Messages

21

General Mach Discussion / Re: Probe-It probing wizard - 2D perimeter probing

« on: December 26, 2013, 08:11:46 AM »

Hi again TP,

Yes, my calibration routine centers the tip to the ring before calibration, builds an initial correction table, then re-runs again to find center using the initial correction table and calibrates once more. Error is reduced every time you run through the calibration utilizing correction from a prior run.  

The one thing I don't do is compensate for the tip of the probe being off center from the spindle axis.  Rather than do that in software, I prefer to use touch probes that are mechanically 'centered' by adjustments.  I much rather see there is no runout when measuring the tip with an indicator (I'm a mechanical guy, not a software guy ).  For general measuring/reverse engineering, the tip doesn't have to be centered, but for setup prior to machining (edge/corner/hole center finding) it is obviously required to have the tip concentric with the spindle axis.

I would really be interested in hearing more about the Mach3 built in calibration that you mentioned existing.  It must be pretty well undocumented, as I did a lot of searching about probing before starting to write my own routines, and I still can't find anything about it.    Can you share any more about how it works, how you use it (how to call it, variables used, is there a table created, etc)?  thanks in advance.

regards,
Eric (CraftyCNC)

22

General Mach Discussion / Re: Probe-It probing wizard - 2D perimeter probing

« on: December 24, 2013, 03:09:41 PM »

Hi TP,  Thanks for the welcome!

Let me explain a little more about how my wizard is setup to calibrate the probe tip.  I don't just mean being able to enter the 'ball diameter' so as to compensate measurements to the radius of the ball, if that is what you refer to about Mach3 built in correction. 

The way my routines are written, so as to allow the 2D tracing of a perimeter with some accuracy, probing may be done in any possible direction in the X-Y plane, not just in +/- X and +/- Y. 

If you have a really fancy probe made by Renishaw, and your machine is super tight and has no backlash, then just entering a single ball diameter is pretty good.  However, most touch probes in reality deflect more in some directions than other before they trigger (ie, a +x probe event might trigger after deflecting the tip .001", but a -X probe event might deflect .003" before triggering).  Also, most of us hobby guys also have machines with a little backlash.  All these little errors add up when trying to measure something with some good accuracy, as I've found on my equipment.

The calibration routine in ProbeIt is set up to probe the ID of a ring gauge in 10 degree increments (36 pie slices if you will), and generates a corrected 'ball tip' diameter for every direction probed.  Then when the actual probing routine is running along, the lookup table is utilized to correct the probe tip diameter to compensate for all the little inaccuracies in your machine and probe.  If the angle being probed at falls in between the entries in the table, the correction is interpolated between values.  The idea behind this is similar to the way a real CMM is 'calibrated' around a reference ball, I just chose to go around the ID of a ring rather than around the OD.

Regards,
Eric (CraftyCNC)

HIYA ERIC Welcome to the probing fun(;-).

You do know that Mach3 HAS probe tip corrections built in right Most never knew it existed.

Just a thought, (;-) TP

23

General Mach Discussion / Probe-It probing wizard - 2D perimeter probing

« on: December 24, 2013, 10:01:06 AM »

Hi all, my name is Eric, and I would like to share a probing wizard I've been working on (for a long time...).  

I saw Jimster's comments in Terry's 'probe wizard' thread about some of his wishes (2D probing, save to dxf, etc), and didn't want to hijack that thread to introduce myself.  I've been a long time reader/lurker, and pretty busy with my day job, kids, and moving recently, but I've also been working on a probing wizard for Mach3 which does 2D perimeter probing and saves to either DXF or CSV files.  It started out as a project inspired by Stirling's old routines, and to see what I could accomplish for fun (I'm not a programmer by any means...).  It's coming along into something that could be useful for some, so I'd like to share it.

The wizard is called 'Probe-It!', and you can find more info about it at www.craftycnc.com.  It is done completely within Mach3 VB macros.   To give a brief run down:

It has a page of basic operations (corner, center find, side/edge find, etc much like other existing wizards) for setup operations,  but you can record the points to DXF or CSV (sort of handy for CMM like or reverse engineering of simple parts).  

There is a 'Z probing' page, which doesn't do much in its current form except it helps tell you if your work piece is 'flat' and leveled.

There is a perimeter probing page, which I think would fit Jimster's request quite well.  On this page, the routine will 'trace' around the external (or internal) 2D perimeter profile, and make a DXF (or CSV file) of points/lines which can later be cleaned up and used to reconstruct your part in CAD.  It isn't perfect and occasionally has issues with sharp direction changes, but it is coming along into something that works.

Finally, what I think makes this wizard unique from currently available routines is found on the setup page.  You have the option to probe the ID of a 'ring gauge' of known diameter, and this builds a 'tip correction' table that is used when probing if you wish.  This takes out some of the error associated with backlash, probe deflections, etc.  Once you've built a correction table, errors are reduced in your measured parts, and you are also able to measure bore diameters more precisely and even get 'roundness' measurements.

I don't want to come across as being here only to 'advertise'.  I would genuinely like to share what I'm working on, have people try it, and let me know what they think.  I would appreciate suggestions/comments/requests/ etc.  

ProbeIt requires a later version of Mach3 (3.43.66 has been my test platform for a while).  I've also done all testing on a machine run via parallel port.  I've had mixed response from users running SmoothSteppers, and I don't have a SS run machine to confirm/deny issues.  So any feedback I could get from a SS owner would be appreciated!  And like anything related to probing, I'd like to think the wizard is pretty robust, but everyone's setup is different and it can be easy to 'crunch' your probe, so please use at your own risk and probe slow until you get comfortable with the settings.

ProbeIt is free to download and play with and is fully functional, except it limits the number of points that the tip correction is on and how many points you can perimeter probe to a file without a license.  If you find it useful for basic stuff, you can use it free forever.

Thanks for letting me share, and please let me know of any quetions/comments/suggestions.

Regards,
Eric (CraftyCNC)

24

Mach4 General Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: December 24, 2013, 09:19:42 AM »

Hi,

My name is Eric.  I'm a long time reader/lurker...   I would like to become a more active participant and share some stuff I work on.

I currently run a Millrite mill I've converted to CNC (mechanical and electrical), as well as a Denford Starturn 8 lathe that I've got running (electrical conversion only).  I've been working on these two machines slowly for about the last 3-4 years and have them working well.

I am now currently working on my own touch probes and a probing wizard, as well as various other 'arts' and 'craft' like projects.  I'll share some more about these a little later. 

Regards,
Eric Brust