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  1. #1
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    Small Concrete CNC Mill

    Hi everyone,
    I've been thinking about building a CNC mill or a router for several years. These are some of my thoughts:

    Objectives/considerations:

    -Main goal is learning about CNC in general and being able to machine plastics, wood and soft metals like aluminum.
    -I don't have much space nor budget, so that has to be taken into account. I'm happy with a 200x200mm work area.
    -Cost must be kept low.
    -I don't have particular tolerance requirements. I think I'll be happy with +- 0.1 mm for most things I do.

    Tools available:
    -I have a small lathe, drill press, angle grinder and stick welder.

    The plan:
    I was thinking of making an L-shapped reinforced concrete base, from which threaded rod would protrude on four places on the base and on other four on the column. Those would be used to attach 20 mm thick aluminum plates, making their position slightly adjustable so they can be aligned, particularly if concrete shrinks or what not. Those and other necessary plates I would have cut to size, and do the drilling and tapping myself.

    On those plates I would mount some SBR20 rails and RM1605 ballscrews as shown on the pictures below. Three nema 23 steppers would run the show, and the spindle could be something like the ubiquitous RT0700C makita router which seems a good compromise for my situation

    I would be buying one of those kits on ebay providing both the rails and ballscrews for three axis, and cutting those to length. Seems to be the most cost-effective option. For shortening the ballscrews, I think the easiest method would be to cut them with an angle grinder, drill and bore a hole on the lathe (as they are case hardened and the inside is soft), loctite a cilindrical piece in place and machine it concentric.

    Regarding electronics, I would be using and arduino and GRBL for starters, as that's what I'm most familiar with.

    I still have quite a bit of work to do on the design, but I'll be glad to receive any feedback regarding this approach.

    Juan



  2. #2
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    Re: Small Concrete CNC Mill

    Round rails (SBR) are not suitable for a metal mill. Don't waste your effort.

    Don't limit yourself to available "kits". Any decent seller will customise and cut to length / end machine (for cheaper and easier than you can). If they won't then they are just a drop shipper and not best to buy from.

    I use Fred at BST Automation on AliExpress. I've done multiple orders and always happy.
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  3. #3
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    Re: Small Concrete CNC Mill

    Round rails (SBR) are not suitable for a metal mill. Don't waste your effort.

    Don't limit yourself to available "kits". Any decent seller will customise and cut to length / end machine (for cheaper and easier than you can). If they won't then they are just a drop shipper and not best to buy from.

    I use Fred at BST Automation on AliExpress. I've done multiple orders and always happy.
    Thanks for the quick answer. I suppose that suitability would deppend on the speeds and feeds, depth of cut and so forth. I'll have to run the numbers, even if the rated load for SBR rails is substantially smaller than that of profiled rails, they may suffice. I originally chose them as they are easier to mount and more forgiving with alignment. I could mount them together with the ballscrew bearing blocks on a single aluminum plate, which I would expect to be reasonably flat. I have no means to propperly mount and align profiled linear rails. I could try to figure something out though. BST Automation seems to be widely recommended, so I may purchase from them.

    What about the general disposition of the machine? Are aluminum plates held to the concrete base with threaded rod going to be rigid enough?

  4. #4
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    Re: Small Concrete CNC Mill

    Em..
    upgrade your expectations and your budget.

    A mill requires by definition the ability to cut steel with a cutter that is unsupported.
    And that has minimal deflection / chatter at typical working loads.
    0.1 mm is totally useless.
    Milling machines need to aim for sub 0.001 mm theoretical, low, to approach 0.01 mm real world.

    Look at existing watchmakers mills for inspiration and scale from them.
    You are never going to do lighter than say HAAS for a particular work envelope.
    Scale from that.

  5. #5
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    Re: Small Concrete CNC Mill

    Em..
    upgrade your expectations and your budget.


    A mill requires by definition the ability to cut steel with a cutter that is unsupported.
    And that has minimal deflection / chatter at typical working loads.
    0.1 mm is totally useless.
    Milling machines need to aim for sub 0.001 mm theoretical, low, to approach 0.01 mm real world.


    Look at existing watchmakers mills for inspiration and scale from them.
    You are never going to do lighter than say HAAS for a particular work envelope.
    Scale from that.

    First one is easy, second one not so much...


    So maybe I should stop calling it a mill, milling steel is not on my requirements nor my capabilities.


    I know 0.1 mm is almost woodworking territory. What I'm trying to say is that I don't have particular tolerances in mind. The main goal is learning, and to end up with something I can use for my projects.


    Regarding rails, I think I'm going with HGR15 profiled rails, and I'll buy those and the ballscrews in the lengths I need. For the price difference it's not worth it to cut them myself.


    I've redesigned the frame, I think I'm doing away with the concrete. I just can't move around a 150 Kg concrete frame. So my new design uses 100 mm steel square tubing for the frame as shown in the images. Tubes will be screwed together and then welded. I'll fill it with sand or even epoxy granite if I see it appropiate. This will make the build more manageable.


    I've done some calculations and FEA simulations and for a 1000 N load on the tool (which should be plenty more than what the spindle would windstand), maximun deflection stays within 0.02 mm for 5 mm wall tubing. On resonance and such I can't really say anything, but the sand should aid with dampening. I suppose bearings would be resposible for most of the deflection anyways.


    10 mm steel plates will be screwed on to the frame to provide a flat surface, and some rectangualr sections are to serve as support for the rails.


    So my plan now is to order rails, ballscrews, motors etc, and visit some of the industrial suppliers around to get an idea of what is available. I'll try to get some cold rolled sections so they are reasonably flat to mount the rails to. It seems advisable to get a scrap steel plate and fill it with tapped holes, so I become familiar with the process.


    I'm happy to hear any recomendations. To provide some size reference, the machine fits in a 700 mm side cube, and the work table is 150*300 mm usable area.


    Juan


    Attached Thumbnails Attached Thumbnails Frame_only_tubing.png   Frame.png   Full_assembly.png  

  6. #6

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    Re: Small Concrete CNC Mill

    Hi Juan!
    I literally made an account 5 minutes ago after spending a while lurking on the site so hopefully I'm not way off base here breaking any rules or anything.

    It seems like you moved away from a concrete design based on your latest posted pics which is good, the concrete is going to move over time with different humidity levels and actually is not nearly as vibration damping or rigid as you'd think. There's a good video series by This Old Tony on youtube making a cnc router which sounds a lot closer to your expectations for actual machining capabilities (wood and plastic easy, aluminum without too much trouble). One thing though, when packing the tube stock with sand you need to ensure its dry and compacted. A vibrating table helps a ton as you see in his video, but you don't need anything too fancy, even like an orbital sander attached to your piece would help vibrate and compact it, or if you're really desperate a soft headed hammer and a whole lot of whacking would do the trick hahahaha.

    By the way, that tube stock it looks like you're using is probably not going to be very accurate, and so bolting linear rails to it will make them inaccurate too. Do you have a method to increase the precision there? I heard of a guy using leveling epoxy which apparently levels to about 5 thou, which may work for your tolerances if not

    Either way good luck with your project, hope it goes well!!

  7. #7
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    Re: Small Concrete CNC Mill

    Hi Juan -
    1) do not order anything until you have fully resolved the design. If you do order stuff this is your first major mistake.
    2) Sand is a waste of effort. So is epoxy to some degree. Epoxy is expensive and you are better off using thicker tubing. Most first time builders use tube that is too thin and this contributes to vibration. Use thick tube say 9mm plus (see later do not use tube)
    3) design a machine with as few parts as possible. By building up tubes with plates you introduce distortion, thin edges that vibrate, poor design. If you are to fabricate then use plate only. In this way you have control over geometry and local thickness. Everytime I have tried to design a router or mill using SHS or RHS it always goes AWOL due to std sizes. Design a plate steel machine. Will not need filling if stiff enough
    4) I'd consider a no weld machine fully bolted up for first machine. Welding introduces all sorts of issues. There are plenty of good plate, bolted machines in aluminium or steel in the forum
    5) Look up the Milli thread covers most of the territory you are going to need
    6) good luck - cancal any orders that you can.... you need to develop the design much more before it gets into the wild...
    7) your original idea with concrete is good, just need to learn alot more about it. Do not use portland cement but study up on UHPC or epoxy granite. Both are used to make very precise and large machines. Easy to cast at home has many possibilities...

    Peter

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    Re: Small Concrete CNC Mill

    Mook512:


    I've watched those This Old Tony videos...multiple times. In fact it's what got me interested in the subject. Yes, it's pretty close to what i'm aiming for, but for size and cost .


    Will keep that in mind if I decide to use sand.


    Regarding the tubes, yes I don't expect them to be flat or on dimension. My idea was to have a reasonably flat plate bolted to the tube, to which I could mount the rails, and behind which I could use some shims for alignment. I'll read about self-leveling epoxy, seems that it could be useful.


    peteeng:


    I haven't ordered anything. Too big of a purchase to make without careful thought. If anything I'll get some taps to practice tapping holes...
    I've had thought about using plate, aluminum extrusions... An option would be to design an aluminum plate machine, aluminum plate beeing expected to be flat, and also easier to work with within my limited capabilities. Regarding welding and screws, I had thought of fixing the column with just screws so it could be slightly adjusted. But again, this design I've posted is what I've happened to be thinking of when I decided to post on the forum. I often change my mind about the design and I'm open suggestions. Luckily my requirements stay more or less constant.


    I've gone through the Milli thread some time ago, lots of interesting configurations.


    On the concrete design, the major disadvantages I see are weight and beeing difficult to modify. A screwed together machine can be disasembled, and if one part needs to be modified or re-done that can be done with relative ease. I'll investigate a bit more and see if I can come up with a new design.


    Thanks,
    Juan

  9. #9
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    Re: Small Concrete CNC Mill

    Hi Juan - I have pretty much resolved Milli if you haven't been there in a while. Was a bit of a ride into new stuff. One thing to think about is to make it in timber. Its easy to change and work with and once you get where you want make the metal bits. There's a couple of builds here who build plywood machines, then use that to build the aluminium machine then that machine to build mills. Personally I'd stay away from construction extrusions, good for making stands but like std tubes have compromises that can't be fixed. An aluminium plate router/mill is very doable. Look up the Katran thread... Peter

    addition - re modelling - I see you are not modelling the radius on the corners of the tubes. These must be included for a couple of reasons. 1) you may be tempted to place something at an edge that is in fact air 2) when it comes to welding the rads are an issue. They can create huge distortion if you weld along them 3) by modelling square you are increasing the inertia slightly so your deflection calcs will be better then they should be. Your FE says an applied load of 1000N and a deflection of 20um ie a static stiffness of 1000/20 = 50N/um. This is small VMC territory. You need to change the way you are applying load and holding the machine... that size machine and tubing is likely to <2N/um in practice... You need a machine at about 10N/um to do steel 1-2 will cut timber and plastic easily and may do aluminium in a struggle.... Keep at it - Peter

  10. #10
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    Re: Small Concrete CNC Mill

    Juan ..
    Your numbers are way off base.
    The best manufacturers in the world are not getting 1/3 of the stiffness your numbers suggest.

    A typical max load on a mill of 2 HP, bridgeport territory, is around 40 kgf.
    400 N.
    This will deflect about 0.1 mm on a bridgeport table, at the edge.

    Go ahead.
    Push on a table at a demo room, with a dti measuring the deflection.
    2 fingers push of 10 kgf or so will deflect about 0.03 - 0.08 mm, give or take.
    And the BP masses 2000 kg.

    Gene Haas told me his VF6 series mills deflect about 0.01-- mm if you hit them with a hand, while they are milling.
    Several microns.
    The dimple is clear to see in the finished work.
    At 6000 kg mass.

  11. #11
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    Re: Small Concrete CNC Mill

    Hi Juan - I have pretty much resolved Milli if you haven't been there in a while. Was a bit of a ride into new stuff. One thing to think about is to make it in timber. Its easy to change and work with and once you get where you want make the metal bits. There's a couple of builds here who build plywood machines,...

    Yes, I've seen it. You have done some extensive design work. I'm sure it'll turn out great.


    Regarding wood, I think a design based on plates lends itself well to wood prototypes. Or one could make the main components out of aluminum, and the more complex parts (read: not rectangular) in the spindle mount could be made out of wood and used to machine the definitive parts... I've seen the work of katran. Beautiful machine.


    My CAD model was a bit rough and ready. Just to test out some ideas. That's why I didn't model the corner's radii.


    I am a complete newbie on FEA if it isnt apparent yet. Those deflections were only of the bare frame, no table, no bearings, just the L shape and an additional section standing for the spindle holder. Base was fixed on a couple points. I'm using Fusion 360 BTW. I did calculate a load case by hand and results were near enough to those of the computer.
    So real numbers, or those from better simulation taking other things into account would indeed be much larger.


    Thanks for the stiffness numbers. I don't really have a sense as to what to expect and that really helps.


    Juan ..
    Your numbers are way off base.
    The best manufacturers in the world are not getting 1/3 of the stiffness your numbers suggest.
    ...

    Thanks, it is a nice thing of online forums like this that one can get an idea of what things are really like.


    I'm more of an electronics person. Now I am like someone in an electronics forum who asks how to charge a 46F capacitor with 15 KV...




    ----


    I've done another mockup based on 20 mm aluminum plates. I have run another FEA on it, this time taking into account the table, rails and bearings. I have specified the bearings as being made out of aluminum, as I have read somewhere that that aproximated the actual behaviour of real bearings. Contact between plates is automatically specified as "bonded", but I can add screws and specify those as the contacts for more accurate results.


    I have added a 400 N force on the spindle holder and fixed the table. Maximun deflection clocks in at about 0.065 mm, so that is 6.2 N/um. With a better placement of the load, and rising the spindle support to its upper limit, deflection would be higher. That seems more reasonable, although maybe still too optimistic. See attached.


    So that could be a plausible approach, everything screwed together, already flat-ish aluminum plates.
    Motor mounts and spindle holder could be made out of wood or 3d printed, then new version machined...


    Juan


    Attached Thumbnails Attached Thumbnails Aluminum_plates.png  

  12. #12
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    Re: Small Concrete CNC Mill

    Hi Juan - Now your looking good. Rails should never be mounted on "air" so move the side plates inboard so they are under the rails. Use an alternating bolt pattern so the rail bolts thru to the webs. Similiarly with the spindle arm, put in a central web. 20mm is probably over kill for your machine spec, 16mm will be good if the details are right.... If the base and arm can be cut as an L it will be much stiffer.... So the big trick with this construction is having the plates cut (or milled) square and flat... then there is all the edge holes, so many holes & threads but then what else are you to do in the evenings? Keep at it Peter

    If you upsize your rails the stack height delta will be less so the spacers will be less height. The cost delta is small overall. Rails are very important for local stiffness. You can remove the spacers by using the web edges for the rails see attached... the aim is to minimise the part count... Your config is traditional and solid. I have no doubt it would cut aluminium if made in good quality plywood. The Mikita is a bit fast for Al but consider making it a bit bigger in solid timber (screwed and glued, epoxy sealed) and then use that to make your alum version. This will get you thru the learning curve of the electronics, wiring, chip loads, cutting set ups, CAM and many more, the journey is still long.

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    Re: Small Concrete CNC Mill

    Great, thanks.
    I'll make a new design including your considerations. I'll also try to get hold of a catalog of aluminum profiles from a local supplier, maybe I could use some suitably sized profiles that can be just cut to length. I may have access to a CNC router at my university (though I've never used it, and I'll have to ask around), I could buy some aluminum plate and cut all pieces from it, even center drill hole locations. Sending it out to a local job-shop would be expensive...but worth checking. I didn't mount the rails as you've shown on the sketch because that would need machined edges, a saw cut finish would not suffice. But if I use suitable profiles or have the plates machined that would be no problem.


    Being an engineering student evenings do fill up pretty quick I am on "holidays" at the moment. I hope to work on the design now, so any parts I have to order overseas arrive before summer.
    Juan

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    Re: Small Concrete CNC Mill

    Hi Juan - You can cut all non critical cuts with a good jig saw or radial saw. Then get the critical surfaces cut at a machinist maybe. If you use extrusions look at heavy channels they will be the best bet. But they are not square... Everything has limits. You need a CNC to build a CNC. Seriously consider a plywood first machine to make the next machine... just make it big enough to do the parts you want in Machine No2! Takes about a year to build No1 so don't panic yet...

    https://www.cnc-holzfraese.de/

    Peter

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    Re: Small Concrete CNC Mill

    Your config is traditional and solid. I have no doubt it would cut aluminium if made in good quality plywood. The Mikita is a bit fast for Al but consider making it a bit bigger in solid timber (screwed and glued, epoxy sealed) and then use that to make your alum version. This will get you thru the learning curve of the electronics, wiring, chip loads, cutting set ups, CAM and many more, the journey is still long.

    Sorry I missed this part last time.


    Hi Juan - You can cut all non critical cuts with a good jig saw or radial saw. Then get the critical surfaces cut at a machinist maybe. If you use extrusions look at heavy channels they will be the best bet. But they are not square... Everything has limits. You need a CNC to build a CNC. Seriously consider a plywood first machine to make the next machine... just make it big enough to do the parts you want in Machine No2! Takes about a year to build No1 so don't panic yet...


    https://www.cnc-holzfraese.de/


    Peter

    The thing is, if I'm able to make a machine out of plywood that can already cut aluminum good enough to make another machine, I would have already fulfilled my requirements and there would be no "need" for another machine . Yet the primary goal is learning, and I'm sure I'll have plenty of fun with a plywood machine and getting the rest sorted out as you say. I could upgrade the frame to aluminum in the future if I saw the need, and keep the rails and such. I could even use the makita for its intended purpose and square up the wood pieces. Seems that a machine made out of plywood or even MDF would be stiff enough for my purposes.


    I've made another design, see attached. The only thing is that attaching the rails straight to plywood doesn't seem right. I'll have to find suitable screws, but I guess it could be done. Alignment is another issue, although I suppose the wooden frame would flex before I risk damaging the bearings.


    I see what you mean, but I don't really have the room or budget for two machines.


    So we have gone from concrete, to steel, to aluminum and now wood. I guess the next material of choice would be wet noodles (just kidding).
    Juan


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    Re: Small Concrete CNC Mill

    Hi Juan,
    MDF has a modulus of 4.5GPa while good plywood can be up to 21GPa. I get F22 which is 16GPa. See attached design guide... Re: screws I use standard metal thread screws. I use a tapered intermediate tap to make the thread. This provides a taper for the screw to tighten to. Once the parts are set up and straight I remove screws one by one and set them with PVA glue or epoxy. Epoxy is for permanent connections PVA if they need to come out in future. You can use wood screws I like the Kreg brand square drive. Fits into the counterbore of the rails as well. You can remove epoxied screws by placing a soldering iron on the screw to soften the epoxy then remove...

    Here's an MDF machine base I'm building at the moment. From the base up its then stainless steel laser cut parts. The original intent was to use ply but melamine coated mdf doesn't need paint and its an experiment and half the price of ply. Mostly its pocket screwed, recommend that as well.


    http://ewp.asn.au/wp-content/uploads...v5-FINAL-1.pdf

    High Modulus noodles maybe something to explore. Peter


    edit- The thing with wood is its not very dense (plywood 700kg/m3) so you could make this solid sections and it would not be very heavy. Instead of making all the webs etc I'd be laminating plywood into solid chunks then shaping them. Then there's no local deflections, perfect shear transfer and nothing to wobble. Timber is naturally damp so thats a win as well. Just seal everything well to slow down moisture ingree egress. Use PVA diluted 1:1 with water as a sanding sealer lacquer. Cheapest sealer there is since your $$$ short. Epoxy is the best but $$$. Peter

    Since your thinking through materials here's something I wrote a while ago. Maybe laminated aluminium sheet and ply is the go...

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    Re: Small Concrete CNC Mill

    Hi Peter,
    Thanks for the tips on the screws and materials. And for the extensive plywood design guide.
    Nice machine base.


    On the laminated aluminum sheet and plywood, I think in my case it is easier to do just plywood, as it can be easily screwed and glued together. With the laminate it may be more difficult to join.


    As I'll have to buy a decently sized plywood board (or two), making it solid should be no big deal. I've attached a new cross section, using 18 mm thick plywood, as that is what I can acquire locally. I've also added some motor mounts.


    ----


    Regarding rails and ballscrews, I think 15 mm rails and 16 mm ballscrews should be fine. I don't think it's worth it to go into bearing life calculations and such as I'll be getting knockoffs made of who-knows-what. Judging by the listed static and dynamic load ratings, I suppose it should be ok.


    On motors, I've played around with a spreadsheet from here: What size stepper motor do I-need., and it seems that something like this would do for my needs:
    https://www.omc-stepperonline.com/ne...s30-3004s.html

    I've considered the moving mass as if the frame was made out of aluminum and cutting feed of say 2000 mm/min, other parameters such as 80% efficiency for ballscrews and other dimensions as advised in said page.


    Juan

    P.D. Just in case, I'm based in Spain. I spent a year studying in Canada. No square socket screws or screwdrivers around here . I've changed my location on my profile, but it seems it hasn't updated.


    Edited: square socket instead of head.

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    Re: Small Concrete CNC Mill

    Hi Juan - attached is the motion calcs for Milli- You can adapt to your machine. The screws are square sockets not square heads. Kreg have square drive and large head good for timber. There are torq heads as well. I dislike phillips or posidrive heads. If you glue your bits together you can remove screws after glue sets and reuse.

    Using steppers means your torque drops off as you go faster so don't count on much torque past 500rpm. Usually design the structure fairly well so you know the masses you are trying to move around. Being small 12mm ballscrews would be fine... but check buckling and whirl (whip)...

    Hiwin publish an excellent design guide for there stuff. speaking of bearings get medium or high preload cars if possible does make a difference.

    something like below makes your first build easier instead of buying descrete drivers and BOB. This is a 5 axis board incase you want to add extra bits.

    https://www.ebay.com/itm/5-Axis-CNC-...-/251315551321

    Keep at it and its looking good. Peter

    I use UCCNC but since $$$ are short go for linuxcnc its free and very powerful just need to know about linux which is very useful for you as a student into the future...

    Make your table 2x thick. When your spindle plunges it will bend an 18mm ply. maybe the table is a candidate fore the AL/ply/Al

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    Re: Small Concrete CNC Mill

    Hi Juan,
    A note about steppers. They all look alike but there are some differences you need to know about.

    https://www.omc-stepperonline.com/ne...m-4-wires.html

    If you look at this one its a few cents more but its inductance is less. Inductance is an indication of its electrical efficiency in terms of how it generates back emf. The lower the inductance the less back emf it makes. The consequence of this is that the lower inductance motor will spin easier and faster at a given voltage. The usual fix for speed is higher voltage but high voltage systems cost more $$$. Now the one above is also rated at a higher current but if you use the driver I suggested you won't be able to take advantage of that extra because the driver is 3A. But thats not a bad thing. Comes down to $$$, torque required and get the lowest inductance motor you can get in the budget. Another thing is that a std motor has 200 steps per rev and there are 400 step per rev motors out there (there's a couple in stepperonline) and this doubles your accuracy for no extra cost. It may be worthwhile looking at N17 motors and 400 step in the stepperonline catalogue. Since your using a ballscrew you will have heaps of grunt from even small motors.. speed vs force always a trade off ... Peter

    also saturate the ply edges with epoxy where you are mounting the rails this will harden the timber edge grain. Use a thin epoxy...

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    Re: Small Concrete CNC Mill

    Thanks for the calculations. I've done my best to adapt them to my case, se attached. Main asumptions are on the first page, an acceleration in the rage of 0.5 g seems to be typical and for speed, 4000 mm/min is pretty fast I think (I have a pen plotter here in my desk i can drive at any speed to get an idea).


    I meant square sockets sorry. I'll try to get similar screws, but I guess philips head would do fine. It's just a matter of convenience.


    I've seen documents by Hiwin. Looking great but hadn't had a chance to read much yet. I'll try to find a compromise option. Genuine Hiwing rails and cars are really expensive. I've seen some kits on Aliexpress that come with a couple 15 mm rails, four cars and a 16 mm ballscrew with its bearing blocks in the rage of 70-80 USD per axis including shipping. Maybe garbage, who knows. I'll have to keep looking.


    I've seen this https://www.omc-stepperonline.com/cn...rice&order=ASC
    kit on stepperonline, basically the cheapest 3 axis kit they have. It is what I have taken into account in the calculations. Motors seem kind of big, but may be appropiate. Having separate drivers appeals to me more, if something goes terribly wrong, I won't end up with a useless board.


    I had thought of using grbl for a start because I'm familiar with it. I don't have a suitable computer with a parallel port, but I'll be looking into using LinuxCNC on a Raspberyy Pi. Plenty to research. I'll make sure I leave myself plenty of room in the control cabinet.


    I made the table twice as thick and modified everything accordingly.


    Will look into other motors though. Still lots to do, but wanted to give an update. I'll be sure to get some thin epoxy to reinforce where the rails mount to. Depending on minimum, quantities, I may still have some left for the rest of the frame.


    Thanks for all your help,
    Juan
    Attached Files Attached Files

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