How many amps? 3mm plate to 12mm solid rod (mild steel)

[adam_lambert]

I need to weld some solid 12mm mild steel rod to 3mm mild steel sheet (flat end of the rod to the flat of the sheet). I have been using a stick welder and can get welds that are strong enough but certainly do not look pretty. Stick welding around a small diameter tube and with thin plate is proving extremely difficult!

I have never used a mig welder before but managed to get a good deal on a Clarke 135te turbo from Ebay which I hope this will be more suited to this kind of job. The welder states it can weld plate up to 5mm thick so know there will be no issues with the 3mm sheet however I have no idea about whether it will penetrate the 12mm rod.

Does anyone have any idea whether this will work?

Thanks,
Adam

 

[Robotstar5]

Unfortunately the sales specs are generally "optimistic" with performance figures. the Clarke 135 will be maxed out at about 3mm so should just about cope with your sheet but won't make much impression on the 12mm rod

...and welcome to the forum.

 

[adam_lambert]

Thankyou for the quick reply.

Do you know what kind of mig welder I would need in order to get this job done properly?

 

[cumbriasteve]

It depends what the welding is for, I have the 135 and recently made a gate out of 25mm box frame with 12mm round bar infills, it managed the task no problem at all, in fact I was surprised how well it managed.

I am sure if you did a test the penetration on the 12mm would not be great but I am also sure if you went mental with a hammer the bar would bend before breaking the weld, so yes it worked for a garden gate but if it was a project where perfect penetration and 100% strength was critical then the 135 would not be suitable.

 

[Bill Edwards]

What's it for? I would think that there is a good chance that provided you do a half reasonable job with the equipment available it'll still be many times stronger than it needs to be even though full penetration won't have been achieved. Weld is pretty strong stuff...

How about grinding the rod down? I grind two flats in it to form a wedge shape and weld both them up (I'm never as happy running lots of weld right round a round bar as it weakens it). You'll then get much better (100%) penetration with a few runs.

Another option could be to stick weld it if you're happy it is strong enough, then use the MIG to run something over the top - probably with a weaving action - to make it look pretty.

 

[adam_lambert]

It is for some table legs, similar to this...

As far as grinding flats, this sounds like a good idea as long as I can make it look good again afterwards. I cant quite visualise it but will give it a go.

I expect from what you guys have said the weld is probably going to be strong enough for what I need which is great. I am going to make some coffee table legs which should be fine, but also some full size dining room/desk ones which I guess may need to be tested a little more carefully first.

Stick welding followed by mig sounds like a good idea too. The other option would be to grind the stick down afterwards but its hassle!

Ill give it a go and let you know how it goes. Cheers!

 

[ben8vgte]

If the end of the bar is going on the plate of the flat side? Then I'd drill a hole where the bar mounts and plug weld the plate to the bar, then you can weld round the outside as well. A little V prep of the bar end might help as well if that's the case.

 

[adam_lambert]

Good idea!

thinking along the same lines, If I was to bore out the inside of the round bar, say a 6mm hole, leaving 3mm wall sections each side. This could provide good penetration and a strong joint?

 

[ben8vgte]

Just drill a hole in the plate, then weld into the hole and onto the end of the bar. You could add a little V round the outside bar as well if you wanted.

 

[BrokenBiker]

drilling into the bar is pointless. Just means you have to fill the hole up again. Drill the plate a little bit smaller than the bar. Maybe a 10mm hole. Plug weld this then run a fillet around the bar on the other side for added strength.

 

[adam_lambert]

Thanks for your help everyone. I have had some good success with the new machine. It's much easier than stick welding around small diameters, not to mention cleaner.

Strangely I can not get a good weld when on the highest amp settings, even trying a range of wire speeds. Any ideas with this? My practice pieces have been a 12mm rod onto 2mm sheet, not 3. Any idea why this may be? I guess at this setting I will be getting poor penetration on the round bar, although I did try and break one - the bar bent first! I have not yet tried the plug weld as it seems strong enough!

 

[adam_lambert]

It's a Clarke 135 by the way. I can only go up to setting 2, min. 2, max pops violently across the whole range of wire speeds and leaves a horrible looking mess!

 

[cumbriasteve]

I will bet your 135 is the same as mine, the wire speed adjuster is very sensitive....very very sensitive.

When on full power, set the speed to about 9..it will probably pop away like mad..very slowly keep dropping the speed but only at the smallest amount at a time...even a quarter of a turn is too much at once, eventually you should find the 'sweet' spot, mine is just slightly above 8 on full power.

 

[adam_lambert]

ok, great. Ill give this a go.

At higher power is will it be any more sensitive to torch distance from the work piece. On the setting i'm currently at it feels like I can go from the shroud almost touching to about 10mm away, maybe a bit more.

Is it likely to be more sensitive to anything else for that matter? Material cleanliness, on an extension lead etc..

 

[Bill Edwards]

Not much should change, it sounds to me like the issue is the wire feed. You could weld on a piece of scrap metal and adjust the wire feed til it gives the best results (while welding) then fine tune it as normal - I find doing this helps when you're a mile off and the control is very sensitive.

 

[adam_lambert]

Should I find myself having to move quite a bit faster at the higher wire feed speeds or is this again down to incorrect settings/technique?