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Linear actuator using ClearPath Integrated Servo System @ 72V DC

Discussion in 'Motor actuators and drivers' started by Dirty, Apr 7, 2018.

  1. Dirty

    Dirty New Member Gold Contributor

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    Hey there,... :)

    So I guess, after a few months of planning I reached a point where I should open a build-threat for my linear actuator design.

    I borrowed heavily from @SeatTime , @wannabeaflyer2 and @pmvcda 's design (to say the least!). Especially @pmvcda changed the game for me, because he made me realise how much 3D printing could change the way I approached a problem. However, I didn't want to take this 3d printing thing as far as @Hoddem. I wanted the load-bearing structures to be made out of an all-aluminum construction. After all, aluminum profiles are cheap and durable

    The basic design is pretty much fixed: Actuator 2nd Gen v6.png

    There are a couple of points where I deviated from previous designs and I will go through those one by one:

    1. Double upper bearing (both IGUS):
    I had doubts if a single upper bearing would hold the bending loads. Even though no-one ever complained about problems with a single bearing, it was literally screaming at me "this is gonna break". And since I needed the actuator to have a certain minimum length anyways, I decided to invest those 180mm for a second bearing. Even in it's fully extended position the rod and the actuator body now have an overlap of about 200mm.

    I initially bought LMU bearings, but after just a few minutes the (stainless steel) rods looked like this:
    IMG_8532.jpg ...so I went with the IGUS bearings.

    2. ClearPath Integrated Servo System:
    I decided to use a ClearPath MCVC-3432D-RLN @ 72V DC :)
    089-130102.jpg Bildschirmfoto 2018-04-07 um 14.53.59.png IMG_8635.jpg

    The biggest bummer right up front: They are expensive! I paid 2100$US for 6 of them. Then shipping and handling (380$) and german tax (400€ or 500$US). So almost 3000$ for the motors alone :-( But they have 1.1KW of power (yes, one of them!) So, definitely no concerns for being underpowered here :) The important part for me was the fact that those motors meant that I could completely ditch all Arduinos, break resistors, H-bridges, Sabretooths, Kangaroos, Capacitors.... all the things I only accepted gruntingly as a "necessary evil". Just serve them 72V DC and give'em a signal telling them what to do and they will go to work. Period. The signal is a speed command coming directly from Thanos' AMC1280USB.
    ...oh, and they're quiet! You hear nothing but a faint humming @ max RPM.

    3. Two beam design:
    Since the ClearPath Motors are NEMA34 size, I couldn't just position them between two continuous 60x20mm profiles. It would've worked, but it would've made the actuator very wide. I wanted the actuators to be as slim as possible near my legs, so I kept them slim around the top, but used two 80x20mm profiles at the base to house the motor between.
    I didn't want to go with the "4-threaded-rods-type-of-design", as I feared it wouldn't hold the frequent torque changes.

    4. All-metal load bearing construction:
    3D printing opened up many interesting design options and @pmvcda and @Hoddem have shown beautiful designs using it extensively. However, I wanted the load carrying construction to be all metal (aluminum). You can get 8mm aluminum plates laser cut for a few €, so I wouldn't have to worry about print times and safety factors. Also longevity was a consideration as PLA and PET-G have their issues after a some time of use under load. So I used 3D printed parts only to keep the metal parts in place, so to speak.

    Orange are the 3D-printed parts:
    Bildschirmfoto 2018-04-07 um 13.39.18.png

    This is the load bearing structure:
    Bildschirmfoto 2018-04-07 um 13.37.25.png

    ...and the force-path:
    Bildschirmfoto 2018-04-07 um 13.37.25 2.png

    Position feedback is through 6 AEAT-6012 12bit multi-turn magnetic encoders. They are not in the design yet. Still to go. I chose them , because I hope for good precision and the 2017 AMC1280 supports them directly :)


    A few words of encouragement for newbies: If you read this and are thinking in the back of your heads: "I'd love to do something like that too, but do not have an engineering degree..." Don't worry! You can do it! I am living proof that all it takes is determination (and ~600€/actuator). To give you an idea of where I'm coming from: Just a few months ago I didn't even know what an H-bridge was! There was someone talking about an "H-bridge" and I had no clue,... but I saw that he was from Australia,... so the first thing that came to my mind was the Sidney Harbour Bridge!!! Seriously!!! If you can read this text, then you can built a full-on 6DOF Stewart platform.
    It will be a challenge,... yes. But it will let you grow! Much more than your Highschool friends who probably actually have engineering degrees but are stuck somewhere in an office of a company doing stuff they hate or are indifferent about.

    DO IT!!!

    Attached Files:

    • Like Like x 4
  2. SeatTime

    SeatTime Well-Known Member SimTools 2.0 Beta Tester

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    Nice work :thumbs. Would have loved to use Clear Path servos, but after getting some quotes, the cost to Australia was even more expensive then yours :eek:. Look forward to seeing it all in motion. Note. The DC motors that I use are also quiet, but ballscrews do create some noise during long strokes.
    Last edited: Apr 7, 2018
  3. Jerry Atrick

    Jerry Atrick this is my sim Gold Contributor

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    Hi Dirty,
    Firstly; Great looking design, and finally someone is using Thanos AMC1280USB, I have one (bare-bones) maybe you can offer me some tips in using the AMC1280USB.
    Secondly; do you mind saying what you choose for your lead (pitch) on your a lead screw?
    So again Great Job and I cant wait to see it in action!

    Regards Jerry.
  4. SeatTime

    SeatTime Well-Known Member SimTools 2.0 Beta Tester

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    I have used 1280s for some time and currently have two in my rig. An old one and the new one.
    Last edited: Apr 9, 2018
  5. Jerry Atrick

    Jerry Atrick this is my sim Gold Contributor

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    Hi SeatTime, Sorry I must have missed the use of the 1280's in your rig, Ive been waiting for a current "up to date manual", in the hope that I can decipher what it all means. (not my area of understanding) Have had a look at Thanos's videos but way over my head, if I had a manual as mentioned, with pretty pictures and some wiring diagrams I might have a chance.

    So; can you say what you use for a lead screw, lead, Ive asked in the forum but had NO response, maybe you can help!

    Regards Jerry.
  6. SeatTime

    SeatTime Well-Known Member SimTools 2.0 Beta Tester

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    5mm.
  7. Jerry Atrick

    Jerry Atrick this is my sim Gold Contributor

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    Hi SeatTime, and thank you for the reply, I will work around 5mm and see what happens.

    Thanks again
    Jerry.

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