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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > Are commercial linear actuators suitable for DIY CNC router?
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  1. #1
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    Are commercial linear actuators suitable for DIY CNC router?

    Hello,
    I am considering buying used commmercial actuators (such as the attached pic) to build CNC router for aluminum milling.

    Would these be suitable for such application? Thanks.

  2. #2
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    I just finished building a CNC machine and I used NSK linear actuators. I also have Misumi and THK linear actuators here ready for my next build.

    In terms of suitability for a CNC project, it really depends on the specific actuator. They come in all shapes and sizes and some are better than others. More specifically, you need to ask what type and size of linear rails they have inside, the number of bearing blocks and the size and pitch of the ballscrew as well as the grade.

    Some actuators use a belt drive instead of a ballscrew. These should be avoided. Also avoid any with just one rail or just one bearing block on each rail.

    If you can find a set of actuators in the specs you need, they are a great time saver. The rail, ballscrew and table mounting will be significantly better than what most people could achieve with a diy actuator. A lot of them come with tapped mounting holes which again, are more precise than I could do myself. Most of them come with an enclosure which is great for avoiding chips getting into your rails and ballscrews. It saves you buying horrifically expensive bellows too.

    If you get lucky, you can sometimes find them with a set of pre-made (and super accurate) mounting plates to join two actuators. This would be a huge advantage when trying to make everything square and parallel etc. They are often sold in 3 or 4 axis sets on eBay as Cartesian Robots which is a great start for a CNC router build.

    The NSK actuators I used came with 25mm square NSK rails and 20mm c3 ballscrews with a 20mm pitch. I only just started testing my machine with aluminum milling but, so far, they have performed extremely well. The only limitations I have run up against have been related to work holding and tool breakage. The actuators all run silky smooth and quiet.

    I should add though, that I spent a lot of time and effort building a very solid (and heavy) machine base to mount my actuators on. My gantry is over 8" thick before I mount the actuators. I would not advise building a CNC machine using only actuators without a sold base. Also, you will probably need two actuators for the Y axis unless you have a very small table. They typically have the rails mounted much closer together than what you see with moving tables on diy CNC machines. If you are building a moving gantry machine, you will definately need to buy 4 actuators.

  3. #3
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    5728

    Re: Are commercial linear actuators suitable for DIY CNC router?

    We built a good-sized router using Adept automation actuators, although we ended up replacing the inscrutable AC servo motors they came with and replacing them with motors that were more comprehensible. The units we used had dual profile rails, good-quality (but fast-pitched at 1" per rev) ball screws and were enclosed in aluminum extrusions with cloth tape baffles that seal out at least most of the dust. Just getting the rails and screws pre-mounted straight and true was worth the price of admission right there. We used 2 long ones as the X axis, and ran another one across them as a gantry; which seemed rigid enough not to need reinforcement. A slightly smaller one became the Z axis, although it needed gas springs to counterweight its mass once the heavy spindle was mounted to the end of it. The whole thing was mounted in a sturdy steel cage over a large rotary table that provides a 4th axis. I haven't tried milling aluminum on it, but it works great for wood. Attachment 419758
    Andrew Werby
    Website

  4. #4
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    I think Geomon hit most of the important points. Here are some of my observations from using a variety of these slides in a automation environment.

    1. As Geomon stated these vary widely in Capability. Some would not be suitable at all, most will require mounting on a supporting frame.

    2. Buy assemblies that use commonly available linear motion parts. If parts come from China or Japan it can be a problem with respect to distance me related repairs. A good distributor network can make it far easier to get special parts.

    3. Servos or steppers should be either NEMA or ISO compliant. That is no specially designed motors that can’t be easily replaced.

    4. The same goes for gear boxes if used.

    5. Very few of these slide assemblies are what I would call self supporting. That is they need to be mounted on something. If that something can be machined for a linear slide of this type then it can also be machined for linear rails. So there is a trade off to consider.

    6. The vast majority of these slide assemblies are not designed for machining however that doesn’t mean some don't have the chops. You need to evaluate each slide assembly to see if it is robust enough for the intended usage. Some of these slide assemblies are so light weight that operation in pick and place machines for very small parts (fractional grams) is about all they can manage. If you are buying this online you need all the information you can get to evaluate the slides. I wouldn’t even consider a purchase until there was enough technical information to consider.

  5. #5
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    Thank you very much for the helpful responses.

    I am planning to purchase this CNC assembly for 400USD.
    Attachment 419914

    The x-axis is a used Parker Daedal 406XR standard series (600mm length). The y-axis is Parker Daedal 404XR (800mm length). I think the pitch of the ball screws is 10mm.
    I do not know the model of the z-axis, but it has 4 carriages on two rails driven by ballscrew.

    The 406XR has the following specs:
    Rated Capacity Normal load – 1390 lbs (630 kgf)
    Axial load – 198 lbs (90kgf)


    The 404XR has the following specs:
    Rated Capacity Normal load – 375 lbs (170 kgf)
    Axial load – 198 lbs (90kgf)


    I am planning to mount the actuators in a more rigid steel frame. I would be using NEMA 34 stepper motors.

    My question is: given the above specs would this be suitable for aluminum milling?

    Parker Daedal actuator full specs: https://www.parker.com/Literature/El...ers_Manual.pdf

  6. #6
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    926

    Re: Are commercial linear actuators suitable for DIY CNC router?

    Quote Originally Posted by awerby View Post
    We built a good-sized router using Adept automation actuators, although we ended up replacing the inscrutable AC servo motors they came with and replacing them with motors that were more comprehensible. The units we used had dual profile rails, good-quality (but fast-pitched at 1" per rev) ball screws and were enclosed in aluminum extrusions with cloth tape baffles that seal out at least most of the dust. Just getting the rails and screws pre-mounted straight and true was worth the price of admission right there. We used 2 long ones as the X axis, and ran another one across them as a gantry; which seemed rigid enough not to need reinforcement. A slightly smaller one became the Z axis, although it needed gas springs to counterweight its mass once the heavy spindle was mounted to the end of it. The whole thing was mounted in a sturdy steel cage over a large rotary table that provides a 4th axis. I haven't tried milling aluminum on it, but it works great for wood.

    Those Adept actuators are also made by NSK. The same design is available under a number of different brand names, The models with two 25mm square NSK rails are all excellent (although specs vary by customer requirements). I believe that some come 15mm ball screws instead of the 20mm ones in mine.

    It sounds like you were equally confused on how to use the Yaskawa AC servo motors they come with. I believe they are an old generation of analog servos that are not easily driven from your average home PC parallel port card... I bought some matching Yaskawa AC servo drives to see if I could figure it out. It seems like they could be driven with standard step / direction but the return I/O is the most confusing thing ever made on earth. It's all non-standard connections and poor instructions...

    Most industrial actuators come with Servo motors which seem to have longer motor shafts. This makes it difficult to replace them with comparable size steppers (unless you Machine a whole new motor mount). When I tried to replace the Nema 24 AC servos mine came with, with Nema 23 or Nema 24 steppers, the shaft could not reach the ball screw coupling. I ended up having to buy the 465 oz in Nema 34 motors (to use with a Gecko g540).

    I agree 100% on it being worth it for the precise rail and ballscrew mounting. When you see how precise they are, it becomes immediately obvious that you would never ever do it as well at home with your eBay dial indicator...

  7. #7
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    Quote Originally Posted by uplb View Post
    Thank you very much for the helpful responses.

    I am planning to purchase this CNC assembly for 400USD.
    Attachment 419914

    The x-axis is a used Parker Daedal 406XR standard series (600mm length). The y-axis is Parker Daedal 404XR (800mm length). I think the pitch of the ball screws is 10mm.
    I do not know the model of the z-axis, but it has 4 carriages on two rails driven by ballscrew.

    The 406XR has the following specs:
    Rated Capacity Normal load – 1390 lbs (630 kgf)
    Axial load – 198 lbs (90kgf)


    The 404XR has the following specs:
    Rated Capacity Normal load – 375 lbs (170 kgf)
    Axial load – 198 lbs (90kgf)


    I am planning to mount the actuators in a more rigid steel frame. I would be using NEMA 34 stepper motors.

    My question is: given the above specs would this be suitable for aluminum milling?

    Parker Daedal actuator full specs: https://www.parker.com/Literature/El...ers_Manual.pdf
    That setup would do a better job milling in the center than off to the edges. If you're reconfiguring it, you might consider mounting a couple of extra linear rails to pick up the edges of the moving table; that would improve overall stability a lot.

    $400 is a good price for those actuators, though - I doubt you'd find the components (linear rails and ball screws) that cheap separately. A more rigid frame will help, especially a beefier bridge.

    34-frame steppers might work, but as Goemon says, make sure the shafts are long enough. You'll want to use flexible couplers between the motors and screws. You might also consider using servos instead of steppers. I started out using NEMA 34 steppers on my machine, but ended up replacing most of them with servos which run smoother.
    Andrew Werby
    Website

  8. #8
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    5728

    Re: Are commercial linear actuators suitable for DIY CNC router?

    Quote Originally Posted by Goemon View Post
    Those Adept actuators are also made by NSK. The same design is available under a number of different brand names, The models with two 25mm square NSK rails are all excellent (although specs vary by customer requirements). I believe that some come 15mm ball screws instead of the 20mm ones in mine.

    It sounds like you were equally confused on how to use the Yaskawa AC servo motors they come with. I believe they are an old generation of analog servos that are not easily driven from your average home PC parallel port card... I bought some matching Yaskawa AC servo drives to see if I could figure it out. It seems like they could be driven with standard step / direction but the return I/O is the most confusing thing ever made on earth. It's all non-standard connections and poor instructions...

    [My actuators came with Takisawa motors, not Yaskawa (although they may be related). But no, I couldn't figure them out either. If anyone knows more about them, I've still got them somewhere and would sell them cheap.]

    Most industrial actuators come with Servo motors which seem to have longer motor shafts. This makes it difficult to replace them with comparable size steppers (unless you Machine a whole new motor mount). When I tried to replace the Nema 24 AC servos mine came with, with Nema 23 or Nema 24 steppers, the shaft could not reach the ball screw coupling. I ended up having to buy the 465 oz in Nema 34 motors (to use with a Gecko g540).

    [I did end up machining new mounts for the motors so they would work, and then modifying them to fit the servos I ended up with.]

    I agree 100% on it being worth it for the precise rail and ballscrew mounting. When you see how precise they are, it becomes immediately obvious that you would never ever do it as well at home with your eBay dial indicator...
    [Yes, that's why actuators are such a good deal - aside from often being cheaper than the components bought separately.]
    Andrew Werby
    Website

  9. #9
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    They are worth buying just for the base. Nobody sells reasonably priced rail mounting bases and any sort of precision machining of large plates costs a literal fortune.

    Also, if you look at how NSK mount the rails on those NSK / Adept actuators, there is more to it than just screwing them down on a flat parallel surface. They are pinned at various points to make them straight and the top rail surface is then machined. You can't remove the rails even if you remove all the screws. I thought they were welded to the base when I first opened them up.

    I agree though, that buying the rails and ball screws for that price as seperates would be at least as expensive (used) and you'd end up with more of a Frankenstein machine of mismatched parts.

  10. #10
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    Quote Originally Posted by uplb View Post
    Thank you very much for the helpful responses.

    I am planning to purchase this CNC assembly for 400USD.


    The x-axis is a used Parker Daedal 406XR standard series (600mm length). The y-axis is Parker Daedal 404XR (800mm length). I think the pitch of the ball screws is 10mm.
    I do not know the model of the z-axis, but it has 4 carriages on two rails driven by ballscrew.

    The 406XR has the following specs:
    Rated Capacity Normal load – 1390 lbs (630 kgf)
    Axial load – 198 lbs (90kgf)


    The 404XR has the following specs:
    Rated Capacity Normal load – 375 lbs (170 kgf)
    Axial load – 198 lbs (90kgf)


    I am planning to mount the actuators in a more rigid steel frame. I would be using NEMA 34 stepper motors.

    My question is: given the above specs would this be suitable for aluminum milling?

    Parker Daedal actuator full specs: https://www.parker.com/Literature/El...ers_Manual.pdf

    I initially tried using a single actuator for the moving table but, with that much of an overhang, you can move it up and down with your hand. I.e. It is unstable and I tried it with a 3/4" thick 7075 T6 plate. So, I end up buying a second actuator.

    I can't tell from the pic but does that Z axis actuator use a linear motor instead of a ballscrew? Retro-fitting ball screws to these things is not easy if they aren't designed that way. There might not be room for a decent size ballscrew.

  11. #11
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    Quote Originally Posted by uplb View Post

    My question is: given the above specs would this be suitable for aluminum milling?
    That depends completely upon what you mean by aluminum milling. A general reply would be no, at least not as implemented in that picture. Reasoning:

    1. you can't get a strongly supported table by balancing it in the middle. The overhung nature of the parts make it impossible.
    2. you wouldn't want the slide implemented as shown because it si a big swarf /chip catcher
    3. The slide itself is unsupported for too long of a distance.

    Now if you take the linear bearings out ,mount them separately to support a table properly, the parts themselves would be very useful

  12. #12
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    Quote Originally Posted by wizard View Post
    That depends completely upon what you mean by aluminum milling. A general reply would be no, at least not as implemented in that picture. Reasoning:

    1. you can't get a strongly supported table by balancing it in the middle. The overhung nature of the parts make it impossible.
    2. you wouldn't want the slide implemented as shown because it si a big swarf /chip catcher
    3. The slide itself is unsupported for too long of a distance.

    Now if you take the linear bearings out ,mount them separately to support a table properly, the parts themselves would be very useful

    If you take the linear bearings out and mount them seperately then you would lose all the benefits of using a ready made actuator. The key reason to use commercial actuators is that all the precision grinding and mounting is done for you....

    On the table mounting I agree that, as picture, the table would not be stiff enough to do a great job of aluminum milling but that does not preclude a table overhand all together. If you look at the design of the moving table on your average knee mill, most of them have a sizeable overhang for both the X and Y axis.

    The key is in the design. A typical mill uses a thick cast iron table (which does not flex) instead of a thin aluminum plate (that does). They also mount the actuator upside down so the spindle is always cutting over a supported area instead of the unsupported overhang. There is no reason why he can't do the same with the table actuator pictured. It would just be better with a rectangular table that can be fully supported by the actuator base.

    If the budget allows though, I think that it is still better to use two actuators for the moving table, even if it is two smaller actuators. For example, I have a set of Misumi LX45 actuators for the moving table on a new build here. They each use one large (4" wide) rail over a 15mm c3 ground ballscrew. They each have two moving tables so you can set the amount of travel (between 8" and 20") depending if stability or available travel is most important. The THK KR line is similar and the NSK mono carrier actuators are also worth a look if you can find an identical pair.

  13. #13
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    Hi Geomon good to hear from you!
    Quote Originally Posted by Goemon View Post
    If you take the linear bearings out and mount them seperately then you would lose all the benefits of using a ready made actuator. The key reason to use commercial actuators is that all the precision grinding and mounting is done for you....
    Maybe, if you look at the item being sold as a collection of parts to build into something then maybe not so much. Honestly I can’t even tell from the picture what sort of slides are in that actuator. Some use profile rails but I’ve seen variants that use crossed roller bearings that are very stiff, these are much harder to disassemble and reimplement elsewhere.
    On the table mounting I agree that, as picture, the table would not be stiff enough to do a great job of aluminum milling but that does not preclude a table overhand all together. If you look at the design of the moving table on your average knee mill, most of them have a sizeable overhang for both the X and Y axis.
    It would in fact do a terrible job as seen in that picture.

    Think a bit about the common knee mill, it’s spindle is directly above the most supported part of the machine. Thetable hanging in free space is hardly every used in milling. If you take the same knee mill and swing the ram around to machine something off the end of the table you will immediately be aware that your table isn’t as well supported as it is in the “normal” position.

    In this case most of the machining in this design is done under unsupported parts of the axis or table. In my mind the only value here is the parts on offer the machine itself is a poor investment if the expectation is good performance for the dollar.
    The key is in the design. A typical mill uses a thick cast iron table (which does not flex) instead of a thin aluminum plate (that does). They also mount the actuator upside down so the spindle is always cutting over a supported area instead of the unsupported overhang. There is no reason why he can't do the same with the table actuator pictured. It would just be better with a rectangular table that can be fully supported by the actuator base.
    Which comes back to the idea that the machine as pictured is not worth the money. So it has to be evaluated based on the parts supplied.
    If the budget allows though, I think that it is still better to use two actuators for the moving table, even if it is two smaller actuators. For example, I have a set of Misumi LX45 actuators for the moving table on a new build here. They each use one large (4" wide) rail over a 15mm c3 ground ballscrew. They each have two moving tables so you can set the amount of travel (between 8" and 20") depending if stability or available travel is most important. The THK KR line is similar and the NSK mono carrier actuators are also worth a look if you can find an identical pair.
    Here in lies the problem you are talking about a completely different implementation. I have no doubt that some packaged linear actuators can be used to build decent machines but it comes down to the characteristics of the specific actuator and how it is implemented. A blanket answer of usability isn’t something that can be offered up because of all the variability in these slides.

  14. #14
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    It's not about whether the actuators have removeable rails. Most do. The key benefit of using actuators is the time saving and accuracy the precision bases provide. It saves all that messing around trying to mount rails parallel, straight and level (which is a serious pain in the ass). It also saves all the time and/or cost of machining precision flat surfaces for the rails. And best of all, it saves the hassle of trying to make your ball screws fit under your table.

    If you remove the rails and do your own mounting, you might as well buy your rails and ballscrews separately as it is usually cheaper. You can search for the exact type of rails and screw you need instead of making do with what comes with the actuators you can afford.


    Either way there is a compromise (if you are on a budget). But, most of the diy crowd are not capable of mounting rails with the same precision as NSK unless they already have a CNC machine to make accurate screw holes.














  15. #15
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    Re: Are commercial linear actuators suitable for DIY CNC router?

    Quote Originally Posted by Goemon View Post
    If the budget allows though, I think that it is still better to use two actuators for the moving table, even if it is two smaller actuators. For example, I have a set of Misumi LX45 actuators for the moving table on a new build here. They each use one large (4" wide) rail over a 15mm c3 ground ballscrew. They each have two moving tables so you can set the amount of travel (between 8" and 20") depending if stability or available travel is most important. The THK KR line is similar and the NSK mono carrier actuators are also worth a look if you can find an identical pair.
    I know this is an old thread, but what you've done sounds very interesting. Did you ever do a build thread or have any pics or additional info to share?

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