How do you guys grind/smooth your welds? What type of sanding disc and what grit? I've seen some of the work on here and after the panel is welded and smoothed its hard to tell where the seam is. I've started body work on my '53 Bel Air and once I start grinding/smoothing my welds it looks like **** and I have to wonder how much metal I've removed from the surrounding area. I am using a 4" grinder with a hard disc take down the high welds and then a medium grit sanding pad. Using the first disc goes just fine but once I start with the medium grit it looks like it forms over the weld and cuts into panels also. I did a search but really didn't see anything that mentioned it.
Good metal finishing starts with a good weld. As a craftmans you need to improve your welding technique to the point where your work needs minial grinding. This takes practice. Make sure you're using the right gas flow and correct wire if you're doing mig. Grinding off a large amount of material makes the area hot and then wavy. You should be able to get your welds to the point where they only need a quick blast with 80 or 120 grit on a flap disc to flatten. Then finish with a rubber backed 180 grit. Dont use a grinding wheel on sheet metal. I get much better result with the thick flap discs found at my local welding supply store. Whenever I pickup a flap disc from a big box store i usually regret it. Consider a variable speed angle grinder. Also consider using ear plugs...for me the noise is so irritating and I get better rusults when using ear protection.
On thick steel, hard stone ('cause they are cheap) until they are about 1/16th. Flap disc on the old 4-1/2" grinder after that. I generally just use 80-grit, and then 120-grit on the DA. On sheet metal, skip the stone. Make your welds as flat as possible in the process of welding. I like Walter abrasives. They seem to last the longest, the way that I use them.
I buy my flap disks form Benckmark Abrasives. They last en time longer than any local store bought disks.
I like to use 50 grit disk with a backer on 4 1/2 grinder. Make sure that you hold the disc flat and don't use the edge only to grind, the disk will last longer and the finnish won't be choppy. When fitting panels the better the fit i.e. no big gaps to fill or metal heights up and down then the better the weld will come out. Control heat and distortion during both welding and grinding. Learn what the metal is willing to do and don't fight it work with it.
Another one for benchmark abbrasives. I usually buy a couple hundred of the 4.5" 40grit flappers with the angle in the discs. They are way cheaper and last way longer than any of the ones from my welding stores . Trick is to not be heavy handed on the grinder, let the disc do its job
start out with a paddle disk and get it mostly down then finish with a file. everyone whos seen me do this tells me how it takes to much time and such but i enjoy making the metal look as perfect as possible so i dont mind spending the extra time and making it perfect by hand, thats how they used to do it right?
I really like the 3M weld grinding wheels on the end of a dotco. They cut fast and last forever. Usually just carefully grind sideways to the weld till I knock it down to almost flush, then hand file flat, and finish with a DA. Using the little 3M wheel, I find its a lot easier to grind the weld a bit more precise, without touching the surrounding metal. http://www.toolplanet.com/product/3...inding-Wheel?gclid=CJzs6uLmh7UCFdRbPAodECEAzg Link as an example......I dont shop there. Are cheaper elsewhere.
i agree on using a metal file then a body file to finish, thats my way too. i use #36 then #80 3M roloc discs with a homemade 18ga stainless backer on a right angle die grinder. i feel it allows me more control. just got snap on's mini DA that uses the small 2 inch discs, but still getting used to it. looks like it is going to be nice. michael
I think it starts with good weldsand strait as possible panels. I try to fusion gas weld as much as possible and all you have to do is take a body file to it and some sandpaper. If if I have to use any filler rod or a mig iIuse 40 to 120 grit 3 inch rolocs then a body file and finally a da or a sanding block. I also have a neat 2 inch stone air grinder that i use for stuborn hard to reach spots like back sides of panels.
All good advice!! I do need to work on the welding technique. But I think the gaps were too far apart on the first ones, I had to remove a section and when I welded it back the gap was almost to the point of a **** weld. Those looked much better and didn't have any blow outs like with the first. I didn't take a picture right after I had it welded the first time but I think it was pretty straight then. After I finished grinding it down with the hard disc that area was sunken In, so I could have warped it while grinding. I never had much luck with flapper wheels, when my son and I were building his bike I wouldn't let him use them because they seemed to remove they weld and surrounding metal too. Just putting too much pressure or going too fast. We got along great with files on the round tubes on the frame. Never thought of using then on a body panel. I have to try a bit more patience.
I dont like flapper wheels on sheet metal they seem too soft and form over the weld (which if you are mig welding is harder than the sheet metal) and dig into the surronding area. Try an abrasive disc with a hard backer (like a 2 or 3 in roloc on angle die grinder or 4 inch abrasive wheel in 36 to 80 grit). Try to keep it flat and on top of the weld til it seems level with the rest of the sheet metal. Then hit it with a body file to knock down any remaining high spots and then you can Da the area with some 120 or a 80 on a block.
x2 on the 0.023 esab for mig. Fusion welding is where you create little to no gap with your **** weld and you use eithee an o/a torch or a tig and you melt the two together using no filler rod allowing you to planish the metal at the same time using a hammer and dolly. It takes some pratice to master. Theres a few threads on here about it.
Should have looked before I commented on the fusion welding. I'm using a Lincoln mig with solid .023 wire. I've a lot of welding to do on the car in the future and am going to practice welding and smoothing with some of the metal I've cut off of it before I put anymore panels on. I've gone around it a bit with a hammer and dolly but it's like hitting a spring. It bounces right back.
Actually welding with no filler is fusion welding but is known by a different term in welding terminology. What welding with no filler is called is Autogenous Welding. http://www.answers.com/topic/autogenous-welding
If you are trying to get a nice finish that isnt thinned and irregular , stay away with the 2" and 3" rolocs. Although they have their place ,that being in tight areas and such , what you need to do (in my opinion) is cut down the pride of the weld with a hard stone of your liking and I prefer a 3-M 3" weld buster on a long nose die grinder for control . Then evaluate your panel for straightness and high and lows and make preliminary adjustments usually meaning hammer on dolly to stretch the weld andd raising the weld line as it will sink from shrinking . The next step is critical and rarely used by the body men trained after about 1980 (it seems) lock the droor that contains your 3" tools and bust out a 8" angle sander with at least an 8-9" 36 grit sanding disc on it . When I was shown this principle from a master , I thought he was going to tear the panel to shreads , and it looked that way when he started his sanding with spark emminating from the panel in showers . Well as it turns out the shower of sparks were onlt the weld as that is the only thing high enough to grind off .Now you still need to moniter your panel for flatnes as you still may need to raise your weld line if your welding skills are not as good as someone that has done this for long enough to learn . This type of sander has such incredible control (it works with a Gyro effect that keeps it flat when reved up) that the man that showed me said he could almost do open heart surgery with it . Another key is to keep your discs sharp so as to not generate any more heat into the panel than needs and nothing other than a shrinking disc will put more heat in than a dull disc . Also save your discs and stop sign cut them with a dedicated old pair of straight tin snips for detail sanding of your welds . Also remember that if your panel was straight before you started welding ,then there is almost nothing you can do to alter that from the welding process .Stay focussed on the HAZ (heat affected zone)and do the correct stretching without over stretching and its all good . By the way the man that showed me was none other than C*** Nawrocki.
I've looked quite a bit more on here and a site called metalmeet.com and realized I did it wrong from the start. I didn't realize when I was finished that I had oil-canned the panel. I would post pictures but the panels are black and don't show the effect well but when I run my hand down the panel I can feel it. Now, what would be the best next step? Should I make some cuts along the welds I put in and try to releave it that way? Most of the effect is over the wheel well area so I can't really get to it with a hammer and dolly so that's not an option. Or do I remove the patch try to straighten the panel then put the patch back in with the knowledge I've learned from the first screw up?
Most times you are able to remove a section of the inner and avail yourself with the are you are talking about .The reason for the oil can most likely is the weld area needs to be stretched back to its normal place it was before you welded it . Like I said earlier you need only concentrate the HAZ area and dont go any further . If you have and want proper suggestions as to how to go further you need to let us know what else you have done . Also there is another site that is very helpful and that is allmetalshaping.com .
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