up profile the entire mach window takes up more space, all the buttons are slightly bigger as if it has been stretched out of proportion and beyond the original size. If i close and load the default mill profile from the new install the size goes back to normal.

Is this a known bug ? Can someone tell me how to fix my profile?

16

G-Code, CAD, and CAM discussions / Mastercam to Mach Problems

« on: February 26, 2010, 01:03:03 PM »

Using Mastercam x4 and the mach3 post, mach3 will not load my code without errors unless I go into config and set it to incremental mode. Could someone tell me how to make mastercam output code with absoloute coordinates ? Do I have to make a change in mastercam or is the the post processor I need to change ?

Would be greatful for any help as i'm a bit new to all this stuff.

17

General Mach Discussion / Re: Limitations of PC Parrallel Port

« on: June 17, 2009, 07:16:37 PM »

I'm trying to troubleshoot a problem which initially I thought was intereference but now having earthed everything and put in loads of 0.1uf caps everywhere that matters and still haveing problems I'm starting to think it is either to do with the computer pulse frequency or needing thicker cable running to the machine.

What I do know is previously I was running at 100khz (on parallel port) and had problems with juddery axis movement which usually manifested itself when i was moving two or three axes at once. After trying lots of other things I dropped down to 75khz and things improved a lot. However I'm still getting intermittent glitching (though much less than before) so perhaps dropping down to 45khz is the answer. Problem with that of course is it will reduce my max speed by half. However I might be able to get away with it by using 'electronic gearing' in the rutex firmware so 1 pulse moves the axis twice as much. That way i should be able to still get 5 metres a minute just by dividing my current mach3 steps per unit by two to give me a figure of nearer 400 rather than 800 and then I should still be able to get 5m/min (or close) at 45khz.

Either that or maybe this smooth stepper thing you speak of is another solution ... but is this not really expensive?


Regards,

Dom

18

General Mach Discussion / Limitations of PC Parrallel Port

« on: June 17, 2009, 11:00:37 AM »

Just wondering what the realistic limitations are of pulse speed when using a pc parallel port. Will it run fine up to 100khz with a modern computer or will I have to limit Mach3 to something much lower?

19

General Mach Discussion / Re: New Machine Build - Mach 3 Help Needed!

« on: June 15, 2009, 09:42:31 AM »

gotcha

20

General Mach Discussion / Re: New Machine Build - Mach 3 Help Needed!

« on: June 15, 2009, 09:06:06 AM »

Cheers Hood, lots of things solved at once there.

If I do as you suggest and set the min soft limits to 0 for x and y and 0 for max on z, wont that mean that I have no soft limits at all operating for one direction on each axis ?