Can someone school me on grinding welds.

[mikesplumbing]

I have such little patience! I'm sick of mocking up and just finished welding the kick-ups on my frame rails. I figure make the front and rear long and just get to work, I can cut them off in the future. Anyhow, I'm sitting here with my rails and thought I should smooth them down like you guys do on your frames. I thinks it's easier to do it now before I weld the two rails together....any opinions on that. I'm thinking it's gotta be easier to do it now then when it's all done because I don't want to flip the frame while I work.

The question I have is the method you folks use. I was about 13 or 14 when I first started to weld and from that point on it was drilled into me "Never grind a structural weld". I see all you guys do it and every other rod builder does it so it must be ok.

Anybody want to offer kind of a step by step instruction on the best methods you have found that works great. I have some great tools for it and i'm thinking one of those Dewalt grinding disks that have glued layers of metal cutting sandpaper on it?!?!? Not sure but I have used them before and they cut pretty good and leave a decent finish without taking to much material off in one crack.

I guess i'm not sure but could use some guidence.
Thanks
Mike

 

[LKE]

Something like this ?

I buy these by the box. if you plan on using a lot of them, try going to https://www.use-enco.com They often have the 4.5" discs for $2.95 each in quantities of 10. I usually get them in something around 40 & 60 grits.
Another trick for smothing welds on inside corners, is to not grind them down all the way. Just get the high spots. Then wipe a little bondo on it with your finger. That will save about half your grinding time.

 

[RPM]

Never grind structual welds!

 

[RexRod]

I was waiting for that.

 

[rooster57]

WAIT a min some one likes chicken coupes now. Thats a flip flop FO-SHO. I cant wait to see what the next quote is after he puts fenders on that new chicken coupe ha ha ha
PS dont grind structual welds. If you had a nice chamfer on both edges of your tubing there should be no weld to grind. Rooster chapter 8 verse 3

 

[mikesplumbing]

What's with all the folks that grind the welds, I don't need to have it ground I just thought that's what everybody did?

Show me a weld that ends up dead flat and i'll give you my welder???

1st Michael chapter 1 verse 1 paragraph1

Mike

 

[RexRod]

Most people do grind their frame rail welds down for a smooth look. It's really important that you get good weld penetration if you're going to grind. Rooster nails it with making sure your joint has a good chamfer on it.

I remember seeing Don do something where he backed up the seam inside the frame rail so he could get some extra strength at the seam after he grinds the face of the rail smooth. I wish more people would do that.

I know that it doesn't apply in your case, but almost all sanctioning bodies will fail you in tech if you grind any welds. They want to see your welds. It helps them determine how safe your car is.

David

 

[mikesplumbing]

Thanks David, yeah, like I said earlier I was always told never grind a weld. Many years ago when I first got my plumbing liscense I had to take a welding class for credits and I decided to take the whole welding program and every teacher said the same thing " Never grind a weld".

It's crazy because everybody does it on car frames and I always wondered about that. I don't think i'm going to grind it, whats the point the rear joints are going to be covered.

Mike

 

[benT]

Grinding welds? Never heard that being done

Seriously, I did grind some of my frame welds, but I used 3/16 tubing and the joints were heavily beveled so the weld was fairly flat after welding. I only ground in areas that were visible or needed to be flat. The rest were smoothed a little with a flap wheel like in the previous post. As for the grinding, I used a cheap harbor freight grinder with their equally cheap grinding wheels then the flap disk.

Say what you want about it, but this frame is stout as hell and is not going anywhere.

 

[mikesplumbing]

I see what your saying Ben, do a little dance on the visible joint and leave the rest alone. I did bevel my joints on a 45 so i'm confident about that....of course it doesn't matter now because i'm going to cut them up in the morning.

Mike

 

[putz]

I have seen people fill the welds with body filler when done to get that smooth look though.

 

[oldtman]

We build a school auditorium a few years ago and I was up in the bucket tagging all the welds I didn't like. The state inspector came a couple days later and made the iron workers do the repairs. when the welds are ground there is no easy or cheap way to inspect or test them ... as said before bevel and use backup fish plates where ever possible and leave a slight gap to get good penetration.

 

[Brucer]

What's with all the folks that grind the welds, I don't need to have it ground I just thought that's what everybody did?

Show me a weld that ends up dead flat and i'll give you my welder???

1st Michael chapter 1 verse 1 paragraph1

Mike

dont say that to someone that tig welds.. you'll owe them a welder..

 

[rooster57]

I didnt grind my welds on my kickups this is the right side one, i wash over them with my tig after i mig and they lay down like they were poured in. Sorry for the dust on the frame it needs cleaning.

 

[VegasBruce]

Me personally I like the look of a nice weld, more so than a ground frame.

 

[LKE]

I grind my welds all the time. The difference may be that I am a competent welder. I gap my joints 3/32" (using tig rod as a spacer), and lay in a hot weld. There is very little sticking up to grind off.
If you grind a weld, and it fails, whoever welded it also failed...

 

[blownt]

those radial fan shaped grinding pads are GREAT. I got them in a bunch of grits 36, 40, 80, 120. And they are great when working on aluminum too. Just made an aluminum battery stand that I glassed to the inside bottom of my jet boat to hold a billet battery box for an Optima battery.

 

[EX JUNK]

BlownT, you may want to rethink that Optima battery. Check the H.A.M.B. for the discussion of Optima batteries. I have one of the older U.S.A. made Optima and have had absolutely no problems. However, once they moved their production to Mexico their quality and service went hell.

Jim

 

[Youngster]

Humm grinding welds? This is always a subject that brings many answers. I do grind my welds. As LKE said "I am a competent welder".

One thing that needs to be taken into account is experience. Another is the type of process you use, TIG or MIG. If you're using MIG, 'V' grind the joint and gap it as LKE suggested. You can then grind safely. Using a back-up piece dosen't always insure penitration. I have pealed the backing off more than one joint with a screwdriver.

TIG welding on the other hand will give excellent results with a back-up. In industry, the backup is usually used when a weld is going to b ex-rayed for inclusions, voids and impurities in the weld. This is done with a Tig. Then a Mig cover pass is added to fill and reinforce the joint. When I tig weld, I also grind a slight 'V' but I don't gap the joint. The Argon will give you a hotter arc providing the penetration.

For the hobbiest I would suggest you dress the weld for appearace sake, remove spatter and ugly starts and stops and let it go at that. As Bruce sad, "where's nothing wrong with a weld showing."

Sorry about the rambling on. Just my point of view.

Ron

PS ... All of that and I didn't answer the question! I use grinding discs. I find it easier to keep an area flat. Grind with the weld first to take it down, then across keeping the disc as flat as possible to blend it into the base metal. I start with 60 grit and then go to 120 grit. Very important .. lift the disc at the end of the pass. Every time you stop or change directions that disc is still removing metal.

 

[fordsbyjay]

A couple other suggestions to help make it look better.

If it is a structural weld and I want it to look nice after sometimes I will just smooth the top of the welder with finer grit flapper pad like mentioned on the first page. Another trick is to use a paint with a hammered finish (like rustoleum). It tends to be thicker and flows into the welds to smooth them out. It actually tends to hide a lot of imperfections.