Mill Scale on Welding Table

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I have a work table/welding table that I have used gas welding. I want to try some arc welding with an old  Lincoln tomb stone I just got. Do I have to remove the mill scale from the table top to use it for arc welding ?? Thanksgg
Reply:I wouldn't mess with it. Once removed it will be a rust nightmare.
Reply:No need to remove the mill scale, throw the steel on it and start welding it together.
Reply:OK thanks. That makes it easy.gg
Reply:Yes, you will need to remove the mill scale if you attempt to ground thru the table top. Mill Scale is not electrically conductive when it comes to grounding.....With a decent ground you can weld thru it, better to just remove it from both ends of your weld circuit.Don't bother if you  attach your work clamp to your actual project providing you removed the scale from where you attach work clamp to project, but certainly remove the scale from table surface if you expect to ground thru the table top by placing your(clean) work there and clamping your work/ground clamp to the table edge.HRS mill scale is actually a wonderful substance until you decide to remove it....Mill Scale not only looks good and deters rust, it also is rather durable layer that can serve to protect steel surfaces and also offer a great surface for compatible paints...I actually like mill scale on my projects and only grind it off where I need a decent weldments.And yeah, I said grind it not sand or wire brush it off but grind it off, because it really is that tuff and best removed by grinding....you can follow up with flap disks and wire wheels to polish it, but to remove it for welding just simply grind it off.Remember this and never doubt it: Mill scale is an electrical insulator....Repeat that after me, and remove it when needed electrically but leave it when ever possible.Last edited by wornoutoldwelder; 11-08-2015 at 08:54 PM.
Reply:I've never had an issue with grounding thru millscale. Seems to be no different from the light scale that is on rectangular tubing.
Reply:Originally Posted by M J DI've never had an issue with grounding thru millscale. Seems to be no different from the light scale that is on rectangular tubing.
Reply:Originally Posted by wornoutoldwelderDon't bother if you  attach your work clamp to your actual project
Reply:Originally Posted by teh603Glad I'm not the only one who has issues with grounding the table instead of the workpiece.
Reply:Hmmm........... The plot thickens.Well I just took my DVM and did some measurements. Should have done before I asked. I have bare steel along the edges of the table top where I cleaned them up, End to end on the 3' edge I got a dead short on bare metal with light pressure on the probes. If I moved in 1 inch onto the mill scale I got 100 ohms to 30 ohms depending on the pressure. Almost bent the probes. I can see it would be hard to get much current thru that.Thank you all for the advice and the compliment on my cart. It is one of the most handy things I have made. I use it for everything inside and out.gg
Reply:Pretty much you have gotten the low-down on mill scale on a table top. Consider this as well, if you are not directly grounding to the part that you are welding on you will be at the mercy of the connection through your table. If the top has a lot of scale, rust, spatter, and other ground inhibiting issues it is likely that arcing will occur between your table and your part. Besides making some difficulties for welding you can add arc burns to your parts in places where you may not want them. The current will always follow a path of least resistance and this is not always what you want to happen. Most shop tables are relatively clean as the fabricators/welders that are working from them, if they are "true" fabricators/welders, will keep them clean and free of the junk. Good luck and best regards, Allanaevald
Reply:I have 7 or 8 tables and all are descaled and seasoned with WD40. For tig work I will occasionally spray a bit of penetrating oil and wipe down. For mig I will spray anti-spatter and then penetrating oil for cleanup. None of them have rust.Last edited by shovelon; 11-09-2015 at 01:54 PM.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:Originally Posted by BistineauNo need to remove the mill scale, throw the steel on it and start welding it together.
Reply:Originally Posted by BistineauI made this statement with the idea of grounding directly to the work piece, not the table. So yeah, if you want to clamp the ground to the table instead, then clean off most of the mill scale.