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Beginner to rail systems/cnc in general.. couple questions on parts.

Discussion in 'General Talk' started by xl97, Jun 8, 2018.

  1. xl97

    xl97 Well-Known
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    Hi gang-

    This is my first foray into cnc/rail systems (this is not for a CNC machine, but for an automated bar bot project)

    I was initially going to get this kit:
    V-Slot® NEMA 17 Linear Actuator Bundle (Belt Driven) (1000mm with stepper)

    However.. I dont really care for how the stepper and idle pulley are on the ends.. which make that piece difficult (in my mind) to mount to some upright 'stands/legs' (think of a capitol letter "H")..

    So upon some more research, I discovered the belt & pinion system. This eliminates the wasted space and clean mounting issues when having the stepper/pulleys on the ends, protruding out/past the rail/beam itself.

    I was directed toward this project and parts list:
    https://openbuilds.com/builds/v-slot™-belt-pinion-example-build.97/#openbuilds_parts_list

    And I have some questions I could use some help with.

    I'm not really 'stuck' on using the V-slot rails.. I would be open to using just two round bar/rails... but being new to all this, a kit seemed like it would cost more, but also include things I wouldnt know about/forget about.

    I actually kind like that approach better.. since I can have the stepper and belt be IN BETWEEN the two rails.. (and hence I dont need to worry about the size/placement/footprint of the stepper motor compared to the rest of the project 'frame').. but having to worry about mounting plates...etc would be a PITA I think? (maybe those more experienced in this area can direct/guide me to a system kit like that?)

    1.) If going the belt & pinion route.. what i your 'real' travel? (ie: how much of each side/end do you give up in inches?)

    2.) The wheels in the kit:
    OpenBuilds Solid V Wheel Kit Solid V Wheel Kit

    Are NOT what is shown or talked about in the videos? The videos use an inner V cut wheel.. to help keep the belt in the channel perhaps? Which are we supposed to use?

    3.) The parts list also talks about these 3m 6mm screws:
    M3 Screws 6mm http://openbuildspartstore.com/socket-head-screws-m3-25-pack/

    ** But the link is broken.... I also have read that some of the screws for kits need to be '10mm' ones and they are too short otherwise to secure anything? Is this still true? (a little misinformation out there and for noobs its hard to tell what is what)

    *** I also noticed some of the parts on the list say 25 packs.. but really are only 10 packs... do you NEED 25 of them? (so multiple items are needing to be ordered?)

    I like the belt & pinion approach as mentioned.. but I'm a little leery about the footprint of the stepper itself.. (and how its mounted..... how big are these things? are the measurements in MM? it doesnt say on the image)

    Is there a specific way/orientation the rail/wheels should be when under load (mine will have a very small load/weight..but I'm still curious).... do they need to be 'up-right'? as in the wheels need to be up-right and be vertical in the rail? or can you turn it on its side? (so the rail is more 'flat' and the wheels are more or less laying down? 'horizontal' riding along the rail system?

    I guess I'll stop here as to not overwhelm you guy or myself! LOL

    I'm hoping to get this ordered as soon as I have a nice game plan/direction.

    Thanks for any feedback!
     
  2. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    You basically lose the width of the plate which for the one shown is 88mm. So for a 1000mm section you'll come up just shy of 36". When you figure a small gap at each end so you don't smack the end brackets it's probably best to assume around 35"
    The example you're working from is a very old example, created prior to adding the Solid V Wheels to the OpenBuilds system. The Solid V Wheels though are the recommended wheels for using the belt/pinion method as they support the belt better where it is pulled up from the track to loop around the pinion.

    Again the example is a very old example. The shop has recently started packaging screws in packs of 10 rather than 25. All screws can be found here Hardware - Screws - OpenBuilds Part Store Once you have selected the type of screw needed the length can be selected on that specific type's page.

    Yes the images are in millimeters. (In imperial units though a Nema 17 motor is 1.7" square, Nema 23 is 2.3" square, etc. But you still have to do metric conversion on the depth as different models have different depths)

    For light loads it doesn't really matter. For heavy loads and constant use though it is best that axle be horizontal (similar to an automobile).

    And please note there is no specific reason to order a kit if the parts in the kit don't specifically meet the needs of your project. The kits only exist to simplify the ordering process. Financially there is generally very little difference between the kits and ordering the same specific parts a-la-carte.
     
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  3. xl97

    xl97 Well-Known
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    hi Rick-

    So the video was 'old'.. and the parts list had broken links.. (and not everything listed to complete the build I guess?.. even though that was the link given to me by support)..

    So now I am left wondering what else is missing: (or at the very least mis-leading).. :) (others may know every piece needed, but beginners, or at least myself do not)

    The build example video:


    (which uses old parts, that have been updated)..

    The first step is assemble the wheel kits to the universal mounting plate..

    Now that I have everything order and here.. it looks like the are no screws to mount the wheels to the plate???

    Or maybe I am wrong.. and not supposed to use those long screws? (hard for a beginner to know what is missing from a 'complete build parts list')

    From some searching around... I guess I was supposed to have also ordered these:

    https://openbuilds.com/builds/v-slot™-belt-pinion-example-build.97/

    I came to that conclusion.. because if you look at the universal mounting plate KIT.. it does mentions these:
    V-Slot Gantry Set - Universal


    not sure? Hoping someone with more experience here can guide me.

    Parts list: (where this par is NOT mentioned)
    https://openbuilds.com/builds/v-slot™-belt-pinion-example-build.97/


    Here is what I ordered:
    Micro Limit Switch Kit with Mounting Plate $4.99 x 2 = $9.98
    GT2-2M Timing Belt $2.49x 5= $12.45
    NEMA 17 Stepper Motor $17.99x 1= $17.99
    Tee Nuts - M5 (10 Pack) $2.99x 2= $5.98
    GT2-2M Timing Pulley - 20 Tooth $5.99x 1 = $5.99
    Solid V Wheel Kit $5.19x 4= $20.76
    Double Tee Nut $0.69x 2= $1.38
    Low Profile Screws M5x (10 Pack) (10mm) $1.49 x 1= $1.49
    Motor Mount Plate - NEMA 17 Stepper Motor $6.99x 1= $6.99
    Eccentric Spacer (6mm) $1.99x 2 = $3.98
    Aluminum Spacers (10 Pack) (6mm) $2.99x 1= $2.99
    Low Profile Screws M5 (10 Pack) (6mm) $1.29x 1 = $1.29
    V-Slot® Gantry Plate - Universal $11.99x 1= $11.99
    V-Slot® 20x40 Linear Rail (1000mm) $13.99x 1 = $13.99


    As I watch the video and compare to the 'list'... (again)

    I noticed there is also no 1/4 aluminum spacers listed!!! Grrr... (how is one to know this if following the provided list?????)
    But the universal gantry plate KIT lists 6mm spacers?

    Which is it? 6mm or 1/4 inch? I dont care for being 'close' in a rail system.. I'd rather be correct.

    I'm guessing (but who knows with all this mis-information).. that the 6mm are the ones to get..since the eccentric spacers are also 6mm?

    So far:
    No 1/4 spacers listed in the 'parts list'. (or is it 6mm now?)
    No M5 low profile hex head screws 25mm in length listed in the 'parts list'..


    Is anything else a noob like myself needs to actual have a complete build that is missing?

    Thanks for any feedback..
     
    #3 xl97, Jun 22, 2018
    Last edited: Jun 22, 2018
  4. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    I'm away from home at the moment (and my main computer) so I can't provide much in the way of answers. I can say on the issue of 6mm or 1/4", it generally doesn't matter as long as the regular spacers are the same length as the eccentric spacers. And yes, you will need some 25mm screws for the wheels but I can't say what if anything else may be necessary until I get home late Monday night and can run out a quick Sketchup model on the big computer, something I can't do on a 7" tablet with no mouse. (Hopefully though, someone else will who understands where you're going with this will chime in and save you the wait.)
     
  5. xl97

    xl97 Well-Known
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    Thanks!..

    if someone chimes in great.. if not.. I appreciate the help! :)

    I tried to run the closest hardware store.. and get some M5 .80 25mm bolts.. but they dont look to be the same 'low profile' heads like the 6mm ones I have.

    When I tried to assemble one of the wheel kits to the gantry plate.. the supplied nuts can 'barely' tighten without make the wheel(s) too tight to move.
     
  6. TrishC

    TrishC OpenBuilds Team
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    Hello xl97 and thank you Rick for helping out here.

    I checked with the Part Store and understand that they have you all taken care of now. In the end, they have confirmed that the 6mm Eccentric Spacers and 6mm Aluminum Spacers are compatible which is great and they are shipping (4) 25mm Low Profile Screws that are needed to mount the wheel kits.

    This week, we are planning on revisiting and reshooting the Build Video for Belt & Pinion and updating the Parts List to align with the updated video. This will definitely eliminate confusion going forward by bringing this Build up to date with the latest, greatest information.

    Thank you for your helpful feedback xl97 & Rick. We appreciate it and are looking forward to posting the new Belt and Pinion project.

    Thanks,
    TrishC
     
  7. xl97

    xl97 Well-Known
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    Well cant beat that!..

    Some pretty top notch customer service.. and a company that stands behinds their product/customers.

    And updating the video/parts list is great too!!

    Thanks for the help OpenBuilds Team!!
     
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  8. TrishC

    TrishC OpenBuilds Team
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    It's our pleasure. We appreciate you becoming an OpenBuilds member and look forward to seeing your Build!
     
  9. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Make sure there's a shim installed between the bearings in the wheels. This prevents the wheels from locking up when tightened.
     
  10. xl97

    xl97 Well-Known
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    There is a shim on both sides.


    Also.. There are no 3M screws/bolts mentioned or listed (or supplied) for mounting the stepper motor to the motor mounting plate.

    (I dont have any of those either) :)
     
  11. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    You only really need one and it needs to be inside the wheel, between the two bearings.

    As for the M3 screws, there's nothing special about them and should be available at any decent hardware store. I do see the parts list has now been updated to include everything that should be there. This has been a largely forgotten build, thank you for calling out its need for updating.
     
  12. xl97

    xl97 Well-Known
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    Ahh...


    Thanks for the update on that.

    1.) I had done it 'wrong'.. even by the old/wrong video standards! I used '2' shims for each wheel kit.
    * As noted in the video.. (he makes a special mention of using the shims that way specifically to add more space..etc).. of using it directly after the spacer.. (nothing noted about it going BETWEEN the bearings INSIDE the wheel.) (DOH!) :)

    I will re-do it.. see if that gives the nuts a bit more to 'bite on'.

    update:

    ok.. so I managed to find some M3 6mm bolts... so I can attempt to attach the stepper to its 'adapter' plate.

    however.. if following the video on how to attach the nema 17 motor mount plate to the universal gantry plate... they no longer line up.

    The holes on the gantry plate and motor mount do not line up?

    Is the NEMA17 stepper supposed to be used on the 'straight/regular' wheels? (with the belt/pulley) or with the wheels with the eccentric spacers?

    The video shows shows the motor mount attached to the 'small' circle side of the universal gantry plate...
    AND
    (I believe) it shows the stepper pulley.. connected to the regular spacer set of wheels and not the wheels with the eccentric spacers? (leaving them open for adjustment I assume?)..

    however.. it does not align like that anymore.

    what -is- the correct way to mount/secure (and where) the motor mount plate to the universal gantry plate?
     
  13. Mark Carew

    Mark Carew OpenBuilds Team
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    Hello @xl97
    As Trish mentioned we are working up a new belt and pinion example video with the new up to date plates and parts but in the mean time we should be able to work though it here to get you up and running sooner.
    Let me build one up here so I have some pics to share as examples.
    I will post as soon as I have them.
     
  14. Mark Carew

    Mark Carew OpenBuilds Team
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    Ok so did a quick assembly of the belt and pinion and all went well.

    The parts that I used are as follows;
    I have included some pictures for your reference

    Tips that may help:
    • I left the belt long on each end and tucked the extra in the V-Slot. (Having the extra length makes it easy to pull the tension while tighten the screw for the blet holding tee nuts.)
    • Flip the belt holding tee nuts over to make sliding them over the belt easier.
    • Set the eccentrics to the halfway position (cam pointed to the side) to give a good preload to start with then adjusted from there if needed.
    IMG_20180625_161437984_PORTRAIT.jpg IMG_20180625_161458403_PORTRAIT.jpg IMG_20180625_161517055_PORTRAIT.jpg IMG_20180625_161559011_PORTRAIT.jpg IMG_20180625_161634344_PORTRAIT.jpg
     

    Attached Files:

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  15. xl97

    xl97 Well-Known
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    Thanks.

    Nice pics.... they do in fact help clear up many questions.. (and mis-leading info from the video)

    however.. I do have a question...

    it looks as if you are in fact using both shim spaces for each wheel (kit)?
     
  16. Mark Carew

    Mark Carew OpenBuilds Team
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    Thank you for the kind words my friend.
    To answer your question yes I am using both shims from the wheel kits.
    One for between the wheel bearings as well as one between the spacer/eccentric and wheel.
    Hope this helps
     
  17. xl97

    xl97 Well-Known
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    Thanks for clarifying..

    While I know this is not the correct section.. is there a wiring diagram for using these NEMA17 steppers and a DRV8825 driver board?


    [​IMG]


    The driver board has the pins labeled as:

    B2/B1 & A1/A2 (in that order)


    I'm not clear how this relates to the stepper motor pinout?

    [​IMG]

    Where it has them labeled as A/A- & B/B-

    I suppose it shouldnt matter.. as the direction should be incorrect.. but should still work.... but I only get a whining sound.. and a sound that ACTS/SOUNDS like the shaft is moving how it should.. but no physical movement of the shaft itself.
     

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