Inexpensive, versatile grounding technique

admin

Grounding a small delicate workpiece for TIG welding often can't be so simple as sitting it on the welding table.   And if the workpiece is awkwardly shaped and difficult to fixture then the job is that much more difficult.  Here is an inexpensive, versatile solution.  Many machine shops run wire EDM machines and each of those runs a small diameter wire, typically brass which upon exiting the machine passes through a chopper which cuts the spent wire into short pieces, typically around 1/8 inches long.  A few pounds of this scrap wire, dumped into a shallow pan and grounded makes a very useful fixturing tool.  Not only does it not arc to your workpiece, it is very good for holding odd shapes in awkward positions.  The cost is low to nothing (or should be since it is sold as scrap).
Reply:I don't think this is good, best may be to get yourself a clamping kit if your having trouble getting a grip, chance you can always weld burrs on and not ground it proper to begin with.
Reply:Some people use steel shot in a container also.  I have been meaning to try a bag of steel shot sometime.
Reply:Please take a moment and tell me how you would solve the following problem.  You have an 8mm polished sphere (Rockwell B 55, about as hard as a typical brass) that you are requested to weld to a 15mm length of 0.75mm x 0.25mm rectangular stock  The end of the rectangular piece will be placed as close as the human eye can position it tangentially off a projected radius of the sphere.   You must not damage the surface finish of either piece with the exception of the weld.  Time is critical; the R&D guys need to have it done in fifteen minutes.  You have a machine that can provide the low amperage required and you are capable of making the weld; you have a typical shop welding table and you have anything else that is normally found in a welding shop.  How would you proceed to make the weld?
Reply:Steel shot is not a bad way to go.  You would like it to be corrosion resistant though.  It does have a couple of disadvantages.  It doesn't pile up well if you need it to and it is still possible, though reasonably unlikely that you'll have a contact burn.  The brass is readily available, corrosion resistant, can be very helpful for three dimensional fixturing since it can be mounded or even placed on top of a bar that itself is held up right by the bulk of the brass to fixture something higher up.  And, not the least, it offers a multitude of contact  points to a workpiece surface and  throughout the bulk of the material, making contact burns practically impossible.
Reply:Mark the weld, then probably put it in a vice(fixture) or ask someone to hold it.If it works for you stick with it.
Reply:Interesting idea of the grounding/support "media".  I would like to see it in action with maybe some pics of what a tray or "bowlful' of such pellets with some workpieces arranged in the media would look like, ready to be tack welded up?I've used welder's fingers to arrange, hold and ground delicate parts for TIG tack welding.  They are basically specialized weights with a pointed tip for holding and grounding delicate workpieces.Last edited by jakeru; 01-14-2011 at 08:35 PM.
Reply:I'll be glad to oblige; will put some examples together and post tomorrow.
Reply:Nice photo, jakeru.
Reply:Originally Posted by glempoppaPlease take a moment and tell me how you would solve the following problem.  You have an 8mm polished sphere (Rockwell B 55, about as hard as a typical brass) that you are requested to weld to a 15mm length of 0.75mm x 0.25mm rectangular stock  The end of the rectangular piece will be placed as close as the human eye can position it tangentially off a projected radius of the sphere.   You must not damage the surface finish of either piece with the exception of the weld.  Time is critical; the R&D guys need to have it done in fifteen minutes.  You have a machine that can provide the low amperage required and you are capable of making the weld; you have a typical shop welding table and you have anything else that is normally found in a welding shop.  How would you proceed to make the weld?
Reply:glemhow 'bout some conductive electric tape for grounding and a plastic fixture. fixtures could be disposable.
Reply:Originally Posted by jakeruInteresting idea of the grounding/support "media".  I would like to see it in action with maybe some pics of what a tray or "bowlful' of such pellets with some workpieces arranged in the media would look like, ready to be tack welded up?I've used welder's fingers to arrange, hold and ground delicate parts for TIG tack welding.  They are basically specialized weights with a pointed tip for holding and grounding delicate workpieces.
Reply:I have posted several photographs at the link below,  I positioned a 'hairpin' clip formed from a piece of 1/16 wire atop a 6.75mm steel ball.  I used a clip formed from 1/8" aluminum wire to heat sink the stainless wire to minimize melt-back.  The wire with heat sink assembly extends approximately 5/16" into the media and is well enough supported for me to make the weld.  Weld current was about 30 amps peak.  There is no sign of contact welding on wire or ball.http://picasaweb.google.com/lh/sredi...7gE&feat=email
Reply:Here is one way to add a picture to welding web:1.  Copy the URL of your picture (IE; from picasa, right click on the picture and select "copy image URL", method may differ based on web browser)2.  In the weldingweb text editor, click on the "mountains and sun" icon.  Paste (Control+V) the URL into the pop up window and click OK.  The image will be embedded into your post wherever the cursor was.Nice interesting technique for grounding and setting up parts, and pictures by the way!I've taken the liberty and post glempoppa's pictures to follow:
Reply:Hello Everyone,First off I would like to say congratulations on having such a wonderful online community. I have often seen your forums in past months and years, but being so busy with life and work, I never found the time to commit to a online forum, and thats any, for that matter. I spent some time browsing through some of the threads, and I was amazed the support and collective brain scanning and picking that was going on. I think in this trade egos can run high and mighty, but don't see this here. Infact I once heard a joke about welders. Its goes something like this, what is the differnce between God and a Welder......... God doesn't think he can weld!!! What I see here is group of wonderful people looking to better themselves, and the people around them in ways that would not be possible otherwise. I have learned so much the few times I have scanned through the posts I just couldn't resist joining, as I am devoted never stop learning about this wonderful art. And I say art with heavy emphasis on the ART of welding. I once had a gentleman tell me welding is not a trade, but simply a tool of other trades.Much to his amazement, I replied, your right, welding is not a trade, its a sophisticated technological ART form. He could not reply back with a stab, as it is the truth.But ya, very versatile. Its a brilliant way to hold finite parts steady and grounded! I would love to have  a tray made up with either edm wire clippings or ss shot in my vacuum purge chamber for holding those small little odd ball one off parts! Great thinking.The saying goes, necessity is the mother of all invention!
Reply:You may have a problem with the edm wire in a vacuum because it is going to be a sizable virtual leak which, depending on your ultimate pressure may take too long to pump down.  Another medium to consider which will yield lower contact resistance as well as better thermal conductivity than stainless steel shot is BBs, like for a BB gun.   The copper plate will enhance surface corrosion resistance and lower contact resistance.  In addition, they should cost less if you can get far enough up the supply chain and yield a shorter pump time in a vacuum chamber.