Grinding problems / tungstens discoloring along length...

[Ali]

Hi Folks,

Been off here for a few years as I haven't had much time for playing around in the garage due to new additions to the family. However, scored myself a nice Tig unit (R-Tech AC/DC 160A - I'm spoilt, it was a real bargain), and have been spending 30 mins or so late every evening trying to learn the process after watching lots of videos and absorbing advice from here and elsewhere on the interweb.

I've ditched the foot pedal as I had some problems with it and got on nicely with the trigger trying to eliminate the bug, so thought I'd stick with it for now as it makes me think a bit about the amps I'm using. The welder is set to 2 step. The torch feels massive - I'm getting used to it but could be convinced to shell out for a smaller one if you folks feel it would benefit my learning curve.

I'm only welding steel at the moment, as I have a plentiful supply of scrap and this will be my main use for the process - motorbike frame & bodywork stuff, and a bit of sculpture maybe. I'll have a crack at AC at some point, but I'd like to build up a bit of technique first before complicating matters.

I've mostly been messing around with 2mm plate, and have had some really pleasing results - managed some really tidy looking fillet welds. However, I then realised I was welding at around 75A with a 2.4mm red tungsten, which is really too big for the amps according to the manual. So I went down to a 1.6mm and although I can weld OK sometimes, the arc seems to dance around a lot making it difficult to get a consistent pool. I can only guess there is some contamination somewhere, or that it's my grinding - I struggle with these smaller ones to get the angle level around the full diameter: would this cause the problem I'm describing? I feel like a harder wheel would help to remedy this - any tips on what sort of wheel to buy so I'm not constantly dressing out the grooves (or is this normal)? The wheel I'm using is dedicated to this job by the way.

I've also noticed that the tungstens discolour within the body of the torch where they're held by the collet - they turn black or blue. I can scotchbrite this away sometimes (along the length, not spinning it), but it's often quite hard. Is this a gas problem? I'm using 6/7lpm as advised on the setup tutorial, pure argon with a flow-meter.

I have tons of other questions but I'll keep quiet for now and hope someone can advise on the above before I start picking brains in earnest.

Thanks a bunch.

 

[Richard.]

What is your gas post flow set at. Before changing anything else up that to about 8 seconds and see if the discolouration goes away.

 

[Richard.]

Other question did you drop to a smaller tungsten because you were having problems with it at 75 amps or because the Rtech book told you so.
Were you getting on better with a 2.4? If so swap back.

 

[Kent]

Other question did you drop to a smaller tungsten because you were having problems with it at 75 amps or because the Rtech book told you so.
Were you getting on better with a 2.4? If so swap back.

If it ain't broke don't go fixing it eh?

 

[Richard.]

If it ain't broke don't go fixing it eh?

Exactly......
If it's been working and results were good before he swapped over then swap back until you've got the issues around the 1.6 sorted. It's just a guide.
Some people just can't grind a 1.6 it's too small for them to prep.
I usually keep things simple and work around a 100 amp rule.
3-100 (1.6) 100-200 (2.4)
Machine is maxed out at 210

 

[henry Kadzielski]

Good morning gents.
I have done some tig in my time, however on DC still use the 1.6 at up to 180 amps without problems. For me at least it was more difficult to use the 2.4 and dropped back to 1.6. I at least had better control of the pool and everything flowed much more easily. It was recommended to me to go to the 2.4 I have gone several times to try, but have reverted back to 1.6, this is for DC only for A/C just use 3.2mm. In reference to the tip grinding, have been told to grind the tip 2 to 3 times the lenght of the diameter. So if the tungsten is 1.6mm in dia, then the grind tip should be about 5mm long. I my self grind the tips longer, the tips should be ground length ways (the grind marks along the length of the tungsten. Also note the tip to be as sharp as you can get it. This helps to concentrate the arc so it dosent wander around, which is what you want. You want to control where the arc goes so you can control the pool. Untimetly it is just practice what work for you

 

[Kent]

Exactly......
If it's been working and results were good before he swapped over then swap back until you've got the issues around the 1.6 sorted. It's just a guide.
Some people just can't grind a 1.6 it's too
small for them to prep.


I usually keep things simple and work around a 100 amp rule.



3-100 (1.6) 100-200 (2.4)
Machine is maxed out at 210

Hey. I can't grind a 17 mm drill bit without my reading glasses now. Lol

 

[henry Kadzielski]

You are not alone Kent.
glasses are the norm for my now. When marking out or reading drawings I use 1.5 glasses chepies, however with the helmet on and tig welding, to see properly am up to 3.5. It is obvious it dosent pay to get old.

 

[Kent]

It does especially when the mortgage has finished
As long as your daughter don't want to do med school that is

 

[Ali]

Thanks for all the replies. I'll try increasing the post flow (was on about 6 seconds previously) and see what happens.

I tried again last night with the 1.6, and had more success grinding it on a (fresh) belt instead of the wheel. It's quire frustrating as I can do a beautiful job of grinding a fairly small drill bit, but I'm finding this simple form tricky! Welding with a better tip made a difference and I saw less flickering, but I'm still finding it harder to get the arc length just right and keep contaminating it. Time to invest in a new lid (with magnifier) maybe? Or some of these glass cups I've been hearing about on here?

So, the reason I swapped down to 1.6 was due to wanting to decrease the size of the beads to keep everything looking tidier. This seems to be down to amps more than anything (right?), but that was when I glanced at the manual and decided to move down a size in order to reduce the amps. Even though they looked quite pretty, when you turned the piece over there was too much penetration so the amps needed to come down significantly (or my travel speed was too slow...?)

From what's been said above though, it sounds like I can assume that if it works, it works - ie., there's no detriment to using the larger tungsten if everything's going OK?

As soon as I have something I'm happy with I'll post some pictures.

 

[Brad93]

Hi Ali, post a picture of your business end setup including where you would have the tungsten in the ceramic (stick out) and how it has been ground.

 

[henry Kadzielski]

Good morning gents.
I don't use the glass cups, though can see that it can be handy, just use the standard ceramic cups. There is also option of the gass lens, which for some people makes a difference. If you are good at what you do you can get very good results with both. The stick out is determined by the job and the reach required, but in normal situations is about 12mm out of the ceramic. If anyone wants I can post some photos of my setup complete, however please let someone tell me how to post photos

 

[slim_boy_fat]

however please let someone tell me how to post photos

Bottom right corner of the 'Reply' box, use the 'upload a file' button.

 

[Ali]

Here's my stick out - albeit after a touchdown. More?

This was just for practise runs.

 

[Chris Stevens]

Thanks for all the replies. I'll try increasing the post flow (was on about 6 seconds previously) and see what happens.

I tried again last night with the 1.6, and had more success grinding it on a (fresh) belt instead of the wheel. It's quire frustrating as I can do a beautiful job of grinding a fairly small drill bit, but I'm finding this simple form tricky! Welding with a better tip made a difference and I saw less flickering, but I'm still finding it harder to get the arc length just right and keep contaminating it. Time to invest in a new lid (with magnifier) maybe? Or some of these glass cups I've been hearing about on here?

So, the reason I swapped down to 1.6 was due to wanting to decrease the size of the beads to keep everything looking tidier. This seems to be down to amps more than anything (right?), but that was when I glanced at the manual and decided to move down a size in order to reduce the amps. Even though they looked quite pretty, when you turned the piece over there was too much penetration so the amps needed to come down significantly (or my travel speed was too slow...?)

From what's been said above though, it sounds like I can assume that if it works, it works - ie., there's no detriment to using the larger tungsten if everything's going OK?

As soon as I have something I'm happy with I'll post some pictures.

Get a tungsten holder from Ebay, and cheap diamond grinding wheel for angle grinder. Make adapter to fit angle grinder wheel to bench grinder, and will find grinding 1.6mm tungstens very easy.

 

[henry Kadzielski]

Thank you for that Slim-boy-fat.
Will take some photos a post them. Pictures tell a thousand words

 

[Richard.]

Here's my stick out - albeit after a touchdown. More?

This was just for practise runs.

Looks about right to me for the conventional flat stuff. 4,5 mm Protruding the cup. Fillet joints can be as much as double that and because it's right in the corner the gas has little choice but to be where you want it even at further length.

 

[Richard.]

glass cups I've been hearing about on here?

A new lid is going to be a much more useful investment if yours is causing you issues to see. The Pyrex cups are ok but honestly wouldn't help you a great deal for the majority of things. I have a couple and I can really only think of 1 job where I thought "yes that was easier because of it" and that was welding a plate inside some box section. I used the tiny flat back cap to get the torch in and it was too tight to have any more than a couple MM of tungsten protruding the cup. I welded both seams with filler watching the pool through the cup. A ceramic in this case would of been very difficult to see. Other wise I don't really bother with them. They are not cheap and unlike ceramics you don't get a second chance if you knock or drop them.

 

[Appyasme1]

Here's my stick out - albeit after a touchdown. More?

This was just for practise runs.

Gas Lens could be your answer

 

[langy]

Good morning gents.
I have done some tig in my time, however on DC still use the 1.6 at up to 180 amps without problems. For me at least it was more difficult to use the 2.4 and dropped back to 1.6. I at least had better control of the pool and everything flowed much more easily. It was recommended to me to go to the 2.4 I have gone several times to try, but have reverted back to 1.6, this is for DC only for A/C just use 3.2mm. In reference to the tip grinding, have been told to grind the tip 2 to 3 times the lenght of the diameter. So if the tungsten is 1.6mm in dia, then the grind tip should be about 5mm long. I my self grind the tips longer, the tips should be ground length ways (the grind marks along the length of the tungsten. Also note the tip to be as sharp as you can get it. This helps to concentrate the arc so it dosent wander around, which is what you want. You want to control where the arc goes so you can control the pool. Untimetly it is just practice what work for you

Am I reading that right ? You use a 1.6mm tungsten at 180 amps !!!