Thread: thin weld bead

hi eskimo, no doubt you have already thoought of this but, just have a bit of a play with some off cuts you have laying around until your happy with what your getting,turn up the amps and down on the wire speed by a touch, do the right prep work for the butt welds and you should be able to get flush welds wil no/minimal under cut.

good luck.

Originally Posted by kraits

hi eskimo, no doubt you have already thought of this but, just have a bit of a play with some off cuts you have laying around until your happy with what your getting,turn up the amps and down on the wire speed by a touch, do the right prep work for the butt welds and you should be able to get flush welds wil no/minimal under cut.

good luck.

yes kraits..I have thought of that and have tried tried it...a little... but as it wasnt working I thought I'd ask before I continued...might be quicker was my thinking
Its obviously easier said than done or easy for those who know how to weld, but very difficult for those who dont !!!
Some of you may ask..why has he got a Mig then?.......cos I didnt have one!!!...and besides it does get some work on occasions..stuff that does'nt need to be engineered of course and where welds can be camouflaged

eskimo

Are we talking about a plain butt weld here? With the correct preparation of the joint it would be possible to end up with a very low bead which could be cleaned up with a flap wheel. TIG would give a cleaner weld with no spatter but MIG would be fine. What's the nature of the work being welded?

I have both MIG & TIG and would be happy to help if you need some assistance.

Rgds - Gavin

Originally Posted by Gavin Newman

eskimo

Are we talking about a plain butt weld here? With the correct preparation of the joint it would be possible to end up with a very low bead which could be cleaned up with a flap wheel. TIG would give a cleaner weld with no spatter but MIG would be fine. What's the nature of the work being welded?

I have both MIG & TIG and would be happy to help if you need some assistance.

Rgds - Gavin

Hi Gavin

I practiced and practiced last evening...maybe I should go and do a welding course...

I want to weld some round stock approx .75" dia into a matching hole on the side of another round item about 2.5'' dia...the hole depth is only about .12" at the shallowest section...its actually welding the trunnions onto the barrel of a model cannon I am TRYING to (insert colourful adjective) make!!..( I can only hope for the day when I get the hang of this machining... and welding.... stuff without too many stuff ups).

I could try silver soldering but I want to get it blued (by gunsmith) so I would need to keep the silver solder away from the surface...which could be tricky as 45% flows very easily especially if the flux flows to the hottest place..eg..where the torch is?...hence the silver will follow.


(I want to make it look as though the trunnions are part of the barrel and not stuck on?..just like they do when the cast the barrels back in those days...the cast included the trunnions.)

God help me when I start the woodwork part of this model
The wheels have 14 spokes and 7 fellows.......I am not a mathematician but even I can tell 14 into 360 doesnt go well....good thing a mate gave me plenty of smaller sized American oak he had lying around..

What's the wall thickness of the 2.5" part? Is the cannon going to be fired (ie strain on the trunnions) or is it static? You're going to find it challenging to get enough heat into the weld to get good penetration whilst ending up with a minimal fillet if the thing is going to be fired.

What type of MIG welder are you using?

Originally Posted by Gavin Newman

Is the cannon going to be fired

being a licenced shooter I'm going to have a static model???...not likely Gavin..if it can go BANG it will

I erred...the barrel is 1.8' at its thickest dia (where I got 2.5 from is anyones guess).....

the remaining wall thickness at each of the trunnions is >0.45".

as for a small fillet I was hoping it could be done so it ends up looking good with minimal hand grinding/polishing.

I didnt even think of that reason (getting enough heat into during welding) as to why I couldnt get a small bead. Now I know why I couldnt do it. Unless tig can put enough heat in and result with the smallest bead possible, I guess I'm stuck with silver soldering?

with the trunnions being recessed, most of the force will be taken at the shoulder where the trunnion fits into the barrel,
the weld or silver soldering is only to hold the trunnion on to stop it falling off during the moment of inertia ...any force will be shear force

the welder I have is a 175 Unimig

Bangs and smoke are always good.

TIG will give a more concentrated heat and more control over the fillet size due to the nature of the process, whether it would achieve the bead size you need along with a satisfactory weld would be a matter for experimentation. Either way if you weld the trunnions in you are faced with a fair amount of fettling if you want to get the one piece look.

Is there a mechanical alternative using loctite or a press/shrink fit?

to set the barrel up to precise bore the trunnion holes deeper now for a shrink fit will require a lot of headaches to get it right
the barrel now has a taper on it

Bugger. If you are going to try welding it you might find that pre-heating helps (as long as that doesn't distort the barrel), otherwise I think you are back to soldering.

Soldering is very common when speaking of firearms, (which is basically what this is), tight fit up is the order of the day. Sight bases, ribs and sling mounts are usually soldered on in traditional gunsmithing.
Perhaps advice could be sought in the gunsmithing section of this forum?
As a matter of interest, what is the legal status of such cannons? Do you require a licence and to register the cannon, which is really a single shot muzzle loading firearm?

After going to all that trouble, I wouldn't spoil it with a crappy weld.
I have built a few of them.
I would take it to someone with a tig and get them to do it for you.
If the trunnions are a good fit I would just fuse it with no filler wire, you get a small undercut but a very smooth weld.
Otherwise add filler wire and polish.
Either way a good tig weld won't take much to get it looking smick.

Just my 2c worth

Andrew

Originally Posted by Barterbuilt

Just my 2c worth

Andrew

thanks for your input Andrew...

I was thinking of doing just that..."take it some one"..i will do next week

Yo Eskimo

Don't forget to put up some pics.
I would love to see the build and the finished Bang Stick.

Andrew

Originally Posted by Barterbuilt

Yo Eskimo

Don't forget to put up some pics.
I would love to see the build and the finished Bang Stick.

Andrew

I certainly will Andrew..I will post in the gunsmith section...I guess that is where it will belong
but dont hold your breathe...the way I'm going at the moment with work and with summer fast approaching ..i'm in the airconditioning industry I dont expect to have a lot of time on my hands