Some Ideas for Ease of Use

MontanaAardvark said:
Now that I have my CNC G0704 running, I've been thinking of ways to make living with it easier and do things faster. I thought I'd put out a couple of ideas running in my head and ask you gurus what you think.

I'm not doing this for money, but a lot of time spent indicating the edges of a part for every part just seems like a waste of time. It's not hard, it's just tedious. Industry uses tooling plates or homing switches that always are (0,0) and I'm thinking of doing something like that. I've assigned a fixture (0,0) for several parts on a little project I'm building, making the front left hand corner of the fixed jaw on my vise into (0,0). All I have to do is put a piece in the vise, press it against the stop and it's ready to machine. Yeah, all my Y numbers are negative, but no big deal.

The issue is that the vise only holds a small range of sizes without changes. Something like this Sherline-sized tooling plate from eBay looks like the trick to do (no relation to the seller, don't know if it's any good, and all disclaimers). Set one corner as the reference point and go from there. Making or getting one for the G0704 might be a good exercise, although I think the clamping screw holes would have to be bigger due to the (much) higher power of the Grizzly over the Sherline.

Do any of you guys do anything like this?

The other thing I'm trying to improve is tool changing. I'd love a Tormach changer and the whole TTS, but they're like $4000 so that ain't happening (I am a retiree, after all). So I was thinking of getting a bunch of R8 end mill holders at $16 or $17, like this from LMS, and making a system of my own. Set the tools to all the same distance out of the holder (1" as example), and then when it's time to change tools, I'll still need to swap tools in the spindle, but they'll all be zeroed once the new end mill holder is in the spindle. I can replace the four sided nut on the G0704 with a regular hex head and stick a socket on a battery powered wrench to speed loosening/tightening. Or maybe a manual drawbar like Hoss shows on the DVD.

Again, anybody done anything like this?


Bob
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Take a look at the Tormach TTS system. You don't need the ATC to gain the benefits of the TTS system. The TTS system can be adapted to any mill with R8 tooling. The principle is that the ER20 collet chuck is mounted in a 3/4 R8 collet and as the R8 collet is tightened, it pulls the ER20 collet chuck tight to the spindle face, ensuring a reproducible tool offset. This allows the chuck with tool to be removed and remounted without losing accuracy.The ER collet chucks can be purchased for as little as $25 and other options such as TTS Jacobs taper adapters or end mill holder for Weldon shanks are available. ER32 and ER16 collet chucks are available as well

You still have to manually load the tooling but it removes the necessity of re-referencing your tooling each time you mount it. I use the Tormach system in both my Tormach 770 and my old mill drill. I believe that Tormach has a white paper describing the process for converting a mill to the TTS system. It basically requires checking your spindle face for runout and truing if necessary. Tormach sells a special R8 collet for use with the TTS system but you can make your own easily by grinding the face of a 3/4" R* collet for clearance.
 
Second the vote to switch to the TTS system. The only similar alternative short of swapping to a BT30 spindle would be a Royal quick-change collet system, and those are very expensive.

You can even make TTS-compatible tool holders for very little money, especially if you have a lathe. Get some 3/4" ground stock and put a groove in it for a C-clip. Drill and ream for your tool shank. Get some 1-1/2" or 1-5/8" stock and bore it for a light press fit on the 3/4" stock. Cut off some 1/2" thick doughnuts and press them on the 3/4" tool holder using the C-clip as a stop - there's your flange that registers against the mill spindle nose. Use loctite if you're paranoid. Put the assembly back in the lathe and clean up the back side of the new flange.

Side-drill for a set screw and you now have a $3-$4 tool holder. If you don't trust the runout or set screw holding power, at least you can use it for indicators, taps, whatever doesn't spin at high RPM. And you haven't spent all day turning 1-1/2" stock in to chips just so you can get a 3/4" shank out of it.

You can build or buy power drawbars pretty cheaply that are based on a cordless or pneumatic impact gun. If you're motivated, an air or hydraulic cylinder-type power draw bar with belleville washers isn't very hard to do.

As for tool heights, I assuming you're running Mach3, Mach4, LinuxCNC, or some other PC-based control software. All of these controllers have software add-ins available for touch-plate Z-height setters. Whether you choose to use the TTS system or not, setting up (or buying and installing) a touch-plate macro is quite easy. Once set up and you have the touch-plates connected, the macro/software will automatically touch off on the touch-plate after a tool change and set the appropriate Z-height. You tool table will be set to zero for all tools, and the Z-offset will be written directly each time you change tools within the program. The systems that use two plates are pretty slick: one plate of known thickness goes on top of your part at the beginning of the job to set part height zero, and then all subsequent tool changes are done on the other plate that's out of the way on your table.

This method is slower (during machining) than entering the tool length in the tool table and calling it up mid-program, but it also means you don't have to stop and re-measure if you break an endmill. More frequently, if you have 3 or 4 drills to use during a program you don't need separate drill chucks for each size with the lengths pre-measured. When the tool change sub-program (macro) pauses for a tool change, just put the different drill in the chuck and it'll touch off and write the new Z-height. Again slower, but you don't need a separate holder for each tool.

In fact, you don't even need the TTS system to take advantage of the touch-plate. Stick with R8 collets for your tools, get a cordless drill, and let the tool change macro worry about the tool length. The reason I prefer the TTS system AND the tool change macro is that it's much faster to change a TTS holder than take the whole R8 collet out for different tool shanks - as well as being shorter (gaining me extra room on tall parts).

If you do go with the TTS system - and I obviously recommend it - you can buy TTS compatible ER11/16/20/25/32 collet chucks on ebay for about $15-$20 per including shipping. Suggest you visit the Tormach section on CNCZone and poke around.

Finally, indicating corners is a pain. I hate it too. I'm not an expert, but it appears that in the absence of a tooling plate with known reference points either a high-quality touch-probe or a 3D taster-style indicator is the quickest thing. Even with a tooling plate, you may need to move the tooling plate or mount something on it in a non-standard location or orientation. To use a tooling plate you'll have to indicate it at the beginning of the session anyway, and then still figure out your offsets for the part edges for different jobs.

Sub-$1k probes will probably get you with 0.002-0.003, perhaps better some of the time. This may be good enough for your work given other slop or tolerances in your machine (if any). A 3D taster (Haimer or similar) is about $400, is good to sub-0.001" and can be very, very fast to setup a part in all three axis. Watch some youtube videos on both probing and 3D tasters; you might find them to be worth your time.

BTW, there's a guy on the Tormach CNCZone forum who is about to launch an 'impact-tolerant' touch probe that appears to be an order of magnitude more accurate than cheap probes and much more robust (crash resistant) for idiots like me than 3D tasters. I'll be sending him money the minute he makes them available.

So... TTS system, power draw bar, touch-plates, and a probe or Haimer. If you get all that sorted out you'll spend more time planning the next part and less time dealing with the irritating setup part of CNC machining.

Good luck...
-S
 
Thanks, Spumco! Great stuff. Lots to digest in there, including terms I'd never heard (3D Tasters).

(and I get the name)


Bob
 
I suspect "taster" is from a German word that doesn't translate quite right. I also suspect it's functionally accurate and amusing enough to English speakers that various manufacturers haven't changed the translation to something clumsy. Like ""3-axis mechanical indicator" or something else stupid.

That, or "Machinist's Shiny Ball Dingus" was already taken.

Or you were referring to my screen name, which of course comes from spending too much time watching TV in the early 90's...
 
spumco said:
I suspect "taster" is from a German word that doesn't translate quite right. I also suspect it's functionally accurate and amusing enough to English speakers that various manufacturers haven't changed the translation to something clumsy. Like ""3-axis mechanical indicator" or something else stupid.

That, or "Machinist's Shiny Ball Dingus" was already taken.

Or you were referring to my screen name, which of course comes from spending too much time watching TV in the early 90's...
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Screen name. I stumbled across R&S toward the end of the first season, and quickly caught them all.
 
You got it in one go.

Give me a shout if you have other questions about TTS or anything else I mentioned. If I don't know the answer, I'll make something up and sound convincing.

BTW, LMS or Tormach seem to be the only source of finished JT taper TTS holder for drill chucks. No ebay joy for those, but there are plenty of 3/4" shank insert tools (fly cutters, end mills, ect.) than can be converted to TTS. I'm about to try out a 5/8" 2-insert end mill I picked up for about $60 that includes 10 APKT polished inserts for aluminum. Sort of a poor-man's ShearHog.

Google ShearHog if you don't know what it is and be prepared for a Holy **** moment.
 
This is the touch plate I made for finding and setting X, Y, Z zero. Set the touch plate on the corner you want to reference then start the script assigned to the Auto Tool Zero button. Using a rod or cutter of known diameter the script moves the table in the X axis until the rod/cutter comes in contact with the touch plate then backs off 1-1/2" then moves in the Y axis and does the same. The next move is in the -Z direction, contacts the touch plate and retracts 1". Done in about 60 seconds.

Tom S.



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TomS said:
This is the touch plate I made for finding and setting X, Y, Z zero. Set the touch plate on the corner you want to reference then start the script assigned to the Auto Tool Zero button. Using a rod or cutter of known diameter the script moves the table in the X axis until the rod/cutter comes in contact with the touch plate then backs off 1-1/2" then moves in the Y axis and does the same. The next move is in the -Z direction, contacts the touch plate and retracts 1". Done in about 60 seconds.

Tom S.



View attachment 232257
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It looks like plastic? Two plastic pieces on the sides - I guess to locate it? Is there plastic on the top?

I don't think I see how it works, yet. Am I looking at the top or the bottom (that touches the piece you're setting zero on)? An outside corner you're going to want to be (0,0) goes in that plastic corner?


Bob
 
I'm pretty sure we're looking at the bottom. The inside metal corner edges are the 'known' X/Y surfaces, and the bottom and sides are plastic to insulate from the work piece. The metal plate is DC+, and the tool is DC- (perhaps through the spindle or another aligator clip. Flat head screws are recessed to maintain electrical insulation from part top surface. Damn clever.

Similar to my Z touch plates. Mine are spring-loaded so I can rapid down at 50IPM without chipping the tool (it does a second probe at about 4IPM). However, mine doesn't do X/Y - that's pretty cool. It's kind of like an inflexible spindle-mounted touch probe.

I don't see why you couldn't make a spring loaded probe that could do the same thing. Use a known diameter and you're in business. You could even make a spring-loaded button on the top instead of a telescoping probe thingie so you could do a two-pass fast-slow probe routine.

I'm still trying to figure out how to touch off quickly on oddball shaped things or the top of round parts without resorting to the old 'creep up on the scrap of paper' trick.
 
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