Opinions on micro servo robotic arm using cables

Lynxmotion Robot Arms
21

Hey thanks for that first ling especially. $5 for a nice strong servo like that. I’ll never put that much weight on it, but that’s still a good price, which i can fit into my hobby budget.

rovingnetworks.com/surf_board.php
$100

  • a better motor controller, $35

  • some small parts, ttl converters, and regulators, and a relay… about $15

  • $10-$15 on stuff i’m sure i’ll need later.

I may not need the wireless adapter, if i can get my bluetooth adapter to work again.
I don’t know if it’s my bluetooth uart adapter, or my $2.50 usb bluetooth adapter… but something isn’t working.

I also need a bluetooth-serial friendly terminal program that supports macros.
Using the terminal software by Br@y++, it worked with bluetooth before, but not matter what i try, i cant get it to work again.
I’m pretty sure it’s my usb bluetooth adapter, If i have to replace that, it’s $18 for a good one from newegg.

Edit:
Gotta find 40 tiny rubber self-adhesive feet. The tracks on my rover are nice, but they don’t grip at all. So it can’t even crawl over a half inch tall smooth piece of wood, it just cant grip it.
I was thinking tiny rubber pads. It’s quick, and the size would be uniform. As opposed to adding small bumps of hotglue to each link.

22

The LM1084-5.0 is a 5VDC Voltage Regulator in a 3-pin TO-220 package that can supply up to 5 amps output. It just needs two caps and one resistor to finish the project.

As for heat dissipation, excessive power dissipation can be due to high input-output differential, even with no load. For the above mentioned LM1084, the Maximum Input to Output Voltage Differential is 25v, so one wouldn’t want to feed more than 30v to the regulator’s input. In cases where the differential is excessive, use a series dropper resistor.

Some wall transformers that feature no active regulation (just a couple diodes and cap, maybe) can easily exceed this voltage with little to no load, so watch out. Remember, for unregulated AC adapters, if it’s rated at 12v @ 1 Amp, that means the voltage output should be 12v ONLY if the load is drawing 1 Ampere. If the load is only half that (0.5 A), then the voltage can be 24v! This is a bit oversimplified and depends on the load line of the transformer. Again, this is for cheap wall wart type transformers, as a general rule.
I’ve seen expensive equipment (press plate bender - $17,000) ruined because someone used a 24v/1A wall wart, instead of the OEM 24v/250mA version. The equipment did not have any regulation whatsoever and literally burned because it only had a 250mA load, causing excessive voltage on all pneumatic switches.

regards,
MAJ

23

Could you link me to a couble, as well as let me know what capacitors to use, and where?

Also my voltages are low, 8.4v atm, no where near the 24 or 30 you mentioned.

24

If you want to add some extra traction to your tracks, you could put a thin coat of rubber cement on them. This is the cement used for paper and posters that is soft and can be rubbed off when needed.

25

I was thinking of taking small pieces of 24 awg wire, cutting it into the same width as the tracks, and then gluing them to each track.
Or get some no mess rubber feet or something.

I definitely want something that can be easily removed, the markup on those tracks are ridiculous. Theres no way those could cost more than 5 cents a piece, but yet they are like a dollar a piece in retail. The markup is actually kind of sickening. If they become damaged some how, i’m switching to cheap wheels.

26

Where did you find tracks for only $1? I has been my experience that finding materials that will work as a track is not easy and generally not cheap. You could use the rubber cement to glue pieces of rug anti slip material (coarse rubberized cloth that comes in rolls) to the track sections to improve gripping (would also be easy to remove).

27

Sorry, misunderstanding, the tracks that are $1 each, are about $1 per link!
robotshop.com/johnny-robot-t … -pair.html

they come in pairs of 2 for $1.90

Now theres no way those links could cost more than 5 cents a piece to make. So that’s one hell of a markup. All you get is pins and molded plastic links, i know for a fact molded plastic pieces of that size do not cost very much,

28

Well, that’s an excellant business opportunity for you. Make and sell them for less. With some products the package the product comes in cost more than the contents. The markup covers the effort others put out to make the product available to you. If you want to DIY, you might try making some “sew-on” tracks from the anti skid material.

29

Ya, probably run into legal trouble though, I could probably make a similar product, that’s compatible, but still different enough to avoid legal trouble. You know, if i had my own factory.

I like my DIY projects, but i have limits on how far i’ll go. My robots arm is about as ghetto-fabz as i’ll go on this thing.
If i had better, stronger servos, i’d use metal. It’s hard to find really strong micro servos though. and the horns are so flimsy.
If only had A: more money, and B: more tools at my disposal.
At this rate though, if i can find another cheap deal on ebay where i get a bunch of servos for dirt cheap, i could make a walking robot out of popsicle sticks and balsa wood, My robots arm, just happens to be an excellent leg design, I would just need more precise tools.

30

Are you kidding me. :stuck_out_tongue: They’re not $1.00 each and not really even $0.90 each. Unless you really want to buy enough from the pair pricing to build something. If you get 25, enough to actually build something they’re $0.60 each.

I know the guy that makes them. He has to mold the parts then plop each one into a fixture to drill the holes for the axles. You going to tell me it’s worth his time to make these for $0.05 each… Yeah right.

I realize it’s always smart to compare prices and get the best deal. But why not give back to the people who are actually making this stuff available. There is a lot more going on than the price of a few grams of ABS. His shop has you know, things like heaters to keep warm, machines to cut molds, and the molding machine, you wanna see a hefty electric bill… Yeah go ahead and DIY something better. :unamused:

31

I can understand that. But still that’s a big markup.

I wasn’t saying he should sell them at cost.
For me, the best price would be $0.25 a piece. good number… 4 for a dollar. 40 for $10 (40 is how many my robot uses).

What’s stopping me from really making my robot a work of art, is the cost. All those cool sensors look like so much fun, but even a simple one, one with a low manufacturing cost, cost way to much. I noticed robot parts have one of the highest markups of any of my previous hobbies.

If the prices were more reasonable, more people (including myself) would buy more gadgets.

Would you rather sell 1 sensor for $10(profit) each, or 5 for $3(profit) each.
I have no clue how big the market for these parts actually are, for all i know, the prices are high, because the demand is low. I don’t know, i can only see it from the consumers side, not the resellers side.

BTW, i do DIY a lot of my parts, power regulators, 3/4 of my wires, most of my stuff i get for free from scrapping old junk i have laying around, broken toys from my youth, burned out power supplies from eMachines computers. Not because i wanted to, but because i had to.
So Instead of making a tiny bit of profit from me, these companies are making zero profit from me on those parts.

Also shipping prices are unfair, 3 voltage regulators, 2x5v, 1x3.3v is $2.57 on basicmicro, shipping, $14.
I can’t find a 3.3v voltage regulator in my scraps, not even the old PC power supply had one, which i thought was super weird. At least if it did, it wasn’t a TO-220 packaged one, i’ll look again though.

There i go babbling again… i don’t even realize i do it!

32

Well, this post is totally populated with lame adolescent excuses why you can’t conquer the robotic world. Just doesn’t past the adult snicker test. “If I had some ham, I could have some ham and eggs, if I had some eggs.”

“It’s easy to sit there and say you’d like to have more money. And I guess that’s what I like about it. It’s easy. Just sitting there, rocking back and forth, wanting that money.”

  • Jack Handey Deep Thoughts
33

Got bills to pay, i only set asside so much of my budget a month. If that’s immature, then please let me know.
This isn’t my only hobby, i also do gaming, computers, porcelain dolls, and watch the occasional movie.
It’s not like i sit here wanting more money, i have money, for bills.

I guess i don’t need to pay rent, or car payment, or buy food for a month. Then i can have a rocken elite robot!

34

Alright guys, you’re making me step in here, and I don’t like having to do that.

Let’s keep the conversation on robot stuff, yeah?

Don’t make me turn this forum around. >:C

35

Try this link search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=LM1084IT-5.0-ND from digikey.com
The datasheet here, national.com/ds/LM/LM1084.pdf, shows the needed components in the Application Circuit.

best regards,
MAJ

36

Excellent, thank you, i don’t fully understand where capacitors come in, some of those tech schematics are a bit above my level.
But i’ll probably order those in a few weeks.

37

Oh, glad you brought that up. The fixed voltage regulator doesn’t require the caps, although it may still be helpful to add the 10uF to the input and GND for ripple rejection if the supply is far from this circuit. The fixed voltage application is in Figure 3 on page 8 of datasheet:

So, no extra components required.

best of wishes,
MAJ

38

Below is a similar looking bot without a gripper. I think a small gripper with a rubberband between the servo and gripper is a worthy project such that the gripper can grip any size object and the rubberband prevents servo failure due to overstressing.

youtube.com/watch?v=M0F4hd5WUns

39

OMG that arm is huge!, i noticed he used thin flimsy materials, i wonder if he used more rigid materials if he could have made it smaller and lighter.

I actually found that double-layered tongue depressors, are light, rigid, and if attached right, still flexible enough not to damage the servos or horns if they are forced to hard.

I’m going to put a wrist rotate servo on my current robots arm, and it’ll be done, at least for that part of the arm, i’m still going to replace the base servos with stronger standard size servos.

Just recieved some of my other power components today in the mail, my TTL 3.3v <-> 5v converter, and a 3.3v regulator, maybe i can get my bluetooth working again.
Also got a nice relay switch.
Going to make one of these simple beauties. viewtopic.php?t=2463

40

You might want to check out Innerbreeds assembly. Although it doesn’t use cables, it does allow for a shoulder and elbow servo to be on the bot. A wrist or gripper could be added to the end of the tube. Just look at the image tilted. :wink:

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