Inside corner/fillet tacks

[BrokenBiker]

Struggling a bit here.

Tacking or starting a weld on an inside corner is frying my brain...

I'm fine with mig or stick, but tig just ends up with 1 side of the joint pooling, then I move the arc to try and get the other side to pool and the first side cools off then I end up cooking it and 1 side melts away...adding filler just makes a blob that only wets into one side.

I've tried steel, ally and stainless now and I'm bumping the amps up 20-30 higher than the standard 1 amp per though for a flat weld, just like I would bump the power up a bit with mig for the same joint.

For instance, 3mm steel fillet weld, 140-150 amps, 2.5 tungsten freshly ground. I've tried different grinds, more stick out, bigger and smaller cups to get in closer but nothing seems to change

 

[tigdlo]

I usually use a tight arc, hot and fast with no filler. If I'm making a number of similar tacks I set the stick out so I can rest the cup on both sides of the joint and have the correct arc length, this may not work for aluminium as you may need to add filler.

The issue with the arc wandering could be dirty material, poor ground on one side or too long an arc length. Post a photo of the joints you are having issues with to be sure.

 

[BrokenBiker]

I usually use a tight arc, hot and fast with no filler. If I'm making a number of similar tacks I set the stick out so I can rest the cup on both sides of the joint and have the correct arc length, this may not work for aluminium as you may need to add filler.

The issue with the arc wandering could be dirty material, poor ground on one side or too long an arc length. Post a photo of the joints you are having issues with to be sure.

thanks for that, ill try bumping the amps up a bit more and remove the upslope so its straight in with the power.

i think ive got a good ground, im direct to a clean bench with the earth lead direct to the steel work top. ill try and get some pics next time im trying it which will probably be tomorrow afternoon.

i resorted to stick welding the rest of the frame just to get it done but have another to make so will bump the amps when i try that.

the joint ive been trying this weekend is some 70x70x3 box section, mitred to make a 90 bend. the 2 flat joints and the outside corner were absolutely fine, set the welder at 120-125, 1 sec upslope from 50, 1 sec downslope to 30 (random numbers that seem to work), tacks and beads are fine. but the inside corner has been a nightmare. i have plenty of access to get the torch and filler in and a good tight fit on the joint.

 

[tigdlo]

I honestly don't know why anyone would use upslope for anything, but then again I'm not that experienced. I usually do the opposite of upslope with the pedal, start higher than welding current, e.g. On 1.5mm box section I start full pedal at about 80 amps then back off to 60-65 or so. For tacking I use the pedal as a switch so it's 80 amps or nothing.

 

[BrokenBiker]

I honestly don't know why anyone would use upslope for anything, but then again I'm not that experienced. I usually do the opposite of upslope with the pedal, start higher than welding current, e.g. On 1.5mm box section I start full pedal at about 80 amps then back off to 60-65 or so. For tacking I use the pedal as a switch so it's 80 amps or nothing.

I'm not using a pedal

 

[BrokenBiker]

This is the frame being made.

No welds as yet as just cut it away from home to fit in the car but you can see now the inside fillets that are needed. The middle tube slides so isnt welded, apart from having a few tabs stick on to make it captive...will eventually house a bottle jack and a small bit of angle iron for a very simple and compact plate bender for brackets and what not when I'm away from my actual press.

Obviously every joint area will be prepped clean and a slight chamfer before welding.

 

[chrismac]

what happens when you really aim away from the side you have arced up on, does the arc still hold hanging of the side of the tungsten, it could be arc blow, try wrapping your earth lead round any part of your frame like a coil, it will eliminate the arc getting pushed or pulled to one side,

To play devils advocate and being used to lift arc, even if using HF, I always start at low amps and build to the required amps, any issues you can see before your committed to blasting the life out of what your tacking.

 

[BrokenBiker]

what happens when you really aim away from the side you have arced up on, does the arc still hold hanging of the side of the tungsten, it could be arc blow, try wrapping your earth lead round any part of your frame like a coil, it will eliminate the arc getting pushed or pulled to one side,

To play devils advocate and being used to lift arc, even if using HF, I always start at low amps and build to the required amps, any issues you can see before your committed to blasting the life out of what your tacking.

If i move the torch the arc follows as you would expect, it just seems to leave a void between the 2 pieces that refuses to merge together, and one side always seems cooler than the other so adding filler creates a mess...

I'm on for an early finish in work today, nothing to lift til tomorrow so hopefully get a chance to have a go later

 

[Misterg]

If i move the torch the arc follows as you would expect, it just seems to leave a void between the 2 pieces that refuses to merge together

Not an expert, but from my experience, it does sound like you need a tighter arc to start with (and bang in the power so you get a big arc straight away).

 

[indykid]

It also sounds like you could do with better fit up, but what filler size are you using? Are your weld preps causing the problem?

I struggled with the same joint for a long time too and still do on occasion, but found a tight arc with a sharp tungsten right in the corner was best. Establish a puddle both sides and poke some small filler in, mig wire if you have to. If it's a gappy joint, put the filler rod in the joint and first tack the rod to one side, then move over to the other. Once the tack's established and there's a conduction path to melt both sides, you can go up to whatever filler you need.

 

[chrismac]

If i move the torch the arc follows as you would expect, it just seems to leave a void between the 2 pieces that refuses to merge together, and one side always seems cooler than the other so adding filler creates a mess...

I'm on for an early finish in work today, nothing to lift til tomorrow so hopefully get a chance to have a go later

with out seeing it it sounds like you need to screw the amps up and feed 2.4mm filler in as hard as you feel the need,

 

[Pete.]

Lay the end of a rod in the corner and arc up on the filler rod. As soon as it arcs feed it in a little.