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MaelXD
06-19-2013, 02:59 AM
Hey,

I was wondering does anyone know what ABS plastic is used by Interbotix Labs for the frames in their Hexapod kits? I'm looking to make custom parts, and if possible it would be nice to match the same matte / gloss finish of the existing Hexapod parts.

Thanks,
MaelXD

CasperH
06-29-2013, 06:49 AM
Keep in mind that not only is the type of ABS (well, lets call it composition) is relevant for how it looks, also the fabrication process used to create it.

There is a big difference in surface finish for a 3D printed part and injection molded parts.

Lupulus
06-29-2013, 01:07 PM
Also--the Mark I frames were ABS, but the Mark II frames are plexiglass.
Trossen has a Youtube video about building materials, you could give that a look.

DresnerRobotics
07-18-2013, 02:35 PM
In reference to the actual 'frames' (F2, F3, etc) it's "Enplas" which is short for 'engineering plastic'. Your guess is as good as mine as to whats in there, but I think its primarily ABS. The frames themselves are made by Robotis and they don't divulge what goes into them.

Our lasercut parts are primarily Plexiglas-G P95 now, which is a acrylic-lexan mix.

jwatte
07-18-2013, 03:52 PM
engineering plastic

"Engineering Plastic" is actually a collective word for a number of kinds of plastics -- those that have suitable durability to be structural under various circumstances. Nylon 6/6, ABS, PEEK, and Delrin are examples of "engineering plastics." These are stiffer, and also more expensive, than soft materials like polystyrene, PP, HDPE, etc.

Just touching the casings of the MX series, they feel perhaps like Delrin (POM / Acetal) to me, but that could be totally wrong.

tician
07-18-2013, 04:35 PM
Just touching the casings of the MX series, they feel perhaps like Delrin (POM / Acetal) to me, but that could be totally wrong.
Out of curiosity, are yours glossy or more of a matte finish? The RX-28M and older MX-28 in our lab tend to be very smooth and shiny, while the newer ones have a matte finish with some sub-surface swirling color patterns (assuming those are left over from the injection molding). I'm guessing there was some sort of material change, but they always said there had been no change whatsoever (even after sending photos showing the clear difference between cases during the gearset bearing debacle, where they again claimed there had been no changes to the bearings or gearsets yet even their US repair site had new trouble with the bearings). Thinking about it, the newest Premium torso boxes have had the same look and feel as the newer MX servo cases.

jwatte
07-18-2013, 05:48 PM
Mine are matte. It may be that the material is the same, but the molds are now internally sandblasted, whereas they were previously polished?
I do not have a "swirly color" effect, though. Maybe that depends on specific lighting?

escott76
07-18-2013, 06:16 PM
Swirling patterns and a matte finish may be indicative of a filled plastic. Plastics can be "filled" with all sorts of things, in all different percentages. Glass is popular, but other fibers, metal or lubricants can be used. A guy I work with has over 30 years as a moldmaker, so much interesting stuff in that trade, he loves to talk about it and I love learning ;) From looking at the MX-28's I got in bulk packs in May of this year I would say it looks like a filled plastic.
Lots of molds are chemically or even electrically treated (EDM) to achieve finish. There are even ablative lasers designed solely for mold finishing and texturing as well. It's real hard to get texture even across something like an automotive dashboard without using something like this.

quantmfizikz
08-18-2013, 05:38 PM
Can anyone suggest some professional looking materials?

That p95 stuff looks good. I was thinking carbon fibre also, but im leaning towards a plastic.

Besides p95 can anyone suggest some materials that are matte? nothing flashy. I like the material that was used on a members project, i think it was OKQ1. Is that also p95?

thanks

jwatte
08-18-2013, 11:11 PM
The easiest way to get something matte is to sandblast it once you've made the parts.

I actually use aluminum, and then sandblast, and then powder-coat in a matte black, which looks very matte and black. Most people think it's plastic :-)

Another material I just can't get enough of is 316 stainless steel in No. 4 finish. Very professional looking, if you ask me, but also very hard to work with :-)

escott76
08-19-2013, 11:02 AM
Another material I just can't get enough of is 316 stainless steel in No. 4 finish. Very professional looking, if you ask me, but also very hard to work with :-)
Most of the 3XX series is a pain to work with, gummy and work hardens easily. Out of the lot 303 is the easiest to machine, but for forming I'll take 316 any day. Coated carbide and lots of coolant at the right concentration help some. Low SFPM, and low resultant feed rates help with tool wear as well.
The 4XX series usually cuts easier in the annealed condition, but really wants to see heat treat to get the benefit of it's increased cost.

jwatte
08-19-2013, 01:08 PM
Agreed! When I said "can't get enough of" I meant the finish, not the working-with :-)
(I gotta check out this waterjet thing they installed, btw. Might make some new things possible...)

quantmfizikz
08-19-2013, 08:22 PM
Ive never thought of sandblasting after. Thats a good idea.

Gonna pick up a sample piece of some plexiglass' and see which i like

thanks

jwatte
08-20-2013, 12:12 AM
There is a significant difference in toughness between regular plexiglas (or the knock-off plexiglass acrylics, which are mainly the same thing,) and Plexiglas-G. The G version allegedly has some small amount of other polymers in it (polycarbonate?) that makes it a lot tougher.
Unfortunately, I haven't found anyone who sells Plexiglas-G in hobbyist amounts on the web or locally in the bay area. Let me know if you find anyone... (I know Trossen buys it by the crate!)

quantmfizikz
08-20-2013, 02:34 PM
^ I found Tap Plastics online. Theyre in california i think? But they sell "cut-to-size" of any plexiglas theyve got. So you pick your thickness and width and the length and your order it. Im going to order from there probably. Only thing i hate is that im in toronto, and an order which is like 2 bucks for a sample 4x4 inch piece, my shipping comes to 22 bucks.

I might just buy all my material at once so i dont pay double shipping and waste twice as much time waiting for it.

http://www.tapplastics.com/product/plastics/cut_to_size_plastic/acrylic_sheets_p95_matte/513

T (http://www.tapplastics.com/product/plastics/cut_to_size_plastic/acrylic_sheets_p95_matte/513)hats what im looking at, is that the real plexiglas stuff thats strong? Or is it some knock-off?

quantmfizikz
08-20-2013, 04:27 PM
http://www.professionalplastics.com/ABSSHEETFORMINGGRADE


W (http://www.professionalplastics.com/ABSSHEETFORMINGGRADE)hat about that stuff? Its ABS, seems good. textured one side, gloss other. Would that be strong for a mx-64 type quad?

jwatte
08-20-2013, 09:20 PM
they sell "cut-to-size" of any plexiglas theyve got

There's a TAP store right across the street from Red Rock Coffee, which is the local coffee spot for work :-)
Unfortunately, their stuff is all regular Acrylic, not the toughened "-G" version.


Its ABS

ABS is a fine plastic. Lego bricks are made of it. If you can find it thicker than 1/16th, it'll be plenty strong enough I think. Somewhat depending on how you make the parts, of course :-)
I don't like ABS because I can't run it on the laser cutter. It both generates toxic fumes, and significantly degrades the optics through those same fumes, I'm told.

quantmfizikz
08-21-2013, 12:50 AM
Hmm crap.

I hate that we cant get p95 as individual sheets.

I wanted to use something which was 1/8 if it was a polycarbonate or a plexiglas or whatever, but if i go towards carbon fiber, id be going like 3/32 most likely, and my order would be like 300 bucks just for the material and then id have to get it machined.

Well jwatte, if you find any material which is like p95 which is strong but not glossy/flashy and professional looking, let me know. Ill post back if i find anything

Lupulus
08-21-2013, 09:47 AM
ABS is a fine plastic. Lego bricks are made of it. If you can find it thicker than 1/16th, it'll be plenty strong enough I think. Somewhat depending on how you make the parts, of course :-)
I don't like ABS because I can't run it on the laser cutter. It both generates toxic fumes, and significantly degrades the optics through those same fumes, I'm told.

Personal experience, YMMV:

Myself and a few others at the hackerspace cut ABS on the laser regularly. It does generate some nasty fumes, but we have strong exhaust ventilation for the laser...usually you can just just barely smell it. Letting the laser vent ~10min before opening it helps. It's also recommended to let the pieces "outgas" for a day or so before working with them, but I'm usually too impatient...

There's horror stories of people melting ABS to the support grate, but I've never had an issue. I suspect that they're using lower melting point stuff. I've mostly used the 1/8" thermoformable ABS from Zoro Tools. FYI--their ABS sheet is pebbly textured on one side, which is not obvious on the product page

I've never heard that the fumes degrade laser optics, do you have a source for that? I'm willing to believe it, but my brief google search did not turn any solid answers.

escott76
08-21-2013, 10:17 AM
Crap builds up on lenses, and then provides something for the light to hit on the lens itself, making it the target and not the part. Heat on the lens itself will mess with the coating if present, or begin to degrade the surface of the glass itself. I've seen lenses at work that were not cleaned, and the results can be catastrophic (but super cool to see the result ;)). Granted we are pushing 2k or higher wattage, but if lasers are engraving glass (many hobby lasers are capable) they can certainly ruin optics.
If you need to keep venting 10 minutes after your part is cut, you need more ventilation during the cut.

Lupulus
08-21-2013, 10:55 AM
Thanks Escott! You have motivated me to check up on our lens cleaning...

All of the fumes produced during cutting are gone in seconds. However, the cut plastic continues to stink for awhile, so the 10min avoids the worst of it.

jwatte
08-21-2013, 04:27 PM
FWIW, "P95" is the finish, matte on one side and glossy on the other. "-G" is the part that says it's better than plain Acrylic.

Regarding cutting ABS (or polycarb) on the lasers: I'd get kicked out of my membership if I tried that on any real scale.
I know that ABS routes pretty nicely on a ShopBot, though, so if I can live with 1/8" bit curves in corners, it works great!
The black ABS from TAP plastics also is glossy on one side and pretty coarsely pebbly on the other -- think cheap car dashboards from 20 years go.

Lupulus
08-23-2013, 11:41 AM
Interesting discussion. Never really considered the issues of laser-cutting ABS much, since other members were doing it already. There's certainly examples of commercial laser-cutting of ABS, such as customlasercutting.com...whether it's a good idea in a DIY setting, maybe not. I'm hoping that regular optics cleaning is keeping the issues minimal for us :tongue:

quantmfizikz
08-24-2013, 11:19 AM
Yeah im not diying it.

Whatever material i buy its getting cut at a laser cutters or a company which can machine it

ezex
09-12-2013, 11:11 AM
Hi,
im not a very good fan of this new plexiglass used, is the second time I have to replace the BOTTOM and TOP plates of the phantomX .
They are always cracked in similar areas, were the servos connect.
The first time I have to remove a servo to repair some cracked gear, I noticed the cracks . I assumed that I tighten the screws to much, so I was very careful the second time.

A couple of days ago, I have to remove one servo again, and I can see the hairlines fracture everywhere.
Im looking on make Carbon Fiber plates, not sure where yet, may be I will try this place http://www.protechcomposites.com/pages/Machining.html .

I asked Kyle/Rick in trossen about this, they are being VERY helpful with this, and I send them the pictures, to check on this.
I hope I can get the CAD files for this plates, or anyone has any suggestion ?

Cheers
Ezequiel

50135014501550165017

tician
09-12-2013, 02:21 PM
The third and fourth pictures in your post show a somewhat reflective disk around the screw where the crack started. Did you use a chemical thread locker, or was that caused by the movement of the screw head polishing the material?

I know that the styrene-rich brackets in the oldest Bioloid Premium Kits would crack horribly at almost all joints after exposure to threadlocker (242 liquid [anaerobic adhesive] or 248 stick [many solvents of styrene]), although the liquid killed it much quicker. I have seen some anecdotes that polycarbonate is also susceptible to anaerobic adhesives like the blue liquid (242) threadlocker, and that is supposed to be what gives this PMMA blend its durability.

If there is any threadlocker beyond the outer diameter of the screw threads at the tip of the screw, then there is likely too much. Just need a little bit on the threads at tip of the screw and it will be pushed up along the rest of the thread when screwing it into the nut.

erazor
10-05-2013, 03:25 PM
Hi ezex!

I got the same issues with the new materials already while assembling the bot :-(. I did not tighten the screws to much it just seems to be tensions because of the drills and maybe bad positions of the servos nuts.

Anyway, since I'm in Germany it wouldn't make much sense to order new plates. I thought about carbon if it really brakes sometime in the future.

Regards,
Alex

DresnerRobotics
10-21-2013, 07:04 PM
If there is any threadlocker beyond the outer diameter of the screw threads at the tip of the screw, then there is likely too much. Just need a little bit on the threads at tip of the screw and it will be pushed up along the rest of the thread when screwing it into the nut.

Bingo. This is the common answer when we have people with broken parts. For what it's worth, the newer kits have a plastic-safe threadlocker included.

tician
10-21-2013, 09:51 PM
Bingo. This is the common answer when we have people with broken parts. For what it's worth, the newer kits have a plastic-safe threadlocker included.
Plastic-safe threadlocker? Does such a thing really exist?

DresnerRobotics
10-22-2013, 11:26 AM
Plastic-safe threadlocker? Does such a thing really exist?

It's closer to mild glue than threadlocker, but it works.

KevinO
10-22-2013, 01:26 PM
Hey Ezex and Erazor,

Your break points spurred a few questions...

How do you pick up your hex?
Do you have any visible bow in the body?
When you move the hex around, do you have a platform to carry it on?

erazor
10-23-2013, 09:23 AM
Personally I tried to be as carfully as possible with carrying and assembling since the material seemed very brittle to me.

I also did not tighten the screws to much.

When it comes to the threadlocker - I might have used to much. Sometimes I put the screw into the locker and then moved it into the hole, leaving parts of the threadlocker at the plastics. But if you ask me that does not seem to be the reason.

There also is no bow in the frame and I even did not carry a battery, just did some tests with a cable attached.

I suppose the reason is, that some nuts weren't perfectly in the dynamixel and the screw went in a bit tilted, thus pushing against the frame on the lower side and the opposite direction at the top. (sorry for the bad englisch, hope you got it right ;-) )

Here are some shots:

5047504850495050

jwatte
10-23-2013, 10:48 AM
Sounds like those plates ought to be cut in ABS instead...

kgranat
10-23-2013, 12:35 PM
erazor, because the old thread-locker is most certainly to blame for this problem, we would like to send you a new set of plates as well as new adhesive to use as thread-locker.

I'll be e-mailing you shortly to confirm your details.

erazor
10-23-2013, 12:48 PM
I was using the blue PALM LABS Turbo-Lock. Part Number 11-010. It even has an US-Flag on it.

TXBDan
01-15-2014, 11:19 AM
erazor, because the old thread-locker is most certainly to blame for this problem, we would like to send you a new set of plates as well as new adhesive to use as thread-locker.

I'll be e-mailing you shortly to confirm your details.

I also had issues with my body plates breaking. I was very careful and felt like they were just crumbling in my hands. Trossen sent me replacement body panels but i have not used them. For now the broken body plates are serving my needs in test, etc.

I am still using my original blue thread locker. Has there been an update? Can you provide detail on what thread locker we should use? I want to make sure i have the right stuff before i use the new plates.

Thanks!

tician
01-15-2014, 11:37 AM
The new threadlocker is a plastic-safe mild glue added to the trossen shop a couple months ago.

TXBDan
01-15-2014, 11:50 AM
This stuff?
http://www.trossenrobotics.com/turbo-fuse-thread-locker-2ml

Yeh, i have this:
http://www.trossenrobotics.com/store/p/6449-Turbo-Lock-Blue-Thread-10ml.aspx

I wish the safe stuff came in a larger size. Glad I found this thread, thanks!

kgranat
01-16-2014, 11:14 AM
Yes, the Turbo-fuse is what we're including in the kits now. Send me a private message with your order number and address and I'll send you a couple of vials.

Thorbear.H
01-19-2014, 05:46 AM
great to see you guys adressing the problems, to few companies does this these days. anyhow, i will be ordering my phantom today, and i was wondering if i could just use some ny-lock nuts instead of applying threadlock on every screw? if so, i could just order up all the nuts on this page, and i am good to go?
http://www.trossenrobotics.com/productdocs/assemblyguides/PhantomX-Hexapod-Mark2.html

jwatte
01-19-2014, 02:26 PM
Ny-lock will probably work, if you can find them in the dimensions needed. The Ny-locks I've seen before are "full nut" size (thick,) and the nuts needed for these servos/robots are more like "jam nut" size (thin.)

KevinO
01-19-2014, 02:45 PM
The screws that tend to loosen the most are the ones that are screwed into the servo "horns" thus ny-lock nuts won't help in those cases.

Thorbear.H
01-20-2014, 03:08 PM
ah, i see. the sides of the servos also seems to acomodiate only half-nuts. anyway, does anyone have a machine-drawing of the upper frame? i will use another system for mounting electronics, so i will need a 'clean' frame to make it look nice. would be great to have a drawing, to save some reverse-engineering effort :)

KevinO
01-20-2014, 04:52 PM
The PhantomX design isn't open source so any design drawings are property of Trossen Robotics. Now there has been a couple of people make their own based off the design but I don't remember who. You could call Trossen directly and explain what your intentions are and maybe they could help you out.

jwatte
01-21-2014, 02:56 PM
If you buy it, you could take a photo of the frame, and trace it / clean it up in something like Illustrator, and then export to the CAD program of your choice.

Thorbear.H
01-26-2014, 05:33 AM
i fun it here: http://forums.trossenrobotics.com/showthread.php?5429-Thinking-about-trying-out-a-different-Hex-robot.../page31