Fitting Tubes at Home for Welding





Introduction: Fitting Tubes at Home for Welding

You have a project that requires you to weld tubing together at a right angle, but you do not have any commercially made equipment for cutting a nice concave in the end of a tube where it joins another tube. This Instructable will show you how to do a good job in your home workshop.

I do not like welding EMT (conduit). I am using it here solely for the sake of illustration. What this Instructable demonstrates would work well with black pipe.

Step 1: My Setup

I am using a metal cut-off wheel mounted on a radial arm saw. The metal tube rests on a small accessory table I made.

Step 2: Make a Table

I made an accessory table from scraps of plywood. It is about 4 inches high. The surface is about 6 x 17 inches. I use it for a variety of things, including holding work while I use a drill chuck on the right end of the arbor for special drilling operations. The table has a flat surface on its bottom so I can clamp it to the saw table.

Any horizontal arbor would work if you do not have a radial arm saw. But, there will be some things about this process that will rely more on your eye and less on the guidance provided by the table.

Step 3: Raise or Lower the Saw Arm

Raise or lower the saw arm so the center of the shaft is at the same level as the center of the tube. When you grind a profile in the top of the tube, the same profile will be produced in the bottom of the tube. That is the key to coping the tube end for the tube to which it will join by welding.

Step 4: Use Masking Tape

I use masking tape to mark something I want to cut or grind. It makes something very easy to see, despite the bright sparks and (normally) dark metal against a dark stone. Wrap a little masking tape around the end of one tube.

Step 5: The End Goal

The end goal will be to cut a profile in the end of one tube so it very closely fits the contour of the other tube's side.

Step 6: Mark the Profile

Use a marker pen to outline the desired profile on the masking tape. Do not worry if you cannot accurately draw the whole profile.

Step 7: Start Grinding

Start grinding. You are guiding the process by your hand and eye while the tube rests on the accessory table. Go slowly. Try not to roll the tube, but to keep pointing up the same part of the tube that was upmost at the start of the grinding process.

Step 8: Check Your Work

Stop frequently to check your work, especially as you are nearer to completion of the task. Here you can see quite a gap. More grinding is needed on the two shoulders. Go slowly and check often.

Step 9: Finished

Here you see the two tubes fitted together ready for welding or brazing. The fit is almost as good as a machine designed for this job might do. Obviously, this is not for the demands of production, but it works well for an occasional project at home. Any small gaps can easily be filled by the welding or brazing process.

With some care, you could use this process to cope tubes that will meet at angles other than 90 degrees. Some extra planning would need to go into your setup.



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    It's a best instruction and easy tip on round tubing using a welding process which can be easily used by home welders. Weld find some more tips on .square tubing using a MIG welding process (an easy one) and make as many items as you can.

    I have used white vinegar on galvanized metal to make paint stick more efficiently, but never used it to prep for welding. I just open the shop doors and turn on a fan.

    I like the idea of doing the double miter cuts as away to make the pipe fit better.

    When it comes to welding EMT conduit, your best solution is to avoid welding it at all costs. However, if you do any projects with welding it, either have a fan handy to get the fumes away from you, or sand down the galvanized coating to bare metal out to about 2"-3" away from where you're working. There will still be smoke coming from the interior coating, so you'll still want plenty of ventilation. Also, invest in a respirator. They're cheap.

    Great tip, thanks. You mention welding conduit: can you give some tips on how to do this without poisoning yourself? If you have the time, an instructable on the subject would be fantastic.

    A coworker at a previous job was a journeyman welder. I remeber him discussing a a job he did on-site in a factory using all galvanized materials for the structures they were making.
    I do not recall him mentioning about grinding off the zinc coating. i DO recall him mentioning that the welding fumes from galvanized were a huge problem. They made every effort to avoid the fumes (masks, etc...) but also he said to drink a lot of milk to absorb and counteract the effects from breathing the fumes.
    Mike Bynum

    Milk SHOULD NOT be used as an antidote for zinc poisoning. This is a dangerous old wives tale! There is nothing in milk that counteracts the effects of the zinc in your system.
    Zinc poisoning occurs in two ways -ACUTE from large amounts in a very short period of time and Cummunlative from exposure to relatively low doses over a long period of time.

    Also remember that grinding the zing off of the out side of pipe/tubing does not remove the zinc from thet insider of the work piece. For flat work you also have to clean both sides as well.

    Weld safe or die!

    i have a breather on my mask 

    Grind off the zinc coating up to an inch beyond the weld and still ventilate well. While welds can be deposited through galvanized coatings, it is not a good idea from a weld integrity standpoint.

    I've done plenty of welding on galvanized material, & we never ground it out, but it does stink & is bad for you, but if you know you're going to be welding it & drink some milk beforehand, it will prevent you from getting sick.  Don't ask me how it works, but it definitely prevented me from tossing my breakfast on more than one occasion. Of course, I do NOT condone, or recommend it. ;)

    I am only a home hobby welder with no real training. I know the zinc coating on galvanized metals creates problems with the weld as well as making unhealthful fumes. The few times I have done it, I have tried for as much ventilation as possible. It is also a good idea to grind off the coating in the area where you will be welding. It still seemed to be difficult to make the arc behave.