advice for cutting brackets-OxyAct or plasma?

72chevy4x4 · Dec 29, 2006

I have a 5' bucket and I'm trying to cut the brackets that pin to the FEL frame, off. The objective is a flat backing to the bucket as I'm making it into a quick-attach bucket.

So far, I've tried grinding, but with a 4.5" grinder, it slow progress and there are areas I can not reach b/c of the pin bungs. Did I mention the slow progress? Will a plasma machine cut the welds or would it only be good for cutting through the entire bracket and bucket? Can the depth of the cut be dialed in as in 'power level'? What about an oxy-acetelene (sp?) torch-I know that they have different cutting tips, but that's all I know. Will that help to cut the brackets? I won't mind cleaning up extra weld w/ a grinder as long as I can get the bulk of the work done more easily.

regarding the plasma machine-has anyone used the Hobart setup (found at TSC)? Is the smallest size 'too small'?

Any tips guys?

MadReferee · Dec 30, 2006

If you want the opinion of people who either weld professionally or who are experienced welders, you should ask your questions in either the Miller forum or the Hobart welders forums. The people in these discussion forums are very helpful and you might even find that a question similar to yours has already been asked and answered.

PBinWA · Dec 30, 2006

How about posting some pictures? There are lots of backyard welders and few pros here that can give some good advice.

I just bought a torch and a full set of cutting tips. I think if you have the right sized tips and lots of practice then you can get good results with a torch. I know I can get a special flush cutting tip for my torch that allows you to cut the heads of bolts easier.

I think a small plasma cutter is going to be pretty limited as far as how thick you can cut.

There is also the American Welding Society Forum:

AWS Forum

It's vendor neutral which may or may not appeal to you.

IslandTractor · Dec 30, 2006

As I recall most bucket brackets are 1/4 or 3/8 steel on CUTs. I'm sure even a small plasma cutter could cut off the brackets but probably not flush with the bucket back due to the tip geometry. Probably the same with a torch. The remaining stump could then be ground down pretty easily though.

BTDT · Dec 30, 2006

I would use the torch. The more you use it the better at it you will become. So what if you gouge the bucket a little, you have a welder right, that's all part of the fun of fabricating.

m7040 · Dec 30, 2006

go with the oxy acce tourch. It will work fine. Use it all the time and have not been able to justify a plasma cutter yet. Practise on some scrap pieces first to get the hang of it. Trick is a steady slow forward speed and closeness of flame to the metal. Try to steady you arm as well to avoid jagged edges

72chevy4x4 · Dec 31, 2006

I bought a small victor setup from TSC yesterday-think I'll upgrade the bottles from #1 to #2 size today as I'm out of oxy/fuel.

I'm finding it difficult to 'cut'. Most likely b/c I'm learning as I go. The manual says to open the fuel (acetelene) and adjust to get rid of the 'soot', then adjust the oxygen until you achieve a white cone. I finally figured out you're suppose to 'preheat' the metal then add in the 'cutting' oxygen. At times it was working well and others I couldn't get any cutting action. seems like practice is the key!

Should the tip be on the metal or hovering above-or does the distance depend on the size of the 'white cone'? I did spend quite a bit of time surfing trying to find details including picutres of the proper flame (or does it matter that much)?

Has anyone made a guide to aid in making straight line cuts?

Brad_Blazer · Dec 31, 2006

I'm not a torch expert but the way it works is the normal flame is set up for pre-heating the metal and when you pull the trigger you get a very oxygen rich flame. The torch cuts using a chemical reaction between the steel and the oxygen. That's why a cutting torch only works on ferrous metals that rust (react with oxygen). Also make sure you understand the safety aspects of using oxygen - many things, including much of you, will burn in an oxygen rich environment.
You need a small gap as the flame needs some burning distance to generate heat. I'll let someone with more experience chime in on the finer points of adjusting the flame.

Brad

Dargo · Dec 31, 2006

72chevy4x4 said:
Has anyone made a guide to aid in making straight line cuts?

I can't say "H*** yeah" here, so I'll just say absolutely! In another thread I spelled out the advantages/disadvantages of both O/A and plasma cutters after a couple decades of use. Actually, it's really been decades of use with O/A and a couple of years with my plasma cutter.

Remember, there's no such thing as cheating. With a plasma cutter you can cut out a pattern in plywood with a jigsaw and go at it. Don't try using wood as your guide with your O/A torch.

Hey! Way back when I tried that I didn't expect that 2X4 to catch fire and burn so easily!! When I'm cutting a straight line with an O/A or O/P (if you cut much, an O/P setup is far cheaper to use), I always clamp a piece of angle down to what I'm cutting. I then even make a few dry runs, if you will, to make sure that the torch tip will follow along exactly where I want it to run. Then, I also always use two hands on the torch and drag my right pinky finger and use it as a guide to keep my torch tip a constant distance from what I'm cutting.

After some practice, you'll learn all sorts of little "tricks" like that. It was once I got into doing more fabricating and cutting complex patterns (read: anything but a straight line) I went with plasma. Good luck. If you clamp a piece of angle as a guide, use both hands, and drag a knuckle or finger to keep a constant tip distance, you'll get pretty good results.

Michael_E_Tx · Dec 31, 2006

72chevy4x4 said:
Should the tip be on the metal or hovering above-or does the distance depend on the size of the 'white cone'? I did spend quite a bit of time surfing trying to find details including picutres of the proper flame (or does it matter that much)?

Proper flame makes a great deal of difference. Here's some general guidelines that might help you along. Set your acetylene to about 5 psi. Set your oxygen to about 20 psi. These are regulated pressures, in other words, these pressures should hold when valves are open.

Since you said it is a small outfit, it probably has a pretty small cutting tip. The adjusted preheat flame should probably end up a little less than 1/4" in length. After starting with the acetylene, open the oxygen slowly and you will see that there is a lighter blue sort of halo around the flame. You want to adjust the flame so that the halo is just about to disappear. You do not want the individual flames to have sharp points on them.

The idea is preheat your starting point until the metal reaches the molten state and then hit your oxygen. The tips of the preheat flames should be just above the surface, not on it. Personally, I would suggest Practicing on 1/8" material. It's a good compromise for learning to cut. Thinner and it will be easier to extinguish your cutting line. If the cutting edge doesn't remain molten, the fire goes out. Thicker material with a small cutting tip will require you to go slower and also increase the likelihood of not keeping the cutting edge hot enough.

Keep your tip clean, both the preheat and the oxygen holes.

The Miller site has a lot of free/low cost educational material. Take advantage of it. I'm sure other sites do as well, but I am only familiar with Miller's materials.

Good luck.

Mike