Welding positioner HF protection

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I was checking out the price of a welding positioner and was shocked at the price and decided to make my own.So far i have a 90v dc motor with a leeson speed controller,a 60 to 1 gear box and chains and sprockets to drop the speed by 1/4 before the gear box.My question is how can i protect it from high freq frying the thing up?This has me stumped.Anybody know what i can do?
Reply:Get an invereter welder?Ground it to a water pipe or electrical panel?Good question.  My TA 185 doesn't use Hi freq, it uses high voltage like a spark plug coil to iniate the arc.Dunno.David the poor speelerReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Completely isolate the motor from the rest of the positioner.  That means mounting your switch controls with a piece of plastic between the housing and any metal.  The motor similarly would have to be sitting on plastic sheet such as UHMW.  To isolate the drive use a flexible spider coupling between motor and gear reduction box.  This is a good design approach in any case because there is always the possibility of full welding current running though the drive line and motor if the ground falls off.
Reply:Positioners have a ground lug made into the base..The lug has a braded cable thats spring loaded to the shaft that the plate or chuck is married to with a brush like in a electric motor...That way it can still rotate and keep the ground..If the ground cable comes off while welding?You'll fry the power cord... ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:The motor and controller must be mounted on a non conductive material ,such as wood or plastic, and use a belt after the gear motor to insulate from welding voltage.  At lower amps and non production welding the ground can be attached to the frame of the positioner but for best durability a rotary ground should be installed.  I used Dayton 90 vdc gearmotors 6 rpm # 4Z724A with Dayton 6X165C controller
Reply:Technically if your welder is properly built/designed welding current should not run through the neutral wires or metal conduit of AC power supplies.  Every once and while scatalogical things happen.  I have seen chain slings turn blue from welding current running through them so it is always wise to take extra precautions by insulating the motor from the positioner.  If there is an alternate path HF will surely find it.
Reply:Thanks for your reply'sI thought about using a belt to run the gear box after i bought the sprockets and chain but i can always return them.as for the ground , I saw the brush contact on a commercial model and just haven't found a source of one large enough to handle the current needed.I don't have a Hf capable welder now but i would like to concider this in my design now so i don't have to redisign it in the future.I will keep you up to date with my progress.Thanks
Reply:I just had an idea.........what about carbon gouging rods for my ground?I have a bunch of them.If I make a holder to hold......say......4 that should be enough to handle the current.let me know what ya think.
Reply:And the more contact points I have ,the less chance I have of loosing my ground.Ya........Ya......dam this is going to work Great.
Reply:Sounds like a plan.. Zap,  I've noticed that you have taken a couple of things apart for us to see "whats inside". Have you ever looked at the brushes in your positioner? This has me curious now. I wonder just how heavy duty those brushes are, and what type of material the commutator is made of.
Reply:Originally Posted by o.c.d.Sounds like a plan.. Zap,  I've noticed that you have taken a couple of things apart for us to see "whats inside". Have you ever looked at the brushes in your positioner? This has me curious now. I wonder just how heavy duty those brushes are, and what type of material the commutator is made of.
Reply:Originally Posted by Winter_FreakAnd the more contact points I have ,the less chance I have of loosing my ground.Ya........Ya......dam this is going to work Great.
Reply:The braided copper strap, spring loaded around the main shaft, is a simple and effective rotary grounding method used by Jetline and by myself.
Reply:Keep the sprockets and get plastic chain. Or the chain with steel cable runners molded in plastic, with plastic 'rungs'.
Reply:I took the chain and sprockets back and swapped them for a belt and pulley'sTake a look at the baileigh positioner and you can see the contact rubbing on the bottom of the turn table.I got an assortment of springs from princess auto(about 200 total) in a kit for $7.....large selection of choices.
Reply:The parts i will be using Attached Images
Reply:Here is the plan. Attached Images
Reply:If you don't mind me asking - where did you get the gear reducer, motor and variable speed controller. All 3 are normally pricey if you buy from Grainger...I was pricing some stuff out today. Thanks.John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:I got the gear reducer at princess auto for $100 (60to1 ratio)and the motor and speed controller are from a scroll saw my dad stopped using years ago.
Reply:Your like a mad scientist.. Keep it going!!I like the "Binford" reference.. ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:My motto is that if you can't afford to buy it .....build it. i love to dig around in scrap yards to see what i can make.....I am addicted to fabricating ...not drugs.Last edited by Winter_Freak; 04-10-2007 at 05:13 PM.If at first you don't succeed, ask more questions.Lots of cool tools and stuff.CWB SMAW 4 positions       FCAW 4 positions
Reply:I am addicted to fabricating ...not drugs.
Reply:Although not a true weld positioner, this fixture is for welding wheel centers into the outer shells. This was to be a test model but with a few modifications it has been in production use for 15 years. Attached Images
Reply:Very cool!! ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Well here it is almost done.i just have to install a pin and holes to lock it in position.and some paint woulden't hurt. Attached ImagesIf at first you don't succeed, ask more questions.Lots of cool tools and stuff.CWB SMAW 4 positions       FCAW 4 positionsGoes from zero to 15 rpmIf at first you don't succeed, ask more questions.Lots of cool tools and stuff.CWB SMAW 4 positions       FCAW 4 positions
Reply:Thats cool!! You get the "Homemade Gizmo" award for the week!!  Now all you need is a 3 jaw chuck and thats that!...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:You will NEVER weld @ 15 R.P.M.Not tig anyway.. ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Wow - looks great. How does it work so far? Have you tried the controller?John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Hey zap.....I just took a guess at the drive ratio and ended up with 15 rpm on 100%.....but I now know that if I build another one that I would use the 100: 1 gear box instead of the 60:1 No i haven't used it yet school days are to short and i did not have time to finish the position lock ........I will finish it tommorow as well as make an adapter for my chuck.P.S. Thanks for the award If at first you don't succeed, ask more questions.Lots of cool tools and stuff.CWB SMAW 4 positions       FCAW 4 positions
Reply:Zap - what does yours turn at?John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:The  RPM will be determined by the diameter of the weld.  On the weld fixture I made  the weld averaged 12" dia. and the base speed was 1/2 RPM or approx. 36" of weld in 30 seconds.The smaller the diameter the faster the RPM.
Reply:Correction to my previous post the base RPM on my machine is 2 RPM.
Reply:Originally Posted by MicroZoneZap - what does yours turn at?
Reply:Okay - that gives me a good starting point. Hahaaha - a very scientific test I see... John -  fabricator extraordinaire, car nut!-  bleeding Miller blue! http://www.weldfabzone.com
Reply:Mechanized TIG welding speed generally will range between 3 to 6 inches per minute (IPM).When setting up the turntable speed, you can take a guess at the IPM you want, then based on diameter convert this to seconds per revolution (SPR), then adust the potentiometer setting on the turntable by watching the clock.To calculate SPR for a 2" diameter weld at 6 IPM:(2pi inches/rev) / (6 inches/min) x (60 sec/rev) = 63 sec/revMechanized spray or pulsed spray MIG travel speeds are generally around 30 ipm.