Machining & Welding Question

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At work we have to recondition these parts so they look like new again. They are all smashed up and they look terrible.  I have to build them up with weld and then they get machined down so they look new again. Every time I build them up, the machinist brings them back and says they need them re welded again. There are little tiny pot marks in the steel that they need filled in. No matter how much I pile it on, they always need it re hit again. I want to be able to do it with one try. The parts are spotless and i'm using a maxstar 150 with foot pedal. When I get the welding done, it looks great until they start taking off stock. No one else in our company knows how to weld, so they're counting on me. I only weld about once every 2 weeks, so i'm not a pro or anything. When ever I weld something that doesn't get machined, there's never any problems or breakage. I need help, i'm tired of doing things 2 or 3 times.Thanks.
Reply:I run into that "Problem" all the time when building up shafts..Most times it's caused by the remains of the bearing race that was making the problems in the first place..You did not say if it's lathe work..Milling in a Bridgeport..what the machining process is..With the shafts I like to skim off the top layer of crash and smash before I weld anything..All the cleaning in the world will not help if the base material is contaminated with foreign material from whatever caused the wear..You don't have to remove a ton of material just the surface trash..Eliminate that FIRST and weld once......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:It's milling and using a surface grinder. No lathe work.
Reply:You can use a disc grinder..die grinder..endmill..whatever it takes to eliminate the trash before you weld..if not it just floats to the top and then it's start over..OR....Try grinding down the weld and go over it again before sending the parts back the the machine shop..It's better than them sending the parts back to you..What is the base material 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:Like Zap said.What filler did you use? I find ER70s6 tig rod is a bit more tolerant of crappy steel.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:ER70S-6 rod. I think it is cold rolled steel, but not sure, they are brought in from the customer.Last edited by Brianstick; 11-22-2012 at 11:16 AM.
Reply:Originally Posted by BrianstickER70S-6 rod. I think it is cold rolled steel, but not sure, they are brought in from the customer.
Reply:We always machine first then weld to build back up when making a repair like you are describing. This way you are not machining where the parent material and weld material are. It is all new weld material that you are machining.
Reply:Well, I'm back again, this time I'm trying to weld on cutting tools with m2 high speed steel filler rod. I'm trying to build up cutting tools that have been screwed up by the cutter grinding department. When I build it up it looks great, but when they finish grind the cutting tooth, there is always one little tiny pot mark. They want it perfect but I don't know how to do it any better, do you think using helium would work any better?
Reply:Using the highest allowable preheat  is about all I can think . The cold boundry  along side the weld bead restrains expantion,cooling is unrestrained and causes a very tiny low spot. If they need perfect parts they have to stop screwing them up.Last edited by ironrail; 01-05-2013 at 11:30 AM.
Reply:The last time it happened, I tried 3 times to fill in the low spot, He kept coming back with a pit mark or 2. They ended up making the cutter over. (It was 6" in diameter and 2" wide).
Reply:Originally Posted by ironrailUsing the highest allowable preheat  is about all I can think . The cold boundry  along side the weld bead restrains expantion,cooling is unrestrained and causes a very tiny low spot. If they need perfect parts they have to stop screwing them up.
Reply:Toolmakers think they are a half step below God but they can't change physics.That mark  may only be .0005 inch deep.
Reply:The cutter was for some aerospace company, so they want perfection. Do you think I could use a propane torch to do the preheat?
Reply:If they want PERFECTION then they should stop penny pinching and just replace the cutter when worn..Having you do it over and over and over is not very cost effective in my estimation.....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:Originally Posted by BrianstickThe guy grinding the tool says that the lighting in his area is poor, that's why he screws them up.
Reply:Originally Posted by BrianstickThe cutter was for some aerospace company, so they want perfection. Do you think I could use a propane torch to do the preheat?
Reply:We send the cutters out for heat treating. We don't have an oven or anything like that. I have a propane torch and I have oxy/acet torch, but that's it.
Reply:Are you welding before or after heat treat?
Reply:After, the tools get finished ground and then they get shipped to the customer.
Reply:Preheat your work a bit if it's large, Make sure your preflow is set and purge a little before that first arc. Stay on the work with your post flow when you finish a pass. If not getting a new filler rod out. leave your rod in the puddle as it cools before lighting up again on that spot. If you pull the rod out, clip off the very end before starting a new bead.IOW, don't let any contamination occur during your welding. Now, I'm no hero weldor. In fact, everything I just said came 20% from my instructor a few years ago, and the other 80% came from weldingtipsandtricks.comIf you watch every single TIG video Jody has produced, your work won't be coming back to you.Hope that helps. Visit my site, maybe I have something for you that will help. Be glad to supply a sample.__________________