Author Topic: Welding training troubles (Read 7744 times)

Brucey · « **Reply #25 on:** 30 October, 2018, 08:09:09 pm »

Quote from: Wobbly John on 30 October, 2018, 07:19:34 pm

I built my first 3 recumbents using a stick welder like the Clarke one pictured upthread...

chapeau, sir. I'd describe that as an exercise in masochism at least, suicidal tendencies at worst (depending on the weld quality......

).

MIG welding is so much easier!

Mr Charley; if you do go for a used small MIG welder (eg a clark one from 90 to 150A) it will be cheap but you will have some work to do for sure. I have some top tips for you;

- under no circumstances run even slightly rusty wire through to the torch. This will contaminate the liner and render the set near-useless until the either the liner is replaced or every last speck of rust is gone. It also isn't any good for welding with, either.

- one reason I like the Clarke machines is that they will accept a 5kg reel (or a 0.7kg reel). Not all small machines do.

[edit; just checked in toolstation and a 5kg reel works out half the cost (per kg) vs a 0.7kg reel. About £5/kg vs £10/kg for 0.6mm wire. Most of that wire will end up in the weld, if you are set up right. Gasless wire is ~£25/kg but from each kg you might only get ~400g of actual weld metal, making it over sixty quid a kg (of weld) to use gasless MIG. In practice it is even worse than that because the welds are less good and you end up grinding more of a gasless weld off after you have done it....

]

- despite some folk's worries, I happily run 0.6mm wire in small clark machines; if the wire feeder and spool drag are set up right it causes no problems, and in fact seems to weld better than 0.8mm wire in several respects.

- it really isn't a bad idea to fold up a piece of scotchbrite into a wad and run the wire through that just before it goes into the wire feeder; this dislodges small particles from the wire; such particles are a major cause of problems (like erratic tip contact) in welding

- it also isn't a bad idea to install a cover over the wire spool inside the welding machine. This helps stop contamination of the wire with welding dust and it also helps stop condensation on the wire which is what causes it to rust.

- if you at doing a lot of MIG welding and are tired of mickey-mouse disposable gas bottles, get a proper CO2 regulator and learn how to attach it to a CO2 fire extinguisher. Out of date CO2 extinguishers are virtually worthless, and each have about 2kg of CO2 in. CO2 gas runs hot but this is OK with a low current MIG welder.

- note that if the work is not perfectly clean, welding steel with CO2 is preferable to other gases as it is really MAG (Active Gas) and gives better welds than you might otherwise get, because it not only shields, it actively reduces the weldpool.

cheers

David Martin · « **Reply #26 on:** 02 December, 2018, 06:46:30 pm »

Quote from: mzjo on 21 October, 2018, 01:27:49 pm

Your rods haven't got damp have they? If so trying to dry them off in the oven may help (the purists may not approve but it has been known to work!)

Thought that is what welders did anyway on site to keep the rods dry.

LittleWheelsandBig · « **Reply #27 on:** 02 December, 2018, 06:54:38 pm »

They aren't meant to get wet first.

David Martin · « **Reply #28 on:** 02 December, 2018, 06:56:56 pm »

Quote from: LittleWheelsandBig on 02 December, 2018, 06:54:38 pm

They aren't meant to get wet first.

yebbut life..

LittleWheelsandBig · « **Reply #29 on:** 02 December, 2018, 07:07:23 pm »

When I'm the Resident Engineer, I tend to condemn that sort of work. That seems to concentrate the Contractor's mind to not do it wrong in future. If it is your own work and failure would be non-critical, you can make your own choices.

David Martin · « **Reply #30 on:** 02 December, 2018, 07:33:49 pm »

Indeed. Probably a misremembering of my dad's site work - ovens for the rods were probably to prevent damp rather than remove it.

Anyhow, I have a very minor repair job to do so will dig my MIG welder out and see if I can persuade it to work enough to make one tack weld on a broken mop.

David Martin · « **Reply #31 on:** 02 December, 2018, 08:53:13 pm »

30 minutes setup and take down for a 5 second weld. Not a great weld (I have a 20 year old MIG welder of the Clarke type bought in Norway - this is one of my first bicycle projects

My first Cycle Trailer by David Martin, on Flickr and the passenger is now 6'5".

Brucey · « **Reply #32 on:** 03 December, 2018, 04:20:59 pm »

Quote from: LittleWheelsandBig on 02 December, 2018, 07:07:23 pm

When I'm the Resident Engineer, I tend to condemn that sort of work. That seems to concentrate the Contractor's mind to not do it wrong in future. If it is your own work and failure would be non-critical, you can make your own choices.

Quote from: David Martin on 02 December, 2018, 07:33:49 pm

Indeed. Probably a misremembering of my dad's site work - ovens for the rods were probably to prevent damp rather than remove it.

Anyhow, I have a very minor repair job to do so will dig my MIG welder out and see if I can persuade it to work enough to make one tack weld on a broken mop.

hope the mop repair went well!

Re MMA electrode drying and electrode storage. The necessity for and methods to achieve this vary with the electrode type and its prior history. Of course all flux-coated electrodes are manufactured using a slurry of flux material; they are thus all 'wet' at some point during manufacture and are dried out again before packaging and sale. Therefore nearly all (an exception being cellulose type) electrodes can be satisfactorily dried out again if needs be, provided they have not become damaged through being too 'wet' for too long.

So some electrode types will, once dried (or removed from hermetic packaging) store virtually indefinitely provided the conditions are simply 10-20C above ambient. Others need to be baked out before use and once baked out, need to be stored under stringent conditions and for limited periods of time before they are used.

A good guide is here

https://www.lincolnelectric.com/en-gb/support/welding-how-to/Pages/storing-electrodes-detail.aspx

which claims to be manufacturer specific but since comparable electrodes are made by others the information is largely generic in nature.

more here;

http://www.esab.co.kr/Web-App/Upload/2012/04/05/Storage%20and%20Handling%20Recommandations%20Consumable.pdf

In practical terms for all kinds of general fabrication work and/or DIY projects a bog-standard mild steel rutile flux electrode can usually be stored for months or years in fairly ad-hoc conditions and it will usually be just fine provided it is baked out again as per instructions prior to use. However if the flux itself is spalling off the electrode it is probably no good any more. Similarly if when the flux is chipped off the electrode looks rusty beneath the flux coating, it is no good.

By contrast if the storage and baking requirements for low hydrogen electrodes are not strictly adhered to, the results can be catastrophic.

cheers

trekker12 · « **Reply #33 on:** 05 December, 2018, 01:38:18 pm »

Slight change of tack (welding pun) but how thin can you weld with MMA? I've borrowed a cheap ALDI MIG for repairing my old MGB which is all well and good but I've recently finished a welding course on MMA and actually enjoy it more than MIG, not to mention the fact decent MMA units are cheaper than decent MIG with gas supply.

I'm looking at buying this - partly because it has a TIG upgrade option which might mean bike frame welding in the future - but I'm concerned I'll just blow holes through the car with it, and it's grown enough of those already by itself. All of the forums I read say don't bother and get a MIG but once I've sorted the car I think I'm more likely to use the MMA for all sorts of other things.

https://www.weldequip.com/parweld-xts-162.htm

Brucey · « **Reply #34 on:** 05 December, 2018, 02:30:00 pm »

I have seen MMA used for welding thin sections (like car bodywork) but it is (IME) about an order magnitude more difficult than trying to do the same work using MIG. Part of the reason is that the currents used in MIG can be so much lower whilst maintaining a stable metal transfer regime.

I'd rather bang nails into soft parts of my anatomy rather than use MMA for such work if I had a choice, but that is just me; I would suggest that you try welding some testpieces using MMA and see how you get on.

If you are letting thoughts of 'expensive gas' put you off MIG, don't; you can plumb a C02 extinguisher in as a gas source for peanuts. In my local car spares shop they will sell you a ~5kg bottle of CO2 for about £30. IME this (with a small sized shroud and reasonably careful setup) lasts for about 5kg of wire. You can be doing welding projects every weekend for a year and you may use about that amount of each. In terms of 'useful weld obtained' I'd say it broadly compares with ~10kg of MMA electrodes which means that consumables costs are not that far apart.

cheers

Jakob · « **Reply #35 on:** 05 December, 2018, 05:58:19 pm »

So, my first career was actually being smiths apprentice...and I was, if I may so so, pretty good at welding. TIG, MIG, oxy/acetylene. Steel, stainless, aluminum, I had a knack for controlling the temperature, feed and a steady hand to move the pool along. Arc welding, however....just completely sucked at it.
Granted, we rarely used it, but I would practice every so often and just never got it.

trekker12 · « **Reply #36 on:** 06 December, 2018, 12:08:32 pm »

Quote from: Brucey on 05 December, 2018, 02:30:00 pm

If you are letting thoughts of 'expensive gas' put you off MIG, don't; you can plumb a C02 extinguisher in as a gas source for peanuts. In my local car spares shop they will sell you a ~5kg bottle of CO2 for about £30. IME this (with a small sized shroud and reasonably careful setup) lasts for about 5kg of wire. You can be doing welding projects every weekend for a year and you may use about that amount of each. In terms of 'useful weld obtained' I'd say it broadly compares with ~10kg of MMA electrodes which means that consumables costs are not that far apart.

cheers

Thanks Brucey, It wasn't the 'expensive gas' as opposed to the initial purchase price difference between decent MIG and decent MMA combined with the slightly larger storage space needed for the Mig+gas in my rapidly shrinking bike shed.

I've got one week of evening class left, I might see if I can find some thin plate lying around for a play. I was more thinking that modern inverter MMA units have quite low ampage combined with a thin 1.6mm stick (not that we have them at my class he only stocks 2.5mm). I'll have a play

Brucey · « **Reply #37 on:** 06 December, 2018, 12:37:37 pm »

you can buy 1.6mm rods (aka 'sparklers') loose at my local car spares shop. Highly amusing to work with, not actually terribly useful in terms of getting things welded up. Maybe some on the spot tuition and a decent power supply will enable you to get the best out of them in an evening class, but I am not holding my breath. Car bodywork is ~0.8mm thickness. I shall be interested to hear how you get on.

cheers

trekker12 · « **Reply #38 on:** 06 December, 2018, 12:47:34 pm »

I think I might just continue to borrow my mates ALDI MIG......

Brucey · « **Reply #39 on:** 07 December, 2018, 11:48:54 am »

although I have no great love for them in general, it occurs to me that if you think the bounds of friendship are being stretched too far, and you don't intend to do that much welding, in your case buying a small gasless MIG machine might be an OK choice. Small machines are indeed small (not all that much larger than a MMA power supply) and start from about £70 on e-bay.

cheers

Efrogwr · « **Reply #40 on:** 07 December, 2018, 05:44:59 pm »

I have been told* that the MIG process is "the hot-melt glue of welding"

* I have a not very good opinion of the person who told me this. Is it the rubbish that I suspect it is?

Brucey · « **Reply #41 on:** 07 December, 2018, 09:37:20 pm »

Tarring all the welds made using any given technique with the same brush would be a mistake.

Any welding technique is only as good as the equipment/materials and the skill of the person using it allow it to be. At their best, MIG welds are more than strong enough for most tasks, but are rarely as good-looking as TIG welds, as welded. At their worst, any welds, MIG welds being no exception --especially those made by the inexperienced-- barely qualify as welds at all. Google image searches for 'MIG weld defects' turn up plenty of horrors.

Fortunately if in doubt about the capability of your welding to make strong joints, basic weld faults such as lack of fusion and lack of weld penetration are relatively easy to test for; just run a few testpieces and destructively examine them; strips that are cut from the test welds can be bend-tested and this will soon show any gross faults with the workmanship and/or the weld quality.

It is also worth looking at welds that are deemed to be satisfactory for any given application. For example in commercially welded bike frames it seems it is not deemed necessary to make nice root beads to most welds. Cutting up such frames soon shows this to be so, the weld fillet takes the load in the tube-to-tube joint such as you might find in a frame main triangle, and a pretty nasty-looking lack of root fusion is usually tolerated, presumably because it doesn't see much stress in service.

Years ago I was party to the results of a survey of weld quality in relation to motorcycle frames. Frames from several different manufacturers were examined. Some of the welds looked OK and were OK, some didn't look (and weren't) good either. But some that didn't look that pretty were actually very strong, with consistently good weld penetration and so forth.

Welding engineers rarely use words such as 'perfect' in relation to weld quality; they are far more likely to talk in terms of 'fitness for purpose' and so forth.

cheers

Efrogwr · « **Reply #42 on:** 07 December, 2018, 09:44:38 pm »

Thanks, Brucey. There's some food for thought... I suspect the person who made the statement of great hubris.

I think that your comment about bike frame welds is particularly interesting.

Beardy · « **Reply #43 on:** 07 December, 2018, 09:57:40 pm »

I was talking to a chap a couple of weeks ago who works for a company that manufacture one off and prototypes using mostly CNC processes. However, the firm concerned is now working on 3D printed metal components and he explained that the process they work working with was laser fused powdered metal. But the relevance to this thread is that he said their main competitor was developing a 3D metal printing process that used MIG like welding at the print head. He reckoned that there were pros and cons with both processes and it was too early to say which would become the dominant tech.

Kim · « **Reply #44 on:** 07 December, 2018, 10:09:34 pm »

I fell compelled to defend hot-melt glue. It's easy to work with and can be - iff you choose the right type of glue for the materials you're sticking - admirably strong. That it can be re-melted in situ and sets quickly without all that tedious solvent evaporation rubbish makes it the electronics bodger's choice for good reason.

As in all things, quality tools (ie. proper thermostatically controlled glue guns) and experience make for better results.

Brucey · « **Reply #45 on:** 07 December, 2018, 10:27:35 pm »

re 3D metal printing;

http://www.arcam.com/technology/electron-beam-melting/

results in good quality parts and has been commercially available for about fifteen years.

It is horses for courses; currently available (lower cost) metal 3D laser-printed parts are often 'printed' as a porous structure and then infiltrated with a lower melting point metal afterwards. Technologies that give a fully dense and highly accurate low cost part are the goal and no-one has really cracked it; cheap, dense, accurate; choose two.

cheers

Efrogwr · « **Reply #46 on:** 07 December, 2018, 10:42:31 pm »

Quote from: Kim on 07 December, 2018, 10:09:34 pm

I fell compelled to defend hot-melt glue. It's easy to work with and can be - iff you choose the right type of glue for the materials you're sticking - admirably strong. That it can be re-melted in situ and sets quickly without all that tedious solvent evaporation rubbish makes it the electronics bodger's choice for good reason.

As in all things, quality tools (ie. proper thermostatically controlled glue guns) and experience make for better results.

I agree with your points and with Brucey's.

The trick is to choose appropriate materials, tools and techniques for the job.

I'm currently working on sculptural ideas; a (very) rough model (calling it a maquette is pretentious with a capital F) made from cardboard and tape will serve to showwhether or not I'm wasting my time.

andytheflyer · « **Reply #47 on:** 08 December, 2018, 08:28:36 am »

Quote from: Kim on 07 December, 2018, 10:09:34 pm

I fell compelled to defend hot-melt glue.
As in all things, quality tools (ie. proper thermostatically controlled glue guns) and experience make for better results.

Any recommendations Kim? I've been hovering over buying one for a while but given that the £5 ones must have something wrong with them, but why pay £40? I can work out where the value lies in a table saw, or a router, but a glue gun? Enlighten me? What should I look for?

Jurek · « **Reply #48 on:** 08 December, 2018, 08:33:51 am »

Quote from: andytheflyer on 08 December, 2018, 08:28:36 am

Quote from: Kim on 07 December, 2018, 10:09:34 pm
I fell compelled to defend hot-melt glue.
As in all things, quality tools (ie. proper thermostatically controlled glue guns) and experience make for better results.

Any recommendations Kim? I've been hovering over buying one for a while but given that the £5 ones must have something wrong with them, but why pay £40? I can work out where the value lies in a table saw, or a router, but a glue gun? Enlighten me? What should I look for?

The ones we have at work come through the till at upward of £170.00 - But I couldn't tell you why.
I have a £5.00 one which is probably 20 years old. No moving parts. Still works, every time.

Kim · « **Reply #49 on:** 08 December, 2018, 01:48:34 pm »

Quote from: andytheflyer on 08 December, 2018, 08:28:36 am

Quote from: Kim on 07 December, 2018, 10:09:34 pm
I fell compelled to defend hot-melt glue.
As in all things, quality tools (ie. proper thermostatically controlled glue guns) and experience make for better results.

Any recommendations Kim? I've been hovering over buying one for a while but given that the £5 ones must have something wrong with them, but why pay £40? I can work out where the value lies in a table saw, or a router, but a glue gun? Enlighten me? What should I look for?

I bough a TEC-810 (which I note has gone up to £BloodyHellHowMuch) when my cheapo one broke, on the "if you're replacing a tool, buy a decent one" principle. The main advantage to me is that being a thermostatically-controlled high power heater it heats up *much* faster, which is handy for the little one-off electronics bodges I tend to use it for. Secondary advantages are that it's a lot less dribbly than my cheapo one was, and that it can melt its way through a lot more glue in a given time, with better leverage meaning less hand fatigue (which has mattered to me exactly once, when attaching acoustic foam panels to the inside of my server rack, but I can see is going to make an important difference if you're making up cardboard boxes on a production line or something). Having a long, reasonably flexible (though unfortunately not silicone) power lead, and a blinkenlight to show that the hot thing is switched on are minor good design feature that my cheapo one happened to lack, but can probably be found on low-end models if you shop around.

As with soldering irons, you can get perfectly good results from cheap glue guns, as long as you aren't doing anything too demanding. Quality tools are of course nicer to work with.

TBH, the more important thing is choice of glue, particularly if you're sticking plastics. The stuff designed for polypropylene is so much better (and more flexible) than the generic card/wood-oriented stuff you tend to get from craft shops.