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  1. #21
    Member ChrisD314's Avatar
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    Default Re: My First CNC Build

    [QUOTE=peteeng;2483578][Thanks Pippin yes you need a driver for each motor or a single box solution. Peter

    Thats why i liked the xpro v5, its all in one



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    Default Re: My First CNC Build

    Hi Chris - You don't mention an actual speed in the thread, so hard to comment on that directly. The xproV5 is low cost because it uses free software to drive it and its a low maker grade component. But it will achieve good speed even though it is 24V as its a trinamic system. It uses a very good driver electronics and is ideal for a beginner machine as its a one box solution. Electronics are the easiest bits to upgrade in future. I wouldn't write it off... its my pick for my next low cost build. Peter



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    Default Re: My First CNC Build

    Hi Chris - Been reading the specs on the trinamatic TMC5160 chip and its rated at 60V. Would be interesting to find out from Spark what the 24V limiting component is... the chip is quite sophisticated will give very good motion...Peter



  4. #24
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    Quote Originally Posted by peteeng View Post
    Hi Chris - Been reading the specs on the trinamatic TMC5160 chip and its rated at 60V. Would be interesting to find out from Spark what the 24V limiting component is... the chip is quite sophisticated will give very good motion...Peter
    I don’t have an actual speed in mind, when I say fast I just want each work piece to be done the fastest it can be that is safe for the machine and to the piece I’m working on. The ball screw is 10mm pitch. I’m still so new to this that I’m still absorbing information and there’s so much info out there and some is right and some is wrong.



  5. #25
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    Default Re: My First CNC Build

    Hi Chris - with a 10mm pitch most steppers will get to 500rpm at half their stalling torque so you will easily get 500x10=5m/min. A good driver will get to 750rpm so say 7500mm/min tops which for your size machine is good for a rapid move. Your cutting speeds will be 1000-3000mm/min depends on material. Production machines are much faster but then they are also much stiffer then yours will be. Although we can talk about max speeds easily it also comes down to accelerations required to get to these speeds. The accels are the limiting factor. If you have lots of run up you can get to these speeds easily with a low accel. I'm sure the V5 will do the job if your happy with a GRBL system. Peter



  6. #26
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    Default Re: My First CNC Build

    No one mentioned but I'd take a look at AXBB from uccnc as an all in one board.

    AXBB-E ethernet motion controller and breakout board combo - CNCdrive - webshop



  7. #27
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    Default Re: My First CNC Build

    Hi Ard - The AXBB still needs motor drivers so not "a one box" solution. I'm off to a wedding be back next week! Cheers Peter



  8. #28
    Member ChrisD314's Avatar
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    Default Re: My First CNC Build

    Just got my linear rails and ball screws delivered. I was surprised about the weight of these 5 foot rails! Very sturdy, but this is going to be a heavy cnc machine.



  9. #29
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    Default Re: My First CNC Build

    Quote Originally Posted by ChrisD314 View Post
    Just got my linear rails and ball screws delivered. I was surprised about the weight of these 5 foot rails! Very sturdy, but this is going to be a heavy cnc machine.
    Hi Chris,

    There are several things I would suggest you consider... Some tips and tricks I learned on my CNC journey.
    Firstly ally (aluminum) is generally not a cheap or particularly good material to build a CNC from. Box steel (RHS) is a much more rigid material to build a frame with, and probably cheaper than ally. The bigger the box section the more rigid it is (less prone to twist).
    Secondly brace in as many directions as you can, it doesn't need to be heavy wall but the more angles the better. Triangulate and box where you can that is where the strength comes from.
    Bit late to say buy longer rails as you have already bought them but the wider the bearings are apart the more stable the gantry will be. I think from memory my bearings are something like 400mm apart. So if you want a 4' work area you need more like a 6' rail.
    The frame rigidity is what will dictate what you can cut. Doesn't matter what motors or controllers you buy if the frame is not rigid enough you will never successfully cut harder materials like steel.
    That will do for now, if you have some drawing of what you plan to build that would help guide you better.

    If my post is missing the n't you might have to mentally add it yourself.


  10. #30
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    Default Re: My First CNC Build

    So heres the update, I built my frame and im very happy how it came out. Just waiting on another ballscrew and its on to the rest..

    Attached Thumbnails Attached Thumbnails My First CNC Build-cnc4-jpg   My First CNC Build-cnc3-jpg   My First CNC Build-cnc2-jpg   My First CNC Build-cnc1-jpg  



  11. #31
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    Default Re: My First CNC Build

    Hi Chris - Very tidy build I like it. Peter



  12. #32
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    Default Re: My First CNC Build

    Thank you Peter!



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    Default Re: My First CNC Build

    I wish you would have read my post before you built it, it would have saved you a lot of heartache. Expect a lot of racking issues. This is all part of the CNC journey. Not the fun part, but a part of it no less.

    If my post is missing the n't you might have to mentally add it yourself.


  14. #34
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    Default Re: My First CNC Build

    I guess well see...



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    Default Re: My First CNC Build

    Unfortunately not too much seeing about it. That design is inherently weak to start with (very popular but weak by design). I wish you luck. Hope you have fun with it. A DIY CNC is a great buzz to own and even more fun to use. I am not trying to rain on your parade, I am just familiar with the design, and its shortcomings.

    Last edited by Bad Wolf; 01-15-2022 at 07:51 PM.
    If my post is missing the n't you might have to mentally add it yourself.


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    Default Re: My First CNC Build

    My First CNC Build-rocking-jpg
    Chris this is one of the big problems with that design. For every action there is an equal and opposite reaction. So while the Z axis is trying to push down into the material, an equal force is trying to push up. If the cutting tip is not in the centre of the bearings, it doesn't exert equal force on the bearings (pushing both of them up). What often happens is the cutter is to one side, or worse outside the bearing, which causes the gantry acts as a big lever. With the bearings close together (another fault of that design) the amount of rocking in the gantry is severely multiplied.

    All bearings have clearance otherwise they wouldn't work. So if one bearing is tilted up (the other goes down) that is going to cause the gantry to tilt off vertical, causing the cutter to also tilt off vertical. This leads to chatter, gouging, broken bits, poor finish. That is why I recommended a wide gap between bearing on the gantry to avoid that problem.

    Attached Thumbnails Attached Thumbnails My First CNC Build-rocking-jpg  
    If my post is missing the n't you might have to mentally add it yourself.


  17. #37
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    Default Re: My First CNC Build

    Hi BW - Plunging is one of the tougher actions on a machine as you explain. Dean has set the Z axis back quite a bit and maybe the spindle axis will be in or near the footprint of the bearings. Depending on what he needs to do and what his plunging demands are, he will figure out if the machine is stiff enough. Being timber its easy to glue or screw more stuff on to correct the issue along the way. Its a learner machine at the end of the day.

    Linear bearings such as Dean has, come in different clearance and interference (called preload) grades. Cheap bearings are usually "zero" clearance which means they are size to size. Good machines use preloaded bearings that have interference. I use medium or heavy preload bearings in my builds for this reason. This is achieved by using oversize ball bearings. This means there is no hysteresis (free motion) when the car changes direction, plus it makes the connection a little stiffer. Preloaded bearings have more friction but that's the trade off. The bearing suppliers provide all this info in their design manuals. Hiwin provide a very good manual if you are interested in these design factors. All machines once built are easy to review and improve even very professional designed and built ones have issues or areas of improvement. I'm sure this is not Deans last machine and by the time he's built a few many things will be sorted out... Peter



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    Default Re: My First CNC Build

    I would add a couple of points to Bad Wolf's critique:firstly I would expect the gantry beam to deflect when cutting along the machine and secondly I would expect the uprights at the end of the gantry to deflect when cutting across the machine.Neither of which is beyond curing if,or when,it happens.Adding bracing webs where needed isn't a huge project and one along the top of the gantry beam would also serve to support a drag chain.One at the bottom doesn't need any additional function beyond keeping things in shape.If you feel a touch of curiosity about how much movement is possible just stand a dial indicator on a block near the bottom of the Z axis and give the Z axis a healthy push.Do so along the machine and across it then consider if your steppers will be pushing as hard or even harder.



  19. #39
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    Default Re: My First CNC Build

    Peter, are you referring to me as Dean? My name is Chris, but no worries. Yeah guys, I'm far from done, i understand its not a perfect design but like Peter said its not my last machine and I'm not going to push it too hard. Throwing another piece of 3/4 wood on top of the gantry beam is a good idea to even square things up even better than they are.

    Can you guys give me some advice on picking the rest of my parts. Stepper motors, how can I calculate how much torque I need to move each axis? I will need two motors for my y axis, and just 1 for the other 2 axis'. I've seen a couple of ideas and equations but I want to know what you guys think. Also how do I determine how big my drag chain should be? Thanks



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    Default Re: My First CNC Build

    Quote Originally Posted by ChrisD314 View Post
    So heres the update, I built my frame and im very happy how it came out. Just waiting on another ballscrew and its on to the rest..
    Looks good for your first build, you will see by this build where you need to improve it. depending on the spindle you choose, the performance will only be able to match the power of the spindle.

    Mactec54


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