[Liberty4Ever]

I'm a month and a half into a lathe CNC retrofit, working part time. I was going to buy a Grizzly G0602 10X22 lathe and retrofit it, but a machine shop friend talked me into an old American made lathe. Those guys all look down their noses at the import machine tools, even though I think the parts I'd keep for the CNC retrofit would have been good (spindle, taper bearings, induction hardened ways). So I haunted Craig's List and found an ugly but lightly used Clausing 4902 lathe about 100 miles north of me for $1200. Buying it and getting it into my basement were epic adventures, but I won't bore you with that. The lathe is in the basement and I've been degunking it. The original owner painted it blue and it's now rough looking with age, but it's still tight and should be a good CNC retrofit.

Getting the lathe:




The lathe is finally in the basement:




I've been researching EMC2 quite a bit, and studying other people's CNC conversions. I'm an electrical engineer and I've designed many custom machines, so I'm not too put off by the electronics and wiring. As I researched EMC2 CNC and found good choices for subsystem solutions, I purchased the hardware. I'm well along the way. I installed EMC2 on a $100 used Compaq D51S Evo PC I bought off Craig's List for $100. It's running the EMC2 lathe simulator. I added a small Logitech K400 wireless keyboard with touch pad ($38 on eBay) that I think will be very handy and might take the place of a pendant. I have some nice Italian 900 ounce inch servo motors left over from my 2005 CNC mill project (never got a round tuit, but the mill CNC retrofit is next, after the lathe). I found some great $23 CUI encoders at Digi-Key. I have a couple of Gecko 320X servo drives. I took a chance on a 2HP Chinese VFD on eBay for $106 (looks OK, packing material smelled like Harbor Freight, Chinglish manual could be better but looks reasonably easy to set up and use). I have E-stop switches and shaft couplings and inductive prox limit/home switches, etc. I just spent $115 at Lowes on the wire, plug and outlet to wire the CNC lathe into the 30A dryer circuit in the basement. I bought a very heavy duty roll around tool cart at Sam's Club for $200. The PC sits on top, various measurement tools and lathe tooling go in the top five drawers, and the CNC electronics will go in the large drawer on the bottom with a lot of forced air cooling. Connectors to the lathe will be on the back of the roll around.

The roll around PC stand, tool cart, and electronics enclosure:




I still need to make some servo motor mounts and buy some fuses/breakers, connectors, etc. The only remaining big piece of the puzzle is the hardware to connect everything to EMC2 and the PC. I have a parallel port, but I don't think it'll have enough I/O. Should I add a second parallel port and use simple optoisolated breakout boards? Is there a better single board I/O solution that works well with EMC2?

I want the PC to be optically isolated from the rest of the electronics. I need to control the X and Z servos via the Gecko 320X drives and the three phase spindle via the VFD (0-5VDC, 0-10VDC, 0-20mA, 4-20mA, or RS-485). I think I'd like to use 0-10 VDC, and I may need a couple of outputs to signal RUN FORWARD and RUN REVERSE? I have four limit switches I need to read, as well as three quadrature encoders with index pulses (X, Z, and spindle). I plan on running the encoders single ended and not use the negative signals for A and B, so I'll need three inputs for each of the three encoders (A+. B+ and Index). I'd like some extra digital I/O because... call me crazy, but I eventually want to build a 5' bar feeder and collet/chuck closer so I can run semi-unattended operation for my short run production (up to 500 parts a month).

Got a good recommendation for an EMC2 friendly I/O solution, that's hopefully reasonably priced? Something that'll work well with my 24VDC digital I/O, the single ended absolute encoders, the Gecko servo drives, and the VFD to control the spindle?

I'm documenting this entire project, and when it's working, I plan on making a web page with a bill of materials, tips & tricks, and a series of YouTube videos to "pay it forward", and make an EMC2 conversion easier on those who follow me along this path.

Thanks in advance for any EMC2 I/O hardware recommendations you might have.

[Tkamsker]

Hi,
i did recently the same (even if i now doing an EMC2 update)
i retrofitted an new Drehmaschinen und Frsmaschinen Hersteller - Klippfeld Turning lathe which also has an Mill head. Thats why i bought it with special Linear gear for the Toolhead.
I am an it specialist and know electronic quite well (do some micocontroller stuff so i personally think when you want to do it easy use the standard parallel ports and if you have to put 2 or 3 of the parallel cards in there.

I searched long but finnaly i found a controller called tripple beast and verry strong steppers ( Benezan Electronics) i dont have the ballscrew so i have to fight backslash.

i found out the hardest stuff was to get an good CAM Programm for what i have to "lathe" (for milling i have an heiz Portal mill and use different software)
my next step is to build an "Handwheel" which i want to use arduino base like
sansbury95's Channel - YouTube so i can then use the lathe and mill as it was on hand or at gcode .

And then my winter project is doing an Turret. Where i bought already the plans but i am not happy with the air compressing stuff and the way it works.
so i think i will do an second arduino based turret. i want to use the design i bought for the shaft and tool holding plate the rest i will do it controller based. my idea is to also use it for manual mills. where you press button tool x and it jumps to tool x or center drill and so on.

And the reason i want to use arduino based stuff because the software support is cool and no parallel board i only need an usb board for it.

so thats my 5 cents
thx
thomas

[dlktdr]

I am a fan of Mesa's products (Mesa Electronics). Buy a 7i43, 7i33 and a 7i37. The 7i43 connects to the parallel port providing 48 programmable io via FPGA. The 7i33 connects to the 7i43. It has four +/-10V Analog ouputs and 4 quadrature inputs for encoders. The 7i37 is an isolated IO board providing 8 outputs and 16 inputs. The drivers are all included with EMC and they are a reasonable price.

On my machine I bought a 24IO G4 Opto-22 Relay rack instead of the 7i37. It plugs directly into the 7i43 and allows you to pick and choose what IO you want. It's a little more money this way but ebay usually has good deals..

[Liberty4Ever]

Thank you both for your comments and suggestions. I'm leaning toward a Mesa solution. A couple of weeks ago, I talked to Peter at Mesa (nice guy!) and it seems that they're realizing that a significant part of their market is now CNC conversions, and they seem to be developing specific solutions for that market, although their products still seem mostly directed toward general purpose PC I/O. They reportedly work well for CNC, including EMC2, but I think they're working on a more integrated CNC solution, hopefully a product that doesn't require three cards to get all the features needed for CNC.

I had the initial impression that EMC2 prefers interfacing directly through the parallel port hardware, and that's certainly the simplest concept. I figured I could get simple low cost optical isolator breakout boards for the digital I/O, and with the STEP and DIRECTION servo controllers I have, the digital I/O would be most of what I needed. I do have a VFD and I'll probably use 0-10V to control spindle speed, so I probably need at least one analog output. I thought maybe someone might make a fairly simple parallel port breakout board that's mostly digital I/O with perhaps a frequency to voltage controller and maybe EMC2 could provide a pulse train on an output pin that could create the voltage I need easily and inexpensively, or maybe a simple integrator circuit to convert a pulse width modulated output to an analog voltage.

I'm fairly cheap, but the expense of the very nice Mesa hardware isn't much of an issue. Mostly, I was wanting to keep it simple. Putting an FPGA card and a couple of daughter cards into the mix didn't sound as simple as I was wanting. On the other hand, maybe it will be easier to let Mesa do all of the work and treat the I/O hardware as a black box. I'm just worried about EMC2 config file problems trying to get it to recognize the Mesa cards. Based on the recommendations I'm getting for Mesa as opposed to using the parallel port hardware, I'm guessing that Mesa is the easiest path to success.

I'm going to try to get my I/O hardware on order today so I can get this project over the hump and on the long downhill run to making some chips. I'll read the hefty EMC2 documentation a bit more to see if I can get a better understanding about the I/O issues. That's still fuzzy to me, and that's keeping me from making the I/O hardware decision.

Thanks again for the info and assistance!

[Liberty4Ever]

I/O Electronics Ordered!

Mesa Electronics

5i25 $89.00
7i76 $119.00
10' DB25M to DB25M IEEE-1284 cable $12.50

The 5i25 is fairly new. The goal is a product that's more optimized specifically for CNC applications, so it has the features we need, not a lot of capability we don't need, and the cost is a bit less because we aren't paying for features and added flexibility in excess of what we need. It's a solution that's a bit more integrated, and down the road that should translate into less complexity getting it to run with EMC2 or the controller of your choice.

Basically, the 5i25 plugs into the PC bus and has a DB25F port on the back of the computer. The cable connects the 5i25 in the PC to the 7i76, which will be in the electronics panel, which in my case is in the big drawer in the bottom of a roll around cart. The PC and monitor and keyboard are on the top of the cart, and lathe tooling, manuals and measuring tools are in the other drawers. There will be connectors on the bottom back of the cart with cables running to the lathe. The cables power the X, Z and spindle motors, carry encoder signals back to the CNC electronics, carry the end and home limit switch signals for X and Z, etc. The 7i76 card has screw terminals so making connections should be easy.

I've designed a lot of machines, including some big systems with a lot of PC based I/O (Opto 22, etc.), and I don't remember fretting over the hardware decision like I did this time. I entered this thinking EMC2 liked bit banging on the parallel port and the I/O would be easy. Just get one or two inexpensive optically isolated breakout boards for one or two parallel ports and program the EMC2 configuration file to know what hardware was where. Not so.

I probably made it harder than it needed to be. I'm glad I finally have the I/O hardware on order. That's the last big unknown checked off the list. All that's remaining are many little details - custom motor mounts, sensor brackets, lots of wiring, and later on, some ball screws... PLUS, all the big gotchas that I can't see from here.

Lots of work left to do, but I'm well under way. Thanks to Peter at Mesa Electronics for some hand holding and pre-sales technical advice in a couple of phone calls. Thanks also to those online who took time to help me.

I'm meticulously documenting this project, so hopefully I can provide a step-by-step guide that will save those attempting CNC retrofits some effort and a lot of the head scratching I did. I may not produce the very most optimal solution, but hopefully it'll be a good solution that others can emulate if they like.

The 5i25 I/O board is brand new, and Andy is apparently just finishing up the drivers. Thank you Andy! I'll need to do a little double clutching to get EMC2 to like it. I'll need to upgrade from 2.4.3 as installed on the live CD to the new version 2.5, but I'm fairly comfortable with Linux. I wasn't going to network the EMC2 machines, but in anticipation of the need for EMC2 version 2.5 and probably a couple of profile downloads, I ordered a three pack of Ubuntu friendly USB WiFi dongles from eBay last night. Those have gotten cheap while I wasn't paying attention. They're about $5 each! The next live CD version of EMC2 should support the 5i25 board without any upgrade hassles.

I need to devote some serious time to this project. I've been piddling around an hour or two a day, and adding more to the To Do list than I'm crossing off the list. At this rate, I'll never finish.

[will gilmore]

I entered this thinking EMC2 liked bit banging on the parallel port and the I/O would be easy. Just get one or two inexpensive optically isolated breakout boards for one or two parallel ports and program the EMC2 configuration file to know what hardware was where. Not so.

I'm in the planning stages of a mill retrofit and the above is exactly what I was thinking. Why not? I haven't read up on the Mesa products yet. If you could point me in the right direction I would appreciate it. --Will

[Tkamsker]

Hi,
i think important is that you can get support if you need to so if mesa is helping you out go for it.
I did use Triplebeast from germany for that and i am happy.

Bzw i will now (in next 2 Months - add the threading functionalty
And i found a nice link of one who did it successfully. And he also has a kind of parllel buffer board which may be of interest for you
Lathe Spindle Encoder

take it as a kind of my 5cents

hello from vienna

thomas

[Liberty4Ever]

I went with Mesa instead of Triplebeast largely because I'm in the USA and international shipping and support seemed like an unneeded complication. I did bookmark their website from your previous post, though.

Speaking of bookmarks, your link to the homemade spindle encoder was also added to my bookmarks. I've been wondering how I'll attach the tiny encoder I have to the spindle. The 7i76 has inputs for a spindle encoder, but mounting that encoder may be difficult. To be honest, the lathe is still up on the dollies and I haven't been able to open the end to look at the back side of the spindle. I'll come up with something. I have access to a laser and it would be easy to cut a spindle encoder disk from black acrylic as shown on that web page. I hope I can use the little CUI encoder I already purchased. Whatever I do, I'll document it so others can share in the idea.

[giz]

Any updates?

[Liberty4Ever]

Any updates?

Well, I was waiting until I had something substantive to post. I've been plugging away an hour of two a day, but work has been busy lately and it's cutting into my lathe retrofit time.

My CNC interface electronics arrived from Mesa Electronics last week, but I haven't plugged the PCI card into the Ubuntu PC yet. I need to upgrade EMC2 version 2.5 for the new Mesa board to work. I received a WiFi router that can be configured similar to a bridge, so it'll connect to the existing WiFi network as a WiFi device to supply wired networking in the shop via the upstairs WiFi network so I hopefully won't need to run an Ethernet cable, but I haven't configured and installed the new WiFi router.

I have the lathe headstock apart and I've figured out where I want to mount the three gear tooth sensors that will implement a spindle speed absolute quadrature encoder, but I haven't built the brackets and wired the sensors yet. It should be a nice installation, well protected inside the heavy cast headstock enclosure, but easy to get to if needed. I'll route the cable through the hole in the back of the headstock that's now available after I removed the FORWARD/REVERSE lever, interlock and drum switch. Those are all spare parts once I get the VFD connected to the spindle. I'll mount an EStop on the hole in the front of the head stock that's open after removing that FOR/REV lever. I toyed with the idea of leaving the lever in place and connecting it back to the CNC electronics so it would switch the spindle direction, but if that's possible, it'd probably be a hassle. I think I'll keep the lathe mechanics as simple as possible and keep the EMC2 controls as stock as possible, dividing the project into lathe mechanics at the lathe, and all control functions at the PC. Similarly, the tumbler and all of those threading gears are going to be surplus when the CNC is working. The lathe mechanics will be a spindle, and X & Z servo motor driven axes with limit switches. The spindle should be single speed mechanically, with all RPM controls at the VFD under control of the EMC2 CNC software.

I ran the 10-3 with ground cable from the clothes drier outlet up into and across the basement ceiling joists and I mounted an outlet for the CNC lathe to plug into on the ceiling, and I ran a short piece of cable from that over to where the milling machine outlet will be, but I still need to buy and wire that outlet. It's a 30A service, so I can run the milling machine and the lathe at the same time, or the drier, but not both. I lucked out on the ground. There was no ground wire to the drier outlet, so I figured I'd get a ground from a cold water pipe. Turns out, the #2 bare copper wire that grounds the breaker box on the other side of the basement (that was per code when the house was built in 1982 but not now) originates directly above the drier outlet, so I can grab a ground there. Too bad the breaker box wasn't accessible, because I'd have liked to run a separate 220V line for the lathe and milling machine so they didn't share with the drier or each other, but this is the next best thing. Have you priced copper wire lately? $50 for 25 feet of 10-3 w/GND. Ouch.

I replaced the cheap plastic knob that someone put on the tail stock hand wheel after breaking or losing the original. How can you break a steel handle? This was a simple 10 minute job (including drilling out and tapping the cast hand wheel) that turned into a 90 minute hassle because the Jergens handle I purchased new from McCmaster-Carr had a manufacturing defect and I basically had to remanufacture it. A lathe would have been very handy for that. Heck, maybe I'll turn my own steel handle.

I found what I believe to be a great buy on eBay. I bought a 1.5 HP 220V 3 phase Baldor motor, brand new and still in the shrink wrap, for $53 delivered. It's a heavy duty motor that I think is intended for large spa pumps or similar pumping applications. MSRP is $567. There are heavy duty bearings on each end and rat wire screen in the cooling vents. The motor shaft is a little odd but nothing too weird. Baldor qualilty, at a treadmill motor cost! I bought it for the upcoming CNC milling machine upgrade, and went ahead and bought another 2HP Chinese VFD on eBay because it looks like the prices were going up from $106 to $140 or so. The dollar will continue to drop against the yuan.

I've spent a lot of time staring at the lathe, thinking where the inductive prox limit switches will go and where the servo motors will be mounted. I also spent a fair amount of time cleaning up the lathe and getting to know her. It looks like piddling, but I prefer to think of it as an important subconscious design process.

I had a new parts and service manual that came with the old Clausing 4902 lathe, but I thought I was missing an operator's manual. I called Clausing, expecting a 16 page manual to be $30. They emailed me the PDF for free. For a 1968 lathe! Great company! It was the electronic version of the manual I already had. I guess they expect that anyone buying a lathe is already trained in basic lathe operations, so the manual only covers operational issues specific to this model. It can't teach new lathe owners how to operate a lathe. I have zero practical experience operating a lathe. I have a healthy respect for them, having seen some lathe carnage videos, but I realize that I can't learn to use a lathe from watching YouTube videos... try as I might! I'm looking for a book, and will either get a machinist friend with several lathes to trade me some training for me running some parts for him one day, or I'll get some vo-tech training.

I'm almost completely finished buying lathe CNC conversion parts. I still need to buy aluminum for servo motor mounts and some piddly stuff like cord grips and probably some Lexan guarding and coolant shield. I spent another $650 today on lathe tooling. I bought a few basic carbide index tools (AR8, E8, and a grooving/cutoff tool). Almost half of the cost was a nice 1" micrometer and set of 6" calipers, both coolant proof, both Mitutoyo. I also got a magnetic base dial indicator for setups. I could have shared some of that tooling with the tooling I already had for the manual milling machine considering they're next to each other and I'm the only operator, but I thought a little redundancy would be good. I'm gradually replacing Chinese tooling for better quality tooling, generally carbide index tooling.

I fixed the crooked cuts on my cheap Harbor Freight horizontal band saw that my dad gave me. Pretty much, clean it up and move the blade guide rollers in a bit. I had put on a much better bimetal blade but it was too stiff to make the quick turnaround at the big end pulley. I haven't used the band saw much, but now that I'm going into CNC lathe production mode, I'll need to chop the 10' bar stock into pieces I can feed through the spindle - hopefully 5' lengths (almost 3' of overhang out the back of the head stock), but I may need 3.33' lengths to be safe. I designed a flood coolant system for the band saw. It'll have an ON/OFF switch, and when in ON mode, it'll only run when the saw is cutting and will automatically turn off when the saw finishes the cut. I ordered a gallon of concentrated band saw coolant as part of today's order. I already had the tubing and magnetic base flexible wand and nozzle. I ordered an 80 GPM Little Giant magnetic coupled pump for $21 on eBay (new, delivered). I designed a chip filter and coolant sump using two nested plastic cat litter buckets - free!

I also bought an electromagnet on eBay today ($7 delivered) that I plan to use to transfer a few pounds of steel chips at a time from the chip collector into the plastic recycling bucket. I hate scooping wet chips, and I think this may be easier and faster. If it works well for the saw, I may do something similar to clean out the swarf tray on the lathe, where there will be a LOT more chips.

The lathe CNC project seems to be at a pregnant pause. I've been gathering up a lot of parts, learning a lot of stuff about a lot of stuff, and doing a lot of piddling. I'm about ready to jump in and start wiring, but I think it's better to think things through and let it percolate and bounce around in my brain pan for awhile so I'm not making too many costly mistakes. I'm sure I'll still make plenty of mistakes, without rushing in where only fools dare tread.

I am enjoying the project, even if it is progressing much more slowly than planned. I should have the spindle turning under VFD power soon. Every day lately, I thought would be the day, but something always comes up. I have a couple of simple turned plastic parts to make, and I probably won't hurt myself on those projects. Now that I have a lathe, lots of projects look like lathe projects. That'll only get worse once I have a WORKING lathe. :-)

[will gilmore]

I have a lathe running Mach3 which I got up and running and then started improving so I have very little time on Mach3 on the lathe. I have some time running mach3 on a milling machine which I found to be a little buggy / quirky so I'm considering EMC2 for this upcoming mill retro.

I'm putting together an I/O list. Are you bringing the encoder signals back to the computer? My impression was that with the G320X the encoder signals only went as far as the drive which took step/dir signals from the PC.

[Liberty4Ever]

For my first attempt, I'm going to run the servo motor encoder signals back to the Gecko servo motor drives only. EMC2 will be running essentially in open loop stepper mode, although I am planning on having the Gecko drives generate a following error to stop EMC2 if there's a problem, so it's kind of half way between open loop and closed loop. I've essentially closed the servo loop between the servo drives and the servo motors but the loop is open between EMC2 and the servo drives (other than the following error signal).

People in the position to know tell me this is probably not a good way to do it, but it sounds better than having a competition between one encoder feeding back to the servo controller and another feeding back to EMC2, which seems like it could cause oscillation if the two control systems became out of phase. Running one encoder signal to the servo drive and getting STEP and DIRECTION outputs from EMC2 and the following error input to EMC2 certainly seems like the simplest wiring.

If it doesn't work to my satisfaction, I'll make another plan.

Ultimately, I'd prefer to measure the actual position of each axis directly into EMC2 to close the big loop for best precision, rather than measuring the rotation of the back of the motor shaft that's connected via a belt drive that stretches, to an acme screw with backlash. At the very least, there are zero backlash ball screws in my future. They're already in my McMaster-Carr shopping cart as a saved order, but I'm delaying that $500 expense until I have a better idea what I'm doing.

The spindle will be directly controlled by EMC2. I'm making an absolute quadrature encoder with three gear tooth sensors to directly measure the spindle speed and direction. EMC2 will generate an analog signal to control the speed of the variable frequency drive that controls the spindle rotation.

[jmelson]

Ultimately, I'd prefer to measure the actual position of each axis directly into EMC2 to close the big loop for best precision, rather than measuring the rotation of the back of the motor shaft that's connected via a belt drive that stretches, to an acme screw with backlash. At the very least, there are zero backlash ball screws in my future. They're already in my McMaster-Carr shopping cart as a saved order, but I'm delaying that $500 expense until I have a better idea what I'm doing.

I have a stepper controller that can generate step pulses at high speed, up to 300,000 steps/second per axis. This may be a real help, depending on encoder resolution.
I also have a device that interfaces between the encoders and the Gecko 320 drive.
It makes an opto-isolated copy of the encoder signals for the Gecko 320, and also sends
a copy to EMC. You can hit E-stop and power the Gecko drives down, and EMC still
knows the position of the machine. If any Gecko drive faults, it powers them all down, signals EMC, and records which axis had the fault.

You likely will need some kind of interface between the encoders and EMC, as the count
rate may exceed the ability of software encoder counting to keep up. (Again, depends on
encoder resolution and motor speeds.)

See Jon Elson's Pico Systems Home Page under stepper systems for more info on these products.

Jon