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Hi all,I did a job today repairing a six inch crack on a hard to find aluminum valve cover. I repaired it in the usual manner (drilled the ends, gouged out the crack, pre and post heated it after welding and let it cool slowly). The client emphasized that the weld had to be blended in without creating a "dip" in the area. Well..... I thought I had blended it in well with minimal material being removed from the area. However despite my best efforts you could feel and see where I repaired it. Granted you had to look down the side of the cover like you would to check the straightness of a 2 x 4 to see it. For most jobs of this nature, my finish was more than adequate and I never had any complaints.'However this client was expecting the repair to be factory perfect and though he paid me, was disappointed with the finish I left. He is a collector and is detailing this car so anything that might catch the eye (like a repaired area) was not acceptable. So....Is there something like a high temp epoxy or filler that could be used like "bondo" to fill the slight dip in the area and then feathered out using an abrasive?I would like to recommend to him how he might repair the uneven surface from my repair.Any thoughts, suggestions?Thanks,TonyLast edited by therrera; 07-09-2014 at 01:17 AM.Reason: to add more detail
Reply:Do you have a pic of what the valve cover looked like before or after welding? With cas aluminum, i normally weld the hole/crack, then after its cooled use a straight drinder to knock most of the weld bead down/off. Then ill work it as near flat as I can with hand files. Then work the miniscule imperfections and scratches down with varying grades of sandpaper. From 220 down to 1000.Here is a set I did, the previous owner before my friend had drilled holes in the tops for breathers, from what he gathered. For a free job, i think it turned out well on my end.Sorry, forgot to take pics of the holes before I welded them. Attached Images
Reply:Is the valve cover painted?
Reply:I would think sanding block would get it smooth and even. There is stuff called lab metal which is supposed to be like bondo for metal, I've never used it but may be worth a shot.
Reply:Ok, I got it. I should have taken the bead down with a grinder or flapper wheel and then done the rest with a sanding block or files. The price I quoted was based on my usual approach which is relatively quick as far as the finish goes. This would probably mean adding another hour to the job to give a nice finish as desired. I will inform my client of Lab Metal. I looked it up and it is just what you said it is. I think it will do the trick. They even recommend it to go over rough welds to give welded metal nice looking weld beads. The valve covers are painted and after the repair they are going to be painted again. They used wrinkle paint.Those valve covers certainly looked "factory". Nice job.Thanks again,Tony
Reply:No, not a flap wheel, a die grinder, and not a rubber sanding block, files. Rigidity is your friend, flexibility is what creates the dip.
Reply:Don't be too hard on yourself - my brother has to remind me "think - show car, not tractor." Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:You might also try Devcon Aluminum Putty. It is a 2 part epoxy-like compound that is highly filled with fine grained aluminum. Surface prep (roughened surface & cleanliness) will be key to good adhesion. Sources would include MSC or McMaster-Carr, I recall.Good luck.
Reply:If it's gonna be painted, use automotive Euro putty. It's very fine white filler that uses blue hardener and sands beautifully. Sanding block and voila.
Reply:Thanks for the replies and suggestions. Rigid!! Got it!!! Next job of this nature I will take this into account and also bill accordingly as it sounds somewhat time consuming. I will mention these fillers to the client and see if it will ease his mind.Thanks,Tony
Reply:If you want future work from the customer (or his car collecting buddies) the correct method would be to build it back up and sand it down properly flat. Now that it's clean it really shouldn't take too long to lay down a few beads and do it right. Of course if he wants perfect he may find that building up with filler would allow him to make it better than factory as I'm sure there are other areas that aren't totally perfect... no casting ever is. Last edited by forhire; 07-12-2014 at 11:02 AM.
Reply:Hi all,I mentioned the Lab Metal to the client and he was very happy to hear that there was a solution to his dilemma. I've been welding for almost 40 years and am just now learning how to give a flat finish. How about that? Live and learn.Thanks,Tony
Reply:Glad the client was happy. Welding is the easy part sometimes. Finishing can be tricky, had a client that asked me to make a steel table and make it look like antique steel. What is antique steel? Antique steel to me was rust... to her it was a chalky white finish.
Reply:My experience with aluminum has always been over fill and file your weld smooth. I normally file it almost flat, throw some 200 grit paper on the file marks to smooth everything uniformly then polish and sometimes repeat! Scotch bright or steel wool will be your best friend if you want a dull finish to match things that aren't polished. It is of no benefit (to me anyway) to not finish polish when done even if I need to dull it back down.The heat from the polish wheel will help smooth the surface pores and give you a nice uniform texture to give a seamless look! Especially on cast aluminum. Might not be for everyone but it works great for mePs. I think your blend looks great!Real welders know how to penetrate!(Equipment)Whatever can be used to beat my opponent into submission! |
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发表于 2021-8-31 23:04:52