Welcome to Our Community

Some features disabled for guests. Register Today.

V-Slot Custom Rack & Pinion

Discussion in 'General Talk' started by Adam Filipowicz, Apr 14, 2018.

  1. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    Hey Guys

    Ive been skimming the board looking for Rack & Pinion ideas
    I would like to come up with a design that will nest in and centre itself into V-Slot channels
    looking to start some brainstorming/discussion

    I am no engineer,, just a hack with Fusion 360
    so if someone can draw this up better please do!

    perhaps we can get this spec'd out and have a company produce them for us.

    using 20 pitch/20 pressure angle for this mockup
    let me know your thoughts

    holes to be 5mm Diam with 9.2mm for head to clear, 3mm depth
    Spacing 50mm apart
    Machined ends so they can be stacked

    Thoughts on making these from Aluminum instead of steel

    these parts originally came from McMaster Carr
    McMaster-Carr

    McMaster-Carr

    cbeam rack 1.JPG cbeam rack 2.JPG cbeam rack 4.JPG
     
    Kyo likes this.
  2. ChristopherBishop

    Builder

    Joined:
    Dec 16, 2017
    Messages:
    3
    Likes Received:
    0
  3. Gary Caruso

    Gary Caruso OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    May 19, 2016
    Messages:
    962
    Likes Received:
    424
    there was a thread of a possible uhmw rack with brass pinion a while back..But the pics were censored out of openbuilds :D
    Aluminum has bad wear characteristics, makes for black residue all over everything.. and for strength nylon or uhmw is good enough with superior wear resistance with no lube requirements.
    But yes this has to happen some day! I played with the idea of making my own rack sections out of 1/4" HDPE, even made a sample that worked out well, but i would have to make a bunch of it and build another system to test it!
     
  4. Jonathon Duerig

    Jonathon Duerig Journeyman
    Builder

    Joined:
    Nov 25, 2015
    Messages:
    261
    Likes Received:
    155
    The CNC Router Parts rack and pinion works well with C-Beams. That is how my current machine is set up. Steel racks, steel wheels. It isn't terribly cheap, but probably cheaper than custom fabrication.
     
  5. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    can you post a pic of your current setup
     
  6. Gary Caruso

    Gary Caruso OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    May 19, 2016
    Messages:
    962
    Likes Received:
    424
    I agree the cnc router parts ones are very good, But there are a ton of chinese suppliers who make plastic racks that would suite our load needs, just a matter of finding one the right size and quality.
     
  7. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    also the CNCRouterparts Belt reduction looks very large.. hoping perhaps for a direct drive.. or gearing down a Nema 23 via 5:1 planetary or worm gear.
     
  8. Mark Carew

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

    Joined:
    Jun 28, 2013
    Messages:
    2,623
    Likes Received:
    2,191
    Hey guys, I want to jump into this discussion. We have been working on this goal as well in hopes we can all work toward an idea that we can call an OpenBuild standard. Racks are the logical next step for the OpenBuilds system and it would be great to be able to use something pre-made to save on custom but I think the advantage of making them to spec designed for the system will have its own benefits. Staying true to the OpenBuilds way with the idea of keeping it simple we were thinking here of spring tension direct drive (use motor tuning to get proper accelerations) Also thinking less thick racks especially with steel, which to be honest in it self may be over kill for the system, but trying different materials that allow for out side use as well as smooth operation, for instance nylon racks. Lets remember all the cool things we are already able to do with the belt and pinion style system so racks will only be an added plus to the ideas of machine building.
    We have been experimenting with a few ideas but most are over kill steel racking so we want to hear some of the applications and ideas you guys may have. This is a great discussion and a look forward to seeing how it weighs out.
     
    Adam Filipowicz likes this.
  9. GrayUK

    GrayUK Openbuilds Team Elder
    Staff Member Moderator Builder

    Joined:
    May 5, 2014
    Messages:
    1,668
    Likes Received:
    622
    We would need a rack that had screws in the bottom of it, the heads of which would, as in the style above,
    slide snuggly into the slot beneath it, and then simply put a plate at each end, holding it in place. SIMPLES! :thumbsup::thumbsup:
     
    Mark Carew likes this.
  10. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    Since most of these machines are fairly low load, looking at other materials is a good idea.. how about Delrin, its easy to machine.
     
    Kyo and Mark Carew like this.
  11. Jonathon Duerig

    Jonathon Duerig Journeyman
    Builder

    Joined:
    Nov 25, 2015
    Messages:
    261
    Likes Received:
    155
    Adam, this is the same machine I mentioned in another thread about this about a year ago:

    https://openbuilds.com/threads/rack-pinion.9874/#post-57134

    Coming up with systems explicitly designed to work with C-Beam seems like a good idea, though. When I did this, I was mostly concerned about what I could build myself based on what was available. If there had been something available that explicitly made for use with OpenBuilds, it would have reduced my nervousness would have obviated a few workarounds I had to do to make everything work. If somebody wants advice and confidence about what works for making a machine today with CNC router parts and C-Beams, I'm happy to advise. But in the longer term I'd love it if there were standard rack-and-pinion plates and parts available at the OBPS.

    Regarding materials, the benefit of steel here isn't the strength, IMO, it is the durability. Right now the plastic wheels are the weakest link in the system in terms of long term durability. When I rebuilt my machine last year, I had to replace all of them. And I expect to need to replace them again at some point. I would expect a plastic rack-and-pinion system to wear even faster. But the disadvantage of steel is weight. I need bigger motors just to move my gantry around even when not carving. I'm not sure the right trade-off here. But atm, the steel works well for me.

    I'm not sure what the best gear reduction is. I think the CNC Router Parts are 3:1 for NEMA 23 motors. It is precise enough that the only issues I have with reproducability are if the material itself moves or deflects. And it moves fast enough that I don't feel like the rapids are slow. But if somebody presented me a machine with direct drive or with a 5:1 reduction, I don't know that I'd really notice.

    -Jonathon Duerig
     
  12. Mark Carew

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

    Joined:
    Jun 28, 2013
    Messages:
    2,623
    Likes Received:
    2,191
    Delrin could be an option but to be honest although POM will give us great sliding wear, we need a higher impact as well and like Jonathon mentioned on a rack you would not want the wear that delrin will give.. We were thinking of going much harder and testing out NYMETAL or nylon66 it has high wear. The idea would be to use perhaps aluminum rack with nylon 66 pinions if replacements are needed years down the line it would be an inexpensive pinion and not the whole rack. just ideas at this time, but testing will tell a lot more.
     
    Kyo likes this.
  13. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    Work in progress
    5D3_2896.jpg
     
    Mark Carew, Kyo and GrayUK like this.
  14. Mark Carew

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

    Joined:
    Jun 28, 2013
    Messages:
    2,623
    Likes Received:
    2,191
    Look great @Adam Filipowicz can you share more info on this rack and pinion. I would love try it out this side as well.
    Thanks man :)
     
  15. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    Mark Carew likes this.
  16. Ronald van Arkel

    Staff Member Builder Resident Builder

    Joined:
    May 7, 2014
    Messages:
    472
    Likes Received:
    242
  17. Gary Caruso

    Gary Caruso OpenBuilds Team
    Staff Member Moderator Builder

    Joined:
    May 19, 2016
    Messages:
    962
    Likes Received:
    424
    Nice, that's exactly what i want!
     
  18. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    can you share info on these parts. what are they, where are they from?
     
  19. Ronald van Arkel

    Staff Member Builder Resident Builder

    Joined:
    May 7, 2014
    Messages:
    472
    Likes Received:
    242
    Hello Gary and Adam,

    The above images were just a design and never produced due to the lack of interest. Gary found the "uhmw rack with brass pinion" topic with no Images so I though to post them again.
     
  20. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    Thank you, can you share the design files with me? also what Pitch is this rack
    and how many teeth are the pinion?
     
  21. Ronald van Arkel

    Staff Member Builder Resident Builder

    Joined:
    May 7, 2014
    Messages:
    472
    Likes Received:
    242
    Sorry Adam, I can not share the design as it is not sold on openbuildspartstore.com or an OpenBuilds design, also still Alpha. Please continue with what you were doing, seems there is some interest for your design.

    The images show a Module 1 rack and pinion, the rack is 410.7mm long, 10mm in height, 20mm width. Pinion is 20t, 19mm width custom made.
     
  22. Adam Filipowicz

    Adam Filipowicz Journeyman
    Builder

    Joined:
    Dec 21, 2014
    Messages:
    256
    Likes Received:
    125
    Hey Mark

    Have you guys made any progress with a Rack system? Would like to buy a Openbuilds Bolt on Standard kit
     
  23. Mark Carew

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

    Joined:
    Jun 28, 2013
    Messages:
    2,623
    Likes Received:
    2,191
    We do have one in the works and we have been testing it for a while now with great results. The main objectives are make it as modular as possible so that it does bolt right on to the OpenBuilds system and of course can easily be modified for custom lengths. We also needed it to be robust but without the overkill of steel racks. All of this while making it as affordable as possible. These challenges have given us a unique system that we are excited to share soon. In the meantime I am looking for some help with beta testing @Adam Filipowicz if your interested pleases shoot me a message. :)
    We will be sure to share news with you guys as we approach a more finalized design. Thank you
     
  24. Troy Proffitt

    Troy Proffitt Well-Known
    Builder

    Joined:
    Oct 11, 2016
    Messages:
    125
    Likes Received:
    96
  25. Sean McVeigh

    Builder

    Joined:
    Jun 25, 2019
    Messages:
    10
    Likes Received:
    1
  26. David Riedell

    Builder

    Joined:
    Feb 11, 2020
    Messages:
    6
    Likes Received:
    4
    Any updates on the rack and pinion design? I have an MPCNC but am interested in getting something more robust. If I had the money and space I'd get an AVID CNC/CNC Router parts one, but I just found you guys and am really intrigued.

    I'd definitely like the modularity and stiffness of a rack and pinion motion system vs a belt driven or screw driven one.
     
  27. Mark Carew

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

    Joined:
    Jun 28, 2013
    Messages:
    2,623
    Likes Received:
    2,191
    Hi David, thank you for your interest and support. Yes the system is still in development and we share the news as soon as we can.
     
  28. David Riedell

    Builder

    Joined:
    Feb 11, 2020
    Messages:
    6
    Likes Received:
    4
    @Adam Filipowicz @Mark Carew

    Ok guys, I've put quite a bit of thought into this in the last few days, and I think I came up with something that could work. Curious to know what you guys think. Is this close to what you guys are doing Mark?

    Onshape

    The upside is that I used as many Openbuilds parts as I could to keep it within the same ecosystem. The bad news is, this design would require a custom rack and spur gear/timing belt pulley combo. I couldn't find something off the shelf that would work. I'm thinking the best way to test it out would be to 3d print them in nylon. Other than that, it would just take a few custom 6mm aluminum plates that would need 1-sided machining.

    It works on the same principle as the CNC Router parts rack and pinon, just on a smaller scale. The blue plate pivots on the right 5mm bolt and is tensioned by the grey bolt and spring on the left. I included slotted mounting holes for Nema 17 and Nema 23 steppers.

    Note that I didn't include every single fastener in the assembly. It should be pretty easy to infer where you need screws that aren't shown.

    Outside view:
    upload_2020-2-13_9-58-55.png
    Some math:
    16 tooth spur gear has a 50.265mm linear travel per revolution.
    With the 3:1 included gear reduction for the timing belt pulley, that gives us 50.265mm/3 = 16.755mm of linear travel per stepper axle rotation.
    With a 200 step/revolution stepper, that gives us 16.755/200 = 0.0838 mm/step. (And that's without microstepping!)

    Inside view with the C-beam hidden:
    upload_2020-2-13_10-18-1.png
    The 5mm x 15 long bolts to mount the rack to the C-beam are a little long, but that's easily fixed.
    There are a pair of Openbuilds standard bearings on either side of the spur gear/timing belt pulley combo so that it can spin freely on its 5mm bolt.

    Clearance view side 1:
    upload_2020-2-13_9-59-39.png
    Clearance view side 2:
    upload_2020-2-13_10-19-54.png

    Non-openbuilds BOM:
    3d printed rack
    3d printed pinion/spur gear combo
    146mm GT2 timing belt https://www.amazon.com/BEMONOC-Timing-Belt-Closed-Loop/dp/B07GR3KXK2/ref=sr_1_1?qid=1581574591&refinements=p_89:2GT+Timing+Belt+Closed+Loop&s=industrial&sr=1-1&th=1
    Spring for 5mm bolt
    Custom 6mm thick C-beam gantry plate
    Custom 6mm thick Motor pivot plate

    Like I said above, I don't currently have an openbuilds CNC to test it out, but hopefully I can get one soon :).
     

    Attached Files:

    Mark Carew and Troy Proffitt like this.
  29. Rob Taylor

    Rob Taylor Master
    Builder

    Joined:
    Dec 15, 2013
    Messages:
    1,347
    Likes Received:
    650
    Looks good to me. Bring the belt to the front side of the plate with a stepper standoff mount and you can use a full-width rack for reduced weakness issues around screw holes.
     
    Mark Carew likes this.
  30. David Riedell

    Builder

    Joined:
    Feb 11, 2020
    Messages:
    6
    Likes Received:
    4
    That's true, I could try that. I was trying to have everything fit inside the c-beam but it's not strictly necessary.

    Actually if I put the timing belt pulley portion on the outside of the plate that would solve several spacing issues, plus I could have a wider spur gear and rack, which would be better force distribution. I'll have to think about that. Might be worth considering for a version 2.
     
    Troy Proffitt likes this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice