oxford oil cooled oil

[Barking Mat]

Good news.

At this point when I did mine, I flipped over the transformation side, so knobs face down on the bench.

I then cleaned up the faces of the pegs on the rotary switch, as I had a couple of dead selection points on some of the knobs.

 

[Bornfree]

When I was an apprentice I was welding with an old 250 amp cytringham on a Saturday morning, I finished and chucked the old crocodile style rod holder on the bench and it must have earthed out. In my rush to finish I didn't turn off the welder, so Monday morning it was still humming away on 110amps the case was warm but not hot. I would hate to think of the power it used.

 

[brightspark]

A very kind offer but you are a little far from essex unfortunately. With today's fuel prices I could probably buy an ibc full of the new stuff just with the fuel bill

you havent seen the price opf the stuff then what youu have will be fine just put the lid on and get it used

 

[Deltic]

Well I think I shall just keep using the oil that's already in it since it seems to be in reasonable condition.

 

[Hopefuldave]

As long as no-one's allergic, peanut oil is pretty good for the job, a lot of radio hams have used it to cool dummy loads with a kw or more dumped into carbon resistors in a big coffee can.

Dave H. (the other one)

 

[Wedg1e]

Following a PM I went to take a sample of the oil and discovered that assorted members of staff have been using the opportunity to offload their waste car engine oil into the IBC, so it's probably no longer fit for purpose: if anyone wants it to burn we'd still be glad to see the back of it.

 

[Wedg1e]

Further to this... I finished stripping a high voltage tank unit yesterday and found it had 20L of reasonably clear oil that hadn't been sucked out when it was decommissioned.
Out of interest I took a sample and ran it through the dielectric strength tester: it broke down at about 27kV.
Then I sampled the contaminated IBC material (guess which pic that is) - it broke down at less than 5kV, even after it'd been left to stand for the air bubbles to dissipate!
Although the 'clear' stuff is still slightly tinted, 27kV is way more than good enough for mains voltage use so I've offered it to a forum member; if he declines I'll open it up to the forum. Watch this space...

 

[Wedg1e]

Found some more of this oil (not from the contaminated IBC, I hasten to add)... see ad on the For Sale page (when it appears) if you need some.

 

[oldbikedavey]

Looking forwards to getting an HF TigStart 190 for my Oxford Bantam 180, but I'm wondering if there is a way to get a finer welding current adjustment out of the old Oxford.
On the basis that the dinosaurs mostly got it right, are there any pointers to be had ?

 

[zzr1200]

Learn to Tig Weld faster or slower depending on the amount of penetration or burn through of the root weld, is about the best answer you'll get.

Oxford Oil Cooled Welders with clunk adjust, just don't do fine controlled ampages for tig use.....

 

[Erie Fred]

Tie the lead in a knot ?

I know....I have the door in sight....

 

[brightspark]

Tie the lead in a knot ?

I know....I have the door in sight....

close it on the way out then

 

[oldbikedavey]

Learn to Tig Weld faster or slower depending on the amount of penetration or burn through of the root weld, is about the best answer you'll get.

Oxford Oil Cooled Welders with clunk adjust, just don't do fine controlled ampages for tig use.....

Giving copper backing plates a bit of thought...

 

[eddie49]

I'm wondering if there is a way to get a finer welding current adjustment out of the old Oxford.?

In theory you could reduce the mains input power to the transformer primary. That could be done with high-power semiconductors such as TRIACs or thyristors ( a.k.a. SCRs ). The circuit would work in the same way as a "light dimmer".
However, this method is difficult to get right, because the transformer is an inductive rather than a resistive load. Some comments and ideas here:
Post #50

Wire Feed Upgrade

Congratulations on all you've done so far. I have done similar mods myself to several machines and the wire speed mod really does make a big difference. Only thing I had to do was add a couple of resistors to each end of the PWM board potentiometer to get the useful wire speed range more evenly...

www.mig-welding.co.uk

Using Triacs for Controlling Inductive Loads – Homemade Circuit Projects

www.homemade-circuits.com

 

[Erie Fred]

In theory you could reduce the mains input power to the transformer primary. That could be done with high-power semiconductors such as TRIACs or thyristors ( a.k.a. SCRs ). The circuit would work in the same way as a "light dimmer".
However, this method is difficult to get right, because the transformer is an inductive rather than a resistive load. Some comments and ideas here:
Post #50

Wire Feed Upgrade

Congratulations on all you've done so far. I have done similar mods myself to several machines and the wire speed mod really does make a big difference. Only thing I had to do was add a couple of resistors to each end of the PWM board potentiometer to get the useful wire speed range more evenly...

www.mig-welding.co.uk

Using Triacs for Controlling Inductive Loads – Homemade Circuit Projects

www.homemade-circuits.com

IIRC SCR's make allot of spikes, would the old xformer be able to handle it ?

 

[eddie49]

Running at only 50 or 60Hz the switch-on spikes will be small, and slowed by the inductance of the primary. There may be ringing as the control device ( TRIAC or 2 x SCR ) turns-off at the zero-crossing point of every half-cycle of the AC waveform. I do not think this will bother the thick primary winding of the massive transformer. Perhaps it could damage old and weak insulation on the wire, or hurt the semiconductors. For the latter, a snubber ( e.g. 0.1uF in series with 100 Ohms ) would provide protection.

 

[zzr1200]

Looking forwards to getting an HF TigStart 190 for my Oxford Bantam 180, but I'm wondering if there is a way to get a finer welding current adjustment out of the old Oxford.
On the basis that the dinosaurs mostly got it right, are there any pointers to be had ?

Oldbikedavey, also wants to use a HF TigStart 190 Unit, which also could be effected by the input from a input voltage choked transformer

 

[oldbikedavey]

All food for thought, and thanks or the contributions.
I'll just set the thing up as is, for the time being, and see how it behaves.
Crossing bridges when you come to them is usually wise, but it's nice to be aware of them in advance .

 

[oldbikedavey]

Fired it up today , using the downstream rectifier arrangement, as a DC MMA setup on both electrode positive and electrode negative in their turn.
Fincord M 2.5mm rods at 65A and 50V laid pleasantly controllable beads of expected height differences, and excellent slag removal characteristics..
Aluminium MMA rods may soon be incoming....
Not a super pretty weld, but likely to be strong, effective, and easily accessible....

 

[Farside]

Related to the OP in this thread, in case anyone's still looking for a source of transformer oil.

Transformer Oil Uninhibited same as Shell Diala B

High Grade Mineral Transformer Oil Suitable for use in Power Transformers, Distribution Transformers, Circuit Breakers, Oil filled switches, Submersible Electric Motors, Pumps, X-ray equipment, Crypto Miners where a highly refined mineral insulating oil is required. Offers excellent dielectric...

www.westwayoils.co.uk