7" grinder faster?

I have no real idea what kind of furniture you are making, how decorative it is, what kind of material, how the weld appears, or why you have to do so much grinding. But, I hate to say this but IMO, you need to work on your welding skills so you don't have as much grinding. Unless what you are trying to achieve is the appearance that there is no weld. In which case I would learn to use plastic filler (aka bondo). A 7' grinder will make your grinding go faster, but just lugging that thing around will wear you out. The whole point in my book is to have the weld as pretty as posible so that not only is the piece admired for it's beauty, but the weld is too. I hope this was of some help, I'm not trying to pick on you. More details would be good, so that we know more about what the trouble actually is.

The whole point in my book is to have

I would LOVE to be able to weld that good - can you do it with arc, or does it have to be MIG - I have to grind a lot of my welds as I am a crap welder. (Getting better, but still crap). (and its taking far too bloody long......) And if I want to put something on top of the welds, ie bench tops etc, then I HAVE to grind them down so the wood sits flush.

Found the 4 inch angle grinder to be the best - easier to use as its lighter, more control too - my 9 inch one wants to go berserk and chop out too much too easily. Its great for demolition when I really stuff a weld and have to start again....The 4 inch was $20 at the local hardware supermarket - and strangely enuff, I get best results from $1 Chinese grinding disks from Trash and Treasure stalls. The expensive ones wear out fast and wont take the meat off. Go figure.

And, if I am feeling artistic, I can sorta grind them into nice symetrical shapes..... but usually dont, as its going to be covered in grey zinc primer anyway.

I feel that when you are competent enough, then you can be artistic. I am glad most of my welds cant be seen....

Andrew VK3BFA.

Thanx for your response. This is what I am looking for - the appearance of no weld. I want to make the surface smooth and flat, so even with bondo, I need to grind out the bead.

I do need to become a better welder, for sure, no offense taken.

I have a good 7" grinder, two 4-1/2" grinders (the el cleapo from Harbor Freight), and a nice 4" Mikita. The 7" grinder with a disk will take off way more metal than the 4". If you want even more serious metal removal, use a grinding stone (be careful to get an appropriate guard, when a stone blows up it gets messy!)

Assuming that you have a high interest in cosmetics and require flat weld areas, I suggest:

-Weld prep with a fairly deep 'V' grove, gives you good pentration, keeps your weld bead down flat. This can be done with a grinder (lay a whole pile of parts with the edges raised on a 2x4 and do them in quantity) but a 2" vertical belt sander is the best way.

-Practice your weld technique to get good looking welds on the underside that don't need any touchup, minimal bead on the outside that need to be ground.

-Use a 7" grinder with a disk to knock down weld bead.

-Use a 4" or 4-1/2" with as sand> I mig weld square and rectangular tubing to make furniture. I use a 4 1/2"

Yes, you can do it with arc. The whole idea is suface prep, knowing your machine, having the right rod, and lots and lots of practice. I've been welding off and on for over 20 years, and I'm still not perfect. I'm also one of those characters that learned to weld on a farm, the first time I took a real welding class and they handed me some clean steel, I was overjoyed. Needless to say after welding rusty, dirty, nasty metal, the class with clean steel was a breeze.

Another thing is playing with the machine, set your temp higher and lower, change your feed rate (moving faster or slower), different arc lengths, all kinds of different things just to see what happens. An old welder told me "You wanna learn to weld? Then practice welding overhead, when you can get a good weld overhead, and not burn yourself to a crisp, then you will be a welder."

Sometimes, when I want a MIG weld to look impressive, I will turn up the heat a bit, and do a series of spot welds. It looks like TIG welding. I set my autodark so that as the puddle cools to the right temp, the visibility comes back on, and I zap it again. Then, I just buff with a cup brush.

If you want flush flat welds, go with a smaller wire and don't deposit so much metal. Anything you grind off will not have anything to do with strength, as it will be gone. All that is left in the root and between the pieces will determine the strength.

Your furniture may require a flat flush finish. If so, just don't put any more on there than you need to get strength so you don't have to grind it off.

Steve

Thanx to all. I do currently use three 4.5" grinders, (2 from HF, 1 DeWalt) with a grinding wheel, a coarse grit flapwheel sanding disk, and a finer grit flapwheel, all plugged in all the time. But I have not been doing much of any v-grooving or other prep work. This is mostly 14 gauge tubing, so penetration is actually less of an issue than burning through, at least for me.

Thanx to these responses, I plan to go ahead and use this month's HF discount coupon and pick up one of these 7" grinders, and I also plan to do a lot more experimenting with prep and with my settings on my Hobart 175.

There is a wide variety in grinding discs. Generally if you want a long lasting disc it is hard and takes metal off very slowly. If you opt for a disc that can remove metal faster you will find that it has a shorter life because it wears away faster exposing the sharp abrasive particles. I worked in one shop where the foreman thought he was saving tons of money. He selected the hardest discs. What happened is that people would discard the discs after only an inch had been worn off the rim. Also his grinders were always burning out because people were grinding longer and pushing like crazy. Try a softer fast removal disc before going up to a seven inch. Randy

__ "All it took was all I had..."

Is this hardness something you just have to try to determine, or is it labeled and I just haven't been paying attention? I think you might have just hit the nail on the head, as the wheel I am using now I got at Home Depot, vs. HF for the ones I had been using, which, now that I think of it, seem to be softer...

OK, Roy, thanx for this suggestion. I would never have thought of doing this, but it makes good sense. I'm definitely going to try this.

Guess you missed it at 4:13 PM PST today when I posted:

But, then, going to a 7" grinder to finish off MIG welds on 14ga. iron IS an option, too.

Steve

Yes Steve, I heard ya, and I appreciate it. Certainly makes sense to put less down, and I can wait on the big grinder until I see the results from that.

I do lots and lots of tubing. I have three hand grinders. Each a 4" Makita. One has a thin grinding wheel, one a sanding disc, and one a cup knot brush. It really saves time from switching them all around.

That being said, I have found that a light touch and a small wheel is better for taking off material than a bigger one. The bigger one leaves bigger marks which, in turn take more time to take off unless they are too deep, then you have to fill them up with weld metal and grind that mostly off. AGAIN.

Try to get the best results you can using the smallest wire you can and removing the least amount of material you can from the final weld. Or just get a good looking weld and buff it with a wire wheel and paint it. Flat "invisible" welds are nice, but a lot of work unless justified by the final price of the item, and then, they should each take the minimum amount of time to achieve.

Just some observances from my shop.

Steve

I think your money would be better spent buying higher quality grinding wheels. Sait make very good ones.

If you try an industrial supplier he will have a catalogue. Most quality manufacturers supply several hardnesses and well as discs intended to aluminum and stainless steel. All I know is the foreman I work for now buys softer discs. He doesn't like seeing people taking forever to bevel prep an edge. We buy 7 inchers and use them up until they can be used on our smaller five inch grinders. Randy

I went out to the tool storage shed for my newish variable speed Sawzall and the 7" Milwaukee grinder today..and they appear to have grown legs and walked off.

Shit.

Picked em up at an auction for $20 for the pair.

Gunner

"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences."

- Proverbs 22:3

Yeah, I had $2500 worth of stuff do the same thing. Put in higher fencing, more gates, more locks, motion lights, fake cameras, and now lock everything all the time. A real PITA, though. Wish I could just shoot the bastards.

Steve