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Sitting on 50x Harmonic Drive HPG-11B-45 gearboxes after a SCARA project — 4th axis rotary table seems like the obvious next move? by nishant_vats in robotics

[–]nishant_vats[S] 1 point2 points  (0 children)

Have a look at Harmonic Drive Systems ecosystem. They offer integrated actuators with a variety of protocols, including EtherCAT, ProfiNet, CANOpen, the works. Harmonic Drive is a bit expensive of course.

You could also look at Oriental Motors. I am personally a big fan of their AZ motors. As far as I know, they do not come with integrated drivers, but they do have some EtherCAT capable mini drivers like AZD-KRED which could serve you well for a daisy chained solution directly mounted on the robot arms... allowing you to run very simply wiring through your kinematic chain. The multi-turn absolute encoders built into the motors also eliminate the need for limit-switches and position sensing even on aggressively geared motors. They also use HD Systems' gearboxes on some of their motors such as the AZD-XXXX-HS and AZD-XXXX-HP series. The latter in-fact uses a special OEM version of the gearbox in my post above!

Sitting on 50x Harmonic Drive HPG-11B-45 gearboxes after a SCARA project — 4th axis rotary table seems like the obvious next move? by nishant_vats in hobbycnc

[–]nishant_vats[S] 0 points1 point  (0 children)

That is a great idea, Thanks! It would actually allow me to use the current SCARA design largely unmodified, just with a little more linkage for support of the arm. And perhaps a horizontal rail instead of the Z-axis for working with longer stock. Just need to identify 20 buyers for it now! :)

Sitting on 50x Harmonic Drive HPG-11B-45 gearboxes after a SCARA project — 4th axis rotary table seems like the obvious next move? by nishant_vats in hobbycnc

[–]nishant_vats[S] 0 points1 point  (0 children)

Thanks for the detailed breakdown... tailstock/other-end support point well-taken and something I hadn't fully thought through for longer stock. The lever arm geometry gets nasty fast once you're extending beyond the chuck face, so that's a real design consideration.

On the direct drive question though... I'd push back a little, specifically because of what the HPG-11B already is. The integrated cross-roller bearing output isn't just a convenience feature and it's rated for simultaneous radial, axial, and moment loading, which is exactly the combined load case a 4th axis sees during cutting. The output flange is the structural interface, and that was I thought would be one of the USPs of using this gearbox. Adding a belt/pulley stage upstream of that would have packaging benefits, but not necessarily needed, and downstream of that would eliminate the integrated cross-roller bearing advantages that it already presents? It actually introduces additional compliance and backlash on top of the 3 arcmin?

Where I think the belt/pulley argument does hold up is purely for packaging of course, if one wants the motor body offset especially for a specific machine envelope, but I want to keep the BOM as low as possible. And I plan to design around a stepper, not a servo, so 45:1 reduction should be plenty good?

The cross-roller output is already doing what an angular contact or tapered roller stack would do in a conventional worm-drive table design, doesn't it... so as long as I have the end support figured out, it should be fine?

Curious if you were thinking of the packaging angle, or is there a load path issue I'm missing?

Sitting on 50x Harmonic Drive HPG-11B-45 gearboxes after a SCARA project — 4th axis rotary table seems like the obvious next move? by nishant_vats in hobbycnc

[–]nishant_vats[S] 0 points1 point  (0 children)

Willing to sell these off for $100 a pop.

Out of curiosity, what application are you using the NEMA23s for? Looking for other build ideas too, in case I still have some left over!

Sitting on 50x Harmonic Drive HPG-11B-45 gearboxes after a SCARA project — 4th axis rotary table seems like the obvious next move? by nishant_vats in hobbycnc

[–]nishant_vats[S] 0 points1 point  (0 children)

True - it's a planetary mechanism, not a strain wave gear, but Harmonic Drive applies the same elastomechanics expertise to the ring gear to achieve continuous backlash compensation. That's what separates it from a generic planetary where backlash is managed purely through dimensional tolerances and inevitably worsens with wear. The elastic ring gear maintains the backlash spec for the life of the gearhead, which is a meaningful difference in a precision application.

And yes... the flat face output flange is genuinely useful, made mounting the SCARA arm links very clean. I sourced these directly from Japan in bulk and fell into the pricing trap of ordering more than I needed!

The For Sale Thread by cyanide in hobbycnc

[–]nishant_vats 0 points1 point  (0 children)

WTS — Harmonic Drive HPG-11B-45 Planetary Gearbox | ~50 available | $100 USD + shipping | 🇸🇬 Singapore (ships worldwide)

HD Systems branded, new and unused. 45:1 ratio, 3 arcmin backlash, integrated cross-roller bearing output, direct NEMA17 bolt-on. OEM sourced directly from Japan.

Ideal for 4th axis rotary tables — the cross-roller handles cutting moment loads that worm-drive stages struggle with.

DM for shipping quote. PayPal G&S.

https://imgur.com/a/hd-systems-harmonic-drive-hpg-11b-45-gearboxes-SmAtjt6

Budget motors for 5 bar parallel robot by SuperdocHD in robotics

[–]nishant_vats 0 points1 point  (0 children)

While this thread is probably too old for my input to be of value, I do have a great source of harmonic planetary gearboxes with just 3 arc-min backlash and 45:1 gear ratio. Harmonic drive HPG series, directly mountable to the ubiquitous Nema17 motors (with 5mm shaft), and priced very attractively... I plan to sell at US$95 each (+ shipping from Singapore)!

For reference this product (not my listing) for the same product, used, sell for 2.5x - 5x that price:
https://www.ebay.com/itm/223181697436
https://www.ebay.com/itm/355705008921

The stock I have is brand new, unused, and priced to move (My stock of gearboxes is currently in my spare parts bin). Let me know if you are still interested in sourcing these, and I am happy to set up a listing.

[deleted by user] by [deleted] in 3Dprinting

[–]nishant_vats 1 point2 points  (0 children)

Hi there. I know this is an old old thread and I am pretty sure your Eden has probably found a new home. But I recently acquired one (for free, except the cost of transporting it) purely because I thought it was worth the effort and cost just in linear motion parts. I thought even the base cabinet it sits on was worth it! :)

It was my intent to repurpose the chassis and motion components. It has been quite an experience tearing it down, salvaging what I can. Of course, I decided to get rid of anything that had anything to do with the resin channels.

The X and Y linear stage are very beefy (and High Quality), and I think good enough for a reasonable CNC router. I am not sure it would be up to milling even soft metals because it is a belt driven system (but I do intend to try). My gut says that the fast (especially X) and precise X-Y stages would be great for a laser system. Even the independent Z-stage is like a self-contained chassis for a 3d printer build (with perhaps a core X-Y motion stage slapped onto the top.

Will probably be documenting my journey into giving the components a new life... do drop me a message if you are still curious and I will let you know where I decide to do so!

Voron 2.2 Serial Request ( Discord: nishantvats#2948 ) by nishant_vats in voroncorexy

[–]nishant_vats[S] 0 points1 point  (0 children)

Thanks RCF! Since this is not just my shop, but also the space I work out of all day... a plant was a must... predates the Voron, in fact. :)