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  1. #1

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    New build questions!

    Hi, I am vary new to designing my first CNC. I feel like iv learned a lot, but I still feel lost. I need a long Z and there’s not a lot out there powerful enough for what I’m doing. At lest in my price range! I also like the idea of building my own so I know how to fix it when it brakes!
    I want to rough out large sculptures out of white pine. It doesn’t have to move super fast, but I don’t want it slow. 4’x8’ table with 36”Z and option to use 4th axis later.
    I have a 20HP spindle motor off my old FANUC CNC that had a fixed head and moving table. (the control board is fried and the table has a lot of play in it, can’t find parts, takes up a lot of space for size of the bed...) that I want to reuse, but it’s heavy. I still have to get the motor off to find out how heavy. I plan on using a ball screw off the old one and 4 rails for the Z. 2’ wide gantry with the motor dropping down from the middle. Im also hoping to figure out a compact design to help counter balance some of the weight of the motor. I’m thinking two motors for the y, one for the x and two for the Z.
    Are 2 medium motors better then one big motor for the Z.
    Can I use LinuxCNC or moch4 and PoKeys57CNC motion controller, motor driver and large servos?

    Iv read a few things about not being able to run the bigger motors like the NEMA 42 with the PoKeys57. But most people are making small cnc, so not a lot of info to go off of. I thought if you had a motor driver why would it mater how big the motor is. Doesn’t the driver just take the signal and send/amplify it to drive the motor. Do these larger drivers still require a stronger input then the PoKeys57CNC would put out. If not what should I use?

    I also read that I can’t use the awsome servos off the old fanuc cnc (I think 94) because the new stuff doesn’t talk the same language. Or if you can it’s not worth the effort. Is that true?

    Are there any recommended books or sites that spell all this out to a newbie? Iv been reading for days and days but I feel like it’s a little bit here and a little more there and always feel like I’m missing one key pice of info! Recommendations on what to look for in parts, what to stay away from...

    I’m trying to plan out as much as I can before starting, but somethings are hard without knowing the weight of the Bridge and spindle motor. But any recommendations or advice to start from would be greatly appreciated! Thanks in advance! Rich

  2. #2
    Community Moderator Jim Dawson's Avatar
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    Re: New build questions!

    Trying to use the original Fanuc hardware is difficult if not impossible. I gave up and went to all new hardware on my project, the only thing left in my lathe that says Fanuc on it is the spindle motor, and it is being powered by a quality VFD now.

    Use only one motor for the Z, trying to sync two would be a nightmare.

    On a machine that size servo motors are the only way to go. DMM servos would be my preference, I've had good luck with them. DMM | AC SERVO DRIVE | AC SERVO MOTOR | ROTARY ENCODER Pricing is very competitive with larger stepper systems, and they are much more robust.

    The DMM servos will take a step & direction input, so can be used with just about any control that you choose.
    Jim Dawson
    Sandy, Oregon, USA

  3. #3

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    Quote Originally Posted by Jim Dawson View Post
    Trying to use the original Fanuc hardware is difficult if not impossible. I gave up and went to all new hardware on my project, the only thing left in my lathe that says Fanuc on it is the spindle motor, and it is being powered by a quality VFD now.

    Use only one motor for the Z, trying to sync two would be a nightmare.

    On a machine that size servo motors are the only way to go. DMM servos would be my preference, I've had good luck with them. DMM | AC SERVO DRIVE | AC SERVO MOTOR | ROTARY ENCODER Pricing is very competitive with larger stepper systems, and they are much more robust.

    The DMM servos will take a step & direction input, so can be used with just about any control that you choose.
    Thanks for the reply, that sounds About what I read about reusing the fanuc servos. Nice to know info about not using two motors on the Z. And really nice to hear I can use the motors with any controller! Is that with most motors or just those?
    Any idea how much weight a larger servo can lift using a treaded rod (I’m sure there’s a better name for that, but I can’t remember it right now!) off the old fanuc. I’m Trying to get an idea of what size servo I will need to lift the heavy motor and if I need to add a counter balance system to lift it.
    Thanks again! Rich

  4. #4

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    Quote Originally Posted by Jim Dawson View Post
    Trying to use the original Fanuc hardware is difficult if not impossible. I gave up and went to all new hardware on my project, the only thing left in my lathe that says Fanuc on it is the spindle motor, and it is being powered by a quality VFD now.

    Use only one motor for the Z, trying to sync two would be a nightmare.

    On a machine that size servo motors are the only way to go. DMM servos would be my preference, I've had good luck with them. DMM | AC SERVO DRIVE | AC SERVO MOTOR | ROTARY ENCODER Pricing is very competitive with larger stepper systems, and they are much more robust.

    The DMM servos will take a step & direction input, so can be used with just about any control that you choose.
    And just to be sure.! I should be fine using the PoKeys57CNC with these servo motors and drivers. Thanks! Rich

  5. #5
    Community Moderator Jim Dawson's Avatar
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    Re: New build questions!

    Quote Originally Posted by Rkoonz2 View Post
    And just to be sure.! I should be fine using the PoKeys57CNC with these servo motors and drivers. Thanks! Rich
    Yes, it looks like the PoKeys57CNC would do exactly what you need.
    Jim Dawson
    Sandy, Oregon, USA

  6. #6

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    Quote Originally Posted by Jim Dawson View Post
    Yes, it looks like the PoKeys57CNC would do exactly what you need.
    Awesome, thanks for the quick reply!

  7. #7
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    Re: New build questions!

    I will repeat my usual advice to anybody stating that they need a long Z axis.Draw a diagram of the spindle and backplate and add a typical tool.Then draw a line from the corner of the tool to the corner of the spindle and see what kind of angle it makes.This will deterine the steepest slope you can machine in that direction.A similar line to the corner of the backplate will illustrate the steepest slope you can machine in that direction.The distance from the tool cutting edge to the spindle mounting bracket will show how close to a vertical surface you can go and the distance from the tool cutting edge to the corner of the backplate will show how close you can get to a vertical feature in that direction.Having done this exercise you may feel like joining the ranks of people who pop up here and ask about free post processors for 5 Axis machines.........

  8. #8
    Community Moderator ger21's Avatar
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    Re: New build questions!

    +1 to the previous post.

    36" of Z travel does not necessarily mean you can do 36" deep carvings. In many (or most?) cases, the capabilities would be much less.

    And with a 20HP spindle, you are looking at a 5000-8000 lb machine to get the needed rigidity at the spindle.
    Gerry

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  9. #9

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    Quote Originally Posted by routalot View Post
    I will repeat my usual advice to anybody stating that they need a long Z axis.Draw a diagram of the spindle and backplate and add a typical tool.Then draw a line from the corner of the tool to the corner of the spindle and see what kind of angle it makes.This will deterine the steepest slope you can machine in that direction.A similar line to the corner of the backplate will illustrate the steepest slope you can machine in that direction.The distance from the tool cutting edge to the spindle mounting bracket will show how close to a vertical surface you can go and the distance from the tool cutting edge to the corner of the backplate will show how close you can get to a vertical feature in that direction.Having done this exercise you may feel like joining the ranks of people who pop up here and ask about free post processors for 5 Axis machines.........
    Hi, yes good advice!
    A lot of the sculptures I cave are just big and with an 8” bit I can carve most of the profile. Iv been doing it with my old FANUC with 24” Z until it died. I prefer to carve two sides but on bigger stuff I’m ok with having to carve a 4 sided... hoping to put a Rotary spindle on it at some point.
    I also thought about having less Z and making the table adjustable hight, because I only really ever gave to carve down 1/2 the hight (15”) at most. But could not think of a practical way to do that with its weight and size and still have it sturdy and not cost an arm and a leg. Any ideas? Thanks, Rich

  10. #10

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    Quote Originally Posted by ger21 View Post
    +1 to the previous post.

    36" of Z travel does not necessarily mean you can do 36" deep carvings. In many (or most?) cases, the capabilities would be much less.

    And with a 20HP spindle, you are looking at a 5000-8000 lb machine to get the needed rigidity at the spindle.
    I know my biggest problem will be keeping control of the huge motor, but it’s going to have to be one of those live and learn things to see if I can! Some things I just have to learn the hard way! Lol. I do realize there is the real possibility of having to redo the gantry and buy a smaller motor... thanks for the advice. Rich

  11. #11
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    Re: New build questions!

    Quote Originally Posted by Rkoonz2 View Post
    Hi, yes good advice!
    A lot of the sculptures I cave are just big and with an 8” bit I can carve most of the profile. Iv been doing it with my old FANUC with 24” Z until it died. I prefer to carve two sides but on bigger stuff I’m ok with having to carve a 4 sided... hoping to put a Rotary spindle on it at some point.
    I also thought about having less Z and making the table adjustable hight, because I only really ever gave to carve down 1/2 the hight (15”) at most. But could not think of a practical way to do that with its weight and size and still have it sturdy and not cost an arm and a leg. Any ideas? Thanks, Rich
    The "Dual column rising gantry with moving table" design might work for you. This would allow you to mechanically counterbalance your entire gantry.

    The disadvantage to this design is that you mentioned 4'x8', so unless you wanted your table axis to be 16' long in total, you'd have to make the gantry the long axis which would make it heavier, not just for the extra length, but also for the extra stiffness it would require being longer.

    36" of travel makes pneumatic counterbalancing problematic. Things like rodless cylinders are not designed to take substantial amounts of weight in the Z direction.

    It's not an easy design problem to come up with the ideal solution. If it were me it would probably take several hundred hours of different design iterations and 3 or 4 initial concepts whittled down to one to come up with something I considered to be a good plan. And the end result would look nothing like the initial ideas.

    It sounds like you are planning to carve things with a rotary axis but for now want to carve all 4 sides individually....why bother?!? Just design a machine around a rotary axis to start with and forget about the table entirely?

    For better comments you need to do up some designs in CAD and start a design thread. Ordering parts and such at this point, I think would be a mistake. Once you've got it all drawn out you are in a better position to build.

    What do you think of the design concept in this video?

    https://www.youtube.com/watch?v=iRe-tn6lmEk

    That's got a dual column rising gantry, which could be mechanically counterbalanced. And designed with a short gantry.

  12. #12

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    I think this is the basic idea.
    Attached Thumbnails Attached Thumbnails 0B4FC3C1-37F6-45FF-927C-6E6B245ED6A2.jpg  

  13. #13
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    Re: New build questions!

    Hi RKz2 - I'd recommend you look at second hand industrial robots. Much better for this sort of thing then a gantry machine. Peter

  14. #14

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    Quote Originally Posted by peteeng View Post
    Hi RKz2 - I'd recommend you look at second hand industrial robots. Much better for this sort of thing then a gantry machine. Peter
    Hi, thanks for the reply!
    could you post a link to an example? We do have a small robotic arm, (that was expensive, don’t want to go that again) I’m sure the elbows would give out to soon if we put anything big enough to even come close to what I need it to do. Right now it has a dig grinder that we made a bracket for it to hold and have it save the movements we make with it so it can repeat them, trying to get it to do some of the finish work...
    We have a Background as a resourceful crazy artist! We can’t make enough inventory... We carve something, scan it with 3D scanner, maybe a little meshmixer, import to meshcam. mill it with a 1 1/4 bit, end up with a roughed out sculpture that we finish by hand.

    I did find a gantry mill that I liked used, but it was in California and I’m in VT and it’s 8,000$ just to transport it. Trying not to spend 30,000 on a used cnc that Is to complicated or proprietary or I can’t find parts...that I cant figure out how to fix. Needing a 400$ an hour person to figure out why it’s not working every time and having it sit there not working waiting to see if we can even find parts has me wanting to put this together my self. Know everything about it. I know I can do this! Well I might have doubts on the 36” Z....but that’s not going to stop me from trying! Lol. I figure the expensive parts are reusable and I can remake the gantry and do a smaller Z if it comes down to it. The picture that Pinske posted is the design we think will work best for what we want. We are vary interested in the experience of the build.thanks, Rich

  15. #15
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    Re: New build questions!

    Hi RKZ2 - If you search for industrial robots routing there are plenty out there. Just have to look for a second hand one. An associate of mine has just bought one that can lift 1000kg to set up as a mould making and composite trimmer machine. I'm helping rebuild a gantry router with 3.5m Z for foam cutting so its all possible. Your issue will be getting the Z stiff enough which is the usual design hurdle in any machine. But since you only want to cut timber its stiffness does not have to be super stiff. I'd not use the 20HP spindle and figure your smallest you can use. The aim is to minimise the weight at the spindle end. If all your works are done on a rotary then I'd think along the lines of a lathe vs a XYZ config. Your machine stiffness will be much better if say the gantry was fixed and the Z was vertical or horizontal and the job moved back and forth. So the stiffest arrangement would be a fixed gantry, vertical Z and XY moving table. cheers Peter

    https://www.youtube.com/watch?v=UwzwzobO5rs

  16. #16

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    Quote Originally Posted by NIC 77 View Post
    The "Dual column rising gantry with moving table" design might work for you. This would allow you to mechanically counterbalance your entire gantry.

    The disadvantage to this design is that you mentioned 4'x8', so unless you wanted your table axis to be 16' long in total, you'd have to make the gantry the long axis which would make it heavier, not just for the extra length, but also for the extra stiffness it would require being longer.

    36" of travel makes pneumatic counterbalancing problematic. Things like rodless cylinders are not designed to take substantial amounts of weight in the Z direction.

    It's not an easy design problem to come up with the ideal solution. If it were me it would probably take several hundred hours of different design iterations and 3 or 4 initial concepts whittled down to one to come up with something I considered to be a good plan. And the end result would look nothing like the initial ideas.

    It sounds like you are planning to carve things with a rotary axis but for now want to carve all 4 sides individually....why bother?!? Just design a machine around a rotary axis to start with and forget about the table entirely?

    For better comments you need to do up some designs in CAD and start a design thread. Ordering parts and such at this point, I think would be a mistake. Once you've got it all drawn out you are in a better position to build.

    What do you think of the design concept in this video?

    https://www.youtube.com/watch?v=iRe-tn6lmEk

    That's got a dual column rising gantry, which could be mechanically counterbalanced. And designed with a short gantry.
    Hi, thanks for the reply!
    As cool of a design as that is, it’s not as multi use as we would like it to be. I like the table because I can set jigs for different size sculptures in different parts of the table. Haven’t done it yet but also hoping to set up once to carve 10 smaller things all at once, just move it and hit the go button again.

    And yes still designing different ways and ideas to do the Z. Really wish I had the skill to mock it up in a program. I’m more of a do it by hand and 3D scan it kind of programmer! And if I showed any of my drawing you would just have more questions! Best thing I can do is show you a photo of the design we are basing off of. See the pic Pinske posted.
    Thanks, Rich

  17. #17

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    Quote Originally Posted by peteeng View Post
    Hi RKZ2 - If you search for industrial robots routing there are plenty out there. Just have to look for a second hand one. An associate of mine has just bought one that can lift 1000kg to set up as a mould making and composite trimmer machine. I'm helping rebuild a gantry router with 3.5m Z for foam cutting so its all possible. Your issue will be getting the Z stiff enough which is the usual design hurdle in any machine. But since you only want to cut timber its stiffness does not have to be super stiff. I'd not use the 20HP spindle and figure your smallest you can use. The aim is to minimise the weight at the spindle end. If all your works are done on a rotary then I'd think along the lines of a lathe vs a XYZ config. Your machine stiffness will be much better if say the gantry was fixed and the Z was vertical or horizontal and the job moved back and forth. So the stiffest arrangement would be a fixed gantry, vertical Z and XY moving table. cheers Peter

    https://www.youtube.com/watch?v=UwzwzobO5rs

    My problem is I have the 20HP spindle... I think we could get away with a 10 or 12HP but really I have no clue.
    But not spending 6,000$ on a new spindle and use what we have seems like the way to go. My logic is if we design it for the bigger motor and it doesn’t work out, it will be over built for a smaller motor. I don’t feel like it’s a big deal if it doesn’t work out the first go... study, adjust and try again. Most stuff is reusable. I don’t see a big risk, just lost time. But I enjoy this kind of stuff.
    If my logic is wrong please don’t hesitate to point it out!
    Thanks, Rich

  18. #18
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    Re: New build questions!

    Hi Rich - setting up to do 10 things "at once" maybe a fallacy. Unless you use 5 tools or 10 tools you don't save time. You have to build a machine much bigger then required which means it has to be considerably stiffer and heavier then required. A pallet changer system maybe better for you. Its always best to design the smallest machine that will do your job. If the vertical machining center in the video is what you want then you need to copy that asap. cheers Peter

  19. #19

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    The big Robots are awesome but most people who use them for milling use them to cut foam as in the video. I think the gantry will work fine if it’s hogging a lot of wood at a slower speed like a bull dozer. It would be nice to have a depth with of cut and feed rate chart. Obviously going fast you can only take a small bite. The 20hp 40 taper spindle could run a 2” bit.

  20. #20
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    Re: New build questions!

    heres a start - Peter

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