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Up Topic Welding Industry / Welding Fundamentals / fixing office chairs
- - By Fritz T Katt (**) Date 02-09-2009 20:41
Ok, this one is for keeps. Everytime a chair breaks at school they send it down to welding for a fix. Today we got in 3 chairs, I fixed the first one no problem. The second one is VERY thin steel (we put a magnet to it, it's steel). I ground off the paint for my ground and the area I want to weld. I set the mig welder at about 60, very low voltage. The problem is that it can't feed enough wire because the speed is controlled by the voltage on our machines.

I had to make like a tig motion to keep the cheap metal from melting while still welding it. I put it down drop-by-drop almost for the most of the welds. Since a lot of people are jealous of my skills they doubt them and I play for keeps. What do you guys think I should do so I don't melt the metal (had to fill a hole drop by drop already) and get a steady bead. I'd say the metal is 3/32" thick max. The way I'm doing it now is a pain in the a**, but I have confidence that it will hold.
Parent - By OBrien (***) Date 02-09-2009 21:39
J.B. WELD lol.  No if you have a tig setup around and know how to use it than that would be your best bet.  If you don't know how to use one but have one around its a good way to learn.  If not than you may just have to keep doing it as you are. 

Oh yea the comment "Since a lot of people are jealous of my skills they doubt them and I play for keeps."  If you can ever get anything helpful out of me this may be it.  In school no matter how good you are when you get out and get on a job that requires any type of quality at all your going to be really suprised at the skill of the guys around you.  It may not show on a bench but when your 2 feet between where your sitting and the cealing and not much room side to side and you need to make a weld it will.
Parent - By raftergwelding (*****) Date 02-13-2009 15:11
can you sleeve it with a thicker piece or even stick a piece of hot or cold roll inside to weld to it wont be pretty but itll work and welding metal that thin it's gonna break again anyway might as well just get new chair
Parent - - By Lawrence (*****) Date 02-13-2009 15:41
Taking this in another direction.

I'm very selective about allowing students to repair chairs...  Usually only horizontal rings on lab chairs..

Remember, if a 300 pounder sits on that repaired chair and the weld fails somebody may be seriously injured.

Sometimes a chair breaks because it is poorly designed or overused, and a weld may put the metal back together but not do anything to solve the problem that made it break in the first place.

Again.. short circuit GMAW or GTAW are almost always the right tools for the job.  If your mig isn't doing the trick and GTAW is unavailable... The answer is:  "sorry, your chair is going to have to wait until the instructor has time to help me along with this."

If you have never Tig welded,,,, a chair is not a good project to learn on...  Lots of scrap needs to be joined before you start welding on things that people sit on.
Parent - By noth50 Date 04-11-2018 07:34
تعمیر صندلی اداری به چه صورت انجام می شود
در این مقاله نکت قصد داریم روند تعمیر صندلی اداری را توضیح دهیم که به چه صورت این کار انجام می شود، قیمت گذاری ها به چه صورت است و آیا باید صندلی را تعمیر کرد یا خیر؟!

و در آخر با انواع خرابی صندلی و نکاتی که باید در مورد استفاده صحیح از صندلی درنظر گرفته شود آشنا خواهیم شد.

http://nect.ir/chair/repair-office-chair/
Parent - - By sparkin (*) Date 02-13-2009 20:07
Reverse the polarity on your mig for the thin stuff.
Parent - By arrowside (**) Date 02-14-2009 17:25
3/32" = 12g. 17.8V, .035 wire. No Problem.
Parent - By Metarinka (****) Date 02-16-2009 00:02
what type of machine do you have?
60 v is impossibly high for MIG welding
In constant voltage machines (which are the vast majority of most MIG welders) voltage is set,  and amperage is controlled by wire feed speed. Any mig machine I've ever used you were allowed to vary the voltage and WFS independtly of each other.

My career has mostly been as a sheet metal fabricator and it is not uncommon to weld as thin as 20 ga 0.050" material with plain ol .035 mig wire.  In this case you would set the machine up for short circuiting approximately 18-20 v and off the top of my head 150-220 WFS. It would be impossible to run 60v on a manual MIG machine with 0.035 wire.

I trained on 14-18 ga and we routinely had to get full penetration on square butt joints. To prevent burn through, yes, you can pulse the gun off and on, this is slow and you may run into shielding issues where the end of your wire gets balled up or oxidized. Other things that help are using copper spoons other wise known as welding spoons on the back of the weld to help sink away the heat.

finally, if I had my choice I would fuse the weld with GTAW or add a bit of filler. Run approximately 50-60 a for something about that thick. For those types of repairs GTAW usually goes in with less fuss.

I agree with lawrence though, there's issues when it comes to repair chairs or any device for that matter, we repair stools all the time at our welding shop, and they rebreak all the time.
Parent - - By the_croz Date 03-02-2009 05:05
Since you don't know what alloy it is, I agree Use a Tig torch and 309 filler. I have fixed Bike and Motorcycle frames up the Wa-Zoo and haven't had a failure that I know of...
Parent - By Lawrence (*****) Date 03-02-2009 06:12
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Up Topic Welding Industry / Welding Fundamentals / fixing office chairs

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