My Techno/ISEL 4 foot square CNC router table build

wanted to brainstorm a bit, on the future "pipe dream" of adding a ATC spindle, and tool change system.
i had thought that having the tool change operations be done in back, but clearance-wise, the best location is a carousel and changer arm in front. this is because i can lift the spindle up high, and have plenty of clearance to change tools. this also requires another idea, changing the Z axis mount around, so the box is stationary, and the spindle-plate moves up and down. though i would have to play around with things to see if it would gain me anything. i think it would... here is why: as mounted, the height clearance changes with the Z axis height. the other way around, the clearance remains more of a constant.

so, if the carousel was just simply pocket holes for the tool-holders to rest in, then the changer arm could engage the tool-holder by using the ring groove to first pluck the tool holder up from the pocket, then slide or swing over to the tool change position, mount the tool, then release it, and swing/slide back to a neutral position.
with that idea in mind, the tool changer needs enough height extension/retraction to lift the tool-holder from the pocket, and also lift the tool-holder up into the spindle to mount it. this could be a dual operation. after the tool changer height clears the carousel pocket, while moving to the spindle location, the tool changer could move down in a syncro-move, so by the time it is under the spindle, it clears it. vice versa for returning a tool to pocket.
i have ordered some things for the machine. an enclosure for the wire hookups on the machine. three fuse blocks (5Vdc, 12Vdc, 24Vdc), though i still need to get a fuse assortment kit. also a large ground terminal block, so i can star-ground my machine.
the terminal block will be mounted onto the copper clad backer board in the control cabinet, to tie the shielding to ground.
the fuses will be located somewhere accessible, in the control cabinet.
replaced the sketchy power taps on the bottom board with 3 fuse blocks (5V, 12V, and 24V). next, i need to clean up the wiring some, and wire up the machine-side junction box.
well, i bought a ATC spindle, with a VFD... i could barely afford it, but i bought it anyway. problem is, it needs so much stuff to make it work, that i am not sure it was a good purchase, but time will tell.
to make it work, i need:
  • compressed air source
  • air dryer
  • regulators
  • air tubing
then i have to setup the RS485 connection, and figure out mb2hal (in LinuxCNC).
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the spindle is mounted, and preliminary wiring is complete. i have even completed the break-in process.
i opted to control the VFD with analog controls, as i could not get the mb2hal setup to work correctly. and without that, i have no LCNC feedback on the RPM, yet. i thought it had a tach output, but i guess not on this model. there is an option available to use the 0-10V analog output, and configure it to running speed, so i could use that as feedback, and i likely will do that. it would just be nice to have more accurate control and readout.
it does have sensors for tool lock/unlock, assuming they work. i think they need a pull-up resistor. but i am going to have to get rather tricky on this spindle to get it to change tools correctly. so far the spindle brake is mostly in-effective, though i don't think it is configured correctly. so i will need to wait for the spindle to spin to a stop before changing tools, so that will take a lot of time.
debating on how to do the actual tool changes. i would like a pre-fetch system, but it may be too complicated. i would like a carousel pot disk, with the tool holders sitting upside-down, then the transfer arm just clips on to the tool holder, picks it up, flips it, and moves it into position for the spindle. it could be done purely with pneumatic, and one stepper, or with several steppers controlled by a GRBL board. for that though, i would have to write a comp file to send the commands.
the issue with a pre-fetch system, i can't have tool holder pots on the machine, because the collets on the bottom can differ in diameter, and therefor would not be consistent in centering in the pot. if the system prefetches, it really needs to be on the transfer arm, but i am unsure how it would be possible. seems the tool holder needs to be picked up by a BT30/ISO30 fork, the transfer arm will need various different movements to complete the process. almost need a robot arm to complete the transfer...

another idea i found, would require i build a pick-n-place machine to store tool holders. it could be built from a smaller CNC router table, but instead of a spindle, it would just have a thing that picked up the tool holder from the pot, and then move the tool holder to the fetch location. this would be exceptionally difficult to design, but would be awesome if it worked. it would also need to store the tool holders in fork clips, and the grabber would have to be able to grab the tool holder, and slide it out of the clip. this system could prefetch, if the grabber had a pair of 180 degree opposed forks on an arm. it would grab the next tool, move over to the CNC machine's change location. the machine would deposit the current tool into a fork, then the grabber would rotate 180 degrees, and the CNC machine would grab the next tool. then the grabber would move back and deposit the previous tool holder into the matrix magazine.

i love the matrix magazine idea, but it would be SO EXPENSIVE, and very complicated, if something went wrong. the matrix would need to be controlled by a separate LinuxCNC computer that simply exchanges a few hardware pins to communicate with the CNC router LinuxCNC. the reason it would need to be separate, is that it would need to be able to work independently. so in short, the carousel would be simpler, though a linear rack would be even more simple.

if i could re-mount the CNC router Z-axis box, then the spindle would have much more clearance for tool changing. but really, before i design the tool changer system, i need to have the changing spindle fully working. i need to know how much the bit in the tool holder sticks down, and make sure i have material clearance. there is an option where i could have a mounting plate made for the Z-box mounting, that would offset the height up several inches, and that would gain me a lot of clearance. if it is made out of aluminum, i could potentially machine the part myself, with the CNC router.
i have come to the conclusion that search engines and SPAMMERS looking for leaks, are the ONLY people reading my posts here. hence why i don't post very often i guess.

so, the ATC spindle purchase is starting to look like a BAD investment. but now i have to complete it, or i waste thousands of dollars in parts. i spend so much time planning out the tool changer, but i can't even hold a tool in my spindle yet. i have ordered the pneumatic stuff i need, but i still need to be able to attach a spoil-board to the able. i am thinking of cutting a piece of plywood to fit the top, and just drilling and bolting the plywood down. not crazy about drilling into the aluminum table, but something needs to hold down the plywood. as far as a cut-into surface, i will just use 1/4" plywood under the wood i need to cut through, and make sure i don't project through more than 1/4". and to start, i may only secure the plywood in two places on one side, simply because of the location it sits in, i have zero access to the other side of the table.
but at least once the plywood is down, i can secure stuff to it and make carvings. i really need money to afford to buy Vcarve Pro, but i will not have that kind of money for a long time.
so, interesting development... using mb2hal on LinuxCNC, and an Arduino project,, i was able to have bi-directional communication between LinuxCNC and the Arduino! i was able to connect a LCNC HAL pin to the pin-13 LED on the Arduino. in ModBus terms, i wrote to a coil. but i was also able to read from the Arduino's 16 analog ADC pins (input register read).
what does this all mean? well, i can control an Arduino powered tool changer system with it, and any number of other things. so, that matrix tool magazine robot, it is now possible! well, once i get the ATC spindle fully working, that is.
once i get the air system connected, then i can work on it to make sure it works correctly, and safely. i am still unsure if the tool lock/unlock sensors even work, as without actuating the system, i can't verify their operation. right now, they are both outputting 0V, when logic would say that at least one should be outputting 24V, but who knows. the spindle is in the locked position with no tool holder in it. if the sensors are in the inactive state when the changer is locked, and has no tool holder in it, than it may be correct.

but in any case, this ModBus project is really amazing! i can now putter away at creating a full system for the changer control system. i am seriously considering using my ISA backplane and ISA proto boards for this idea. i also should start a new GitHub repo for this project, and mirror the ModBus library, just in case it changes and breaks my setup.
so, if i build a matrix tool magazine, the tool holders would be filed into BT30 forks. that means that the tool grabber needs to grab by the taper, and retain by the retention knob, somehow. my best guess on how to do it, would be a grabber "hand" with pincers sized for the larger end of the BT30 taper, and also further up, to grab by the shank of the retention knob. one pincer hand, 4 total "fingers". could be 3d printed...
so the magazine will be like a router table, but turned on it's side. Y = forward and back, X = up and down, Z = insert/retrieve from storage forks. the transfer will be done with a sliding pair of BT30 forks that slide between the tool magazine, and the tool change position. one fork for bringing tools to the CNC, and one fork to return from the CNC back to the magazine. there is one single change location, the slider will be in position depending on if it is picking up or returning.
i will need homing sensors for the magazine's 3 axis, with a tool sensor on the tool grabber so it knows if it grabbed a tool or not. the transfer slide will have a home, as well as tool sensors for both forks, so it knows if it really grabbed something.
the XYZ tool matrix will need 4-axis, so actualy it will be XYZA. the controller will be a GRBL controller, modified so the serial input can be done via a TTL serial port, vs the USB port.
ok, so the tool transfer device will not work as a slider. it will have to be a swing arm. though with this idea, the magazine XYZ-home location will need to be out of the way of the swing arm.
i have pretty much given up on the Matrix tool changer idea, in favor of a rack tool changer. mostly for the simplicity, though somehow i will likely make it complicated.
I have raised the spindle on the Z-box for tool changing clearance, but i will have to have the rack in front. i just have to decide how long of material i will be working with. if the rack comes up from below the front, then i will need to not have material longer than the front of the table. if i have it drop down into place, i will need to not smack my head into it.

in any case, i have ordered a Mesa 7i44 (SSerial IF board), 7i70 (SSerial field voltage input board), and a 7i73 (SSerial control panel/pendant board).
the 7i70 input board will primarily be used for rack tool sensor inputs.
the 7i73 board will be a on-machine control panel. i will have a MPG encoder for each axis, including the rack changer axis if i use a stepper for that. i want to setup enable switches for each MPG, in case somebody bumps one. i will use a 8x8 key matrix to handle the majority of keys, with dedicated inputs for e-stop. it will also have a LCD display that will primarily be used to display machine position.
been thinking about my 7i70 board, and i think i will use it for more than just the changer inputs. i can use it for any PNP sensor, so that could be everything but the homing sensors, as those are NPN. just as long as i still have enough inputs for the rack changer. then can get rid of one of the 24V to 5V opto boards, and just have the one for the homing sensors. this will also free up some 7i80HD GPIO pins. i will need to mount the 7i70 board in the machine-side enclosure, and run a 24v power feed for it. shouldn't be too bad, i don't think. though this could be considered a fairly major re-wire... i think it will be better in the end.

now, for the 7i73 board. when i have more of an idea exactly how i want to lay it out, i can build a control panel enclosure for it (or buy one...), that is sized for it. i have ordered 3 MPG hand-wheels, 100ppr. i wish there was a way to connect a switch to the operation of the hand-wheels, so the switch must be activated in order for the hand-wheels to jog the machine axis. if i can't do that, i will simply have a cover for them to prevent bumping.
the E-Stop button will have a dedicated input (not on the key matrix).
the key-matrix will be decoded with a comp file.
Thoughts for buttons:
  • pause/resume
  • go home
    • will need 2 MDI commands (safe-z, then go home)
  • return tool (T0 M6, via MDI)
  • set work X-zero (MDI)
  • set work Y-zero (MDI)
  • set work Z-zero (MDI)
the LCD screen for the 7i73 will be a 2004 that i already have, assuming it functions.
I have some terminal breakout boards coming for the 7i73 connections. though i will have to check if i have cables (40p and 34p).
had some success today. i wired the PNP sensors to my 7i70, leaving room for the tool pocket sensors.
also, i played with the tool change script a bit, and got it to wait for the spindle to lock and unlock before moving. still have to fine tune the dwell to wait for the spindle to stop. it would be much easier if it had the spindle tach signal, but as it does not, i need some other method. i could time the spindle and shorten the dwell, but it would seem that i also have instability with braking. sometimes it works, sometimes not.
I have been making a control panel for my machine. so to start with, i have cut 4 holes in a PVC sheet for the LCD screen, and three dial encoders.
the holes came out a bit too small, but i can finish them off with a dremel.
trying to figure out the best way to move the ATC tool rack out of the way...
i have a belt and gear reduction assembly that i salvaged from an old lab equipment. i could mount a pipe over the output shaft, and use the pipe as an extension shaft. then the rack could be on slides, and the shaft could have some arms welded on it that could be used to actuate the rack forward and back.
the biggest problem here, is swarf getting onto the slides...

if the rack doesn't move, then i run the risk of a collision when the machine is in use, or homing...
it could be possible to home ahead of the rack, and set machine zero ahead of the rack. then the Y would travel into the negative for a tool change. though, not liking that idea...

whatever the case, the tool rack will need a cover to keep the tool-holders clean. i am starting to realize why generally the rack is on the back of the machine...

maybe if i have the tool rack slides up high, then i would have more room to make slide covers. the tool rack could park inside a sort of box that kept the tool-holders clean, and had a brush-front so the box didn't need to open to let the tool rack pass in and out. this would be cumbersome to work over, to get the work material mounted on the table.

...seems like my way-too-complicated changer idea, the matrix tool magazine, or even a carousel of sorts, may turn out to be a better option, even if it is very expensive to build...

if i made a carousel, i could have it swing out of the way somehow. perhaps using the pneumatic actuator i have. the carousel rotation could be done with the belt/gear drive thing i have. the machine could take the tool-holder directly off the carousel disk, that would have the tool-holder forks mounted on it. i could potentially mount the forks on the under-side of the disk, so there is room for a pocket tool sensor to verify if the pocket is full or empty. the disk could be a round piece of plywood, as if the forks are under it, the thickness shouldn't bother. the plywood would need to be sealed very well to keep it from warping. not sure yet how i would cover the tool-holders from dust...
on the carousel changer idea. if the disk has a cover, all but where the change location is, then the home location on the carousel could have a cover built in. so to cover the tool-holders, i simply send the carousel axis to home position. it will be set as a rotary axis, with the forks mounted X number of degrees from the last. the disk would need to be big enough to allow for some expansion, but not so big as to be always in the way. will likely take some experimenting. perhaps start with a 18" to 24" disk? perhaps i could make the plywood disk on my machine. if i can figure out CAD enough to do the measurements correctly. still not sure how to connect the disk to the shaft of the gear/belt reduction i have.