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Black_Moons
03-24-2011, 06:27 AM
Found this vid today, Check it out:
http://www.cncinformation.com/CNCBlog/cnc-hexapod-technology/

Iv heard of this concept before, But this is the first large scale demo I have ever seen of it. Must have some intresting axis/rotation limits.

wierdscience
03-24-2011, 09:02 AM
With the forces involved in maching I don't see how they keep all those ball joints and swivels tight.Seems the least amount of slack would be a deal killer.

Here's G&L's version-

http://www.youtube.com/watch?v=7TowJZQi-qY

lazlo
03-24-2011, 09:42 AM
The rigidity of the hexapod comes from the opposing pistons or leadscrews. It's the same mechanism that drives a flight simulator, upside down:

http://upload.wikimedia.org/wikipedia/commons/a/a7/Hexapod_general_Anim.gif

I mentioned a couple of times the Nova episode about making the replacement cases for the Constitution and the Declaration of Independence. It was a bunch of high-precision machining. The backplate itself, with all the lightening pockets, was milled by the giant hexapod at NIST.

gwilson
03-24-2011, 10:01 AM
The first hexapod I saw was a separate attachment bolted to the floor BEHIND a regular Bridgeport. The head of the Bridgy was turned around to face the rear. The struts of the hexapod went down to the floor. It was really great to watch in action. Wonder if they are still made?

DFMiller
03-24-2011, 10:28 AM
That is so cool? Hand coding G Code must be a treat? With processing power so cheap these days I am surprised there are not more of them around? Will EMC control one of these?
I think this would be a good project for Sir John and Evan to co operate on?
Should be a piece of cake? John has some ball screw cut off? Evan can make up some zero backlash nuts?
Dave

macona
03-24-2011, 12:02 PM
The first hexapod I saw was a separate attachment bolted to the floor BEHIND a regular Bridgeport. The head of the Bridgy was turned around to face the rear. The struts of the hexapod went down to the floor. It was really great to watch in action. Wonder if they are still made?


Not sure if they are still made. I think they are. I have seen maybe two pop up on ebay.

Of course the software to program is a killer.

lazlo
03-24-2011, 12:41 PM
Of course the software to program is a killer.

No doubt -- the Stuart platform doesn't look that hard, but the simultaneous multi-axis kinematics necessary to drive a hexapod are incredibly complicated.

I posted several years ago that a hexapod control system would be the ultimate home-shop project. I've still never seen a hobbyist hexapod, but I've haven't been by CNCzone in awhile either...

jugs
03-24-2011, 12:46 PM
With the forces involved in maching I don't see how they keep all those ball joints and swivels tight.Seems the least amount of slack would be a deal killer.

Here's G&L's version-

http://www.youtube.com/watch?v=7TowJZQi-qY

Thats rubbish, see what hexapods can realy do HERE (http://www.youtube.com/watch?v=msaWXY3OuQQ&feature=related)

john
:)

mochinist
03-24-2011, 12:53 PM
Thats rubbish, see what hexapods can realy do HERE (http://www.youtube.com/watch?v=msaWXY3OuQQ&feature=related)

john
:):)even better, someone posted this one, one of the last times a hexapod thread was posted here.
http://www.youtube.com/watch?v=quN37YskoaM

Evan
03-24-2011, 02:50 PM
I don't think the software is all that tough. You know where the cutter must be placed in three space. You know what the X, Y and Z is and the Roll, Pitch and Yaw. The cutting head is placed on a polygon (triangle) which is a face in a 3D mesh. The triangle is then translated in X, Y and Z and rotated in R, P and Y. The position of the face vertices determines the length of the sides of the triangles that connect to the vertices of the cutter triangle and connect at the other end to fixed 3D locations. It is calculated backwards from the vertices of the the cutter triangle using a 3D best line algorithm to the fixed points of the other end of the support trigons. That gives the length of the six variable sides of the three support trigons. All you do then is make it so, increment after increment.

lazlo
03-24-2011, 04:07 PM
:)even better, someone posted this one, one of the last times a hexapod thread was posted here.
http://www.youtube.com/watch?v=quN37YskoaM

LOL! For those who don't get the joke -- those are hexapod (i.e., 6 legged) robots, which have nothing to do with a hexapod CNC machine :)

Jaakko Fagerlund
03-24-2011, 04:31 PM
I have some memory image that EMC2 supports hexapods and I've seen a few built, though not for milling, by hobby guys/girls.

Thanks for the video links, nice piece of machinery :)

skunkworks
03-24-2011, 05:04 PM
I have always wanted to build a hexapod... Some day. Yes - emc2 has kinematics that allow for a translation between actuators and xyzabcuvw.

http://linuxcnc.org/docs/html/motion_kinematics.html

this is a delta robot running emc - kinda cool.
http://www.youtube.com/watch?v=FgnxBaFFDi8

real hexapod.
http://www.youtube.com/watch?v=7hztl4eWpZM
read about it here
http://translate.google.com/translate?u=http%3A%2F%2Fwww.imac.unavarra.es%2F%7 Ecnc%2F&sl=es&tl=en&hl=&ie=UTF-8

lazlo
03-24-2011, 05:13 PM
I have some memory image that EMC2 supports hexapods and I've seen a few built, though not for milling, by hobby guys/girls.

I'm not finding any with a quick Google search, but there apparently was some hexapod support in EMC in the distant past. Lot of comments like this on the EMC discussion list:

> As far as I know hexapod code is in EMC2, but does it (still) work? Back in
> march there where some mails about it. Unfortunately there was no success
> story follow up.

Edit: Sorry SW, I had that reply up on my screen for 15 minutes and cross-posted...

lazlo
03-24-2011, 05:20 PM
this is a delta robot running emc - kinda cool.
http://www.youtube.com/watch?v=FgnxBaFFDi8

That's very cool! He's planning to use it as a hexpod extruder head for a rep-rap :)

Black_Moons
03-24-2011, 05:55 PM
I have seen a tabletop hexapod bot (like those dancing robots) mill a PCB before. Not sure if it had much accuracy however.

wierdscience
03-24-2011, 09:12 PM
The first hexapod I saw was a separate attachment bolted to the floor BEHIND a regular Bridgeport. The head of the Bridgy was turned around to face the rear. The struts of the hexapod went down to the floor. It was really great to watch in action. Wonder if they are still made?

Yup-


http://www.google.com/imgres?imgurl=http://www.prsco.com/images/p2k_05_thum.jpg&imgrefurl=http://www.prsco.com/p2000.html&usg=__UmeATkoXLs5VousxylXTw02_8WU=&h=267&w=200&sz=153&hl=en&start=4&zoom=1&um=1&itbs=1&tbnid=g-QFFEggREyLnM:&tbnh=113&tbnw=85&prev=/images%3Fq%3DHEXAPOD%2BCNC%2BMILLING%2BMACHINE%26u m%3D1%26hl%3Den%26sa%3DG%26tbs%3Disch:1&ei=b-uLTYbVJs-O0QGWtpWsCw

Black_Moons
03-24-2011, 11:03 PM
Very cool URL, More impressive I think is the page it came from: http://www.prsco.com/p2000.html

They actualy show specs of the machine in question. Very intresting.

2ManyHobbies
03-24-2011, 11:30 PM
Very cool URL, More impressive I think is the page it came from: http://www.prsco.com/p2000.html

They actualy show specs of the machine in question. Very intresting.
I can just see detention for remedial CNC 101.
Tram (calibrate) this thing. :eek:

Jaakko Fagerlund
03-25-2011, 01:05 AM
I can just see detention for remedial CNC 101.
Tram (calibrate) this thing. :eek:
While I don't have experience with them, I'm guessing you do parameter corrections just like with regular 3-axis cartesian coordinate system. Take a reading from three table positions that are supposed to be "Z0" and input them as correction parameters. I'm not giving this much thought now, but I'm quite sure that something along this line is used.

skunkworks
04-04-2011, 11:53 AM
This showed up this month.

http://www.youtube.com/watch?v=MTPkw5BNmVw

sam

macona
04-04-2011, 12:17 PM
Dont know if I would really consider that a hexapod. Yes it has 6 legs, but they are paired off and connected to three actuators.

skunkworks
04-06-2011, 10:08 PM
the last one I posted? pretty sure it is 6 separate actuators. The one I posted previously is a delta (3 actuators).


Dont know if I would really consider that a hexapod. Yes it has 6 legs, but they are paired off and connected to three actuators.

macona
04-07-2011, 01:29 AM
Look at the bars. Wrong setup for anything but a delta. They are parallel to each other. They should be like this:

http://www.youtube.com/v/yLKR6RrhGJs

skunkworks
04-07-2011, 09:08 AM
I see what you are saying - but the physical layout of the ends of the actuators really only dictate the motion/work area. This is a hexapod - and its actuators are in parrallel. You still get the 6 axis of freedom. (xyzabc) just how much movement in each is the varable.

http://translate.google.com/translate?u=http%3A%2F%2Fwww.imac.unavarra.es%2F%7 Ecnc%2F&sl=es&tl=en&hl=&ie=UTF-8

The kins in emc allow you to position the ends of the actuators where ever you want. iirc.

sam

Rustybolt
04-07-2011, 03:13 PM
Wasn't there an article in Model Engineers Workbook several years ago about a CNC hexapod mill from Giddings and Lewis?

skunkworks
04-12-2011, 03:49 PM
some more video of above hexapod. (you can see it doing full xyzabc movements)

http://www.youtube.com/watch?v=G_UmhUjZhNo

boy - I want to make a hexapod

sam

macona
04-12-2011, 09:13 PM
Cool, the earlier pics made it look like the bars were parallel but they are not. It will be neat to see it doing something more complicated.

DR
04-12-2011, 10:12 PM
The first hexapod I saw was a separate attachment bolted to the floor BEHIND a regular Bridgeport. The head of the Bridgy was turned around to face the rear. The struts of the hexapod went down to the floor. It was really great to watch in action. Wonder if they are still made?


I saw one like that at WESTEC a bunch of years ago.

For the demo they cut an aluminum part, then ran back over it cutting air to show the motions. The cut was really bad,a chattery mess, so bad that I suggested they weren't doing themselves a favor by showing that. Came back past their booth 4 hours later, they had removed the cut part and were only demo'ing the motions.

Black_Moons
04-12-2011, 10:53 PM
Woah, Never realised it could do (limited) Z rotation. Though I have no idea why you would want to :)

Maybe makes more sense with a small right angle geared cutting head or something in confined spaces..

skunkworks
09-12-2012, 12:55 PM
another video.. Darn cool

http://www.youtube.com/watch?v=nebJ59TcYlQ&feature=share&list=ULnebJ59TcYlQ

sam

Evan
09-12-2012, 03:49 PM
Here is free hexapod software. No idea if it is usable as I haven't tried it yet.

http://sourceforge.net/projects/visual-hexapod/

skunkworks
09-12-2012, 03:56 PM
That is for the 6 legged robot...


Here is free hexapod software. No idea if it is usable as I haven't tried it yet.

http://sourceforge.net/projects/visual-hexapod/

Evan
09-12-2012, 04:55 PM
Same thing. Just turn the robot upside down.

kf2qd
09-12-2012, 08:51 PM
Will EMC control one of these?

Dave

Yes, the kinematics info is part of EMC, you just have to figure out all the correct information to fil in all the data.

Programming can be done with X Y & Z as the interpreter takes care of the physical movement.

lazlo
09-12-2012, 09:07 PM
another video.. Darn cool

http://www.youtube.com/watch?v=nebJ59TcYlQ&feature=share&list=ULnebJ59TcYlQ

Wow! That's the first real amateur hexapod CNC I've seen! Judging by the electric sockets, German?

macona
09-12-2012, 11:36 PM
Pretty neat, even with all the chinese components it must have cost a fortune.

A friend in the local dorkbot is building one of the three motor type rigs. Probably for pick and place of SMD components.

Black Forest
09-13-2012, 02:02 AM
Look at the bars. Wrong setup for anything but a delta. They are parallel to each other. They should be like this:

http://www.youtube.com/v/yLKR6RrhGJs

I think my wife would like me to buy one of those and strap it to my butt! I can think of a couple of girls that could have used one strapped to their butt!

Ian B
09-13-2012, 06:23 AM
They're not just used for machining - here's a slightly larger one in a rather different application: http://www.youtube.com/watch?v=aBn7w1S8MtY

Ian

lazlo
09-13-2012, 10:33 AM
They're not just used for machining - here's a slightly larger one in a rather different application: http://www.youtube.com/watch?v=aBn7w1S8MtY

The "Stewart Platform" has been in use for many years before CNC, for flight simulators and such. But that's a very cool video! It's gyro-stabilized, so the ladder stays very still on a heavily rocking ship.

I'd imagine a smaller version of that is what the Navy snipers used when they took out the whole Somali pirate crew simultaneously.

lazlo
09-13-2012, 10:34 AM
Pretty neat, even with all the chinese components it must have cost a fortune.

The fabrication of the truss is immaculate. So much so that I wonder if he's a pro building this for a startup...

skunkworks
09-13-2012, 11:30 AM
The video that I posted is run with linuxcnc (formally emc2) They do have a demo setup with an actual simulated machine. I played with it a little bit.. Some day I want to build a table top one to play with.

http://electronicsam.com/images/KandT/testing/Screenshot.png

sam



Yes, the kinematics info is part of EMC, you just have to figure out all the correct information to fil in all the data.

Programming can be done with X Y & Z as the interpreter takes care of the physical movement.

lazlo
09-13-2012, 06:32 PM
The video that I posted is run with linuxcnc (formally emc2)

I thought EMC2 had support for hexapod (simultaneous six axis) control since the National Institute of Standards (that wrote EMC) also was big into hexapod CNC development.

My office mate at the Naval Postgraduate School was a Ph.D. in Mechanical Engineering, specializing in parallel kinematics. Gawd, that's some nasty math!

skunkworks
09-14-2012, 11:20 AM
Yes - IIRC the kinematics have been a part of linuxcnc from the early stages. It is more than just hexapods though. It can do serial arms and such - really - almost anything you could think of.

I have a puma arm that I want to get setup some day....

http://juve.ro/blog/puma

(he helped get the generic serial kins into linuxcnc)

sam


I thought EMC2 had support for hexapod (simultaneous six axis) control since the National Institute of Standards (that wrote EMC) also was big into hexapod CNC development.

My office mate at the Naval Postgraduate School was a Ph.D. in Mechanical Engineering, specializing in parallel kinematics. Gawd, that's some nasty math!