Removing welded pipe bead?

I need a suggestion. I need to telescope a length of 3.5" x.120 steel
tube inside a piece of 3 1/2" sched 40 welded pipe 24" long. I have
.05" of clearance which is just right for my purposes EXCEPT for the
weld bead on the pipe. I could go get a stick of seamless but that
would defeat the principle of using up my drop and add even more. I
only need to take off about .02" to get a nice slip fit.
My first thought was to dress an old grinding wheel down to 3.5",
mounting it on a long arbor and driving it through with my heavy 5/8"
drill but I can invision the possibility of a broken arm should the
wheel grab.
Can anyone suggest a safer or easier method?
Reply to
Glenn Ashmore
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A hole saw might do the job. You would have to grind the first half inch of the weld down to start it but that would be easy with a Dremel or similar tool. Do it in a drill press (or lathe) - kep the speed way down and pressure moderate and lots of lube. Ken.
Reply to
Ken Davey
Hole saw or other edged cutter with a pilot pin that has a groove in it for the ridge?
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works evevery time it is tried!
Reply to
Bob May
I did the same thing only the size was a piece of 2.5" sched40 that I wanted to slip a piece of 2" into for a grinder stand. I tried sanding cones in a die grinder with drill rod modified to reach down the pipe about 18" or so, the halfway point. If would have taken forever to get this done, and very quickly got too sloppy, couldn't control the sanding cone and keep it on the burr. So, like you, I thought, why not make a cutter that can be turned with a handdrill, and cut the burr out (this was all before I had a lathe, drill press, or mill). So I borrowed my dad's lathe and made a round plug, the same diameter as the I.D. of the pipe, tapped the center .5-13NC, hacksawed a 1/4 wide groove to accept HSS bit, and added some screws to retain the cutter. I ground the bit to be similar to a lathe bit. It worked, but I would suggest using a large drive shank than 1/2 all-thread. The cut is interrupted, so it shocks the shank and drill every time it hits the burr and tends to bind the plug up in the pipe as it gets twisted off axis. I couldn't slow the drill down because it didn't have the torque needed to drive thru the cut. Because I was manually feeding the drill, the cut was way to deep too. So this all made for a very choppy, brutal method. This method doesn't really provide you with a way to incrementally cut the burr, you need a way to control the depth of cut and a way to keep the drive shank center in the pipe. To do it again, I would build a more rigid drive shank, and probably figure out how to do it in the drill press, or the lathe with the pipe mounted on the cross-slide. Come to think of it, I used a stone that I took off of its short arbor and put it on some all-thread and drove it carefully with a air die grinder at probably 3-6000 rpm. Used wood blocks to take some of the whip out of the all-thread. This was mostly to clean of the rough spots, not to cut all the burr.
Glenn Ashmore wrote:
Reply to
nic
Use the dressed grinding wheel, but make a key slotted eccentric disc to follow the bead down the pipe ahead of the wheel.
The disc keeps the grinding wheel positioned along the bead and the bead makes a temporary key that you remove as you go.
Something like an 1/4" disc turned to 3.5" diameter with a center pivot hole for a pilot on the grinding arbor offset 1/8" from center. Dress your grinding wheel to 3.25 in. and as an added benefit the rest of the id will be protected. Cut a slot clocked to the offset axis to fit the weld bead and off you go. Might need to install a cheap bronze bushing int the disc for the pilot to turn in.
There will be a slight undercut to get a flush surfacec with a 3 1/4 " wheel, but probably a lot less than what you would get just tossing a 3 1/2" wheel through it with no guide.
Haven't tried this yet, but I have the same issue with some welded stainless tubing that would be near perfect except the bead. My original thought was a custom set of push broaches but that seems like it would be too much effort to save...very little.
StaticsJason
Reply to
Statics
Glenn,
If the inside pipe does not need to turn you could simply grind/cut a groove in the outside of it to make room for the burr.
Regards, Jim C Roberts
Reply to
Jim Roberts
Ok, here's an idea. What about making a large D-bit just the size of your desired ID of the pipe? Grind away just the first 1/2" or so with a die grinder, then put your pipe in a stout vise and run your D-bit in from the end. Since a D-bit has over half of a cylindrical shape it will follow straight down the pipe, and just (ideally) nip away a bit of the weld on each rotation.
If you have a lathe with a big spindle bore you could mount your pipe in a chuck and feed the D-bit in using the apron.
Sort of like a big homemade gun drill.
Grant
Reply to
Grant Erwin
It has to rotate. This is going to be the pedestal for my "dream" rotating, adjustable height, lighted, dust collecting 5 position sharpening/grinding/polishing/buffing station with lazy susan wheel and compound storage.
Right now I have all that equipment crammed in a corner of the shop generating grit, lint and dust. It takes longer to find, clean and set up than it does to do the job. I want to be able to select the wheels and compounds I need, mount them all and move immediately from one to the other. I don't have enough room is my shop to spread it out so a rotating pedestal is the logical solution.
Jim Roberts wrote:
Reply to
Glenn Ashmore
Ah. Why not redesign with clearance, and use a surplus Timken tapered roller bearing at the top? Whenever I think "telescoping" I think of 1/4" of clearance with 1/4" bushings welded where they need to be. This is how the boom on my old boom truck worked, and it worked really well. I'd suggest forgetting the idea of removing the internal weld bead.
Grant
Glenn Ashmore wrote:
Reply to
Grant Erwin
Agree on bushings. Everytime I ever used a nice good slip fit of an entire length just a small amount of rust made it a bi%@* to get to telescope again. Now I is smarter, I use bushings, not as much contact area to give me grief, and if I have some that fits, I usually use brass or bronze or even nylon etc.
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Reply to
Roy
A bit hard to describe but you can also scrape it out. The inside diameter is 3.505" so get a piece of bar stock, weld a bar on one end at a slight angle, a cutter on the other end, total length about 3.600. Drill a series of holes near the cutter end to allow adjustment, and pull it though. If it is real hard to keep it from binding, exhange the cutter end for a half round file thta is wedged in place.
But the real way to do it is to put bushings on one end of the outer, one end of the inner. Cut a grove in the inner tube bushing to accomdate the weld seam.
Cheers.
Glenn Ashmore wrote:
Reply to
Roy J
Glenn,
You've got some pretty good suggestions on this, and I'm going to add my suggestion, not because I think it's a particularly good one. I just took it personally that I had to come up with a suggestion. You could take a hand held air driven cutoff wheel and cut all the way through the pipe lengthwise along the weld joint. That will remove the weld bead at the expense of leaving a burr that can probably be cleaned up just by running your tubing down it a few times. If the slot weakens the pipe too much, you can weld it at the ends where you can easily clean up the inside with a die grinder.
Bob
Reply to
Bob Thomasson

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