I'm a hobbyist who makes telescopes. I recently received a small arc welder as a gift (I've never welded before). Last week I had a chance to try it out. I would appreciate some advice.
I know welding is a real skill-- I plan on taking a welding course that offered next fall at a nearby tech institute, and I've read a book on arc welding. This summer I would just like to get to the point on my own where I can pratice running short beads. For this first attempt I just wanted to practice striking the arc and keeping it going.
My welder is a Chicago Electric one that runs on 115v and goes up to about 70 amps. I'm using 1/16" 6013 rods. My practice piece was a flat piece of galvanized steel, about 2" wide, three feet long, and I think 1/16" thick.
I started with the current deliberately low just to get the feel of things (I was also worried about blowing fuses, etc.). As I increased the current to 60-70amps it got much easier to strike and maintain the arc. But the bead would just sit very high on the surface of the steel-- the steel didn't seem to melt at all (I kept looking for a little molten pool like my book says, but nothing). The flat didn't even seem to get too hot-- I could touch it a few seconds after stopping the arc.
I would appreciate some help:
1. I came across something that said galvanized steel produces toxic fumes. I won't use it again. I know I'm supposed to use "mild" steel. Home Depot sells steel rods and flats. Some are zinc plated (which I understand I can't use-- fumes) and the non-zinc plated ones are marked "plain." Does "plain" mean "mild"? These "plain" ones have a rough, gray surface. What makes steel "mild"?
2. Is galvanized steel unusually hard to weld? Was that why it wouldn't melt?
3. How long do I have to maintain the arc in one spot to get the steel to melt? I assumed just a few seconds. But I was having a hard time keeping the arc going, and had to keep it moving. Could this have been the problem? For steel 1/16" thick do I have to keep the arc blasting at one spot for more than a few seconds?
4. All I want to do is practice running short beads. I would welcome any clever ideas on on cheap, available materials for doing this (cookie sheets?).
Thanks.
-- Tim
It sounds to me like you are keeping way too long an arc. Try getting closer- 6013 rods are designed to let you touch the surface a little without sticking.
Your questions-
1-Plain in this context probably means unplated. Mild steel is low carbon low alloy steel.
2-Not super hard but not what I would want to try first. It might be part of your problem.
3-A few seconds should do it.
4-Most any steel junk should do- pieces of pipe, an old car wheel. Anybody who works with metal will probably give you a wheelbarrow full of stuff for free. Cookie sheets that I know of are so thin you will get a lot of practice making holes. Clean the paint and rust off whatever you get and have fun.
Bill
By TimH
Date 06-12-2002 18:07
Bill--
Thanks so much for the advice. I wasn't really watching the length of the arc, I was just trying to get/keep one, so that is most definitely a factor. It seemed the rod would stick with any contact, so I probably over-compensated and was too high. I'll also find some better steel as my next victim. I'll try the dump, for a start.
-- Tim
Tim
I am not sure zinc fumes ARE toxic... they will make you "temporarily" sick but I have read reports claiming the Zn is safely metabolized; I avoid inhale of fumes, but it's nothing like chromium, cadmium, and other highly toxic metals welders regularly encounter. There are mechanical reasons to burn off (oxy-fuel torch) the Zn from the steel prior to welding (causes cracking); check out year-old or newer archives but galvanized is welded all the time
Be sure the rod diameter matches the current setting (larger dia rod requires more power) being used, also (as previously stated) shorter arc length means a hotter, deeper, more fluid weld when all else is equal
HomeDepot steel is overpriced and from my experience subject to lamellar failure (comes apart like plys in plywood delaminating) which will make your independent practice that much more frustrating with an "underpowered" welder and no instructor
Are you planing to use your weldments in your telescopes?
regards
D
You have received some good replies so far, but I will also give some advice:
1) In excess, breathing galvanizing is bad news. I would stay away from it while practicing! Besides, it makes it more difficult to weld.
2) Most brands of 6013 are quite easy to weld as long as you get the technique right. I would do the following:
a) Check on the electrode package what the recommended amperage setting is. Set your machine on the high side of this range.
b) When stiking the arc, keep the electrode "moving" so that it does not stick untill you have the arc stabilized.
c) Keep the end of the electrode that is in the torch, ahead of the weld puddle. (A pull technique. - Hold it at around 45°.) DO NOT move with the arc ahead of the electrode, (Push technique) as this pushes the flux ahead of the arc and can lead to complications. (For uphill welding, you will typically use a push technique, but this comes a little later!)
d) Once a stable arc is established, rest the electrode (actually the flux) against the plate. (Drag technique) If you want a relatively thin deposit, pull it in the direction of welding. If you want a thicker deposit, let the electrode merely burn itself along the joint.
3) If you break the arc and you need to re-start the arc, you can have some complications due to the fact that the wire tends to burn away inside the flux. As the flux is non-conductive, you have to remove this flux before the arc will start. In this process, too much of the flux often comes off. This will lead to sticking of the electrode to the workpiece and makes it difficult to establish a stable arc.
Hope this helps
Regards
Niekie
By TimH
Date 06-14-2002 00:14
Thanks again to everybody for the replies. This is exactly the kind of detailed description I need. I want to go watch someone weld, too.
Someone asked if I intend to use welding in my telescope. My current telescope project is a 6" Newtonian reflector. It has an aluminum truss-tube and an aluminum split-ring mount. Everything is bolted together, which is a pain because of all the drilling, and having to design around this type of connection. But I have balance problems with this design and am thinking of something simpler/more elegant. This would be a steel disk, with the mirror cell on top of that. This disk would have a narrow steel beam coming out of it at the edge, parallel to the axis. The eyepiece, diagonal mirror, and a tripod would be mounted to this beam. I would like to weld this design if possible. This telescope is supposed to sit on the ground with the eyepiece accessible to someone sitting in a chair.
After I finish this 6" mirror I already have a kit to make a 12.5" mirror. This telescope would be 6' long. I purposely tried my aluminum design to give me experience working in metal before tackling a large telescope like this would be. Large ones like this are usually aluminum or plywood with an aluminum truss-tube.
You can see my efforts at:
http://home.earthlink.net/~timh615/ATM/ATM.htm
Thanks again for the help. I'm sure I'll be back with more questions after I try welding again next week.
-- Tim
Tim,
You've received some great advice. It sounded to me like you weren't getting enough heat to the material. One other thing to consider is the actual voltage your getting to your welder. If you've got a long run of 12 or 14 gauge wire to a garage where you're doing the welding or you've got a light gauge extension cord, you may not be blowing fuses but still losing considerable voltage to your welder which (depending on the welder) can translate into much lower currents than the the welder dial indicates. Just another thought.
Bob
