Yet Another Cycling Forum
General Category => The Knowledge => OT Knowledge => Topic started by: mrcharly-YHT on 21 October, 2018, 01:08:10 pm
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MsC is trying to learn to arc weld in a hurry.
She's done a bit of mig welding, using fancy kit in her (ex) uni, and is fairly proficient at that.
She needs to weld 3mm strap together for a project.
I have a basic arc welder, so this weekend she came home to have a go with it.
She is struggling to get on with it - finding it so different to the mig, very hard to get an arc. I'm not a welder, only know very basics, not a good teacher and we have run out of time for practise. Wierdly she was doing fine with some rods, used them up, tried some others and just can't get an arc. I thought they were all 6013 rods.
I'm wondering if it is sensible at this point for her to be getting a basic no-gas mig. They seem to be cheap, but not having used them don't know if they would be any easier than my arc welder.
Anyone in London have one of these and can comment or even let her have a go?
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For some reason I think Ham may have welding kit of some description - (but, I could be wrong, and it might not be the kit you are looking for) ???
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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!)
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New rods, so that isn't the prob.
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Firstly, welding with posh kit is nicer and easier than welding with cheap kit.
As long as there is a circuit the arc welder will weld, up the current till it does.
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I do have mig kit, and I'm East London if that would help? I've not used "gasless" mig but mine can do that too (I Think). I just don't have any of the wire. It's this one (https://www.r-techwelding.co.uk/mig-welder-r-tech-i-mig180/) (I just love the fact that it looks like it's LGBT)
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6013 rods are great for clean metal work but 6011 are better if the work is not perfectly clean. If you have to, you can weld rusty or painted metal directly using 6011 rods.
Obviously the current needs to be set for the welding rod diameter and you should expect (current for current) slightly less penetration with 6013 rods than 6011 rods, if that is what you were using before.
A little trick that helps control is to cut rods in half and to use the shorter rods; this is a fair bit easier than long rods, especially if they are skinny ones.
I'm guessing that you have a basic AC set; this should be fine with 6013 rods (and 6011).
Re gasless MIG; in tests I have done, 1lb of wire only contains ~1/2lb of steel to start with (the rest is flux) and much of the steel disappears in spatter etc anyway. You might get 1/3lb weld metal deposit from 1lb of wire. The wire is fiercely expensive (about x5 vs standard MIG wire), feeds less well, the contact tip is more likely to overheat (no cooling gas flow), there is more fume emitted, more spatter, more UV and the fume is more likely to be poisonous than when using MIG or MAG welding. The welds are less good too, despite a higher heat input into the work. This makes it a process that is about the most expensive per unit of deposited weld metal. The advantage is that it is all position and you can weld outdoors even on unclean material. The niche that it best occupies is one of welding fairly thin section material in outdoor repair applications. For pretty much anything else there is a better welding process variant that works easier/better/cheaper/less hazardously.
So gasless MIG might well work fine for your present need but I wouldn't recommend it for every use by any means. Buying a machine that has reversible polarity and will do conventional gas MIG as well would be a much better idea.
Anyway I'd probably try some 6011 rods with the stick welder first BTW.
cheers
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great feedback, thanks brucey. The gasless mig sounds to be an expensive limited use machine (might work out for her sort of artwork stuff though; always going to be small welds on new steel).
She was working on new, clean metal. so the 6013 rods should have been fine. I think it was mainly not having used an arc welder and lack of practice. Cutting rods in half was something she wondered about herself.
I might get some 6011 rods for my own use, since whenever I have to weld, it is on old rusty material.
Ham, that looks like a good bit of kit. I'll have to read a read of the site you linked.
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Ham, that looks like a good bit of kit. I'll have to read a read of the site you linked.
I'm happy to report that appears to be good value, I've had a few bits from them and no complaints. When I was looking I was after something better in the 240v line than the cheap'n'cheerful Clarke boxen, but didn't think I could justify the spend of the pro gear (like what Aunt Maud splashed out on). After much deliberation I ended up with the queer welder (as I like to think of it), it seems well thought of in the wending forums, one reason was the "spool on gun" aluminium option which might be useful in the future. If you're considering don't forget that there's additional cost for the gas. (pm me if you want a 7.5% discount code). Only negative issue I've found with it so far is that the "digital display" for welding is only visible while welding, so effing useless, but as it's all down to "twiddle a bit this way/that way" it doesn't really matter.
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Ham, that looks like a good bit of kit. I'll have to read a read of the site you linked.
I'm happy to report that appears to be good value, I've had a few bits from them and no complaints. When I was looking I was after something better in the 240v line than the cheap'n'cheerful Clarke boxen, but didn't think I could justify the spend of the pro gear (like what Aunt Maud splashed out on). After much deliberation I ended up with the queer welder (as I like to think of it), it seems well thought of in the wending forums, one reason was the "spool on gun" aluminium option which might be useful in the future. If you're considering don't forget that there's additional cost for the gas. (pm me if you want a 7.5% discount code). Only negative issue I've found with it so far is that the "digital display" for welding is only visible while welding, so effing useless, but as it's all down to "twiddle a bit this way/that way" it doesn't really matter.
Am quite jealous, nice welding equipment makes the job easier.
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Ham's machine looks like pretty good value to me. It has a eurotorch fitting and that makes for rapid changes of torch when required.
FWIW I will say that for the money, the Clarke machines are actually pretty good. They use M5 threaded contact tips and the gas shroud nozzle is that bit smaller than most M6 threaded ones (most eurotorches) and that means better access into tight corners, and lower running costs; the minimum gas flowrate can be less with a smaller torch.
The Clarke machines have one very cunning feature that you wouldn't realise is there. It may arise from cost cutting, it may be deliberate; I am not sure. But anyway the two controls are wire feed speed and transformer voltage tapping. Almost all traditional welding power sources have a feature which is called 'droop'; this means that when you draw current the voltage drops slightly. The more current is drawn, the bigger the droop.
Wire feed speed in MIG welders directly affects the current drawn; faster wire feed, more current. In many machines the wire feeder has a separate power supply, so that the feed is as stable as possible. In the Clarke welders they usually have a tiny 12V power supply that just drives the mains relay (that engages the main power supply when you are welding, so that you have a so-called 'dead torch' the rest of the time). However the wire feed motor itself is driven from the main power supply (which delivers the wending current), but the voltage is scaled to a certain fraction of that by the speed control. This means that as more current is drawn, or the voltage tapping is changed the drooping/lower voltage slows the wire feed rate down automatically. This means that there is less fiddling around with wire feed speeds required even when you change voltage tappings. Essentially the heat input per unit length of wire delivered remains more constant than it would be otherwise. It also influences the stability of both the arc and the welding process, probably both in a beneficial way.
So I have owned and used a lot of welding kit, covering a wide range of qualities and costs; however I have always been surprised at how nicely some of the small hobby MIG machines weld; they (like any machine really) just need to be kept in good shape and used in the right way. I would go as far as to say that if you want to weld thin gauge material, some cheap low power sets are actually better than many quite expensive welding machines; there is no delay before the wire feed starts up, and the simple trigger gives fully independent control of the gas flow too; almost ideal for doing tricky delicate work in short bursts.
cheers
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In defence of my extravagance, M'Lud......I just wanted to learn to mig weld in an hour, which is why I went and bought the expensive stuff. Plus it was cheaper to do it myself, even after I bought the decent gear.
It should last a long time, so I'm happy with that.
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If you stick (excuse the pun) with the arc welder, you need to be sure you have the current right. If it's a basic one, I'm not sure how much adjustment you have. Lower current won't penetrate as far (nor will it burn through thin metal so quick) but is harder to strike the arc. At higher current the arc is easier but burns down the stick faster and eats it's way through thin metal rather quick.
Some packets of welding rod have basic ranges for the current suitable for the stick diameter printed on the box, check you are within the range given by the manufacturer and have a play with current settings on some scrap metal if you can.
I've been doing night school which is predominantly arc welding on lovely expensive kit in a nice clean environment but if she can get the hang of arc welding, I've since found MIG welding in the real world to be even easier than it was before.
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'traditional' cheap stick welders output AC and have the simplest controls possible; for example
(https://dccf75d8gej24.cloudfront.net/images/products/01/010110974/4AEAC81D-B423-42FD-821A-EF92124DF4F6-huge.jpg)
this is typical. The big knob in the middle adjusts the current output by a simple transformer; the adjustment is actually performed by sliding an extra piece of soft iron in and out of the transformer core, which affects the total flux linkage between secondary and primary windings, and therefore the output of the transformer.
IME such welding sets work quite well (for hobby uses) if you use them in the upper part of their current range. However IME if you take a 150A set of this type and try to use 'sparklers' (1.6mm rods, which require 20-50A) on thin section material then you can have the most miserable time you can possibly imagine; bird poo, unstable arcs, blow-through, rods sticking, rods wobbling around, you name it. In fact I would go as far as to say it is often 'impossible' to stick weld using this combination, if you are an inexperienced welder.
However is not 'impossible in absolute terms; I have seen skilled welders make really good welds in situations that I have found 'impossible'. The welds look fine, the welding process looked stable etc whilst they were welding but afterwards they will often say 'that was a bit tricky' or 'I wouldn't want to do that all day' or something like that. So I have seen skilled chaps use the thinnest electrodes and they welded car bodywork thickness steels using some crummy hobby welder and they made it look quite straightforward. I have done quite a lot of welding (various ways) and I find the same thing nearly impossible.
Modern stick welding sets are increasingly becoming switch-mode type and these sets output DC. Crucially they behave much better at low currents and are usually easier to weld with at any current. They were quite expensive, but you can now buy a nice switch-mode type welding set for cheap; eg there is one that is sold by Aldi and it costs just £60.
https://www.aldi.co.uk/workzone-inverter-welder/p/085506226214500 (https://www.aldi.co.uk/workzone-inverter-welder/p/085506226214500)
OK it only goes to 80A but this is enough for 2.5mm electrodes. [I have a 'proper' set and it is a similar size but does 200A off a 13A plug; however it did cost a lot more...]
You can often use the same PSU for scratch-start TIG too. I suppose that if a cheap MIG welder blows up you would be able to rebuild it using such a PSU.
Soon the only reason for buying a 'traditional' (AC transformer) stick welding power supply is that for some reason you want to use AC, and/or you expect to leave the thing for extended periods in a damp shed and want it to work when you come back to it. I leave my inverter welding PSUs indoors where the damp won't wreck them.
cheers
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'traditional' cheap stick welders output AC and have the simplest controls possible; for example
(https://dccf75d8gej24.cloudfront.net/images/products/01/010110974/4AEAC81D-B423-42FD-821A-EF92124DF4F6-huge.jpg)
That's my welder.
IME such welding sets work quite well (for hobby uses) if you use them in the upper part of their current range. However IME if you take a 150A set of this type and try to use 'sparklers' (1.6mm rods, which require 20-50A) on thin section material then you can have the most miserable time you can possibly imagine; bird poo, unstable arcs, blow-through, rods sticking, rods wobbling around, you name it. In fact I would go as far as to say it is often 'impossible' to stick weld using this combination, if you are an inexperienced welder.
You've described what MrsC was trying to do.
Hmm. I'm wondering if she needs to get a mig for this job, even a cheap second hand welder.
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cheap secondhand MIG welders are brilliant for learning.....
...how to fix secondhand welding machines.....
All of which stands you in good stead for the future (without doubt) but can be very frustrating if you are just starting out.
A working MIG will be a piece of cake to use but if it isn't quite right and you don't know why....
cheers
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Hmm. I'm wondering if she needs to get a mig for this job, even a cheap second hand welder.
Have only skim read the thread, so this might not be appropriate, but...
might the Black Horse Workshop be a solution? (Either to identifying the original problem or providing use of a MIG welder.)
http://www.blackhorseworkshop.co.uk/about/
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+1 ... the lady that taught me welding there was fantastic. I have her contact info if that's useful.
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Hmm. I'm wondering if she needs to get a mig for this job, even a cheap second hand welder.
Have only skim read the thread, so this might not be appropriate, but...
might the Black Horse Workshop be a solution? (Either to identifying the original problem or providing use of a MIG welder.)
http://www.blackhorseworkshop.co.uk/about/
That would be perfect, Nikki. If it were in Sheffield. . .
I know I was originally asking about London, however there has been a hitch. My daughter needs to make this 'thing' in Sheffield and was originally going to build it at the university. The uni has now said that they will not permit welding on their grounds.
So we are looking for a similar place to blackhorseworkshop, but in Sheffield. I had a search last night, but drew a blank.
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Is she at University of Sheffield?
https://www.sheffield.ac.uk/architecture/about/facilities
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You could try Sheffield Hackspace:
http://www.sheffieldhardwarehackers.org.uk/wordpress/
(Their online info is annoyingly thin, but I spotted a few forum posts about welding and metalwork)
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She isn't at uni anymore - that is probably the problem.
I've messaged the hackspace people. They might know of venues.
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Brucey is right about the transformer welders at low current. The arc is unstable, and you get blow through at the worst times. I had one for years and the only thing I could do with it (with thin stuff) was set stuff on fire!
The little inverter welders are much better at low current, so are definitely a better bet. If you want to do TIG, then it's
worth getting one that has lift start at worst (ideally HF start), otherwise you will blow through your precious argon repeatedly failing to create an arc or sticking the electrode to the work surface (DAHIKT). I ended up buying a large secondhand Murex MIG from a guy who services welders for industry - it meant it was set up properly, came with a regulator for a decent sized gas bottle and had capacity for a big drum of wire. If you are practising, then this website is invaluable - post pictures of your setup and welds and people will help you out and get you on the right path: https://www.mig-welding.co.uk/forum/ (they do TIG and ARC as well as MIG).
No useful information about Sheffield, but if anyone in Oxford wants to play with a MIG welder for some reason (friends of mine built a tallbike in my garage - I've almost finished an Atomic Zombie trike), then send me a PM...
Good luck.
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I built my first 3 recumbents using a stick welder like the Clarke one pictured upthread... ::-)
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Good job none of them were intended to ride a straight line :demon: ;D
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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
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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.
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They aren't meant to get wet first.
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They aren't meant to get wet first.
yebbut life..
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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.
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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.
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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 (https://farm4.staticflickr.com/3319/3441761361_79c0f647d2_b.jpg) (https://flic.kr/p/6f8VK8)My first Cycle Trailer (https://flic.kr/p/6f8VK8) by David Martin (https://www.flickr.com/photos/davidmam/), on Flickr and the passenger is now 6'5".
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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.
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 (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 (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
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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
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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
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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.
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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 :)
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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
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I think I might just continue to borrow my mates ALDI MIG......
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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
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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?
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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
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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.
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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.
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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.
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re 3D metal printing;
http://www.arcam.com/technology/electron-beam-melting/ (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
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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.
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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?
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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.
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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.
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I'd echo what Kim says - particularly that of glue choice when glueing plastics.
Polyprop is notoriously difficult (but not impossible) to glue.
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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.
<dusts off very old metallurgy degree>
One thing I do remember from the course (and from a vacation job where I spent six weeks polishing, etching and photographing some welds in very thick stainless steel pipes) was that no weld is ever perfect. There will always be a weakness somewhere. Part of the skill is ensuring that the weakness is somewhere where it won't matter.
Disclaimer: I have never actually welded anything! This is probably a good thing knowing my general lack of ability with such things.
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I'd echo what Kim says - particularly that of glue choice when glueing plastics.
Polyprop is notoriously difficult (but not impossible) to glue.
I had good results with Techbond 261 when using correx to improve the hairodynamics of The Red Baron. Important thing was getting everything in place quickly before the glue could cool (which is probably another argument for a higher-power gun).
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I'd echo what Kim says - particularly that of glue choice when glueing plastics.
Polyprop is notoriously difficult (but not impossible) to glue.
I had good results with Techbond 261 when using correx to improve the hairodynamics of The Red Baron. Important thing was getting everything in place quickly before the glue could cool (which is probably another argument for a higher-power gun).
You may've seen the tool bottle from my Van Nic
(https://c1.staticflickr.com/5/4912/45519061804_20e4ce90c8_z.jpg)
It's had a ~20mm extension added to one end, which means a bit more storage, and I don't need to have fingers as long as Gollum's, as there is no bottom to this bottle.
That was done by roughing up the mating surfaces, coating them in RS's Polyolefin Primer and running in some very thin cyanoacrylate.
It has held intact since 2008.
No HMG was involved.
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Double-ended tool bottle! Those really ought to be a thing. Or just have the cap at the bottom end, so the small items migrate to it, rather than hiding from Gollum...
And I have now learned that Polyolefin Primer is a thing. :thumbsup: