I am welding patch panels in my truck and can’t seem to grind them back flat with out eating into the surrounding steel. I am using a 4 inch angle grinder and have tried a regular metal grinding disk and a course flap disk. So what is the secret to grinding just the weld and not digging into the steel around the joint on a flat panel? Is there a technique I am missing or maybe a better cutting wheel I can get. I have had to end up putting bondo over the joint. Incidentally I am new at welding too so I end up with quite a bit of weld to remove.
I use the edge of a cutoff wheel to smooth out welds and then finish off with a right angle air grinder and Roloc discs.
I use those thin ( maybe 1/16" or 3/32") wide cut off wheels and stack 3 or 4 of them on the die grinder, works for me.
The best way I've found is to use the grinder with a flap disc to knock them down quickly without touchcing the rest. Then the 2" angle grinder with 36 grit Roloc wheels to smooth and blend them. I would like to try the cut-off wheels on the 2" though. What kind of arbor did you use?
PRACTICE, but i've been known to use a die grinder with a cutoff wheel carefully too it's a little more delicate
Hey, I like a 7" grinder and a 24 grit open coat disc. A larger disc will last longer, produce less heat, allow you to blend the weld into the surrounding area. Be VERY careful stacking cut off discs on the mandrel of your die grinder. If the mandrel breaks from being overloaded, or is out of balance from too many discs stacked on it, you'll be the first to know! The cut off discs arn't really ment for paint and filler removal, but I see guys usin' them for jus' that. Keep in mind, that every one of those deep gouges that you put in a panel will have to be sanded filled or polished out. Why create extra work for yourself, and thin out the metal that much more? Swankey Devils C.C. "Meanwhile, back aboard The Tainted Pork"
I hate grinding hard-ass MIG welds... but yeah, 1/8" cutting wheel followed up by a Roloc 24 and/or 36 grit (I think). Did I mention how much I hate grinding hard-ass MIG welds??? Good incentive to learn proper welding techniques! Nice FLAT tack-welds!!! -ns
Weld from the backside of the panel whenever you can-don't need to grind the outside hardly at all then.
Knock the head off the weld with your 4" grinder, then blend it with a 36 grit sanding disk. A 7" or even 9" sander is best. Sand so that all the sander marks go one direction, then change so that they go across the previous marks. That way you will see where needs more work and where is done. It takes practice. And a bit of bog ( bondo ) never hurt anyone.
one more vote for the cut off wheels on your air powered die grinder. takes a bit longer, but you are only knocking down the weld and not thinning the whole surrounding panel. MUCH less heat also. I read this technique in Street Rodder when Ron Covell had a monthly column.... does he still do that column? ... I kind of think if there was a better way to do it he would have mentioned it.
Gas weld! Much less weld bead to remove, and it will grind down like butter. Im never going back to MIG for sheet metal.
A die grinder with a small cut off wheel is my choice followed with a 4 1/4" grinder with flap discs. Go slow and carefull with the edge of the cut off wheel until it's knocked down almost flush, and finish up with a flap disc. Here are some additional tips.... 1. Make sure your panel is reasonably flat after welding, keep the distortion to a minimum while welding. 2. I use ESAB easy grind wire. Expensive but it really does grind a lot easier. I've heard negative stuff about it being the same as other wire, but I bought some and swear by it. 3. Use high quality cut off wheels and flap discs. I can't stress that enough. You get what you pay for. Norton makes a cut off wheel thats good for stainless. It makes quick work of the ESAB easy grind. The Harbor Freight stuff and the like are a waste of money where time is concerned. 4. And move around just like when you weld to keep the panel cool. Have fun!
I couldn't agree more. Also learn to hammer weld. It is provides fantastic results. I hardly ever grind anymore. on sheet metal. This was hammer welded and 90% of the "grinding" was done with a file. Took about 5 minutes to go around the whole window.
That Looks great Low! With Gas, I dont think you have much of a choice but to hammer weld. If you dont, you'll have a terribly warped panel. However, if you do about 3/4" at a time, and hammer the shrinkage and distortion out of each 3/4" bead, you will have a lot less distortion than you get with MIG. Plus gas welding is so much more fun! Really, it is.
Thanks! I fully agree with needing to hammer weld gas, as well as the fun aspect of it. Plus its traditional
What are you using for a torch set-up? I'm looking at the Henrob. I've heard lots of praise for it, and some that say it's not worth it. I've hammer welded in the distant pass but still feel the standard torch sizes put too much heat to the sheet. I'm really leaning toward a speciality torch set-up, hate the mig grinding even though I have it under control. And your right, gas is fun...
I have an old Victor set up. I like to weld with the 000 tip, and I like to use the RG45 welding rod as it hammers out easier than the 70 and is plenty strong.
Cool, I just had my old Victor referbished. Got it from my father back in the 70's and it was getting grungy, couldn't turn the knobs very well. It's super slic now. I need to invest in a smaller tip it sounds like. I've got a 00 and up. Thanks for the input.
I have a Henrob, I LOVE it. I want to try out a Meco Midget, its really small and light, and a lot less money than a henrob. Here is a 47 hood I chopped up and am almost done hammer welding back together.
Hi. I couldn't help but notice your wheel tub. Do you have anymore pics of that. I'm building something similar for my 37 Ford this weekend. I purchased a couple of raw trailer fenders to fit into place and some sheet metal for the backs. Yours looks really nice. Would appreciate any advice. Thanks
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