Welding and Cutting Equipment (Updated 27th January 2017)

Oxford 120s MIG Welder

There seem to have been a lot of English welding equipment makers over the years, Oxford being just one of them. Probably best-known for their chunky oil-filled arc ('stick') welders, at some point they found time to make MIG sets as well, and this is one of them. Probably classed when new as a 'light industrial' unit, the MIG 120s dates from the 1980s. It had lain in a mate's garage for some years in a faulty condition, having been given to said mate by his brother who couldn't fix it. As the brother worked for a welding hire company I suppose he thought it was probably scrap, but as I got it for free I thought it was worth a look!

In the event it just needed a couple of new relays and has proved to be a reliable piece of kit. I added a cooling fan under the main transformer (copper-wound, none of that modern aluminium rubbish here!) and, when it was pressed into service for a job at work, the boss insisted that I buy a new torch for it! I stripped most of the outer paintwork off and repainted it but apart from the cosmetics, it's a nice enough unit. I keep it supplied with CO2 in pub-sized bottles and it accepts wire spools up to industrial 15Kg size, which is handy. As it's a 'proper' MIG set it has a 'Euro' connector so the torch can be detached and stored when not in use (it coils up under the side panel)... but one tradeoff of the copper transformer is weight: it's a bit of a heave to get it in and out of a van!

MIG 120S

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Oxford MIG300

I must be mad ;o) It's not as though I don't have enough welding gear - or, for that matter, that I use any of it much! - but I hate to miss a potential bargain... so when one of the guys over at mig-welding.co.uk stuck his head over the internet's parapet and offered his faulty Oxford 300 for sale, well how could I refuse. Dating from 1987 and clearly part of the same range as my 120s, the MIG300 can provide up to (obviously) 300A of welding current - from a single-phase (albeit massive) supply. The data plate proclaims it to be able to make 225A at 100% duty cycle! The set had a blown rectifier and was also seriously full of crud: the dust and debris in the wire spool compartment was so thick that I discovered the original instruction manual buried under it! Paint had been spilled over the welder and it was generally in a dishevelled condition. I searched the entire world (well, that's what it felt like) for a new rectifier and in the end bought one from Technical Arc Services in York - a snip at £38 with postage. I was being sarcastic there, about it being a snip, just in case you missed it. Still, it was cheaper than the Ebay comedian who wanted six quid for the diode... and £95 carriage from the USA! Here's the 300 after I made the front panel legible again (at the expense of some of the lettering, unfortunately):

The ammeter glass was missing and the movement full of ferrous debris; once I'd blown it clean it seemed to work OK. The voltmeter worked fine and a quick check against my AVO multimeter showed it to be reading within 1 volt of the actual current present at the torch on all 18 voltage steps. The spot and stitch functions worked fine; the wire feed ramped up and down nicely and once I'd borrowed the torch from the 120 and plumbed-in some Argoshield, I was able to lay down some nice test beads. I couldn't get it anywhere near maximum poke of course, from the household supply (it takes 60A flat-out) and anyway I'd need bigger wire, but it was well worth saving. It came with a large torch but the shroud was missing, hence using the 120s torch. I blagged a free shroud whilst buying a load of other stuff and when I found a job at work that needed the grunt of the 300, I bought some new torch tips and made up a heavy earth lead. The set may be old but welds beautifully... however [mid-2016] I ended up selling it as it just wasn't getting any use at all. We had a bit of a mouse invasion and having found nesting materials in all manner of spaces I took the 300MIG's cover off to check for invaders (none found). Once I'd dragged the set out I realised I'd used it about three times so decided the time had come to part with it. A chap from a few hundred miles away wanted one so badly he bid a lot of money on Ebay, so much so that I thought it was a hoax but sure enough he turned up, counted out the twenties and off went the Oxford to a new life.

Here's the 300 alongside the 120, for comparison (note that paint spilled down them seems to be a common theme) :

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SMP 170A TIG Welder

SMP are (or were) a supplier of welding-set test and calibration equipment. Based in Kidderminster, they evidently decided to move into selling welding sets as well and started advertising this unit on Ebay in mid-2005. So I bought one! :-D

Why? Well, I've always fancied being able to make 'stuff' from aluminium, but of course welding it is a black art and requires an AC-output welder. I started by trying to find a used unit at local auctions, then moved on to Ebay but it seems that decent branded kit fetches top money regardless of age or condition.

There are any number of DC-only units on the market now, especially the inverter designs which tend to be cheaper - Ebay is awash with Chinese-built inverter units. Once I realised I was going to have to spend a lot of money to get an AC-capable machine, I thought I may as well buy a new one, and the SMP fitted the bill.

Close inspection reveals the 'cottage-industry' construction of the welder, but it's presentable enough. Interestingly, the welder bears more than a passing resemblance to the products of Portamig, which are built in York by a specialist manufacturer (Technical Arc Services) on Portamig's behalf, so I suspect that the SMP unit was built under a similar arrangement (I believe Oxford welders are now also made in York!).

The welder can take full-size Argon bottles as shown. SMP supplied only the basic necessities of regulator, TIG torch, earth lead and a few tungstens, so I added a stick torch, assorted tungstens and various spare ceramics, collets etc. for the TIG torch. I've also built a foot pedal (to control the output while you weld) because I thought SMP's £125 was a bit steep for a case, a switch and a 1K pot! At the time of writing I can make two bits of aluminium stick together, but I wouldn't call it pretty. As the welder will run as low as 10 Amps it's possible to weld very thin steel; a rule-of-thumb is one Amp per thousandth of an inch, so 10 thou" or about 0.25mm! The set was ten years old when it suddenly stopped generating HF (to strike the arc)... if I 'scratch-started' the weld it worked fine, so at least I knew what the fault was. I stripped the welder down and traced the entire circuitry, in the process identifying a blown semiconductor and and open-circuit resistor. The power device was easy to identify but the resistor lacked any markings so I tried calling the manufacturers who were as unhelpful as they could be and declined to give me any information, instead suggesting I pay them to fix the thing for me. In the event I guesstimated the sort of value the resistor would have to be and obtained a few to try; on the second attempt the HF kicked in and worked perfectly - and has done ever since.

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Even more welding gear! :D

You know how it is: you're browsing a welding forum and spot someone flogging some welding sets for scrap value. So you jump in the van and nip over, thinking you might buy one of them, but when you get there the seller tells you he needs the space and you can have two for the price of one. Well, what's a chap to do? Thus it came to pass that I acquired a Romarc 200 MIG and a Portamig RL35swf wire-feed unit. OK, I concede the wire-feed is not much use without a power-pack... but having poked a few test voltages into it I've worked out what it's supposed to do and it all seems to be working as far as I can test it, so I'll bung it in a dark corner until I come up with a plan.

I've sorted out the wire feed issue and a few other glitches that the Romarc had and it too seems to be working fine! As of February 2016 it's proven to be a useful set; with 16 output current steps, stitch- and spot-weld functions. As to weight: I thought the Oxford 120 was heavy, but this thing needs a ramp to get it in and out of the van, and that's without a gas bottle! I deduce from various markings on both Romarc and Portamig units that they were made in York: the name Technical Arc Services just keeps on appearing...

 

I picked up a couple of heavy-duty 4m MIG torches from another forum user having a workshop clearout. They're Parweld types I think; both have 'issues' - one's missing the liner, one has no O-rings and so on. One of them had a bent spring-pin connector (one of two that connects the torch trigger to the electronics). I tried to straighten it but it snapped, so I extracted the broken bits, measured it up and made a replacement on the lathe. Quite entertaining trying to drill a 1.5mm hole into a piece of brass 2mm in diameter! No doubt they're off-the-shelf somewhere for pennies but hey, what's the point of owning a lathe and not using it?

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Plasma Cutter

I occasionally visit a certain forum aimed at DIY welders. Some time back, one of the contributors was having a workshop reshuffle and offered his plasma cutter for sale. As I had one on my 'wishlist' (see bottom of page!) I thought I ought to at least consider it. So I did. For about half a second; then I emailed the guy, made an offer and became the proud owner of an Oerlikon Citocut 10i plasma cutter :D

 

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Bosch Cut-off Disc ('chop saw')

Of course if you're going to weld stuff together it's always useful to be able to cut the material to the size you need and after years of persevering with angle grinders I finally bit the bullet and bought a chop saw. Via Ebay, where else. It came from a small company that made aluminium window frames and was used on-site a lot, hence the scratches and scrapes. However the brushes had plenty of length remaining and the motor sounded smooth enough... and several years on it still works fine.

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Vertical Bandsaw (maker unknown)

Yet another Ebay find, the bandsaw is an old cast-iron monster that will probably see very little use - but which will also probably prove to be indespensible for certain jobs (like chopping up 12mm alloy plate!). I bought it from a firm in Leicester that makes plastic mouldings; this was their first bandsaw, bought 'used' in 1972 and used in their toolroom till it was squeezed out by successively bigger units! It's not exactly small at 5' 6" high, with a 22" x 38" footprint. I had to lose a workbench just to fit it into the workshop. Nor is it light: although I manhandled it out of the van and into position by myself it's all cast iron - the table alone weighs 25Kg! The saw came fitted with a HUGE 3-phase motor which I reckoned was worth the price I paid, by itself. So it went back on Ebay... and sold for a quid! Oh well... :-D

As I expected it uses now uncommon-length (108") saw blades but there are a few places that can make them up - I got the most recent ones from justbandsawblades. The drivetrain uses a 4-step pulley to give different blade speeds. The drive shaft runs in BIG bearings that have no play; once I'd cleaned all the sawdust off the machine I used the Stauffer lubricator to add grease to the bearings; also all the slideways for the upper wheel adjustment and the motor belt tension were oiled. There's a chunk out of the rubber coating of the drive wheel but it doesn't seem to affect the blade's running as there's so much of it in contact at any one time (the wheels are 15" diameter). It looks as though the original wire guards have been supplemented over the years, with sheet alloy and plywood covers; probably to keep the sawdust down. No maker's marks anywhere on the unit although the lubricator was made in Leeds! I found a large 1.5hp single-phase motor that runs the saw OK; I just had to TIG-weld some mounting brackets to make it fit the sliding mounts on the bandsaw (used to tension the drive belt). The pulley set has a 1" bore whereas the motor spindle is 24mm, so I packed it out with some shim steel and left the grub screw slack till the running belt had pulled the pulleys into correct alignment.

Once I'd finally got the motor fitted I turned my attention to the installation of the blade. I realised that the only way the saw was usable in the space I had available was to run it with the blade the 'wrong way' round - the work needs to be fed in from the left of the machine whereas the blade guide assembly is obviously intended to support a blade with the teeth on the other edge! Although I found that without any support I could still cut thick plate, the blade would eventually jump off the wheels, which one day resulted in the blade snapping as it snagged. I made a new blade guide that supports it using three small sealed ball-bearings and now I can shove stuff merrily through without incident - especially Acetal, where the blade goes through even 30mm thick stock as fast as you can push it. Just need to practice my blade-joining technique now...

I did some maths and worked out that from a motor shaft speed of 1430 rpm and with the pulleys giving (approximate) drive ratios of 0.56:1, 0.78:1, 1.27:1 and 1.77:1, the drive wheels will spin at 804,1122, 1818 and 2541 rpm which means, given that the wheels have a 47" circumference, linear speeds of the blade will be around 968, 1346, 2180 and 3050 metres per minute. Whatever it is, the slowest speed fairly rips through thick alloy plate! Having worn out a couple of blades 'dry'-cutting alloy and steel I think I need to look at adding some kind of coolant system; the first blades I bought were a fiver each but now they're more like £15 each, hardly disposable.

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Peddinghaus Guillotine

Oh look: another freebie! A customer was having a clearout and this was propped against a skip. You get nothing unless you ask, so I did and here it is. Although it looks a shade rough the blades are undamaged and it works fine... although at the moment I have to resort to clamping the guillotine in the bench vice to be able to get any leverage on it! Good job I built that bench heavy...

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Lesto GEG1 Electric Shear

I inherited this from my dad; back when he ran his own business repairing cards, one of his customers acquired it for him to speed up the production of repair panels for those rusty old heaps that the British car industry produced. Prior to that he'd made them the hard way, with Gilbow manual shears. I'm not sure how old it is but it was second-hand in the early 1980s! It still has its original box and the rubber cable is still in good condition... this dates from when electric tools had metal casings and could electrocute the unwary user if the wiring was faulty. So far, so good...

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Belt and Disc Sander

Typical cheap Chinese-made thing once sold by B&Q I think, this one dates from 1997 and hasn't been too bady abused. The disc table is a bit flimsy and the motor has less power than a ladies' bedroom toy but it does what it's supposed to... notwithstanding the missing belt release lever!

 

Sealey Metal Bender

Bought from a fellow forum member over at migwelding.co.uk, I thought this might be a useful bit of kit... although a year on and I don't think I've bent anything with it yet! It's one of these.

Mine came with a fabricated bracket to allow mounting it on a convenient wall pillar rather than a bench:

 

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