Model Aircraft Servos

[Shox Dr]

If I was selling a Mig welder that had the goose neck turning from left to right automatically,how many people would you think would be interested in buying it?

In a word NO.

When weaving or any other type of technique for that matter you need to be able to control the speed and movement throughout the weldment, For your idea to work the fitup, etc has to be perfect and consistent. Not many are unless you are working on new material

 

[Wozzaaah]

This sounds to me like a fun project and I'm looking forward to seeing how it progresses but I think you're on a bit of a hiding to nothing to be honest.
Having a manual torch do the weaving for you will take away the natural 'feel' for the the job in hand and will probably create all sorts of problems.

 

[Robotstar5]

A welding environment is VERY electrically noisy. I can see you having all sorts of fun with the servo doing weird things as you weld. I have a Fanuc welding robot tucked away as a project for time to come, and all its electronics are especially hardened to cope with the nasty interferance caused by the welding.

As long as you use screened cables and make sure the screen is grounded it will protect it from weld generated noise.

If you look in the bottom of your Fanuc cabinet you will see where all the cables come in and are clamped by their screens to a grounded bar.

 

[Wedg1e]

I think I'd look at fitting a wiper motor into the welder body and using a tiny Bowden cable up to the torch to wiggle a thingummy... bellcrank? Something along those lines...
Devise a facility to vary the radius of the wiper's ouput arm and you'd alter the sweep range of the 'zig-zag'. Feed the motor through a simple control and you'd have variable speed too.

Feck me I'm good

 

[GeorgiePorgie]

Feck me I'm good

Not good enough I'm afraid,Wedge....It would seem that my torch is not able to adapt to change.....

Looking at the real robotic welding arms it would seem that the torchs are just clammped to the robot arms on the outside and its the actual arm that does twisting an turning.

 

[GeorgiePorgie]

As long as you use screened cables and make sure the screen is grounded it will protect it from weld generated noise.

You can also use RFI clamps to further reduce the chance of interference.

 

[Wedg1e]

Not good enough I'm afraid,Wedge....It would seem that my torch is not able to adapt to change.....

Looking at the real robotic welding arms it would seem that the torchs are just clammped to the robot arms on the outside and its the actual arm that does twisting an turning.

Nobody said it had to be easy, nobody said it had to be fair... hang on, wasn't that a TV theme tune?

We built a machine to inspect artillery shells using a tiny (but £20K) Fanuc robot; after our morning's training course we soon had it stirring a cup of tea so the sort of motion you need would be a doddle

It would appear that what you need is a handle within a handle, whereby you hold the outer one and the inner one has the motion facility. You may have to resort to designing your own parts - maybe even build a torch from scratch. Let me have a think...

Edit: from your pic it looks as though the gas valve is built-in to the torch? A quick mod. with a solenoid valve in the welder chassis would get rid of that, which would be a good start...

 

[Robotstar5]

We built a machine to inspect artillery shells using a tiny (but £20K) Fanuc robot; after our morning's training course we soon had it stirring a cup of tea...

Had something similar when I taught robot programming, after a couple of hours we had steel covered in the participants initials done in weld beads

 

[GeorgiePorgie]

How do Robotstar....
What software would be needed for training the robots moves? ie manipulating the robots arm/s by manual movement and the software reads this into the program to have the robot automatically carrys it out when manaual movement is finished.

I ask this as the programming side is out of my depth but if I could get some software like the above mentioned I'd like to delve into the building of a robotic arm.

 

[Robotstar5]

How do Robotstar....
What software would be needed for training the robots moves? ie manipulating the robots arm/s by manual movement and the software reads this into the program to have the robot automatically carrys it out when manaual movement is finished.

I ask this as the programming side is out of my depth but if I could get some software like the above mentioned I'd like to delve into the building of a robotic arm.

Trust you to want the most complicated programming system! what you are describing is known as "lead through" programming, commonly used for paint spraying. The robot arm is put in "neutral" (servos take the weight) and an experienced painter will "lead" the arm through the motions required while the robot records all the movements, then the robot "plays it back". The most common system is to move the arm manually with buttons/joystick recording the points as you go.

The last time I used a robot controlled by a PC was in 1987 so they must have advanced a lot by now for the hobbyist, since then I have only worked with industrial robots.

You have piqued my interest so I will have a look around for hobby robot info when I have time.

 

[Wedg1e]

The most common system is to move the arm manually with buttons/joystick recording the points as you go.

... and what a riot THAT is, when the arm needs to track a fragile sensor/probe along the surface of the item under test, preferably JUST in contact with it, no force, AND the item has a varying-curvature radius to it (think of a 155mm tank shell )

We became the first company to use a robot in this kind of inspection. Bizarrely, the lash-up of a probe carrier (on the end of the robot arm) that I assembled from bits and pieces in my garage was good enough to be left on for the finished product!

 

[Robotstar5]

... and what a riot THAT is, when the arm needs to track a fragile sensor/probe along the surface of the item under test, preferably JUST in contact with it, no force, AND the item has a varying-curvature radius to it (think of a 155mm tank shell )

If you need to do anything similar, contact one of the robot systems integrators. Most robots will accept an input from a sensor (your probe) and modify the path accordingly.

A good example is a welding robot can search for the workpiece using the end of the welding wire sticking out of the tip, then start it's programmed weld paths varying speed, current or voltage to accomodate material variations.

 

[awemawson]

Robotstar5,

Sounds like I should offer you a holiday down here on the farm, and you can get my Fanuc robot arm up and running holding my plasma cutter. I had the idea of using it in 2D for profiling, but it just sits in a corner gathering dust ast the moment.

 

[Robotstar5]

Robotstar5,

Sounds like I should offer you a holiday down here on the farm, and you can get my Fanuc robot arm up and running holding my plasma cutter. I had the idea of using it in 2D for profiling, but it just sits in a corner gathering dust ast the moment.

Let me know which arm you have, and controller type (RJ3 etc) I may be able to supply info to help you get going.

 

[GeorgiePorgie]

Fanuc robot arm up and running holding my plasma cutter. I had the idea of using it in 2D for profiling, but it just sits in a corner gathering dust ast the moment.

Thats an expensive piece of equipment considering you don't know how to operate it.

 

[Robotstar5]

Thats an expensive piece of equipment considering you don't know how to operate it.

Older ones aren't too dear, we've just sold 4 working Arcmate 100i with RJ3 controllers for £1K each!

 

[malcolm]

The MIG Tutorial needs a rewrite. Very often going in a straight line is much better than zig-zag. For anything over 2mm on the flat I'd generally run in a straight line.

The advantage of a zig-zag is that it makes sure the welder arcs to both sides of the joint (important for inexperienced DIY welders) but most of all it helps control travel speed when you have a little sideways motion. Automating the zig-zag could be counter productive.

The project sounds like fun though.

 

[awemawson]

Thats an expensive piece of equipment considering you don't know how to operate it.

Well considering it was free I don't reckon it owes me anything! I bought a CNC mill that had been used at Bristol University, and this robotic arm had been used in a student project popping bits of aluminium in a hydraulic vice in the mill. The dealer was contracted to clear the lab and didn't know what to do with the robot so I let him give it to me

Robotstar I'll get back to you with the part numbers - I know it's an Arcmate with a big cabinet and a big hand held control and has seen very little use. It's top heavy - I need to make up a custom pallet so it and it's controller can easily be moved about.

 

[GeorgiePorgie]

Well considering it was free

I take my hat off to you sir for being there at the right place at the right time...its obvious here that the dealer was thick as pig sh*t not realising the machines potential or value.

 

[awemawson]

Yes he was. Bought the CNC mill including insured carriage and he failed to secure one of the axis, so it went crashing about in transit - cost him a few hundred quid to get the ball screw and nut rebuilt!

Here is a link to the robot arm:

http://www.antenen.com/htdocs/downloads/files/files_dl/ArcMate Sr.pdf

Robotstar5 I'll PM you