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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > 80/20 with HGR25/HGH25 Linear Rails/Bearings
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  1. #1
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    80/20 with HGR25/HGH25 Linear Rails/Bearings

    Hey guys. I've been reading the forums here for several months now, but I haven't made many posts. I currently have a CNC router from www.cncconversionkit.com, but it uses supported linear rods and I'm not all that enchanted with it. I have decided to design and build my own machine. After several days of designing in Fusion 360, This is what I have so far. I think it's kind of a cross between a CNC router and mill. So I'm calling it the CNC RouterMill (clever right?). I still have some serious design work to do, but I'm getting there. The table measures 48" wide by 28" deep. I should have about 10" of Z axis travel when it's done. The outer extrusions are 80/20 15 Series 1545-Black (1.5"x4.5"). The table consists of (16) 80/20 15 Series 3075-Black (3.0"x0.75"). The linear rails are Hiwin HGR25 (25mm). The linear bearings are Hiwin HGH25 (25mm). The left/right gantry plates and supporting pieces are 3/4" aluminum plate. Let me know what you guys think of this so far. Thanks!

    Justin

  2. #2
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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    It looks like a narrow gantry-type router. What makes it like a mill? Why spend all that money on aluminum extrusions for parts that never move? That could all be solid steel, which would work better and cost a lot less. Why waste weight on extending the gantry legs lower than they need to be? It doesn't look like those extensions do anything for you. Why build up the back edge like that? It will keep you from being able to extend your stock over the limits of the table.
    Andrew Werby
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  3. #3
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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    It's a router AND a mill because I do milling with it, not just router stuff. I use aluminum extrusions because they are awesome. And because I don't have to fabricate some steel parts. The gantry plates extend down because that's where the ballscrew nut will attach to it. I just haven't designed that part yet. I built the back edge like that to keep dust/chips/etc from going behind the machine. I have 28" (probably 24" useable) of Y travel...that's more than enough for the stuff I do. In fact, that's more than a Haas VF2/3/4. Thanks for the questions. I'm open to all questions/comments/criticisms. It will help me build a great machine.

    Justin

  4. #4
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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Linear rails are not a stiffening structure. The 25s are not going to help make the machine stronger. You would be better off buying 15s and putting the money you save towards strengthening the rest of the machine.

    Ben

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Quote Originally Posted by justindewoody View Post
    It's a router AND a mill because I do milling with it, not just router stuff. I use aluminum extrusions because they are awesome.
    Actually they aren't that awesome. Further the extrusions you have chosen are to small in cross section to support the linear rail you have chosen to any advantage. In other words 25mm rails are a complete waste here.
    And because I don't have to fabricate some steel parts.
    Fabricating steel is not that difficult, it does require an investment in tools that you may not have! However there are two things you have said here that strongly suggests that you need an improved design. You specifically stated that the current machine isn't good enough and that you want to use the machine more like a mill. If that. Is the case you aren't even close mechanically to getting the better performance you want.
    The gantry plates extend down because that's where the ballscrew nut will attach to it.
    With the gantry oriented on the long axis you will want a dual lead screw drive. This is a doable arrangement but you would likely be better off with the gantry axis oriented across the short axis. If you want maximum performance keep the gantry short and stiff, better yet consider a moving table design.
    I just haven't designed that part yet. I built the back edge like that to keep dust/chips/etc from going behind the machine.
    Dust and chips are a big issue. However you really need a full machine enclosure if that is a problem.
    I have 28" (probably 24" useable) of Y travel...that's more than enough for the stuff I do. In fact, that's more than a Haas VF2/3/4. Thanks for the questions. I'm open to all questions/comments/criticisms. It will help me build a great machine.

    Justin
    If you think you will get Haas like performance out of this design you are mistaken.

    In any event define for us more precisely what you expect to be doing with this machine.

    If you want a significantly better machine you need to start at the bottom and work up from there. That means a significantly better frame to support the table and gantry.

  6. #6
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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    After looking at the kits from cncconversionkits I'd have to suggest that your machine will be worst than what you currently have. I would strongly suggest starting over.

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    I never said I was going to get Haas performance. That would be foolish. I just said that I have more Y travel. This machine will be plenty good for my needs. Thanks for all the input.

    Justin

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    I don't know why you come here and ask for advice, but disregard it when people who know about this stuff take the time to give it to you. That was a particularly good criticism you got from Wizard, about reorienting it so the gantry goes across the short span rather than the long one. That one change will improve the quality of the cuts you'll get considerably, because it won't be flexing nearly as much. You won't really know how well a machine will work until you actually try it out, but there are changes you can make in the design stage that will improve its performance - you can implement them or not, as you please.
    Andrew Werby
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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    I'm not disregarding the input. How have I disregarded the input? I explicitly designed it this way with the longer X and the shorter Y because it works for me better than the way wizard suggested. I already have a machine with the short X and long Y...and I just don't like it. I will not be milling steel with this machine. I will be milling wood, acrylic, some aluminum, and other material that's not so hard. I don't need MASSIVE rigidity. And I think the design I'm working on will be just fine when complete. It's not complete yet though...in fact, I have a LONG way to go. I DO want the input. I like hearing others' opinions. And I will take it all under consideration. But I have a basic design idea that I want to stick to, so I'm not going to overhaul the entire design. I will simply make it the best I can make it. Thanks.

    Justin

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Quote Originally Posted by justindewoody View Post
    I'm not disregarding the input. How have I disregarded the input? I explicitly designed it this way with the longer X and the shorter Y because it works for me better than the way wizard suggested. I already have a machine with the short X and long Y...and I just don't like it. I will not be milling steel with this machine. I will be milling wood, acrylic, some aluminum, and other material that's not so hard. I don't need MASSIVE rigidity.
    You have already said that your current machine isn't good enough, what I'm trying to get across is that you will have a less rigid machine. This based on what I say online of your current machine. Plus the linear rails you mentioned would be overkill on the extrusions you have designed in
    And I think the design I'm working on will be just fine when complete. It's not complete yet though...in fact, I have a LONG way to go. I DO want the input. I like hearing others' opinions.
    The arrangement of your table rails and X axis rails is less than optimal. We maybe misunderstanding why you are building a new machine to replace the one you currently have, but if you don't address the rigidity in your current design I really think it will perform worst than your current machine.
    And I will take it all under consideration. But I have a basic design idea that I want to stick to, so I'm not going to overhaul the entire design. I will simply make it the best I can make it. Thanks.

    Justin
    I really have no problem with an odd design if it serves a specific purpose. However the long gantry introduces issues you won't have with a shorter one using the same materials. I'd rather see you over build a machine slightly rather then end up with something that is noticeably less substantial than it needs to be. If you want to implement a long gantry then I suggest reading the stickies as there are some good threads there including one that dives into gantry beam design.

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Thanks for the input wizard. Here's a few pics of the current design. I definitely DO appreciate your input. You sound like a logical guy. Using the current basic design, what do you think I could do to increase rigidity across the gantry (and the whole machine for that matter)? Thanks.

    Justin
    Attached Thumbnails Attached Thumbnails CNC RouterMill v40.jpg   CNC RouterMill v40 Back .jpg   CNC RouterMill v40 Back Angle.jpg  

  12. #12
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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Quote Originally Posted by justindewoody View Post
    Thanks for the input wizard. Here's a few pics of the current design.
    Interesting, the gantry is improved significantly? However I'd still consider a large square steel beam for the gantry. Yes it is harder (somewhat) to work with but you do gain some positives

    As for side access I will once again suggest at least thinking about orienting the gantry the other way. With your current design, using extrusions, you would gain a stiffer gantry and a better mechanical arrangement of the parts. Now I understand the importance of side access to the machine, however you can simply make the machine longer giving you access to the same space. That is if you need a 4 foot table for your normal workloads make the machine 5.5 feet to 6 feet long and park the gantry out of the way when doing setups.

    Having lots of time and little money I've actually have considered building a machine as you describe. That is a long gantry and a short X axis. In my case the goal eventually is to have a multipurpose machine to handle up to light metals. The long gantry would make designing for stiffness more difficult while still keeping the machine compact. I've actually thought seriously about going moving table here.

    In the end the machine only needs to be good enough for your needs. I just think you are taking the hard way here. Not impossible mind you but your approach will require at least two lead screws for the X along with driving electronics.
    I definitely DO appreciate your input. You sound like a logical guy. Using the current basic design, what do you think I could do to increase rigidity across the gantry (and the whole machine for that matter)? Thanks.

    Justin
    Big square beams are the easy solutions for gantry beams. The more Z clearance you want the bigger beam you need. The key to understanding gantry beams is that they are unsupported except at the ends.

    Beyond that the supports for the gantry need to resist any rotational torque that the beam may apply. This requires spreading the bearings out further along the X axis. This is where your design looses it a bit as you have to compromise the spacing on the X axis saddles to avoid wasting a lot of usable area on the table top.

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Here's a few pics of the current design. I believe I'm just about finished. I have tweeked just about everything I could think of...
    Attached Thumbnails Attached Thumbnails CNC RouterMill 9.jpg   CNC RouterMill v63.jpg   CNC RouterMill v63 Back.jpg   CNC RouterMill v63 Back Above.jpg  

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Quote Originally Posted by wizard View Post
    8><---------

    As for side access I will once again suggest at least thinking about orienting the gantry the other way.

    8><-----
    I have a similar problem that of space so I too was seriously considering mounting "sideways" ie I have a 1500mmx1000mm corner space and I need to be able to machine pieces about 1200mm long (gun stocks). My problem is the router has to go in a corner on an existing massive bench (900mm x 2000mm with 4 off 200mmx50mm wood as the top surface to build on. I have which means one long side and and one short side are inaccessible due to a wall and the other short side is a bit tight.

    Before I commit to doing this, why is such a layout less suitable? I can see you mention rotation but I cant fathom what you mean, could you explain a bit more please? and the consequence? For what I am making right now I just dont see that a tiny bit less accuracy will matter V significantly improved ease of use/access. It maybe I do a trial on this, ie build it one way and then build it the other as the extrusions are bolt together...hmmm.

    One thing that does raise a concern is the g-code, I will have to design everything "sideways" and may have "fun" using other ppls code?

  15. #15
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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Quote Originally Posted by stevenj View Post
    I have a similar problem that of space so I too was seriously considering mounting "sideways" ie I have a 1500mmx1000mm corner space and I need to be able to machine pieces about 1200mm long (gun stocks). My problem is the router has to go in a corner on an existing massive bench (900mm x 2000mm with 4 off 200mmx50mm wood as the top surface to build on. I have which means one long side and and one short side are inaccessible due to a wall and the other short side is a bit tight.
    Tight fit!
    Before I commit to doing this, why is such a layout less suitable?
    I'm not sure less suitable is the way to phrase this, the long axis as a gantry introduces a number of issues.

    For one the additional length impacts rigidity of the unsupported gantry. Of course you can always implement a larger stronger beam so the beam itself isn't an issue.

    Second the design pretty much demands dual leadscrews for the gantry drive. While many designs would assume that already the problem here is that the motors add depth to the machine which creates issues on bench tops. There are ways around this but you don't want your motors in a place you can't access.

    Third the bearings for the vertical uprights supporting the gantry need to be a distance apart determined but the height of the gantry and how much torque on those bearings you will be building for. In other words the bearings need to be some distance apart, for stiffness, which keeps the gantry from rocking back and forth. This is unusable space that must be made up for in some way or another. If you determine that the bearings must be 12 inches apart and you want a 24 inch wide working area then you end up with a machine 36 inches deep. Area wise that is a lot of wasted space for a given machine capacity.

    Fourth access isn't improved all that much, you would still be working under a considerable length of gantry to fasten stock down. A gantry oriented the short distance will have a similar problem but you can minimize this by making the machine a bit longer without loosing as much area. Effectively you can design in a parking area for the gantry if you have enough space.
    I can see you mention rotation but I cant fathom what you mean, could you explain a bit more please? and the consequence? For what I am making right now I just dont see that a tiny bit less accuracy will matter V significantly improved ease of use/access.
    Well there are a lot of qualifications but the orientation won't make access easier in every case. Here is the problem in my mind, by design the machine will have to be wider that required due the gantry verticals and their bearings. How much depends upon the specifics of the machine design and the required working area. However you can end up with human factors issues operating the machine and constantly reaching across the table. Remember you effectively have access from one side. You don't say how wide of a working area you need or want so I can't say if it is an issue in your case. For gun stocks you could produce a very narrow machine and not have any issues at all. If you want a general purpose capacity then you might have problems.

    I'm on my iPad right now and haven't found the phrase where I talked about rotation, so I'm in the dark as to what I was talking about. However I may have been talking about the Xaxis bearings and the need to help them far enough apart to resist the gantry tipping under load, in other words the issue of stiffness. You can also rotate in the direction that is right angles to the rails. Again the bearings should be far enough apart so that the gantry can't twist significantly under a lopsided load. In other words you don't want to rely upon the leadscrews solely to keep the gantry square. Within reason as the dual leadscrews will ultimately keep everything square
    It maybe I do a trial on this, ie build it one way and then build it the other as the extrusions are bolt together...hmmm.
    Or get some cardboard and mock up various designs. This is especially useful for special purpose designs.
    One thing that does raise a concern is the g-code, I will have to design everything "sideways" and may have "fun" using other ppls code?
    I hear this all the time and still don't know why it is an issue.

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Here's a few pics of the base. This is all I have had time to do so far. But I think it looks great! I'm excited about this project! I think this will be a fantastic machine when it's done.
    Attached Thumbnails Attached Thumbnails CNC Router Base 1.jpg   CNC Router Base 2.jpg   CNC Router Base 3.jpg   CNC Router Base 4.jpg   CNC Router Base 5.jpg  

    CNC Router Base 6.jpg   CNC Router Base 7.jpg  

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Quote Originally Posted by justindewoody View Post
    Here's a few pics of the base. This is all I have had time to do so far. But I think it looks great! I'm excited about this project! I think this will be a fantastic machine when it's done.
    Great thanks, looks very similar to what I want to do, please keep the pics coming.

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Quote Originally Posted by wizard View Post
    Tight fit!

    I'm not sure less suitable is the way to phrase this, the long axis as a gantry introduces a number of issues.

    For one the additional length impacts rigidity of the unsupported gantry. Of course you can always implement a larger stronger beam so the beam itself isn't an issue.

    Second the design pretty much demands dual leadscrews for the gantry drive. While many designs would assume that already the problem here is that the motors add depth to the machine which creates issues on bench tops. There are ways around this but you don't want your motors in a place you can't access.

    Third the bearings for the vertical uprights supporting the gantry need to be a distance apart determined but the height of the gantry and how much torque on those bearings you will be building for. In other words the bearings need to be some distance apart, for stiffness, which keeps the gantry from rocking back and forth. This is unusable space that must be made up for in some way or another. If you determine that the bearings must be 12 inches apart and you want a 24 inch wide working area then you end up with a machine 36 inches deep. Area wise that is a lot of wasted space for a given machine capacity.

    Fourth access isn't improved all that much,8><----
    Great, long and detailed reply! You have not raised anything I have not contemplated. Mounting it this way means I almost certianly dont have to leave space for one of the steeper motors and extracting it (it will be dual drive). In fact the steeper being is on the gantry (probably) means its powerable (assuming its working) to the front, a lot easier to work on. Also sides I have space I can "waste" not the depth. Rigidity comes back to how much accuracy do I need which is related to the speed and depth of cut? I can stiffen the gantry a bit with relative ease by adding a taller beam. Food for thought, thank you.

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Here are some more pictures of the machine coming together. It's REALLY sturdy, strong, and rigid. I know some of you had concerns over the rigidity of the long gantry, but it's EXTREMELY strong and rigid. I am very happy with my machine design and build so far. I'm having lots of fun building this thing!

    Justin

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    Re: 80/20 with HGR25/HGH25 Linear Rails/Bearings

    Quote Originally Posted by justindewoody View Post
    Here are some more pictures of the machine coming together. It's REALLY sturdy, strong, and rigid. I know some of you had concerns over the rigidity of the long gantry, but it's EXTREMELY strong and rigid. I am very happy with my machine design and build so far. I'm having lots of fun building this thing!

    Justin
    Great thanks, it sure looks heavy.....LOL. I have just been doing some hand routeing this weekend repairing a door and frankly even if a "cross gantry" is going to flex a wee bit more its nothing like as much as how my arms flex!!!

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