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Topics - HimyKabibble

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21
General Mach Discussion / Dumb Turning Question
« on: August 09, 2011, 07:32:51 PM »
I'm doing something perhaps a bit goofy, but....  I need to make a batch of parts that basically look like a tootsie-roll pop - a cylindrical section, with a sphere on one end.  The cylinder is roughly 1/2" diameter, while the sphere is 1" diameter.  The goofy part is I'm doing it on my 3-axis mill, with a lathe tool clamped in my vise, since I have not yet gotten around to CNC'ing my little lathe.  I've got it programmed to do the right motions, but it appears to me it's not really practical to do this without using at least two tools - one right-hand, one left-hand.  Use the RH tool to cut the bottom half of the sphere (up to the "equator"), and the LH tool to cut the top half of the sphere.  Either tool can be used to cut the cylinder.  Is there a better way that I'm not seeing?

Regards,
Ray L.

22
General Mach Discussion / Well..... That Was Weird....
« on: July 20, 2011, 09:41:19 PM »
Today, I used my mill for the first time since early 2010 - Just making a simple fixture plate of 1/2" 6061.  A tiny bit of milling, and a bunch of drilling.  Halfway through peck drilling one of the holes, Mach3 spontaneously E-Stopped, leaving ALL FOUR DROs completely whacked - miles from their correct positions!  Never seen anything even remotely like that before!  Re-zeroed, and ran the rest of the program with no problems.

Regards,
Ray L.

23
General Mach Discussion / Saving Tool Table...
« on: January 30, 2010, 03:30:46 PM »
What is the trick to getting Mach3 to SAVE the tool table when you exit?  My probing macros correctly setup the length offsets, but when I close Mach3, and re-start it, the offsets are all gone.  Surely there is a way to save the offsets to XML??

Regards,
Ray L.

24
General Mach Discussion / A Really Exceptional Vendor....
« on: January 19, 2010, 11:20:09 PM »
It's relatively rare these days to come across a truly exceptional vendor, so when I do, I like to give them a plug.

Several months ago, I bought several very inexpensive ($25 ea., IIRC) 1/2" 3-flute carbide endmills from CNCToyBox.com  (http://www.cnctoybox.org).  When I finally got around to actually trying them, a month or two later, I used the same RPM, feed, etc. that I'd been using with Accupro 3-flute carbides for months.  Unfortunately, it turned into something of a disaster, with several of them getting broken very quickly.  I contacted Curt at CNCToyBox, just to see if he had a recommendation for better parameters to use.  Instead, he made what I thought was a remarkably generous offer - He sent me a couple of very good, and very expensive, "Ferocious" hi-helix endmills (http://www.cnctoybox.org/store/page18.html), at no charge.

Well, a few days ago, I discovered that the broken endmills were really my fault, so I contacted Curt and told him I had scerwed up, I wanted to pay him for the Ferocious endmills he sent, and he refused to accept my payment, just saying "stuff happens"!

Needless to say, I will be ordering from Curt again!  In fact, I just did!  :-)

Regards,
Ray L.

25
I tried to machine some 6061-T651 wrought plate today, with rather disastrous results - four broken/dulled endmills later, I'm stumped.  If I go fast, the tools load up and break in seconds.  If I slow down enough to not get chip welding, the tool edges get destroyed VERY quickly - I ruined two brand-new high-quality HSS endmills in less than 24" of cutting each.  All the cutting edges were absolutely destroyed.  How the heck do you machine this cr@p?

Regards,
Ray L.

26
Now that I have my knee setup to do tool length compensation, and macros for loading the tool table by probing, I wanted to have a proper means of measuring tool length.  I've always done this in the past using just a small piece of PCB material.  But, unless you probe very slowly, there's always a chance of chipping the tool, especially with carbide.  So, I wanted something with a little "give" to deal with any over-shoot when probing.  After thinking about it a bit, I realized I could make something incredibly cheap and easy.  I took a piece of scrap metal (part of an old Jaguar wire wheel hub), that was 2.5" OD, and about 2.25" ID, and about 3/4" long.  I faced the two ends parallel, and cut a small recess in one end.  I then cut a circular piece of PCB material that just fit into the recess, and glued it in place with some CA glue.  So, the 2.5" round piece of PCB material is supported only around the edges, leaving the center to flex a bit to absorb any overshoot with no risk of harm to the tools.  The CA is still setting up, but tomorrow I'll try it out, and take a picture or two.

Regards,
Ray L.

27
General Mach Discussion / Using The Knee For Tool Length Compensation
« on: January 03, 2010, 08:44:08 PM »
Below are my new macros for using the knee for tool length compensation.  This is a capability Mach3 does not currently really support, so I had to use a slightly kludgy, but perfectly functional, approach, that will be done away with as soon as v4 is released.  This means you cannot use G43 and G49, but instead must use M843 and M849 to perform the same functions.

Four macros are provided:

M808 is used for probing the length of the "master" tool.  It is strongly recommended that a "dummy" master tool be used that is as long, or longer, than any real tool  I use a piece of 1/2" rod, with a spherical end, in a spare endmill holder.

M809 is used for probing the length of all tools but the master tool.  The probing procedure is to first run the M808 macro on the master tool, then run the M809 on each subsequent tool.  See the header of the M808 macro for more details.

M843 is used, in place of G43, to enable tool length compensation.  The P parameter is used, in place of the H parameter, to specify the tool whose offset is to be used.

M849 is used, in place of G49, to disable tool length compensation.

The macros currently use one non-standard DRO, and one non-standard LED.  The macros themselves are quite simple to modify if you wish to change this, as only the main body of each macro uses the DRO or LED, and each is only a few lines of code.  All subroutines are identical to ones in the probing macros I posted earlier today in another thread.

Regards,
Ray L.

28
General Mach Discussion / New Probing/Measuring Macros
« on: January 03, 2010, 03:56:24 PM »
Below are my latest set of probing and measuring macros.  They provide the following capabilities:

Locating any edge of an objects, the mid-point between two edges, the center of a circle or pocket, and precisely aligning a vise to the X or Y axis.  All of these can either zero the axis DROs to the probed features, or simpy position without zeroing the DROs.  In addition, most operations can be performed for measurement purposes only, simply reporting the distance measured - for example, from the current position to an edge, the distance between two edges, or diameter of a circle.

The major improvement here is use of a two-stage probing technique - First, a high-speed probe is performed, to find the edge quickly.  Then, the probe is retracted about 0.020", and a second probe performed, at slow speed, for better accuracy.  This has consistenly given me 0.0001" repeatability, using a 50 IPM fast probe pass.  Since over-shoot is likely at such speeds, I do NOT recommend use of rigid probes.

These are not quite usable "out of the box", as they get a number of parameters from non-standard DROs.  So, you will have to either add these DROs to your screenset, or modify the macros to hard-wire these parameters.  All parameters are loaded in a subroutine, and the subroutine is identical in all macros that use it, so modification of the code is quite simple by simply modifying one copy, then copying/pasting it into the other macros that require it.  A brief explanation of what's required is contained in the included .txt file.

Note that I am providing these as-is, and cannot provide more than very minimal support and hand-holding.  If you're a "newbie", or not comfortable with Mach3 VB code, this is probably not for you.

Regards,
Ray L.

29
General Mach Discussion / Stupid Probing Question....
« on: January 01, 2010, 11:46:11 PM »
I now have one of those spiffy probes with the little, tiny ball end, and the switch consisting of the three little arms at 120 degrees apart, resting on ball bearings.  In terms of precision and repeatability, it's excellent - I get very consistently +/-0.0001".  But, I have two problems:

1) It's near impossible to get it calibrated to where the ball end is *precisely* aligned to the spindle center.  Getting much under +/-0.0005" is a real chore, and I'm not at all convinced it'll stay there for any length of time.

2) Even worse, the distance the probe tip moves between the time it first makes contact with the workpiece and the time the switch opens is completely unknown, and, I suspect, due to the gemotry of the switch, probably varies based on the angular position of the contact point.

So, how in the heck are these two problems resolved?  Certainly, it would work just fine as-is for probing an object to get a point cloud, but I want to use it for machine setup, so I have to know *exactly* where the spindle centerline is relative to the contact point, as I did when I used to use a rigid probe (which Mach3 liked to break off from time-to-time....).

On a related note, I'm working on a "semi-rigid" probe design that will have a 0.200" diameter tip just like the rigid probes I've used, but will ber able to "give" on over-run by having the probe mounted in a spherical ball bearing, with a spring-loaded centering mechanism.  I think this will be far easier to adjust perfectly concentric to the spindle, and should return precisely to that position after being bumped off-center.

Regards,
Ray L.

30
General Mach Discussion / Peck Drilling....
« on: December 25, 2009, 12:00:42 AM »
Are there any good rules of thumb for setting the Q parameter when peck drilling?  It seems to me this probably should vary with hole depth, doing shorter pecks as the hole gets deeper, but there is no provision in G73/G83 for doing that.

Regards,
Ray L.

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