Quiet

Sorry folks

I have posted before, but since I have moved over to BT Yahoo from Claranet enticed by faster connect and less money thimgs have changed.

I tried to post to another NG earlier and it failed to appear, so just thought I would try again here, sorry to pull the tails of the tigers in here!

Anyway since I'm here...............

I was on Colin Ushers site to download the ME index, and while I was in there I also took down the CNC proggy, now never having even seen a cnc machine running, can someone tell me how does it know where "zero" is i.e. where to start and how does it overcome backlash?

Also (nearly afraid to ask this) is it possible to control stepper motors from a Windows pc?

I think there was some minor debate over this just before I drunkenly tripped over this NG.

Amd John.......how the hell do you see the other NG's on my list.......;o))

Rich

John Stevenson said

Depends upon the outcome of the investigation I should imagine.

Hope it's nothing serious.

JG

Depends on the reason it went there in the first place...

Peter

I was referring to 'our friend who shall not be named '

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

Have a look at the following website:

Art has developed software at 'device driver' level which allows the stepping to be carried out in real time. You will need Windows 2000 or XP, and a fairly zippy machine will do you no end of good...

This depends a lot on the controller or the operator. we all have our own little ways. Some controllers can remember the last position at switch off. Some require you to switch on, run to the home switches then enter a stored number from the last settings you ran. Others require you to reset at every switch on.

I personally use the left hand side of the fixed vise jaw as 0,0 or if using a jig plate the top left corner. If you go back to 0,0 when you have done, switch off and don't touch the machine at start up it defaults to 0,0 which is where you are.

Backlash is a black art. Ideally you should have no backlash at all. This is possible on more expensive machines by the use of preloaded ball screws. Cheaper machines using acme screws have to rely on software controlled backlash where you enter the amount in. This then makes the machine move that entered amount extra at each axis reversal. Ideal for linear moves but doing something like a circle isn't always satisfactory as the tool can grab the work and pull it in whilst it's in the 'dead zone'

Yes, Many fully professional systems now use windows. Some of these like MDSI cost around £15,000 for the software and no one is going to pay that if it doesn't work. Some of the simpler ones do have to wait whilst windows goes it's own way but remember computers are running at least 10 times as fast as a mechanical machine can.

One of the popular windows controllers mach3, can send pulses out at

45,000 per second, on my machine it takes 10,000 pulses to move 1" so in theory the machine can move 4.5" per second or 270" per minute. Most cutting is done at around 5" per minute to 40" per minute so you can see you have plenty of leeway.

-- Regards,

John Stevenson Nottingham, England.

Visit the new Model Engineering adverts page at:-

Ah! Too cryptic for me at this time of night John :)

It has been quiet on that front long enough for me to forget it.

JG