Tripteron Implementation

Re: Tripteron Implementation

madscientist_42 — Wed, 26 Jan 2022 19:57:48 -0500

Shame. It's actually a bit of an interesting design.

When do you think you're going to resume discussion on this one...and where?

Re: Tripteron Implementation

MechaBits — Sun, 21 Mar 2021 12:05:18 -0400

a cool example Single rail, [www.youtube.com]

Re: Tripteron Implementation

see3d — Tue, 02 Mar 2021 22:24:05 -0500

Just finished reading through this whole thread. I believe that the arm joints would be easiest to make as a compliant hinge out of the material that was used for this KS:

[www.kickstarter.com]

It is a project I backed, but just before it could be delivered the creator came down with cancer and never completed the last bits and shipped the project to the supporters.
The hinge concept was great though and I think it would make the Tripteron or Deltron practical.
Perhaps a 50cm wide arm with a stiffener attached to it.

I looked into getting some of the sandwich material, but not in my budget to get it from Europe and play with it.

I hope you can find your way back to getting the Triptrons built again.

Re: Tripteron Implementation

oliof — Sun, 24 May 2020 12:42:54 -0400

Thread necromancy! I have rebuilt @Apsu s Tripteron prototype and intend to implement the kinematics in RepRap Firmware. It'll be a while, maybe the patent expired until then (-:

Re: Tripteron Implementation

MechaBits — Sun, 22 Dec 2019 04:31:05 -0500

Someone got inspired [www.youtube.com]

Re: Tripteron Implementation

Apsu — Thu, 03 Oct 2019 15:35:36 -0400

Quote
Pougnagna
Hi Apsu (and everybody else),

I've registered an account only to make you sure your work is still closely looked at.
It was exciting to read every post in one go, and I'm now like a kid in a candy shop.

Thank you for all you have done and for what is coming!

Hey there, sorry for the delayed response.

I appreciate the feedback and sentiment! The project has been a lot of fun, but for the time being given the patent situation, I'm focusing on my DiffBot and maybe Inverted Delta projects for now. I made a thread for DiffBot here if you'd like to take a look.

Re: Tripteron Implementation

Pougnagna — Sat, 28 Sep 2019 19:56:03 -0400

Hi Apsu (and everybody else),

I've registered an account only to make you sure your work is still closely looked at.
It was exciting to read every post in one go, and I'm now like a kid in a candy shop.

Thank you for all you have done and for what is coming!

Re: Tripteron Implementation

JoergS5 — Sun, 15 Sep 2019 09:47:43 -0400

@Apsu please don't be disappointed about low participation. Like me I am sure several people are reading your thread with interest and wish you good luck implementing a good printer.

I would be interested in a category here in the forum to list all patents and when they expire. We could also collect prior art examples in this area.

Re: Tripteron Implementation

nicholas.seward — Sat, 07 Sep 2019 09:49:22 -0400

2022 is soon. Patents don't prevent your own building adventures. You can also document your work as long as you aren't monetizing it. I think a disclaimer is more than enough in the name of the law. They wont sue anyone unless they actually sale a tripteron.

Re: Tripteron Implementation

Apsu — Sat, 07 Sep 2019 09:17:13 -0400

Thanks Nicholas, I appreciate your input. I did pursue the non-commercial aspect and even talked about acquiring the patent, and they informed me that they value it for its commercial and research potential, and are only willing to license for commercial use. I also met someone who worked on a *pteron industrial machine, so they have had some large commercial licensees in the past, which makes it all the more likely they're not willing to do a non-commercial. Any way you slice it, the patent expires in 2022, so maybe we just need to wait it out :P

But I do take your point about the 6-DOF model, and I appreciate how you've kept it in the open. Ideally I'd love to be able to end up with a unique design that could become a business, but it's not my primary goal.

Re: Tripteron Implementation

nicholas.seward — Sat, 07 Sep 2019 09:12:15 -0400

They might be amenable to a free noncommercial creative commons license. At least they should be. It preserves the ability for them to dual license it for money and it makes them look good.

That said it is easy for them to say no because it would require lawyers to do work and it is not risk free. If you have some contacts, I can get the inventor to put pressure on the licensing department to play ball. Last time I talked with him, he had talked to them but they wouldnt talk back. (Asking for a noncommercial licensing agreement is one of those things that require work so they probably ghosted him but it might not have been intentional.) Now that you have a dialog, we could potentially insert him into the conversation.

If you want to make money then the royalties will make it annoying at best. You are free to jump to a Sextupteron/Hexapteron if you want. AFAIK no one has patented it and I am the inventor with clear prior art. With people starting to embrace the idea of non planar printing...there is a potential value add here if you want to make printers for money.

Good luck!

Re: Tripteron Implementation

Apsu — Sat, 07 Sep 2019 07:55:39 -0400

I've decided to put this thread on hold. It's too large and I'm really the only one posting now. I have run into some patent licensing roadblocks (they want a company to license to with a business plan and sales forecasts to determine royalties, etc), as well.

If I develop this idea or specific design further, I will post something new, but for right now I don't have a lot of new things to say. You can find me in the usual places as Apsu or Apsuity if you want to follow up on building one of these.

Re: Tripteron Implementation

Apsu — Sat, 17 Aug 2019 02:26:33 -0400

Welp, I decided to go ahead and model it up. I was able to connect everything with literally just the parts from 80/20, which is kind of amazing. I got a clever idea about using a 2"x2"x2" extrusion for the effector and with a little more mounting cleverness, it works shockingly well. I also reduced the outer frame lengths to 16" instead of 18", to avoid Z arm jackknifing.

Here is a video link and here is the A360 3D viewer link. I know the navigation is a little messy, but I'm trying to show all the angles, some of the joint interference spots that need a little engineering (like using spacers on the X/Y effector mating surfaces to keep their joints away from each other), but overall this looks like an extremely successful way to combine these parts, assuming the rigidity and performance is there.

The 2"x2" effector has a > 20mm minimum radius through its central hole, and a square arrangement of 4 screw holes, meaning a hotend clamp could be attached on the bottom, and a direct drive extruder on the top.

And lastly, the low profile linear slide setup with offset mounting points pulls the arms out some, which is always good, and can use the mount holes to attach belt/screw attachments on the other side.

I'm looking forward to testing the joints and slides to see how they do, but this is looking reeeeeally good as a basic assembly idea.

Re: Tripteron Implementation

Apsu — Fri, 16 Aug 2019 23:40:44 -0400

Welp, turns out, even for shops that specialize in small runs of custom parts, these pieces are going to be extremely expensive to do in milled aluminum.

I'm investigating an alternative approach right now, using a US vendor called 80/20. They have a variety of awesome products centered around aluminum extrusion, and although they do have some common metric sizes like 2020, they mostly deal with imperial sizes. This is important to the discussion because while I've known about them for many years, and have a bunch of their 2020 extrusions, I wasn't able to try out some of their specialty components as they're only made in the imperial sizes. So I decided to rethink everything from the start and see what they had to offer, and found their pivots to actually be really awesome.

So here's what I'm thinking. I can use arm links made of 1020 (1" x 2") extrusion, and use one of the pivots, to create a joint like this:

AaxNldb.png

These pivots are all aluminum, have self-lubricating bronze sleeve bearings, shoulder bolts, and 2 thrust washers to clamp the pieces together. There's a very large radius of surface contact and I suspect given the geometry and materials and joint design, it's going to be extremely rigid, especially on a profile that's nearly 51mm wide (2"). That's more than twice as wide as my 2020 joints, and no ball bearing play to try to preload against.

Here's a cross-section of the pivot:

fj4lN4Y.png

Then I started looking around for other components that I could use to fashion into shoulder and wrist connectors, and I found these amazing self-lubricating creatures:

HwV85F0.png

DBKZeXb.png

They even make shims to put under the sliding polymer fixtures to adjust their fit. I'm not sure if they'll be strong enough in the directions I would need them in, but I think I'm going to get one to try out, and enough 1010 profile to build a frame out of, because if it works it would be an amazing low profile linear bearing setup without needing a rail and ball-bearings. Also no need to try to match up rail and frame lengths or do any custom cutting, as well as the hit-or-miss quality of buying cheap MGN rails. I've gotten a few with pretty messed up carriages/balls, so it'd be great to go the polymer route if possible.

A full frame of 18" 1010, 8 links of 10" 1020 (dual Z towers), 12 1020 pivots, and 4 1010 linear slides would cost $537.28, which is twice as expensive as the printed version, yes, but has a really strong chance of working extremely well with easy to assemble, off-the-shelf parts.

I should get the pieces to test the joints in the next few days, so we'll see how well the pivots perform, as that's the most important part of the whole equation. If they work well enough, I will grab a linear slide to test, and ultimately start designing an effector that can mount to the pivots.

Re: Tripteron Implementation

Apsu — Thu, 15 Aug 2019 13:48:07 -0400

Hey folks, sorry for the delays, got hit with a bunch of work stuff and took longer to make some progress in redesign work.

I also have an update on the patent situation. I'm in talks with the University that holds the patent on obtaining a license, and I likely will be able to obtain one for the purpose of a small startup with an eye towards being legally able to sell kits or completed printers. I'm not trying to advertise and won't, but I think I can make a viable product with my current development direction so I figured I'd try to figure the legal side out.

In addition, I have learned that although US Patent Law explicitly states that making a patented device without a license -- even for personal use -- isn't allowed, there is actually court precedent that's long been accepted that there is an exception for research, personal amusement, or philosophical inquiry (Research Exemption). That's why universities can use patented ideas to further their own research and face no repercussions. Which means that legally speaking, we're all in the clear for purely DIY personal use, so long as it doesn't benefit your "legitimate business". So if you make one for your printing business, that's not allowed, but just for your personal non-commercial use or research, you're fine.

Ok with that out of the way, as I mentioned above, I'm redesigning my approach to the arm link assembly, starting with aluminum as a prototype material, but I believe carbon fiber and possibly some reinforced engineering plastics might work as well.

Here's a short video of the idea I am playing with currently. The links are solid pieces, and identical, with right angle joints for proper clearances, and are basically I-beams with tongue/fork ends. This increases their width substantially and are pocketed to decrease weight where possible.

The joint design idea is to press-fit Igus polymer flanged sleeve bearings (like these) into the tongues, and then use a steel dowel pin or possibly shoulder bolt to secure the forks into the tongues. I confirmed with Igus that the flanges can work as thrust washers against the flange/fork mating surfaces, so compressing them together should work great for this low RPM/low load application.

I also found that another research team at the University of California had the same idea around the time Gosselin did for the Tripteron, and built a prototype/published some papers on it. They also applied for a patent but it seems it was denied, so presumably they filed too late. Hard to say who came up with it first or if they did independently, these are all robotics professors who share a lot of information.

Anyhow, looking at their construction design gave me some ideas and led to my current approach.

CAhPPJ1.jpg

This is a good example image I pulled from Prof. Tsai's old page which I found on archive.org.

Here's a render of the link design so far

mvbGGlu.png

.

I'm also exploring the idea of having an effector platform that can accept different tool inserts -- a manual tool-changer, in essence -- as well as having adjustable shoulder brackets to mount onto plates attached to the linear rail carriages, for adjusting the shoulder offset from the frame, as well as using different mounting plates for different kinds of linear bearing systems.

Last bit to talk about is the dual Z arms in the video above. I modeled it up to see if the clearances of all the links would work, and as you can see it works great. The benefit of a dual Z linkages is that the gravity load would be shared, which would further increase stiffness and ideally improve Z speed and accuracy. Now, for a 3D printer, that might be overkill, but again, considering having a swappable toolhead has me thinking about light duty CNC applications being possible as well. Pen plotting, engraving, soft material carving, etc. A dremel or small spindle mount would be relatively easy and in that scenario, higher Z speed and stiffness is a benefit.

Once I get some prototype parts made and get the mechanism hooked up and moving again I'll post another big update. And this time I have dc42's IR sensor working and a Duet2 WiFi board ready to go, so I'm looking forward to making use of it all!

Re: Tripteron Implementation

Apsu — Thu, 15 Aug 2019 13:15:59 -0400

Quote
Ohmarinus
What if you were to use long polymer bushings or some long version of this: [www.robotdigg.com]

I think that could take care of both having linear movement as well as rotational movement and have a tight diameter without much play? Am I missing important details why this is or isn't a good idea?

I definitely think polymer bushings are a great way to go, and in fact that's where I'm focusing right now. I'm going to make another post in a sec with an update on where I'm at, which does indeed include polymer bushings and much simpler joints.

Re: Tripteron Implementation

Ohmarinus — Wed, 31 Jul 2019 05:08:16 -0400

Quote
Apsu
So I've been thinking about this a lot lately, and I think that one of the difficulties I was facing even with the machined joints is that the bearings are the weakest point now. It occurred to me that I only went down the bearing route in the first place because I was trying to solve for printed joints. But if I get the machining route, there's some extremely simple and cheap to make part geometries that could be used instead.

For instance, using something very similar to a 3 or 4-hole flat plate designed for aluminum extrusion, bolted to the end of extrusion to form a fork, and similar on the other extrusion (to go outside the first fork), then a shoulder bolt or smooth shaft + low friction thrust washers/bushings could be used to fasten them together. Assuming there weren't premade parts that would work, these sorts of plates are extremely easy to machine so cost would be very low.

I may get some nylon or PTFE (or maybe even Igus) thrust washers and try a proof of concept with the simple 3-hole aluminum plates I have on hand, and report the results. But really, I don't think the bearing system is necessary and is an extreme overcomplication when not trying to use entirely printed parts.

What if you were to use long polymer bushings or some long version of this: [www.robotdigg.com]

I think that could take care of both having linear movement as well as rotational movement and have a tight diameter without much play? Am I missing important details why this is or isn't a good idea?

Re: Tripteron Implementation

Reanimator2k — Tue, 30 Jul 2019 14:25:11 -0400

Following this topic. I want to assemble something like this, but when it go to release candidate. Not skilled to engineer that myself.
Good luck to you in building this interesting machine.

Re: Tripteron Implementation

Apsu — Tue, 30 Jul 2019 01:10:21 -0400

So I've been thinking about this a lot lately, and I think that one of the difficulties I was facing even with the machined joints is that the bearings are the weakest point now. It occurred to me that I only went down the bearing route in the first place because I was trying to solve for printed joints. But if I get the machining route, there's some extremely simple and cheap to make part geometries that could be used instead.

For instance, using something very similar to a 3 or 4-hole flat plate designed for aluminum extrusion, bolted to the end of extrusion to form a fork, and similar on the other extrusion (to go outside the first fork), then a shoulder bolt or smooth shaft + low friction thrust washers/bushings could be used to fasten them together. Assuming there weren't premade parts that would work, these sorts of plates are extremely easy to machine so cost would be very low.

I may get some nylon or PTFE (or maybe even Igus) thrust washers and try a proof of concept with the simple 3-hole aluminum plates I have on hand, and report the results. But really, I don't think the bearing system is necessary and is an extreme overcomplication when not trying to use entirely printed parts.

Re: Tripteron Implementation

Apsu — Thu, 25 Jul 2019 14:31:14 -0400

Hello anyone still following this thread!

Man, it's been a while. I've had a lot of major life events happen that have kept me away but I haven't given up on the Tripteron development process, and I believe I'm in a place now where I can continue.

I also got a new job (one of those life events), and now work for a subsidiary of Autodesk(!), which means I have full access to fun tools like Fusion360, AutoCAD and Inventor. So I'm excited to get back into this.

To recap and expand on my plans:

I've got an Ender 5 with a bunch of upgrades as my new workhorse, so I can print new parts easily
I have a full set of the machined Aluminum joints for the 1515 extrusion, minus the effector and shoulder brackets. I may get them machined as well, we'll see
Rebuild the orthogonal Tripteron frame, and I may use 400mm rails and frame, since I have rails and pieces that long now
Use a lead screw with anti-backlash nut for Z instead of a belt (requires redesigning the Z motor mount)
Complete the full cube for the frame, for maximum stiffness and squaring
Figure out mounts for a heated bed/fancy glass plate, like the new silicon/carbon ones that stick when hot and release when cool

I now have a group of friends who started up a rapid-prototyping shop near me with a CNC, lathes, vacuum-former, and a bunch of printers, so I can probably get more parts machined or printed in super strong engineering materials to improve on this build.

And lastly, with regards to my original "as many parts printed, low cost, and easily obtained as possible" goal, I've decided to abandon it for now and just try to build the best orthogonal Tripteron I can. I achieved a working printer with worse parts than I have now, and a bed that wasn't even attached to the frame lol. My new goal is to make something as stiff, fast, and accurate as possible, without worrying about material/part choice, even if the BOM is > $1k, and then we can think about working backwards towards a cheap version with clever material/design choices to meet that goal.

But really, I'm just itching to make this thing become a Real Printer™ and feel like I've finally completed this project.

If anyone is still interested or has thoughts or ideas, feel free to chime in. It might still be a few days before I really get back in the swing of things, but you can expect pics and videos as per usual :P

Re: Tripteron Implementation

MechaBits — Thu, 26 Jul 2018 15:40:32 -0400

Quote
Apsu

Quote
brazenrain
I also ran across these but they're for larger profiles

[www.minitecframing.com]
[www.minitecframing.com]

But man are they rated for high lateral loads and appear to be rock-solid!

I wouldnt mind some of these, but cant see a price do you have any idea how much & who has them?

Re: Tripteron Implementation

PeterPozorek — Sat, 30 Dec 2017 13:51:19 -0500

Quote
o_lampe
Good to see it working. But the overkill in part count you mention above, will make it a rare beast.
I gave up on my project, because printing those critical parts is almost impossible. I tried round carbon tubes and cam-followers as bearings but the housings either were too loose or cracked from pressing in the bearings.

There is the number of quality high precision hinges that will take radial/ lateral load, cam-followers are just to hard fit/lineup as you mentioned.

Re: Tripteron Implementation

o_lampe — Sat, 30 Dec 2017 03:35:14 -0500

Good to see it working. But the overkill in part count you mention above, will make it a rare beast.
I gave up on my project, because printing those critical parts is almost impossible. I tried round carbon tubes and cam-followers as bearings but the housings either were too loose or cracked from pressing in the bearings.

Re: Tripteron Implementation

PeterPozorek — Thu, 28 Dec 2017 04:02:53 -0500

Here is my tripteron trip.
Obviously, all the hard work was done by Apsu and there is not much to add, I really admire his design approach.
With my take on it, I decided to make it symmetrical with four bearings at the base actuator, three in the knee and two 604ZZ bearings in the end effector per arm.
The linear rails are 400mm but decided to make shorter arms due to flexing so print area is 320 by 320mm .
Most of the joints are printed in CFPLA also did try PC+ and ABS but as mentioned before, stiffness is your friend LOL. Also injecting epoxy resin into print does a great job making it stiff and strong.
Applied topology optimisation to win with the backlash while keeping low weight.TopOpt is mostly used for SLS printing but with a little fiddling was able to get pretty good results.

My observations are:
The support frames should be at least 2040.
The Z axis has to be on the lead screws.
The End effector should be as light as possible so is the arms should be made out of carbon fiber tubings.
You could also cheat the RepRap ideology and simply water jet the aluminum arms.
There should be two bearing blocks per X and Y axis, one is simply too wobbly due to it's lengh.

To sum things up I just did some first prints and it looks like it still needs work such as bed leveling, slicer settings, firmware etc. but I'm positive that tripteron could become a decent printer ,if not it could become an open source burger flipping bot.

Here are some videos not in chronological order, if anyone wants the files I will be posting them later on github , just drop me a line for the link.

MK2 one the first iterations(there was an MK1 but didn't bother filming it LOL) :

Prined with ABS 400mm stroke from Peter Pozorek on Vimeo.

MK3 just a servo probe initial test

Tripteron Three point servo bed probing from Peter Pozorek on Vimeo.

MK3 first print at 400mm/sec LOL

First print ,wrong stepping on Z axis,bad slicer settings from Peter Pozorek on Vimeo.

Re: Tripteron Implementation

MaurinoWeb — Thu, 05 Oct 2017 10:16:33 -0400

I follow
thanks for sharing

Re: Tripteron Implementation

siderala — Thu, 14 Sep 2017 15:06:25 -0400

Admin note: please avoid using foul language. This is a warning. Thank you.

Re: Tripteron Implementation

scottyo — Sat, 02 Sep 2017 13:44:01 -0400

I should add, I think a taller tetrahedron (with actuators underneath the arms) would be a good model for a 3-D printer, but that's not where I'm starting.

Re: Tripteron Implementation

scottyo — Sat, 02 Sep 2017 13:30:11 -0400

Thanks - both of you!
The application I am designing for will not require much z-height. Also I am looking at a variation of the "other" of the three implementations listed in the paper.
(The one attached below.) However, I am thinking I will probably incline the actuator rails a bit (and maybe flip it upside down - a shallow tetrahedron).
Thanks again,
Scotty

Re: Tripteron Implementation

nicholas.seward — Sat, 02 Sep 2017 12:23:42 -0400

Arm length needs to be just long enough to reach across the work volume. A smaller angle will allow the arms to be shorter. The flex of the arms is proportional to length^3 so you definitely want to minimize it.

Re: Tripteron Implementation

Apsu — Sat, 02 Sep 2017 12:23:25 -0400

Hey Scotty,

That was referring to the second design I began working on, where there's an angle the actuators are rotated with respect to the arm joints. The actuator arms have 3 joints -- actuator-arm, arm-arm, arm-effector. So really when I say "joint plane" I mean that those three joints are all aligned the same. However, how the two end joints attach to the actuator and the effector has a fixed angle like 30deg, for instance. You can adjust this angle a bit up/down around that value and it results in what I said. A smaller angle (closer to 0deg, or in-line with the arm joint plane) means that the same actuator motion (up/down) results in the same effector movement as a higher angle would with more actuator motion.

The tradeoff is a loss of resolution, because the relationship of the arm angle to resolution boils down to a simple ratio that varies only by that angle value. Likewise, higher angles give higher resolution but require more actuator motion for the same effector motion (higher ratio) -- practically this means you have less Z space to move in at the extreme top/bottom range, since you'll hit the end of the rails "sooner" to achieve the same amount of build space coverage. This is all assuming you're trying to maintain the same build area at every point in the build volume.

Hope that helps! I'm still around, even if not working on this anymore, so feel free (you or anyone else reading) to hit me up if you like. To be honest, I tend to jump between my hobbies every 6 months or so and this was a new one to me, so I dug in deep for awhile and now I'm back to music and gaming, but that doesn't mean I have no interest, I'm just not spending time on it right now :)