smoothing welds

[Northstar T]

A very good point, Ironhead. Our CAA here don't allow it either. If the aircraft guys don't allow machining welds, then we should think at least thrice about doing it on a vehicle as well.

I strongly suspect the reasons the FAA doesn't allow grinding of welds is for ease of inspections, which many of us know the FAA is very good at. as someone here said earlier, a pretty weld is a strong weld. wile that may or may not always be true, an ugly weld IS always a weak weld. by remaining it it's "natural" state, an unground weld is less subject to suspicion in the FAAs eye.

.02

Russ

 

[RPM]

I got some radius rods here that came from Speedway. That are tig welded and the welds look great. Till they broke in a crash and you can see little if no penetration. As we all know penetration is good!

I can take pictures tomorrow if ya want.

 

[Duke]

I put hanging pedals in my 38 pickup that I got from a well known manufacturer. Stepped on the Clutch after about a months use and the bracket broke at the mounting plate. Nice welds with no penetration - zip, zero, nada. Took apart and cleaned up the parts and got out my mig welder. Welds are not as pretty put passable, but I will guarantee the mounting plate will bend before those welds break. I am very careful now a days on parts I receive, it maybe my imagination but it seems like more and more stuff is second rate.
I did buy some hairpins from RPM and they were top notch workmanship. Not a plug for RPM just stating a fact.

 

[Gerry]

I put hanging pedals in my 38 pickup that I got from a well known manufacturer. Stepped on the Clutch after about a months use and the bracket broke at the mounting plate. Nice welds with no penetration - zip, zero, nada. Took apart and cleaned up the parts and got out my mig welder. Welds are not as pretty put passable, but I will guarantee the mounting plate will bend before those welds break. I am very careful now a days on parts I receive, it maybe my imagination but it seems like more and more stuff is second rate.
I did buy some hairpins from RPM and they were top notch workmanship. Not a plug for RPM just stating a fact.

Just as well it was not your brake pedal???.
Heres the way I did mine.
I turned up the shaft so that it went through the chassis rail from the inside to outside. Once in the correct position I drilled thro the rail, making sure it was at 90 degrees. Dont want a bent pedal do we.
Placed the shaft through the holes and welded it around the large diameter on the inside, which means the weld was kept away from the working bit of the shaft. Then plug welded the other end and ground it flush. The length of the part of the shaft that went thro the rail was calculated so the when it was in place it came to half the thickness of the outside rail wall. This left a nice 'well' to plug weld.

I now have a good mechanical location as well as the two weld to secure the shaft. I have seen shafts like this just butt welded to the inner surface of a chassis, which would worry me to death.
Gerry

 

[Northstar T]

I put hanging pedals in my 38 pickup that I got from a well known manufacturer. Stepped on the Clutch after about a months use and the bracket broke at the mounting plate. Nice welds with no penetration - zip, zero, nada. Took apart and cleaned up the parts and got out my mig welder. Welds are not as pretty put passable, but I will guarantee the mounting plate will bend before those welds break. I am very careful now a days on parts I receive, it maybe my imagination but it seems like more and more stuff is second rate.
I did buy some hairpins from RPM and they were top notch workmanship. Not a plug for RPM just stating a fact.

ruh row. I hope it wasn't a well know manufacture like.... ahhh... Mr Convertable?? I just ordered a swing pedal assy from them for my A. was yours the version with the aluminum hanger bracket?

Russ

 

[Ted Brown]

I had a friend that had a company making many hot rod parts for mail order... I started to get fix it jobs on cars with those purty parts.. All TIG welded... Parts were breaking in/at the welds.. I told him to take a few parts and lock them in a vise, then beat them to pieces with a BFHammer... If the welds broke, fire your purty welder or as RPM says, weldor, still not correct... that is a great test, the part should fold over at any weld and not hurt a weld... You can not always tell a book by it's cover...

 

[blownt]

if you can TIG weld and make it look like a stack of dimes, then yes, I say no grinding or smoothing. But a stick weld or MIG I will grind and smooth it a tad. JUST A TAD.

 

[Youngster]

I've seen some 'purdy' tig welds that pealed off like the slag on a stick weld. As those of you that weld know, joint prep is something that needs to be addressed on all welds. I know the tig guys are going to snicker at this but I do grind V's in my suspension parts and make multi passes. Nuttin busted yet!

Ron

 

[lkeuten]

I was working on another project and came across this from the Welding Tech Institute of Austrailia I hope it attaches. I would bet a donut that the American Welding society will say the same thing. Like Youngster says prep is a big piece of the pie. I've also seen some pretty welds shatter like glass when they were dropped and Ted's hammer method testing is one I've used for more years than I care to remember. Another thing don't be afraid to grind out a bad weld and start over, I've seen industry pro's do this many times.

 

[Screaming Metal]

Of cours one could play devils advocate here and say that under the right conditions, grinding the welds smooth could actually strengthen them by eliminating stress risers.

Russ

Thats why I use a special air hammer or descaler to clean my welds....it helps with stress....

 

[Ted Brown]

Yes a smooth polished surface is stronger than a rough surface, no starting point for a failure...

 

[Northstar T]

Yes a smooth polished surface is stronger than a rough surface, no starting point for a failure...

That's kind of what I was saying in the quote screaming metal used above. I'm no engineer, but my logic tells me: why does a welded piece of steel always break right next to the weld? never in the weld, or an inch away, but always right at the edge of the weld. my theory is that the hard edge of that weld creates a stress riser, and by feathering out the edge, the transition is more gradual, which should actually "strengthen" that welded area. Of course the weld has to be a large enough fillet, and of good enough quality (penitration) to begin with. I use a MIG welder for all my welding needs, so I'm basing my statements on that. If I had a TIG welder, and the ability to use it, I might feel differently about smoothing my welds, but I've never had one of my welds break (kow) so I plan to keep on keepin on till further notice. I like the "one piece" look of the finished part better anyway.

Russ

 

[Gerry]

That's kind of what I was saying in the quote screaming metal used above. I'm no engineer, but my logic tells me: why does a welded piece of steel always break right next to the weld? never in the weld, or an inch away, but always right at the edge of the weld. my theory is that the hard edge of that weld creates a stress riser, and by feathering out the edge, the transition is more gradual, which should actually "strengthen" that welded area. Of course the weld has to be a large enough fillet, and of good enough quality (penitration) to begin with. I use a MIG welder for all my welding needs, so I'm basing my statements on that. If I had a TIG welder, and the ability to use it, I might feel differently about smoothing my welds, but I've never had one of my welds break (kow) so I plan to keep on keepin on till further notice. I like the "one piece" look of the finished part better anyway.

Russ

Normally the reason for a weld breaking along its edges is 'undercut' This is where the edge of the weld (or run if you like) has burnt into the surrounding metal too much and leaves a small edge between the weld and the original steel. Its one of the things they look for when they BOMB or X ray welds for certification.
I have to admit, I am old fashioned here and use a stick or arc weld wherever I can... great penetration and strength.

MIG is ok but I dont trust it on critical welds (dont shout at me its just my way) I have seen too many MIG welds break. There are 2 methods for MIG. Spray and dip and I dont like either unless its for build up or non critical parts. Now I could go on to the ones that certain car makers use that have a ECU which will calculate the right AMPS and feed once its struck the arc, but the last one a friend on mine bought was over $7500.00
TIG is brilliant but is really just a fancy gas weld. No doubting that modern TIG is probably the best weld you can get in the right hands. Problem for me is that my eyes are not so good and you need good eyes for TIG; or do it every day so that feel and experience produced the weld you want.
IMHO.
I have NO problem smoothing a good arc (stick) weld, especially if it has more than one run on it.

Just remember if you find it hard to get a good weld then you should either take a course or get a professional to do it. I always think about going down the highway with my grandson in the T and if I should worry about that 'not so good weld on the rear end'
Go figure

Oh and just a bye the way. I have seen the best welders you could wish for fail a BOMB test and have to' redo'
Gerry

 

[lkeuten]

I mig, stick, and gas weld. If it's something critical on stainless I have a pipe welder buddy do it. I prefer stick for the wide range of rods you can get reasonably priced and the ability to get into tight places. Set up my own rod oven using a light bulb, thermostat, and an old dorm fridge.

 

[Gerry]

I mig, stick, and gas weld. If it's something critical on stainless I have a pipe welder buddy do it. I prefer stick for the wide range of rods you can get reasonably priced and the ability to get into tight places. Set up my own rod oven using a light bulb, thermostat, and an old dorm fridge.

Good you brought that up.

I started welding last weekend and got some bad starts on my welds. Sat back for a while and suddenly remember back to my apprenticeship. Stick rods have a tendency to get damp. The flux coating is hydroscopic and attracts water. Hence bad weld.
Tip is.
Keep them in a dry place or in an oven just like LKGTO says otherwise they dont work.
G

 

[VegasBruce]

I'm not allowed to grind or dress welds on this project. The FAA doesn't allow any grinding or dressing of welded structure.
[attachment=4897ictures 222.jpg]

Nice work :hoist:

 

[VegasBruce]

Just thought I would throw these up. Make your own mind up if you think they make the grade or not. This is the rear hub. There is about 6 '' of weld around that block, which survived on 4 tacks for years while I roller the chassis around. It also survived an A bar tow for 20 miles or so in that state.
[attachment=4898:smooth weld.JPG][attachment=4899:smooth weld1.JPG]
I am more than happy that this will be OK under power. What say you?
Gerry

Nice work Gerry, smoothing welds has its place too. :hoist:

 

[Youngster]

There are several things that can cause undercut but mostly it occures when the torch angle is incorrect. The key to solving this problem IMO is watching and working the puddle to fiil the crater from the arc. Excessive speed is the culprit for many welders also.

Russ you are correct about the stress along the side of a weld however most of the failures I've seen in that area are from a cold lap to the base metal. Again controling the puddle will help. If you don't see the base metal fuse into the fillermetal, chances are good a cold lap will result.

Consistant good welds require 3 things ... practice, practice and more practice.

Ron

 

[Screaming Metal]

Take a bow. Thats as good as I have seen anywhere.
Gerry

:hoist: I believe this person deserves a award for the best MotorMounts in the 2009-2010 season! :hoist: Cheers!!!!

 

[Gerry]

:hoist: I believe this person deserves a award for the best MotorMounts in the 2009-2010 season! :hoist: Cheers!!!!

Got my vote
G