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Protoptimus - O.B. CNC mill in Brazil

Discussion in 'CNC Mills/Routers' started by Jeferson SImoes, Apr 29, 2014.

  1. Jeferson SImoes

    Jeferson SImoes Well-Known
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    Hello guys!

    This thread is only a sumary/first version of my build. As soon I can, I intend to post more detailed information about what I done util now.

    I share here the Solidworks files that I made, and used to build the machine. But it's not perfect named in english and as I making changes, may I not have deleted some part that is no longer used, as well as the folders are not very well organized.

    And unfortunately, I have not had time to add the nuts and bolts.

    The aluminum plates are only 1/8" and to make matters worse is a very soft alloy. Soon as I can, I will look sheets of 1/4" in a better alloy.

    Is very painful for us here in Brazil to import parts. Sometimes we have to pay taxes in importations (depends on luck), and it's about 60-70% above the price of parts + shipping.

    So I decided to import only what it's absent here. The openbuild v-slot system and electronics.

    As I said, this topic is just an introduction, and to share photos and design.

    It is likely that I have committed many errors in the construction of my prototypes. But I am very excited to get some results that I consider satisfactory, and it is very rewarding to see a project run.

    For now, here what I'm using:
    Arduino Uno + GRBL
    BigEasyDriver
    Sparkfun Nema 17 400steps

    I already received some DRV8825, Nema 23 and Balls Leadscrew, that I will use to build a large and strong machine, just to mill all aluminum plates that I use in the little machines. This little machines I will sell here. For that, soon I will launch a crowdfunding campaing at Catarse. As I said, it's very hard to get some things in Brazil with a nice price. A Shapeoko that's a U$700 machine, arrive here at least arround U$1500. Thats is to expensive to our reality.

    I will negotiate discounts on large scale components buy, and try to locally produce the maximum components as possible, in order to minimize the dreaded importation.

    Here we go:

    SolidWorks Files to the last version of my build:
    https://www.dropbox.com/s/vrqni4xcr61wr3u/Protoptimus CNC.zip

    Here, the first version:
    [​IMG]



    The second version:

    [​IMG]

    [​IMG]

    The first version using V-Slot, with leadscrew, that don't work well. I cound't get both Y leadscrew in perfect parallel, and the nut I got have a lot of backslash.

    [​IMG] [​IMG]

    Use only one 8080 in the X axis, made the gantry very flexible.

    Videos of this version:




    (I love that video lol)

    And here, the current version:




    (sorry this video rotation)

    [​IMG]
    (Federal University of Itajubá), also known as UNIFEI, formerly known as EFEI(Federal Engineering School of Itajubá)
    [​IMG]

    [​IMG]
    [​IMG]
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    [​IMG] [​IMG]
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    [​IMG]
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    [​IMG]



    Any suggestion and criticism is welcome!

    I look forward to feedback from you, and now take the opportunity to leave some questions.

    What thickness and aluminum alloy you recommend to make the plates?

    My priority is to be the easiest alloy to machine, because I'll do them by myself after building a larger machine. Forgot to mention, but soon I will receive a three-phase 0.8kW spindle. I hope it's enough.

    For now I found local suppliers that have the following alloys in this thickness range:
    1100, 1200, 5052, 7075.

    And lastly, how will I sell these machines, how can I do stress tests, and determine the useful life of components?
    Which components tend to wear faster?
     
    #1 Jeferson SImoes, Apr 29, 2014
    Last edited: Jul 3, 2014
  2. Tweakie

    Tweakie OpenBuilds Team
    Staff Member Moderator Builder

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    Excellent work @Jeferson SImoes :thumbsup:

    Thanks for posting the pictures, videos and describing the strengths / weaknesses in your earlier designs - I am sure this will be of great help and encouragement to others that are just starting out on the road of CNC construction.

    That 60 - 70% import tax is very steep indeed :(

    Tweakie.
     
  3. Florian Bauereisen

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    Way to go!!
    Well done on your part.
    A way to test your machine is to mill Symetric pattens (like holes) into two plates and then flip over one of them.
    If patterns line up your good to go.
    As for milling aluminium, mill a plate using multiple passes, and see surfaces. Any steps/chatter will show direktly.
    For longelivety?? no idea, i would not guarantee a certain time at all, as you do not know how stupit someone elese will use your machine.
    How will you find out if someone simply crashed your machine and now blames you?

    Surely someone else will chime in too.

    greets
    Flo
     
    joe.carson likes this.
  4. Florian Bauereisen

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    Btw
    I use a 800w Hf spindle myself .... good enough for say a 4mm bit in anluminium if you want to retain some speed while milling.

    greets

    flo
     
  5. andrew

    andrew Journeyman
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    I really the design of your x-axis. It looks quite strong, and the stepper/belt placement was clever.
    Nice build!
     
  6. steelspinner

    steelspinner Well-Known
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    Awesome looking build!!! Nice clean design.

    What is the spindle that you are using the final version? Is it one of those 300 watt Chinese spindles?

    As far as aluminum goes 7075 is the highest strength (close to some steels) although it is prone to corrosion. The best compromise, imho, would be 2024 aluminum if you can get it. It machines pretty easily, not very prone to corrosion, is very stable and generally pretty cheap.
     
  7. Jeferson SImoes

    Jeferson SImoes Well-Known
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    @Tweakie

    That's right. 60% of the value of the product + shipping. Sometimes the government itself sets the value of the product, if they think the value stated in the invoice is not in accordance with the market value here in Brazil, and sometimes they add ICMS and another taxes. Like taxes of states and city.

    @Florian Bauereisen

    Thanks for the tips.
    Truly this is my biggest concern. One user using the machine the wrong way and break it.
    I will create tutorials, and even before the user read them, I will detail with cautions maximum specifications that should be used in terms of speed, depth per pass, cutters and materials.
    I believe that good communication with each buyer before, during and after the sale, will minimize problems this problem.
    But it is a risk that is always hanging around my company .
    Any suggestions more that I can do?

    @andrew

    Thank you very much.

    Some of the requirements I have for this machine is achieve the best ratio between the size of it, including the space it can occupy to be at the beginning and end of course (spindle or motors that can overcome the body of the machine), and the working area.
    I'm struggling with SolidWorks to achieve the following ratio to X and Y
    Machine : 500x500mm
    Work Area: 400x400mm

    @steelspinner

    Exactly, it's a Chinese DC Spindle 300W. The version that I will put int the market probably will have a chinese Spindle DC 600W. Despite the 500W and 600W versions of these spindle works on 12000 rpm if I'm not mistaken. The current 300W is up to 24000 rpm. Can be a problem?
     
  8. Mark Carew

    Mark Carew OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

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    @Jeferson SImoes love the look of this build clean and neat with strength in all the right places, nice job. :thumbsup:
     
  9. andrew

    andrew Journeyman
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    Those are good ambitions. Height is probably less important, but could be reduced with a belt transition like I did here:
    http://www.openbuilds.com/threads/cubefoot-cnc.464/#post-4211
    It's hard to find much more wasted space in your machine though. Good Luck!
     
  10. Jeferson SImoes

    Jeferson SImoes Well-Known
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    @andrew, thaks. It's a very nice idea. And we can make a reductor (? don't know the right word), I mean, improve the motor torque.

    This design use this in all axis, and I think about too, because our little motors. I will make some trys soon.

    http://www.instructables.com/id/Building-a-CNC-router/

    Some more wasted space is in connections between v-slots and v-slots and plates. This machine I made only with I had in hands. I will make some mix with anothers brackets and plates of OB, and as soon my bigger machine came alive, I will be able to make the plates with more complex design, with cuts that can "receive" some bracket or anothers parts inside its, at the end of courses.

    In another words, make all carriage/whells go up to the end of v-slots.

    I pick up the spindle today, and again, pay taxes =/

    Next weeks I will start the desing of the bigger machine.

    [​IMG]

    Some one, just by looking the detail picture of belt, can tell me if it is GT2 or MXL?

    I know that GT2 have less backslash than MXL. I have a lot of backslash =/

    I think the brasilian seller that sent me this belt just make me a fool.

    The version I will sell, will use the GT2 3mm, and I have to be sure, from experience of OB members, that don't have backslash.

    DSC00531.jpg
     

    Attached Files:

  11. Jeferson SImoes

    Jeferson SImoes Well-Known
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    Hello people.

    I'm having backlash trouble.

    I Did some movement testing through the arrows of UniversalGcodeSender, making some squares, with each line always moving every 5mm.

    Unable to accurately measure the size of the gaps, but they are much visible.

    IMG_20140520_184906_826.jpg

    I'm beginning to suspect that could be a little angle between the entrance and exit of the belt on the pulley. Or do you think the angle is enough?

    belt-pulley.png

    I stretched the belts as much as I could with pliers, and apparently I could tighten the screws without twisting/rotate the belts between the V-slot slot.

    What other causes can generate backlash in systems with belts?

    Apparently they really is GT2 (2mm pitch), becausa the machine was uncalibrated if they were MXL.

    Can be low quality belts / pulleys?

    With so many things in mind, I could only perceive that great backslash when I started testing PCB milling.

    IMG_20140520_195438_214.jpg
     

    Attached Files:

  12. Mark Carew

    Mark Carew OpenBuilds Team
    Staff Member Moderator Resident Builder Project Maker Builder

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    It looks more like it could be missing steps or even the pulleys slipping on the motor shaft.
    Make sure your pulleys are one solid unit with the motor shaft and that they do not have any play and see if that helps.
     
  13. Tweakie

    Tweakie OpenBuilds Team
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    My guess would be that the pulley is loose on the x axis motor shaft or that there is some lateral movement in the Z axis.

    Tweakie.
     
  14. Jeferson SImoes

    Jeferson SImoes Well-Known
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    Hello guys

    I redesigned the plates, so now the belts "mesh" (touch? I don't know the word) more tooth of the pulley. And I changed the belts/pulley for new ones. Now I'm sure I got the GT2. It's really good now. I already received the GT2 3mm setup from OB last week, and soon I will replace for it, as soon I get some light/slim Nema 23 steppers. The heavies I have I will use in the big machine with the spindle and VFD.

    [​IMG]
    [​IMG]

    To be perfect, only when I got the 6mm aluminum plates. This 1/8" plates that I cutted, it's ok, but is not the ideal.

    My crowdfunding campaign is online. I prepared this kind of FAQ, that explain the campaign in English. There, I share a DropBox link, with a very lot of pictures.

    http://www.protoptimus.com/p/arduino-cnc-milling-machine-router.html

    The campaign it's mainly for residents in Brazil. But I need some help.

    The biggest help I need now is that some charitable person to read the text in this link, tell me what you think, and if there are many grammatical errors in English.

    If this person liked my proposal, will can help me a lot if can correct the grammatical mistakes for me, and send to my e-mail.

    My next step will be to create a very complete wiki in Portuguese. The best information on the opensource community are in English. This reduces the number of Brazilians who would like to join the maker movement.

    As soon I can, I promise, I will leave the Solidworks folder very well organized, with every nut and bolt, and publish here in the community, not just in this thread.

    Thank you all.

    (edit)
    Here, a video that show the machine in my bedroom. It's a dream to have my own machine, right in my side, with no dusty, or loud noise.
     
    #14 Jeferson SImoes, Jun 23, 2014
    Last edited: Jun 23, 2014
    Mark Carew likes this.

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