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Topics - bigandy

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1
General Mach Discussion / Feed rate strangeness.
« on: June 08, 2009, 02:16:01 PM »
Hi folks.

I've just been testing out my limit switches on a small 3 Axis mill, and I have encountered a bit of a strange one.  I have slowed down the feed rate using the little + and - signs in the feedrate box on the main screen.  This works great, and has the mill moving at a snails pace, so I don't damage anything if the limit swtich fails in some way.

However, I have noticed that if I hit a limit switch (thus triggering an Estop) and the reset that condition by clicking the reset button on the PC (i'm manually winding the axis off the limit switch), the feedrate goes back up to 100%.  The strange thing is that the display in the feedrate panel still shows the much reduced rate.

If I change the feedrate slightly (say reduce it by a couple of percent), it then starts behaving as expected, with the axes moving very slowly.

Has anyone encoutered this before?  Anyne got any ideas why it may be happening?

I'm using the R3.042.020 lockdown release.  I am driving my mill through a SmoothStepper USB device (which I suspect may be the problem here).

Cheers
Andy

2
SmoothStepper USB / SmoothStepper plugin noise filtering.
« on: June 08, 2009, 01:55:28 PM »
Afternoon all.

Just a quick query about the noise filtering in the SmoothStepper plugin control menu.  I have connected up all my limit switches today (6 in total) and I have found that my system has become unusable.  Everytime the reset button is pressed in Mach 3, it would immediately trip out again.  On the odd occasion where it didn't trip out, I could jog an axis for a fraction of second, before it tripped out.

I have tried a few things like tidying the cabling up, and re-routing a few wires, but the problem does seem to be down to noise getting onto the limit switch lines.  Some switches are worse than others (I've tried enabling them each indiviually) but they all seem to suffer.

I have also tried the noise filtering in the SmoothStepper plugin control menu.  This seems to have had a good effect.  I tried setting the noise filtering on the "Limits" to 5µs and this didn't really help.  Increasing it to 10µs made things better, and as I incremented it upwards, things got better and better.  I have been tinkering for about an hour now, with it set to 50µs, and have not had one noise problem.

Can anyone tell me if they have had to use this noise filtering, and if so, how much?  Also, are there any negatives of using it at all?  I'm a bit wary of just masking the problem here, but despite re-routing wires, I cannot seem to eliminate it.

Cheers
Andy


3
General Mach Discussion / Limit switch location on axis?
« on: January 12, 2009, 09:29:26 AM »
Afternoon all.

Please forgive the rather obvious question (it's not for me though, otherwise I wouldn't be asking!).  I am nearly ready to run my 3 axis router, and I just need to mount the axis limit switches to the machine now.  However, I am not sure of the best place to locate them, in terms of the axis total movement.

For example, my X axis can move a total of 12".  If it travels any more than that limit, the carriage will hit the machine frame, and something has to give (either the leadscrew nut, the motor coupling or the machine frame!).  Although that is my ultimate machine limit, is it good practice to mount the limit switches at (say) 90" of the axis total travel?

I'm thinking that perhaps it is, that way there will be time for Mach3 to detect the limit switch trigger, and stop the axis moving (allowing a bit for deceleration too).  The only thing I am wondering, is the amount of room required for this, which will determin where to mount the limit switches.  Are there any guidelines for this sort of thing anywhere?

Any opinions would be much appreciated!

Cheers
Andy

4
SmoothStepper USB / Just got my Smoothsteppers, have a few queries now!
« on: December 04, 2008, 05:42:40 PM »
Evening all,

Thanks to the quick shipping and good service from the guys at Warp9, I'm now the owner of two Smoothstepper USB boards.  I have just started setting one up for my mill, and I have a few queries already!  Hopefully they won't sound too silly, and perhaps someone might know the answer?  I would be most grateful for any help if you do!

1.  When I am configuring Mach 3 with the SmoothStepper in the "ports and pins" setup box in the config menu, what should I be entering here?  I can only enable parallel port 1 and 2, and these need an address (a hex number).  Also, the Smoothstepper has 3 ports that can be used?  What should be entered to use the inputs on the 3rd port (do I just enter the number "3" in the boxes that are asking for port numbers?)

2.  Charge pump output.  I was originally planning to use a parallel port output from my laptop, and thus make use of a charge pump circuit for safety reasons.  As I am now going to be using a Smoothstepper board instead, is the charge pump still required? Is it recommended?  Or is the function of the chargepump now not needed as the smoothstepper does effectively the same thing?

3.  Are there any known issues, or features that are not implemented/supported by the smoothstepper in Mach3 at present?  I have read a few threads that mention the odd thing (soft limits?  Backlash compensation?) but not seen a current "list" anywhere.  Maybe this could be a sticky at the top of this forum?

4.  Can anyone give me, or post a link to, any resources that will explain what a differential input is (as seen on the Smoothstepper port 3 input 2), and what benefits it has over normal inputs?

Other  than that, it looks pretty straightforward.  I already have it communicating with Mach 3, but I haven't decamped out to the (bloomin cold!) workshop yet to hook it up to a stepper driver!  I may resort to bringing one inside this weekend if the cold weather continues!

Cheers
Andy

EDIT:  remembered the 4th question I had!

5
General Mach Discussion / Mach 3 hardware drivers
« on: October 10, 2008, 06:53:36 AM »
Good afternoon all,

I have just registered with this forum as I am looking for a software system to drive my small CNC router/mill project that I have been working on.  It is a 3 axis gantry mill, which has a cutting area about the size of an A4 bit of paper, and around 100mm travel in z.  I currently have the mechanicals complete, and the Stepper drives all wired up, and I am about ready to build a breakout board and get the software side of things configured.

I have been recommended Mach 3, and looking at the website it seems like it will do everything I am looking for.

I do have a slight issue though, and that is that I only have access to a fairly low powered laptop (Dell Latitude D505 with a 1.5GHz Celeron M Processor).  I know it is not recommended to run the Mach 3 driver on a laptop, but I was wondering if anyone has had any success doing so?

The other option that I have just seen on here, is the ability to use an external hardware driver.  I have had a quick look over the "SmoothStepper" USB interface, and I was wondering if there are any other products out there that would do a similar job.  I quite like the idea of having an interface that allows some buffering, and is not entirely dependant on having a good spec desktop computer, and can work using a laptop or similar?

I'm off to do a LOT of reading of this forum now, and see what I can find out.  If anyone has any links to threads that might be useful to read, or has any advice, I would love to hear it!  Apologies for the "newbie" questions :)

Cheers
Andy

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