Miniature welding

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Miniature welding

This topic has 48 replies, 22 voices, and was last updated 5 March 2012 at 13:04 by jomac.

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8 January 2011 at 08:31 #61978
Paul Boscott
Participant
@paulboscott25817
To more accurately represent the machine I am trying to model I would like to be able to electric weld some of the steel parts together. In particular a fillet of 1.5 mm when joining a piece of 1mm sheet to a 4mm plate. Has any one any experience achieving this.
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8 January 2011 at 08:31 #15499
Paul Boscott
Participant
@paulboscott25817
8 January 2011 at 09:15 #61980
JasonB
Moderator
@jasonb
I’ve seen thinner plate tig welded together with very small fillets.

The other option would be to do as the armour modelers do and use either an epoxy or liquid plastic to form dummy weld seams thats assuming its all going to be painted.

J
8 January 2011 at 10:51 #61983
Nicholas Farr
Participant
@nicholasfarr14254
Hi Paul, it will depend on your welding skills. I’m not sure that I could achive it myself as most of the welding I’ve done has been on 6mm plate upwards, and I think I’d need a little more dexterity than I have got now. The problem you have is being able to get enough heat into the 4mm while not over heating the 1mm. As the 4 mm will tend to chill the weld quickly, preheating the whole job, even if it is only 60 to 100 degrees with a hot air gun will help. As Jason says TIG is one way of possible achievment.

Regards Nick.
8 January 2011 at 11:03 #61985
Howard Jones
Participant
@howardjones35282
the results are quite variable, quite problematic, but you can arc weld these sizes.

2 mm welding rod, around 60 amps or less on the electrode and an angled rod

if the metals are perfectly clean. you’d need a fairly practised hand.

however a damp rod, slightest hint of oil on the surfaces and you will go insane.

as the guys suggest Tig is a gentler weld. ask whaterver the PFA have become for the name of a nearby aircraft welder if you or a friend cant do it.
8 January 2011 at 11:11 #61988
Terryd
Participant
@terryd72465
Hi There,

Why not soft solder? That will create a small fillet, or silver solder and create a fillet with a filler such as Milliput. Once painted it will look authentic. In my experience you will have a problem creating a small fillet with welding, even with tig. Aside from the difficulties already mentioned it doesn’t scale down.

Regards

Terry
8 January 2011 at 11:39 #61991
Chris Trice
Participant
@christrice43267
I don’t think the fillet he’s after looks like the smooth fillet you get from either soft or silver solder. Welding only produces a molten pool in a tiny area at a time and the finish is more akin to oil paint applied with a pallet knife or squirted straight out of the tube. Is the model functional and/or likely to get hot or is it purely for show? Artists tube acrylic paint squirted through a syringe is good for faking weld seams in miniature but obviously the scale of the model dictates the application method.
8 January 2011 at 11:48 #61992
Ian S C
Participant
@iansc
    An uncle of dads, worked at Bletchly Park during WW2, he told me that for making valves (radio) for the computor the welded them using darning needles. Apparently they went all over that part of the country, buying every needle they could find. I think they used batteries as a power source, don’t no the voltage.

    I have had some very thin (.007″)stainless TIG welded, it requires minimum power on the welder, and a sharp point ground on the tip of the electrodes, also a steady hand. Ian S C
8 January 2011 at 12:21 #62000
Terryd
Participant
@terryd72465
Hi Chris,

I have considerable experience of MMA, MIG and gas (oxyacetylene) welding (I began with MMA during my apprenticeship in the early ’60s) and although not particularly highly skilled I can produce welds with very small ripple which would be almost unnoticeable when scaled down to the extent Paul intends. I have welded 20 gauge (0.91mm) sheet using MMA with 16g rods but was unable to produce anything smaller than a 4mm fillet in order to achieve decent weld penetration. Also I doubt if welding materials such as 1mm to 4mm ms would be possible with needles as there would not be enough heat generation to penetrate the thicker materials. You don’t get material that thick in a thermionic valve.

It is possible to weld materials of dissimilar thickness by aiming the heat source accurately so that it is directed more at the thicker material, the angle depending on the actual thicknesses, but it takes quite a bit of practice to be successful.

Hi Paul,

What scale are you working to as that will affect the welding method for example down to 1/4 scale the weld ripple may be noticeable but at 1/10th it would not be discernible, especially if the original was painted. Also are the materials to be fillet welded at say 90 degrees or are they to be butt welded flat? This would affect the method used.

Best regards

Terry
8 January 2011 at 12:52 #62002
John Stevenson 1
Participant
@johnstevenson1
Perfectly doable with TiG,

It sounds a big difference but 1 mm to 4mm isn’t that far out.

One point to take into account is the advances made in recent years with welding products as they have moved from the older transformer based machines onto inverter based machines with oddles of electronics inside, square wave, pulse, arc boost, ear of bat etc.

Unless you have used the latest machines you just can’t compare, as an example I have a 12 year old TransTIG 200 amp machine here, bought new and never put away wet.

I could weld that 1mm to 4mm but it would have a pronounced fillet.

I recently invested in an inverter 200 amp machine and using this is like night and day compared to the Transtig to the point the transtig is there only as a backup machine.

A while ago the body shop across the road came in with a flexible pipe assembly, alloy block with two alloy pipes coming off then went into flex pipes, then back to alloy and onto two separate blocks. This was off an air-con pump of one of their curtsey cars that had had a bump. A new pipe assembly was part of the pump and was £800 and they would have to stand this.

One alloy pipe was broken clean off on a 90 decree bend and could I weld it back?

Pipe was 13mm diameter and 30 thou thick, seeing as it was scrap I couldn’t do anymore damage and they accepted this.

Played on a bit of scrap sheet to get settings and set the TiG to 22 amps and welded this pipe all the way round, not very neat but I was frightened of allowing it to collapse and close the hole up.

No way could the Transtig have done this.

John S.
8 January 2011 at 13:12 #62008
Nicholas Farr
Participant
@nicholasfarr14254
Hi Terry, oxy-acetylene, I used to like that method, and still do now and again. My advanced gas welding exam was a 60 degree 1-1/2″ into a 3″ pipe stab with about a 4mm wall thickness, in the overhead position, on a red hot summers day, phew! It was set up by the examaner and you were not allowed to move it at all.

Although it has a high heat input into the whole job, I’ve always found it the most controlable weld method. Of course one of the disadvantages is a large amount of distortion on thin metal, due to heating of the HAZ (heat affected zone) being broad, compared to electric arc methods. This can be overcome in a lot of cases by keeping the heat input as low as possible and peening the weld afterwards though.

Regards Nick.
8 January 2011 at 13:20 #62010
JasonB
Moderator
@jasonb
Its surprising how small the weld will still be visible, as I said the Armour modelers add weld detail and this is typically on 1/35th scale models, granted they were big weld seams but pauls structure is quite a size as well.

I Think I would join the parts with silver or soft solder as Terry said and then add the weld detail afterwards, that way you can get a good structural joint first and then worry about what it looks like later.

The small weld seamd that I said I’d seen were done with a modern TIG welder as JS mentions, wish my welding was as good

Jason

Edited By JasonB on 08/01/2011 13:22:15
8 January 2011 at 13:35 #62011
John Stevenson 1
Participant
@johnstevenson1
You can always bodge it !!

I think enough time has gone by now for the statute of limitations to run out

Years ago we were responsible for preparing HGV’s for annual test and for many it was the first test they had ever had and believe me they needed one.

One particular bad vehicle was the Dodge D308, this had a double and triple skinned cab in places and rotted like crazy but because the main bearers were sound it was still safe.

It’s just the testers didn’t like to see rat holes in the sheet work, problem was welding to one side was OK but nothing to weld to on the other side.

I spent literally hours on these chasing cob webs.

So one day I cut a piece of plate and hammered it to shape to fit nicely, then put the plate in the vise and ran a perfect bead of weld along two edges, this was then welded in and blacked over.

At test the examiner commented he’s never seen a nicer piece of welding and passed it.

John S.
8 January 2011 at 16:15 #62020
Nicholas Farr
Participant
@nicholasfarr14254
Hi John, call that a bodge!

In the seventies we used to have to patch up plant where 6mm plate had been worn paper thin in the middle of panels, so you would weld where you could and then finish with putty. By the late eighties onwards and with the more popular use of silicone sealent, well !! we didn’t even bother with the welder, and often the patch was rubber if it wasn’t a hot zone.

Looks and testing wasn’t an issue though, just had to keep the product in, untill the next major maintenance shutdown.

Regards Nick.

Edited By Nicholas Farr on 08/01/2011 16:33:20
8 January 2011 at 20:24 #62033
Ian Abbott
Participant
@ianabbott31222
At one time, I quite often had to weld dissimilar thicknesses, with one edge down to about 1/16″. Like Terryd, I would heat only the thicker piece, with a tiny flame. When I had a puddle, I’d let it come up to the thin edge, then carefully run the bead just beside the joint and let the puddle do the welding. Often the job would be on a machine, so there was no way of using firebrick to help keep the heat even. Patience, patience, patience…..

We’d do something similar with solder repairs. Heat an area away from a soldered joint and then nudge the flame towards the joint, just enough to let the solder run, then backing away, keeping the heat just below the melting point. Quick nudge would allow a series of additions, then a pass over to smooth the joint.

Ian
9 January 2011 at 03:06 #62049
Dave Tointon
Participant
@davetointon92281
G’Day All,

Talking of bodges, heard this story from an Aircraft Engineer in New Guinea. Some of the lads were working on an early model Pilatus aircraft with a pusher prop. Finally in the early hours of the morning, they test ran the aeroplane, however unfortunately someone had left a big spanner sitting on the wing which went through the prop. A spare prop wasn.t held in stores and was unlikely to be available anywhere in the region. Nevertheless, the aeroplane was back on the line in time for it’s scheduled run later in the morning. It was a few months later when the prop went in for overhaul that the sh@# really hit the fan. Frantic correspondence came from the horified overhauler that one of the blades had a large dint, had been stop drilled , automotive body filler applied, filed up and had been painted over. Consensus was that the engineer concerned was a good bloke and that his judgement was sound as the prop had run to its full service life without coming to bits!!!

Regards

Dave Tointon
9 January 2011 at 05:50 #62051
Paul Boscott
Participant
@paulboscott25817
Thank you for all of your contributions BUT I would like to get this thread back on to its original question

I would like to know before I spend to £200 to £300 on equipment if it is possible assuming that I acquire the necessary skill to produce a miniature weld that would any where near replicate at 1/12 scale the type of construction the that in real engineering practice makes a component / structure by seam welding 2 – 3 inch steel plates together?
9 January 2011 at 08:11 #62054
JasonB
Moderator
@jasonb
The welders I have seen doing the small fillets are nearer the £1000+ mark and thats for a small one that will work of a 13amp socket, as John said you need the controls and gizmos like HF start, slope up, slope down, pulse, etc The arc/tig welders from machine mart with the additional tig kit are just not upto it or any touch tig for that matter.

The other problem you will have is that your 1.5mm 1/12th scale weld will have been run as several runs as you cannot do an 18mm weld in one pass so you would at best have to run something like 3 or 4 0.5mm beads of weld.

Jason

Edited By JasonB on 09/01/2011 08:13:20
9 January 2011 at 10:52 #62066
Terryd
Participant
@terryd72465
Paul,

From reading all the previous posts (not the OT ones) I think that your question has already been answered and that answer is “unlikely”.

I would not fancy even attempting it, but I have only 50 years experience. As I said, welding doesn’t scale, even with the best equipment, the ripples of the weld will still be 12″ to the foot scale.

Regards

Terry
9 January 2011 at 11:19 #62071
John Stevenson 1
Participant
@johnstevenson1
Is that 50 years experience using the latest equipment ??

As I said earlier unless you are familiar with the equipment that has been released in the last 2 to 3 years than all this ‘experience’ will not really count and that also includes my experience.

I can weld things today I could not weld last year, simple statement.

I can’t match 50 years experience, only been welding for 47 but in all fairness that is not 47 years solid welding however as a guide out of two bottles of gas on rental, Argon and Argon mix, I need about 10 refills a year.

I no longer do enough gas welding to warrant a set of bottles and they were handed back about 5 years ago.

I was looking at some titanium pipes the other day that had been welded to a 6mm flange, the pipes wire about 16mm and the welding was exquisite, tiny, tiny horseshoes of perfect weld, probably as many as 50 around one pipe.

John S.
9 January 2011 at 11:42 #62074
Terryd
Participant
@terryd72465
Hi John,

i don’t think 50 years would be possible with the ‘latest equipment’ would it? I don’t have a time machine. I only managed a couple of months with it before I retired last year. I think that the welding Paul requires is possible but doesn’t scale down to 1/12. I did say the process was ‘unlikely’ to be successful with the sort of equipment Paul was suggesting with obviously little or no previous welding experience. Even with the ‘latest equipment’ welding is still a highly skilled process not easily picked up without skilled tuition.

As a ‘Jack of All Trades’ I was never highly skilled but could turn out welds good enough for structural steelwork etc with any of the methods mentioned earlier. However I used to marvel at the guys who were welding the large pressure vessels we used to turn out for use in the nuclear reactors of the power industry. I now only average a couple of bottles of ‘Argoshield’ a year in my home workshop.

Regards

Terry
9 January 2011 at 12:03 #62076
John Stevenson 1
Participant
@johnstevenson1
This is what has become an everyday job for me as people who visit will confirm.

Bridgeport Varispeed rotor, worn as usual.

Turned down undersize on the worn part and welded back up, continuous weld.

Final machining.

Time for a cuppa and bring on the next one.
9 January 2011 at 12:07 #62077
chris stephens
Participant
@chrisstephens63393
Hi Guys,

As usual John has it right, modern techniques are amazing. A friend of mine works for one of the V. expensive Swiss watch makers and they use Laser welding kit to repair cracks in wrist watch cases. I am told that it is so fine that little or no clean up is necessary. Downside, I hear you ask. Of course there is a downside £15K price tag for one.

Just remembered, reading in a book on welding about being able to weld razor blades to anvils with a Laser welding kit, nice to be able to but I don’t see much call for it myself.

Jewellers have a nifty bit of kit, they use mains powered Oxy-Hydrogen generators, which uses all metal hypodeemic nurdles as the jet. As you can imagine it produces a very fine flame.

chriStephens

I now sit back and wait for all the 50 year welders to mutter “hydrogen embrittlement”
9 January 2011 at 12:38 #62079
Anonymous
I would have thought it was perfectly possible to achieve what the OP is asking; given enough skill and the right equipment. See this website:

http://www.microfusionwelding.com/index.html

I certainly don’t have the skill, but that doesn’t mean others don’t either.

Regards,

Andrew
9 January 2011 at 13:08 #62081
Terryd
Participant
@terryd72465
Hi Chris and Andrew,

Of course it is possible given the right kit and skills . I never said it wasn’t. I said that given a £200 – £300 piece of kit and limited or no experience of welding it was unlikely that Paul would be able to achieve what he intended. Not that it wasn’t possible.

Chris,

No one said that modern techniques were not amazing, it was not only John that said or thought it, but a laser welding kit is not likely in a home workshop. I thought that this was a discussion of what was possible in a home workshop given relatively cheap equipment, not a treatise on modern industrial welding techniques. I do wish that folks would read postings and answers accurately.

Terry

Edited By Terryd on 09/01/2011 13:09:43
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