New Shapeoko Upgrade Day! Buh-Bye Belt!

Discussion in 'Luthiery, Modifications & Customizations' started by Randy, Feb 9, 2020.

  1. Randy

    Randy Taste the Rainbow™ Super Moderator

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    I know there's a few guys on here with the Shapeoko so I figured I'd share.

    It's a great machine that I've gotten a lot of use out of but the Z axis has been an issue since day one, and that seems to be a common experience. I get a lot of skips or slips, and it's easily bound up because the inside traps sawdust easily and it binds up the wheels.

    Because the G code usually sends a single up or down coordinate, any skip or skip means the unit can either dive too far or not extract fully and cuts where it's not supposed to. It got to the point I was partially disassembling after every use and cleaning the wheels or tensioning the belt to keep from ruining a project.

    I was googling Z upgrades literally just as this guy got posted and it looked like exactly what I was after at a reasonable price.

    http://rover.ebay.com/rover/1/711-5...0001&campid=5338014327&icep_item=233480338446

    I know Carbide has the HD-Z but that's too much ($400) and they've got a dumbed down version on the way but I needed this fixed ASAP and the limited supply of these seemed like it was worth a shot, especially with the return policy.

    Anyway, I ordered it and it came in yesterday. Installation took way longer than expected but that's mostly my fault. Directions are okay but left some things out. I spoke to the designer and he clarified a few things, so installation worked out alright in the end.

    Haven't gotten a chance to use it yet other than tramming but moves nicely and accurately when homing and returning to zero. The Z motor sounds noticeably less strained.

    20200209_124201~2.jpg 20200209_124223~2.jpg 20200209_124149~2.jpg
     

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  2. IGC

    IGC SS.org Regular

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    Looks like a switch from the original belt drive to a direct lead screw? Did you need to re-flash the arduino firmware or is there a setting in GRBL or Mach3 ?
     
  3. DickyTripleD

    DickyTripleD SS.org Regular

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  4. Randy

    Randy Taste the Rainbow™ Super Moderator

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    Basically, yeah. Same motor just mounted on top, bottom belt tensioner repurposed as a lower guide for lead screw, then a piece screwed to the sliding plate using existing holes with a brass ferrule that mates with the lead screw.

    Directions include two small codes you punch into MDI in Carbide Motion and directions on how to reverse it if you so choose. That part is super simple.

    I'll report back when I get to actually cut something. Returning to home and to zero back and forth seemed to be as good as stock.
     
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  5. Randy

    Randy Taste the Rainbow™ Super Moderator

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    Main thing that ate up time was my fault, I dropped a screw between the 'X' belt bearings and it was almost impossible to get out.

    Second install issue was the drag chain mount. There's no mention of it in the directions but it doesn't work with the mount in the stock location, there's an extra piece to use as a 'stand off' and you need non-stock, longer screws to attach it. I was able to work around that by bending the mount a little and that seemed to work okay. Hopefully he adds that to the directions and includes the longer screws in future versions.

    Overall I'm digging the design and the fact it uses 99% unmodified stock parts and stuff from the kit. If you know what you're doing it's probably a 10 minute job.
     
  6. IGC

    IGC SS.org Regular

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    @Randy ,
    Lately I'v been questioning how well the belt driven cnc routers work under the load and potential problems if using them . Seems like belts are fairly common use for this type of equiptment. I'v been contemplating a belt driven design anti - skip and foreign debris optimal.
    Do you have a dust shoe?
     
  7. cip 123

    cip 123 Vendor

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    From what I've heard Belts are generally less accurate than Lead Screws, I'm not particularly experienced in the components of CNC, but hearing this from a few people was enough for me to go for a screw driven machine.
     
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  8. IGC

    IGC SS.org Regular

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    Thanks for the insight.

    You check out the Shapoko xxl review and it seems pretty good, at least for wood cutting, it's what got me considering belts.
    https://www.matterhackers.com/store/l/carbide-3d-shapeoko-xxl-cnc-router-kit/sk/MH3XDXDJ



    Btw @Randy yes or no, did yoy notice skipping before the foreign debris ?
     
  9. MikeNeal

    MikeNeal SS.org Regular

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    I've got my belt driven shapeoko 3 very accurate +-.005", which honestly is good enough for anything wood. it has taken me a ton of time to get this repeatable though. I've been working at it for the better part of 2 years.

    As for belts vs screws - generally its screws for accuracy, belts for speed. If you try and move a screw design at the speeds you can move a belt, you will get screw whip and loose accuracy significantly.
     
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  10. Randy

    Randy Taste the Rainbow™ Super Moderator

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    I think @MikeNeal covered it pretty well. I'm getting within .1mm accuracy on my X and Y motion consistently. Even though they're belts, they're kevlar reinforced and don't flex to the point of losing accuracy very easily, if at all. The Z is a little different between the enclosed space, the belt doesn't seem reinforced, its especially hard to adjust tension because of the confined space and overall design, and the nature of Z coordinates in general.

    I'm not running a dust collector currently, partially because I previously had concerns about it getting in the way (I'm less worried about that now) and mostly because the wiring in my shop has limited amperage supply, and overloading the circuit can cause the controller to lose G code lines in my experience. I tried running a ShopVac off the same outlet a few times and the machine lost where it was on the piece. If you've got a better supply or run off a different circuit, I guess that likely isn't an issue.

    The wind generated from the machine repels sawdust pretty well, and then I use a brush between procedures or even during. I'm sure the lack of dust collection has something to do with my buildup but it specifically happens during really deep cuts that would likely make the dust shoe setup hard to use. :2c:
     
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  11. MikeNeal

    MikeNeal SS.org Regular

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    one of the things we did is run a dedicated outlet on its own breaker for the cnc machine. i had the same issue of skipping a step here or there.
     
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  12. IGC

    IGC SS.org Regular

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    @Randy seems like a dust shoe would also be more load for the -z- to move around. And you don't want to stand there holding a shop vac hose right next to the cutter every move it makes.
     
  13. Bobo

    Bobo SS.org Regular

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    Can you give a summary of why it takes so long to get acceptable accuracy? If it's not the belts, is it something else about that specific machine? Or is it just in the programming? These are questions from a cnc noob btw.

    Sorry if this is somewhat of a highjack Randy :p
     
  14. Randy

    Randy Taste the Rainbow™ Super Moderator

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    Most of the popular dust shoes attach to the carriage at the back, not necessarily the part that raises and lowers with the Z. You manually raise and lower them to match with the height of the workpiece, which is probably fine for a lot of things but when I'm cutting 1.75"+ deep and it's at the extreme end of what the cutter will do, I'm weary of any potential drag over the surface. I'd also imagine it's only marginally effective when you're cutting out contours like this and the gap is so narrow.

    Screenshot_2020-02-15-09-30-48.png

    No hijack, I think this is the perfect place to ask.

    Because of the way the machine goes together, you have to consider how square you have the frame of the machine, how well adjusted the V wheels are into their channels (no wobble), how straight and square the spindle is to the work surface, how level the work surface is and how tight your belts are.

    The two year number is potentially how long something like that can take from trial and error, but if you're focused specifically on taking dial indicator readings and making adjustments, I'm sure you can do it in a few hours.

    I was getting what I'd consider acceptable results after my initial assembly (I'm sure that's most people's experience, Mike included), so it's not like the machine is especially in need of fine tuning to work; if anything, quite the opposite. I only started needing to fine tune adjustments after my belts initially "broke in" (I needed to tighten my X belt by a tooth or two because it was skipping under load), after I added a spoilboard (had to resurface it because of inconsistencies in thickness and how well seated it was), and after initial wear on the Z axis delrin V wheels (they started to clunk back and forth under load, just needed to adjust the asymmetrical nuts to seat the wheels tighter in the channel).

    The machine worked fine up until that stuff, which came on after using to for a couple months. Since then, it's needed very little adjustment besides maintenance for over a year. It always helps to test on scrap and monitor what the machine is doing, as opposed to bolting in an expensive blank and walking away.

    As far as accuracy, I did a personalized brass plated sign for somebody where I engraved it with their name. The plate was .063" thick and I had to cut a max of halfway through it's thickness without cutting too deep or to shallow (so, .0315" with a maximum deviation of maybe .015"), across about 30" wide and 8" tall, and it did it perfectly.
     
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  15. IGC

    IGC SS.org Regular

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    .015 over a 30-inch span is pretty darn acceptable for this type of machine/ guitar cnc. I've been checking out those Delrin V wheels and their eccentric spacers online, interesting to hear about possible issues with them. I guess you could use use the eccentric spacers to tram the gantry?

    I also hear that with belt driven the belts can stretch at higher feeds if you don't ease your moves...accel and decell
     
    Last edited: Feb 16, 2020
  16. Randy

    Randy Taste the Rainbow™ Super Moderator

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    I suppose, although you can tram it by hand when you have the controller powered off anyway. My guess is that they're just there to adjust for wear on the wheels over time.

    Speaking of Z upgrades, Carbide released this and surprise, it sold out in hours (minutes?). $250, which is better than the HDZ ($500) but not as inexpensive as this thing. Design looks similar but looks like the whole piece got redesigned. The big upgrade on the Z-plus over the True-Z is the elimination of the wheels, but how necessary that is, I won't know until I make some cuts.

    https://shop.carbide3d.com/collections/accessories/products/shapeoko-z-plus?variant=31524471144509
     
  17. IGC

    IGC SS.org Regular

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    Seems like a good upgrade, with the ball bearing guide rails and lead screw. Are the original mounting plates aluminum? The new plates are 1/4 steel could this be more weight for -x- motor to pull?
     
  18. LiveOVErdrive

    LiveOVErdrive CNC hack

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    Oh holy crap I need this so bad.
     
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  19. Randy

    Randy Taste the Rainbow™ Super Moderator

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    Old ones are also steel, somewhere in the same thickness range so probably not much more weight on that end. Old one has a lot of empty space though, and this upgrade kit is mostly ABS, I'm not sure how much beef is in the Z-plus.
     
  20. LiveOVErdrive

    LiveOVErdrive CNC hack

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    What happens if you crash your z axis with a screw drive? Does something have to break? Belt slippage is a nice failsafe against damage when you move your axis where it oughtnt go.
     

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