Help required - Project TIG Table

[Hybrid_From_Hell]

Right

I wnat a rotating TIG welding table, only probs is they are VERY Spendy.

Been looking on ebay for year+ now, little turns up, what does is either HUGE or spendy .....

So, thinking of making one ??

I have thouight about this, problem is going to be getting a Single Phase motor to turn at a slow enough speed, so I was thinking of a single phse motor and then a reduction gearbox, but am having trouble getting this idea to come together at all !

Help would be good.

MUST be single phase, wnat the end roat5ional speed to be adjustable, say 0.5 - 12 RPM ?

HELP, links thoughts and suggestions welcome !

One of my more mental outside the biox thoughts was to use a train set transformer with adjustable output - like this :

http://www.ebay.co.uk/itm/HORNBY-OO-GAUGE-R965-CONTROLLER-AND-TRANSFORMER-GREAT-FOR-TRAINSET-L-K-/221245328593?pt=UK_Trains_Railway_Models&hash=item33833fccd1 but my little warped brain is struggling to think what sort of table this could control ??

Nige

[CwazyWabbit]

Have you thought of maybe using a DC motor as varying the speed on that will be easier.

EDIT: .... and cheaper

[FridgeFreezer]

You can buy rotary tables for £cheapish from people like Chronos, or something like this: http://www.ebay.co.uk/itm/CNC-Router-Rotational-Axis-the-4th-Axis-A-axis-for-the-engraving-machine-4-jaw-/251289785620 plus something like this to control it.

If you just want it to turn at a slow speed then you need to work out how many torques you need and bodge up some sort of motor to drive it. If you can gear it down then you get away with a smaller (cheaper) motor, potentially a noddy low-voltage DC motor with speed controller from Maplins or eBlag.

[CwazyWabbit]

Also adding something like the brushes from a starter motor to ensure the welding current doesn't go through the bearings .... but I'm sure you have thought of that.

BTW Does your TIG use HF at all?

[Hybrid_From_Hell]

HF Start yes !

What about the guts out of a Microwave + some means of slowing it down ?

I did wonder what the risks are with me adding a TIG torch through a electriclaly rotating doodah ??

??

Nige

[CwazyWabbit]

IIRC you can end up with the HF start stalling the table due to it interfering with 'stuff' so a strategically placed capacitor or two may also be required. I'll have a chat with me father this evening see if he remembers from his years of TIG welding.

I'd guess that a microwave was using a small synchronous motor so you have to alter the mains frequency to slow it down .....

[zardos]

My thought are to adapt a pillar drill.
Turn it upside down.
Weld a rod to a flat circular piece of steel, mount in the chuck.
Get a scrap drill for some additional stepped pulleys, so you can step down the gearing more.

As the motor is isolated from the table by rubber belts electrical interference should not be a problem.

[steve b]

What about an old leccy window motor with a pulley/belt reduction to rotating table and a variable resistor type thing .

Then a brush contact for your earth and away you go....

With good bearings you shouldn't need many torques , belt and pulley off an old washing machine for good reduction and maybe mount turntable onto a LR stub axle / hub etc

cheers

Steveb

[Cynic-al]

Can't believe you've posted this now, there was an auction that ended last week in S****horpe with dozens of new industrial drives and reduction gearboxes that went for very little money. They would've been ideal as there would've been no backlash.

That aside I have a really nice one here that used to be part of a robot welding station (we wanted the robot and the table came with it), all the drive has been removed and we just use it as a manually rotating table for welding. You can't have it but I can take photos for you of any part if that would help your thinking process!

[zardos]

How about just a stripped down washing machine

The motor is already speed adjustable and reversible, cut the drum off leaving just the back plate for the table, it already has the bearing mount and just lay it on it's back
replace the electronics to get better speed control.

[CwazyWabbit]

I can just see the story now...... well I accidentally knocked it and ended up on the 900rpm spin cycle.....

[CwazyWabbit]

[CwazyWabbit]

How about this one? Using a cordless drill for the variable speed

[simonr]

Nick & I made one!

The issue in addition to wanting it to turn slowly is that it needs to have fine adjustment, be reversible and needs to maintain the speed accurately.

Our solution was to use a big old right angle drive gearbox then make a boss for the output to connect to an old lathe chuck. The gearbox is a worm drive with a ratio of about 10:1. As an alternative, you could use something like one of the little ATV winches - Superwinch X1 for example which can be had for about a fiver at Sodbury and replace the motor with a stepper.

The gearbox is as much to provide a solid base as for the reduction.

I used a big-ish stepper motor to drive the input and a stepper motor driver:

We used one from this company: http://www.greenwichinst.co.uk/products/GSM2

They used to sell one for Bipolar Stepper motors, but seem to have discontinued it. This one will only drive a unipolar motor (so make sure you buy the right sort!)

Eg: http://www.ebay.co.uk/itm/Stepper-Motor-11-50mm-Price-for-1-Each-/390566808043?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item5aef9889eb

It has a preset potentiometer on the board - I just removed this and replaced it with a panel mounted potentiometer on the control panel.

There is provision for a direction switch and a Full / Half step switch. You don't have to worry about what half or full stepping is, suffice to say, if you put it in full step, the motor speed doubles.

Put the whole lot in a box with a 12v (old laptop charger) supply - and you have a very controllable, accurate manipulator.

Instead of a commutator, the spindle that the chuck is attached to is long (and smooth) enough just to clip the earth clamp on to.

As you can see - it's had a LOT of use!

The board Fridge posted at the top looks a simpler option - just using accelerate / decelerate buttons - and it controls bipolar and unipolar motors. I tried one like that (but not the same) - but it quickly let the smoke escape. The Greewich one, though more expensive has been bulletproof.

Si

[Anderzander]

How about potters wheel and you build up your calves ?

[CwazyWabbit]

How about potters wheel and you build up your calves ?

That could get confusing, pedaling with one foot and using the TIG foot pedal with the other

[dirtyninety]

hows about using an air ratchet, connected with a long extension to a lathe chuck. No need to worry about electrics, you've already got a meaty air supply, reversible, speed controllable with a simple valve and flow meter and you can remove the ratchet for other uses as well!

[CwazyWabbit]

IIRC you can end up with the HF start stalling the table due to it interfering with 'stuff' so a strategically placed capacitor or two may also be required. I'll have a chat with me father this evening see if he remembers from his years of TIG welding.

....

Spoke to my father and turns out that he has a far better memory than me

It wasn't HF start causing the problem but it was the AC when welding aluminium (they used syncrowave machines). It caused interference with the electronic controls on the welding positioners they used (these were commercial positioners not home made). So it seems going ghetto could be the way to go if you are doing ali welding

[TheRecklessEngineer]

I'm surprised no one has mentioned a windscreen wiper motor.

Again, all the advantages of DC drive (infinitely variable, reversible etc) and a big speed reduction built in. And cheap from a scrappy!

I have actually seen windscreen wiper motors used in industrial machines.

[dirtyninety]

I'm surprised no one has mentioned a windscreen wiper motor.

Again, all the advantages of DC drive (infinitely variable, reversible etc) and a big speed reduction built in. And cheap from a scrappy!

I have actually seen windscreen wiper motors used in industrial machines.

The corn auger system used in our milking parlour is actually powered using volvo lorry wiper motors!

[simonr]

I'm surprised no one has mentioned a windscreen wiper motor.

Again, all the advantages of DC drive (infinitely variable, reversible etc) and a big speed reduction built in. And cheap from a scrappy!

I actually used one to turn a rotary table. The problem was with low speed control. Even with a PWM speed controller, at low speed it had so little torque that it stalled intermittently.

Fortunately, the job on the rotary table I made it for (making dies for a tube bender) needed it to turn at a reasonable speed.

The stepper has a big advantage that the torque is the same regardless of speed - so you could run it at 1 rev per year with the same reliability as 1 rev per second.

With a stepper motor the table was much more reliable! I then upgraded it to a servo system where the controller delivers as much power as is necessary to achieve the demanded position. They can deliver more torque than a stepper with higher precision and speed but at the cost of complexity (and cost).

For my money, a stepper motor gives the best compromise.

[CwazyWabbit]

Could you not connect a windowscreen wiper motor through a second windscreen wiper gear box to increase the reduction and then drive it with a PWM controller? ......

[integerspin]

Make the table from an old flywheel and cobble together a motor to drive the ring gear?

I needed a new handle for my bead roller and couldn't find a steering wheel, hanging where

I had put a steering wheel was a raro flex plate. So the bead roller got a flex plate put on it,

it would be rude not to motorise it now.

[Hybrid_From_Hell]

^^

I like that idea !

I have a old flywheel or 6 about the place, prob have a knackered Starter motor too, and I was thinking I could machine a stub axle so I could then have a base with a LR stub + wheel Bearing mounted under a Flywheel, so close to the bench surface, take the engage gear off the starter, machine a shaft and then use this to drive the Flywheel around.

As to how to power it, erm, that involves electricity, er, which is not my strongest point ?

Thinking I could get a old cordless drill, rip guts out and mount with a adjustable screw instead of the trigger ....but how else could I do this maybe better

the attrcation of the flywheel + starter dog + Stub Axle etc = Its Free ! and shouldn't take an age .....

so, motor type, power how and adjust speed how ?

Would prefer something non battery powered, but at least if its battery can't electicute meself (so easily)

??

Nige

[Cynic-al]

If its a 12v drill a PC power supply will usually do around 7 amps and your bound to be able to get one for free. They're soft switching too so you just short two of the wires on the big connector for on / off ('tinternet will tell you which ones). I've had one running a water pump in the garden for ages and its been perfectly happy. Some don't like no load so stick a resistor or a bulb or something on the 3.3v or 5v line.

RE the drill speed control if the trigger is just a variable resistor you could swap it for an unsprung rotary one, just stick a meter across it to find out what resistance it is.