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Post by gdmarsh on Dec 27, 2011 5:51:35 GMT -8
I spent an entire day trying to get my probe set up for axis zeroing.
I have the probe working fine in MSM .. all operations work well & I LOVE the probing functions by the way!
In trying to use the probe as the Master Tool is where I'm missing something. Every time I go through the routine when I change to the next tool it always runs up to the very top of the Z travel, slowly retracts back down and starts cutting air approx 5" off the top of the part. What's interesting is that my probe is set to 5.088 as a 'tool length' in the tool table.
I've read & re-read the sections of the manual that seem to pertain, but there must be something I'm not understanding.
The tutorial that explains this also included at touch plate for measuring tools on the fly .. but all my tools are measured off line and I don't have a touch plate so I'm trying to leave that function out of it.
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Post by DaveCVI on Dec 27, 2011 9:16:58 GMT -8
Hi, For what I think you are attempting to do, you will need to have a good understanding of how TLOs are calculated when using a master tool. The needed info is in section 5.2 and 7.1.3 of the MSM Manual. When MTM is on, MSM understands how the TLO calculations are different when measuring tools - and it does this for you when using a touch plate to measure tools as part of a tool change. However, since you are measuring tools offline, you will have to be responsible for calculating the correct TLO values for MTM and entering them into the tool table. The MTM implementation was really designed for use with auto tool measurements. Frankly, while the use of MTM with offline tool measurements if theoretically possible, it would probably be less work to install a TCP TP and let MSM do the work for you (that would be much less error prone also - every time you do a manual tool measurement off line you will have to do a calculation and that introduces lots of times for you to miss hit a digit on the calculator etc). If you want to proceed down this MTM + offline TLO measurement path, here are some hints to get you going: To use MTM with offline tool measurement, you need: 1) MTM turned on 2) probe tool # set = to the master tool number # Now look in the tool table - what is the TLO value for the probe/master tool? I'd guess that you have the PTL (that you measured off line) of the probe tool as the TLO value - am I correct? In MTM, the ***TLO*** for the master tool will ALWAYS = 0. If the TLO value you entered for the master tool is not 0, some more time absorbing the concepts of MTM is probably in order  3) set the TLO for the master tool = 0.000000001 (yes I know that is not exactly 0, but using that value will let you avoid some very irritating mach bugs that MSM handles internally for you - MSM does some ugly things to compensate for Mach bugs and this make mach appear pretty to the MSM user). Now look at the TLOs for the other tools - they have to be the difference between the physical tool length (PTL) of the master and the tool (NOT the PTL of the tool). This is why you have to make the TLO value calculation for each tool you measure off line. Note that some Tool's TLO values will be <0 and some > 0 depending on the relative length of the tool to th ePTL of the master. Make sure to get the sign correct as to which is which - getting that right is a good check on one's understanding of how to use a master tool as the TLO reference. Attempting to use MTM, with MT=PT and use offline tool measurements is really not the best approach. That MTM and MT=PT combination is complex and MSM has knowledge about the special needs of MTM in many places in the MSM code - all of which depend of the TLO values being correct for MTM use. I'd like to encourage you to seriously consider adding a TP for use with a Tcool Change position - I believe you will find with a much better MSM user experience that way. Dave |
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Post by gdmarsh on Dec 27, 2011 13:00:07 GMT -8
Dave,
Thanks for the info .. I wound up looking at all the videos & figured out where I was going wrong.
I would agree it's easier to let MSM measure everything for me .. but for now I really just wanted to get things going.
I'm also a little concerned about giving up room on the mill table and would rather avoid a movable TP because of accuracy due to the possibility of swarf being under the TP when measuring.
What I came up with is using the surface plate & height gage to measure each tool & subtract the PTL of the probe from each measurement. This does give me + & - numbers and so far everything is working great.
I'll change the TLO on the probe to .000000001 as you mention cause you certainly know more about whats going on under the hood than I do.
I've got everything set up to use the TP in case I decide to make one, but in the mean time I'm just making sure that all my tools are called out as RH with the 'skip RH' feature turned on.
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Post by DaveCVI on Dec 27, 2011 14:02:45 GMT -8
Hi, please see the comments below... Dave What I came up with is using the surface plate & height gage to measure each tool & subtract the PTL of the probe from each measurement. This does give me + & - numbers and so far everything is working great. That should work fine - you are essentially doing what MSM does when it measures a tool in MTM using the TCP TP. Just be careful that you always leave MTM on when setting Z0 etc - the mixed use of MTM and non-MTM can quickly get you into trouble. I'll change the TLO on the probe to .000000001 as you mention cause you certainly know more about whats going on under the hood than I do. Never ask how the sausage is made....  This is a work around for mach bug 4.23 in the MSM release notes. By making the value really small, it will not impact the real cutting surface by a measurable amount, but it will avoid the internal mach test of "if TLO = 0...". If you really, really want to be precise, you can account for the 0.000000001 when you subtract the MT PTL from the Tool PTL... but pragmatically, the error is much smaller than the minimum motion of any machine mach is likely to be running. I've got everything set up to use the TP in case I decide to make one, but in the mean time I'm just making sure that all my tools are called out as RH with the 'skip RH' feature turned on. This is fine but the simplest thing to do is to leave the "TC Atuo TLO" button off. IF MSM is not doing Auto TLO measurement as part of a tool change, it does not look at the RH attribute. RH is used to decide if we can save some tool change time by not doing a measurement - if we are not measuring anyhow, it does not matter. Dave |
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Post by gdmarsh on Dec 28, 2011 16:20:24 GMT -8
Yep, with TC Auto TLO off .. tool changes are even quicker!
The system works very well now that I understand it a little better. I've ordered a digital height gauge so I can measure the probe PTL, ZERO the gauge, then I'll get an exact reading to input for the TLO on other tools so there's no calculations to do. Turning it off shouldn't change anything, but just in case, I"ll write down the PTL of the probe so I can reset the height gauge by touching down on the surface plate, raise it up to the Probe PTL, hit zero & go ..
Getting a little more comfortable with MSM now & I am a happy customer at this point!
I love the feature that disables the spindle when the probe is the current tool, saves a disaster from happening.
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Post by DaveCVI on Dec 28, 2011 22:24:00 GMT -8
I've ordered a digital height gauge so I can measure the probe PTL, ZERO the gauge, then I'll get an exact reading to input for the TLO on other tools so there's no calculations to do. Remember to measure the Probe PTL at the point in the probe travel where the probe is just triggered. Getting a little more comfortable with MSM now & I am a happy customer at this point!  I love the feature that disables the spindle when the probe is the current tool, saves a disaster from happening. Me too! (Don't ask what happend to me that caused me to invent that feature....  ) Dave |
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Post by gdmarsh on Oct 13, 2012 14:13:52 GMT -8
Dave,
Getting ready to build the little circuit for using Probe & TP together .. My local Electronics store does not carry the 74LS06 .. a quick check on the net says it's obsolete. Fry's carries the 74LS05 .. will that work? I'm not going to include the optional signal indicator.
Thanks
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Post by DaveCVI on Oct 13, 2012 17:04:16 GMT -8
Working from memory as I write this: You can pull the 7406 series to higher output voltages (30v? max), while the 7405 is limited 5.5v (TTL levels). I use the 7406 to drive 12 or 24 lamps etc so I had them around when I drew the circuit. In the little circuit in the MSM manual, the outputs are only pulled to +5 anyhow so no need for the higher voltage tolerance of the '06. BTW - a source I use for hobby quantity orders for electronics is www.jameco.comDave |
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Post by gdmarsh on Oct 17, 2012 11:41:36 GMT -8
Thanks Dave,
Finally got both Probe & TP working today ..
Have to finish up version 2.0 of the swing-out TP and I'm off to the races!
Thanks for the great support!
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Post by DaveCVI on Oct 17, 2012 12:27:38 GMT -8
Great - I think you'll like the combination.
I've taken to just letting MSM measure a tool whenever it's mounted.
Even if I could skip the the measurement, it doesn't take long and since I'm not doing production runs the time optimization doesn't matter much to me. I like the simplicity/consistency of that approach (and it lets me avoid the mistake of not measuring a tool I should have).
Dave
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