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View Full Version : To grind or not to grind, that's the question?



sparky567
10-14-2007, 10:12 PM
I have 4 grinders with an assortment of wheels mounted on them. Wire wheel,flapper wheel, cutting, and an actual grinding wheel.
After I've welded something I usually wonder if I should grind it smooth, or leave it!

I good honesty I really don't know when to do or not.
Examples, with reasons why it should be grinded down would be great, or vice-versa...is their a book at Barnes & Noble I can get...

Just another Hobbyist trying to learn on his own.

TexHand
10-14-2007, 10:20 PM
Grind it if you want it to look nice. If aesthetics aren't important, leave it.

hankj
10-14-2007, 10:36 PM
I'm with TexHand. If it needs to be smoothed for paint, appearance, or whatever, grind it. If not, leave it be!

Hank

sparky567
10-14-2007, 11:02 PM
Ok, I know esthetics is important, but if grind to much… I’m I going to remove some of the “structural integrity?

TexHand
10-14-2007, 11:17 PM
Not so much - the majority of your structural integrity is via fusion and penetration. All you'll be removing is the reinforcement portion of the weld. As long as you have good complete fusion and adequate penetration, it should be fine - generically speaking.

keenavv
10-15-2007, 01:01 AM
Rustic is wonderful!!

Rocky D
10-15-2007, 01:15 AM
Ok, I know esthetics is important, but if grind to much… I’m I going to remove some of the “structural integrity?

The answer to the question is "yes", however, there are other things that come into play here. It is important not to grind below the surface of the base metal. Then IF the weld has sufficient fusion, and penetration, you're OK.

enlpck
10-15-2007, 06:37 AM
Key things are the type of weld (fillet, butt joint, etc), the prep, how the weld is put in, and how it will be loaded.

Often it makes no difference, sometimes it can reduce strength, sometimes smoothing the weld off can increase strength.

How can it increase strength? Failures generally start at a stress riser (a crack, a point of undercut at the edge of the weld, a groove) and these are removed by grinding. If the weld is done well, and of sufficient size, grinding is usually not needed and usually won't hurt. IF the weld needs to be of minimum size, or needs to match existing surfaces, grind. If the weld is full penetration butt joint, and needs full strength, especially against a bending load, grinding to dead flush is common to avoid the stress riser at the weld toe.

Rocky D
10-15-2007, 10:06 AM
The answer to the question is "yes", however, there are other things that come into play here. It is important not to grind below the surface of the base metal. Then IF the weld has sufficient fusion, and penetration, you're OK.

I will have to stand by my statement here, and to make a blanket statement that you can remove undercut by grinding it out, is not what I would tell newbies just starting out. In the aircraft welding business, we were never permitted to grind below the surface of the metal...we have to fill up the undercut. No weld test that I know of will allow you to do it either....while I agree it does happen, (especially on weldments from China) and loading plays a big part on whether to grind or not. You should, however be proud of what you weld and want others to see your skill.

k.a.m
10-15-2007, 06:56 PM
i like the you should be proud of what you weld, sometimes when i want what i would call a sharp crisp look i will take one down but it isnt very often, i have had welds i was not happy with and ground them out to do over mostly because got in a hurry or something to that affect i still stand by the statement, cant remember who say's it (poor welders make great grinders) i love that motto:)

thingy
10-19-2007, 07:05 PM
Yeah,if its ugly or you need to grind cap/cover for fit of something,,but,,never grind a pretty weld down [flat top],unless you have to,,,welding is an art,,ain't you heard? thingy

FABMAN
12-12-2007, 02:34 PM
i like the you should be proud of what you weld, sometimes when i want what i would call a sharp crisp look i will take one down but it isnt very often, i have had welds i was not happy with and ground them out to do over mostly because got in a hurry or something to that affect i still stand by the statement, cant remember who say's it (poor welders make great grinders) i love that motto:)

I agree ! Welding is not only a skill it is an art to be proud of. :D

weldgault
12-12-2007, 03:14 PM
If a WELD is done correctly and good, be proud of it and leave it alone. I quit going to the OTC show in Houston because of the crappy welding done on the units on display, grind or heavy paint. John