Weld Positioner Lash Up.

[Richiew]

Here's my shoddy attempt at a weld positioner. There was no design or plan other than shamelessly copying off a variety of better made ones that are documented online. Dimensions were dictated by available materials and guess work. Not even a fag packet was employed.

The box section was salvaged from an old desk. It's 25mm square with 1.6mm wall. The two uprights are linked with three horizontal pieces. The 20mm bore pillow block bearings have 80 or 85mm spaced mounting holes so they dictated the spread. I welded a piece of 3mm plate with mounting holes drilled and to this I've mounted a 24v Parvalux motor. The motor was left over from another project that I didn't get round to which was to motorise a bead roller. I've cut up a cheap plastic chopping board to help isolate the motor, the motor mounting bolts are taped up along their lengths too. I've used a multimeter to check and the motor appears to be electrically isolated from the frame.

A vee belt turns the turntable pulley. The rubber belt also allows the motor to stay isolated. I've welded another length of box section and gouged out the centre so I can run a tensioner pulley mounted on 10mm threaded bar using a pair of nuts clamping the box section keeping the belt tight. The tensioner system is handy as I have a load of spare old vee belts and the sizes don't really matter as I can take the slack up as needed.

I need to apply a welder return connection and I think I'm going to use some spare 25mm2 copper cable to wrap round the top of the shaft. There's a little Chinese control module off Ebay wired between the motor and the Makita 18v battery. It has a switch to allow forward, stop and reverse plus a rotary knob to adjust speeds. The motor/gearbox combo output is rated at 7.5 rpm, the different pulley sizes lower this a touch more and the lower battery voltage drops this further. Finally I can use the electronic controller to get the rpms down to as low as zero. The gearbox on the motor means there is plenty of torque even at extremely low speeds. I plonked the 110v transformer on the turntable and everything continues to rotate just fine. It has grunt.

The welds are shoddy and nothing is particularly square. If I can get this to work I might get round to making the frame again properly. The wiring will be fine as it is . I've got a worn old 3 jaw chuck to mount on the turntable. It's not sufficiently accurate to use on the lathe any more but it should be fine for this. I'll also need to mount the positioner somewhere much lower than the bench vice. I may need to make a stand for it otherwise I'll be welding above my head.

Apologies for the busy photos. There's too much stuff lying around on the bench.

 

[brightspark]

slip a brass ring on the top of the shaft and use a flat braded copper battery strap wrapped round on it with a spring tensioner that is insulated from frame and clamp return to that

 

[overload]

I would add a "earth" wire connection from the motor/gearbox to the bench. I've seen a diy positioner that would turn a little every time the torch button was pressed even though the positioner wasn't turned on. Adding an earth connection stopped that.

 

[Richiew]

A little bit more done during the week. I am in the process of remaking the frame properly so it wont fatigue when hanging off a stand for long periods. Anyway here's a little pic following Brightspark's suggestion on here. I do appreciate all comments made on this forum. I'm not sure it is the finished article as I would like a ring with a lip at the bottom to prevent the battery strap slipping down. I might turn it down to achieve this. I thought it was a reasonable first attempt though with a scrap of brass that I had. I am just enjoying messing about with materials right now. Hopefully more to come over the weekend.

 

[Dutch Welder]

You could (I have done it, works a treat) turn down the metal shaft, and sleeve the metal with nylon/delrin material, that way you get the strength of a metal axle, but because the plastic sleeve you can never arc your bearings
(As they are insulated from the metal shaft/chuck/ground strap)

 

[Jim Davey]

A couple of big spring loaded carbon brushes against the back of the faceplate works well for an earth.

 

[Robotstar5]

A couple of big spring loaded carbon brushes against the back of the faceplate works well for an earth.

That's what we used on the automatic positioners in the robot welders.

 

[Jim Davey]

That's what we used on the automatic positioners in the robot welders.

View attachment 133295

Where do you get those from? They look just the job.

 

[Robotstar5]

Where do you get those from? They look just the job.

I did a lot of searching for suppliers, but could never find one

We only ever bought them from the machine vendor - Reiss Robotics, their UK supplier is Olympus Technologies

 

[DAPPH]

Just put " Graphite blocks" into Google & take the china link .... thar's blocks there bigger than a man for sale .

 

[Richiew]

Bit of a thread resurrection but I've got back on with this project. I lost the use of my garage for over a year as it was full of household stuff due to renovation of the house. I did a City and Guilds in TIG at college to keep me sane while the garage was out of bounds. I can now play with all my toys again.

The positioner is bolted to a stand from a bead roller I already had. I just added a plate and used the bolt holes already on the stand. Its not adjustable for angle but I'm not too bothered by that. I could fit an intermediate plate to achieve this. The positioner and motor combined is really heavy so it's nice to have something to hold it. It might be a bit too high depending on what gets welded but I can always stand on something to gain a bit of height.

Spring loaded carbon brush.


I bought some 10mm carbon rod off Ebay. (Have I underspecced this?). I've learned to cut threads on the lathe courtesy of This Old Tony and Doubleboost Youtube videos. Normally your supposed to practice on soft material before making the part of out the real stuff but I did it the other way with a piece of 3/4" steel bar before buying some brass and cutting a 3/4" Whitworth thread. I already had some nuts in that size and the lathe is imperial so the size was dictated to me. I drilled a 25/64" blind hole and reamed it out to 10mm so it is a very close fit. I always end up mixing my units of measurement on a project.

I had to take a little bit off the rod diameter otherwise it would get stuck as the air got trapped and could not escape. There's a compression spring in there to keep pressure on the carbon rod and I can use the thread on the body to take up any major slack. I've no idea if this is enough to get a good earth. I can easily make a second one to double up. Just an excuse to play around and learn some skills. I'll weld the nut to a bracket and weld that to the frame.

It was Baltic in the garage today.

 

[DAPPH]

An aside ..just had a thought that using a brass cup on the bottom end of the shaft and locating the spring loaded carbon brush so it presses into one side of the brass button with a small cup ring cut into it , might be a simple way of transferring the earth circuit up the mounting shaft to the turn table . the whole turn table could be parallel mounted on a ribbed tube ( like a ribbed caravan jockey wheel tube ) frame so that to get a different height you undo the tube clamp & slide the whole device up or down as needed , then re clamp it back up solid . Your comment of is it going to be sufficient . Three or four equidistance spaced such brushes would give a fantastic return path with very little likelihood of any arching / burning

 

[Agroshield]

An aside ..just had a thought that using a brass cup on the bottom end of the shaft...

Have a look at TXSViking on Youtube, one of his recent videos. He shows how he grounds his turntable.

 

[Richiew]

Had some leave booked this week so after doing a few jobs got back to playing around with this.

This cable was bought a long time ago. It's much thicker gauge than the wire coming from the motor so more than suitable.

The forward/reverse switch on the original controller broke but I found I had a spare better specced controller while digging through my electrical bits. I had forgot I'd bought it, it had been that long. The new wiring got soldered and heatshrinked together. Battery connection/power supply is still a work in progress. I don't do much soldering so it was good to practice.

Two sprung loaded brushes welded to the frame. Its a bit of an excuse to use my toys so the one on the right is knurled and I put a hex on the end of the other one using a collet block in the mill. I learned an important lesson that you should clamp off and lock the Z axis on the mill table when doing this. The knurled one is easier to adjust by hand in practice.


I presume they are working as intended but it could be arcing through the bearings. Who knows? Will find out if they get grumbly.

Temporary return connection. The cable was cleared away from the belt after this picture was taken.

In my excitement I didn't tack the pipe to the plate so it pulled something rotten and contributed to a poor weld when it lifted.

First attempt. You can see it going awry as the plate pulls away and lifts as it wasn't tacked down.

Its a 3.2mm 6013 arc rod at 120amps. A bit too much for the material. I am a bit out of practice with stick welding and using a positioner is new again. I am used to setting my own travel speed and welding in straight lines. Will have another attempt with the MIG tomorrow. At least the electrode will sit at the same position when using the MIG.

This is the second attempt. I think rod angle and being out of practice is contributing to a poor weld. It seems to start OK and then fall apart. Travel speed is an issue too, it is hard to gauge. The error accumulates if the speed is only marginally too fast or too slow.

This is a later attempt with a 2.5mm 6013 at 80 amps. Too fast, too slow, and the Goldilocks setting in the middle. Just about.

I think that using the MIG will reduce the human element variable a bit. It is still a bit of a faff as I have to leave the table turning at the start and I don't want to be moving at the start of the weld when generating a puddle. Work in progress. Plenty to resolve yet and just a bit of a play around with bits and pieces. I know its not pretty.

 

[Tigman]

dont matter what it looks like if it works ok !

 

[nickk]

This is a great thread as I’ve been meaning to make one for yonks ,how come you power a24v motor from an 18 v battery,or does it just affect power and speed ?

 

[Richiew]

18v slows it down which is a good thing. I am just using what I have to hand. The motor is geared so there is still plenty of torque. I had the transformer back on the turntable again today to check and it is still turns fine at slow settings. The belt will slip before the motor stalls if I try to stop the turntable.

 

[DAPPH]

I like your slip ring earths … .

I found that mig welding much above elbow height is more difficult than welding at elbow height but having to stoop forward unsupported made me weld like a donkey crapping razor blades after a few seconds .

How's about a simple foot pedal for stop & start & sitting on a high stool to give you more stability for welding . You could also add a wooden arm/body rest to lean on using the blue legs on the upright of the stand as a place to anchor the metal work for it ...also have it so the arm/ body rest can be swung out of the way for access to remove the welded item off the turn table ?

 

[Richiew]

Arm rest is definitely going to be a thing with this. I like to prop myself when welding and as I shouldn't have to move the torch I think it makes a lot of sense. I don't weld very well at all when unsupported. I had considered a foot pedal for this a few years ago. I even bought a motor controller for a kids toy car with a pedal for the motor speed. Never managed to get it to work properly.

I suppose I could splice in an on/off switch into the wiring to activate with my foot. That's a good idea Dapph thanks.
Will peruse Ebay again in the morning. Am a bit gutted as I have just been looking at DC motor controllers again and the usual suspects are now selling them with LED displays for pretty much the same price. They would be good for keeping a record for settings and speeds.

 

[DAPPH]

Could you fit a larger pulley on the shaft of the turntable a smaller one on the drive motor to alter the speed or at least make it run slower ? Do you have a lathe ? If so I have some inch thick or so Delrin round blanks about 8 inches in dia that pullies might be made of . FOC but you pay the postage , PM me if you're interested.


One last thing .. think of putting easily removable covers over anything that can burn whilst you are concentrating intensely on your welding .
I nearly set the whole mancupboard on fire when hot metal blobs melted an orange B&Q plastic bucket and eventually it burst into flames whilst I was about to sit down & have my evening meal ..something made me walk down the hallway to see if I'd closed the roller door , when I saw 15 " high flames … also lost a few bits of burning/burnt Delrin at the same time for they were in the bucket at the time .