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robotic arm arc welder Answered

Is it a robotic arm capable of arc welding feasible for a diyselfer ?
I spotted some robot arms for cheaper than 200 $ over the web .
Vantages for the operator would be no weld fumes breathing , no uv rays and such ..


Depends on the arm, kind of welding needed and if you can program it to do the weld properly. Any commercial arm under $200 isn't going to work. They won't be able to support the weight of the welder pistol.

Now you can put your own robotic arm together if you have the know how and the money to do so. But you will spend more than $200 on all the electronics needed to run the thing.

Robotic welders are great in an industrial setting where the same welds need to be made over and over again. BUt not practical for a DIYer. You'll spend more time setting up the welder, programming it, and testing the program then it would take to just knock it out yourself.

I saw a really nice professional welding robot at an engineering show in the UK last year which was only 15,000 USD, which was amazingly cheap I thought.


5 years ago

But you will spend more than $200 on all the electronics needed to run the thing.

A very basic robot arm , coming at 34 $ , being able to lift 100 gr makes me optimistic .
A stick pc with Lubuntu installed at 50 $ plus some geared rc motors  on an adequate arm metal structure would work on my opinion ..
I guess the target lift capacity would be around 1 pound or 1/2 a kilogram .
I am not afraid of programming as I am preatty well versed with it .
I am afraid of breathing toxics and burning myself with molten metal though .
Plus I guess a proper pc camera filter would allow to visualize the welded surface better than a dark glass in a black mask .

Welding equipment weighs far, far more than 100g, and any cheap arm is going to made largely of plastic that will not survive the reflected heat of the weld.

Instead, have you thought of building a robotic arm hot wire cutter, carving foam or polystyrene under computer control?

Welding equipment weight far more than that , but clamps that hold the electrode weight exatly 1 pound : http://www.amazon.com/dp/B007KBDI3I
A hot wire cutter might be more suitable as a cnc implementation maybe .. working in 2D ..
Might be interesting having it working in 3D , but a 3D printer for very light plastic would be better I guess .

You're getting your units confused - 100g is slightly under 4 ounces.

No confusion here , even though I recognize myself as a confused one :D
I am after a payload of a couple of pounds for the robot arm ..
The toy arm was only for illustrative pourposes ..

As kiteman said the motors in those cheap arms don't have the lifting capacity to deal with the weight of the welder head and cables. The plastic of the arm will not stand up to the heat of the welding environment. It will also not be stable enough to allow for any amount of accuracy. Upgrading the arm structure adds significantly more weight.

The motors needed to operate the arm will cost you about $30 per. So if you go with 3 motors to cover the full range or motion you're looking at $90 there. Then you need to have a proper motor controller for each motor. Those will also cost about $30 per motor considering the amount of power the controllers will need to handle to support the motors. So you have another $90 there. Then you factor in a controller of some sort, be it an Arduino, Pi or other small computer. The one your looking at is $50. So your already at $230 in the electronics and you haven't even started to build the arm itself. Which will need to be aluminum or steal and have sealed joints and bearings to prevent any slag or shop debris from gumming up the system.

If you want to weld then you should be doing it in a well ventilated area thus preventing noxious gasses from being inhaled. You should also have the proper PPE. Such as a leather apron, leather gloves, and face shield.

Worth adapting a chinese robot arm sort of this one (70 $ all metal , servo motors and electronics not included ) ?

You realize that arm isn't much larger than the welding gun itself right? There is nothing in that cheap arm you could actually use. The stepper motors you will need to run the arm will probably need to be Nema 23 motors who's mounting brackets are a little over 2 inches by 2 inches. Even then you may need to gear them down to give you the holding torque you need. This is the kind of motor kit you need to make the arm you want. You can get the cost down by using different stepper controllers and say an Arduino to control them. 


What range of motion are you expecting from a robotic welding arm? How large do you need it to be to do the kind of work your looking to do?

It's safe to say your main limiting factor here is cost. Unfortunately DIY doesn't always bring the cost of things down as much as we would like. You may be able to put together the mechanical parts of the arm for less than $100 by building it from scrap material. But you still gotta spend the money for the electronics. The electronics are still the most expensive parts of DIY CNC routers and 3D printers. You gotta have the right electronics otherwise the machine won't perform as you need it too. 

I am interested in bicycle frames welding .
By the way 6D , adaptable reach and 2 pounds payload woud be optimal.
Surely not something I would be able to make with my actual finances .
I wonder if using worm gears would let you use mini servos , like in rc cars ..
I saw a video on youtube where the guy used that set to lift an heavy object .
Maybe one could use optical rotary encoders to mimic stepper motors .

You would be better off doing that sort of welding by hand. Unless your planning to do hundreds of frames building a cnc welding rig would be a waste of time and money.

I would recommend going the analog route. If your main concern is not getting hit by the sparks and breathing toxic fumes, just build a big welding cabinet similar to those hood boxes used to handle uranium or something. You can run an extractor exhaust fan to it. And the extension leather gloves through the wall of the shield give you the tactile feedback of actually doing the welding which is an art in itself. I guess you could make the entire glass window dark for UV protection.

Might be an option .. I doubt that making the glass window dark would suffice as uv protection strategy though .
Welding masks use actinic glass : glass that transmits light of high visibility (as green) but reduces the intensity of both infrared and ultraviolet and is often used for protecting the eyes of industrial workers.
(from : http://www.merriam-webster.com/dictionary/actinic%20glass )