Need help cutting 3" hole

admin

I'm still working on that "pasture roller" I'm making out of a 250 gallon propane tank. It's going fine, until now.  I'm trying to cut a 2 3/4" hole in each end, to run an axle through, but I can NOT get that hole cut.Tonight I tried a 2 3/4" Lenox bi-metal.  Last week I cut a 1 1/2" hold in it with one, and it worked fine.  Just went slow and used some cutting oil and it bored right through it. This 2 3/4" saw, however, will NOT cut past about 1/8" deep.  The points feel razor sharp, but it just won't cut. I've tried everything. Can somebody give me a tip on how I can get this hole cut without spending too much money?-RuarkLincoln 3200HDHobart Stickmate LX235TWECO Fabricator 211i
Reply:Borrow a plasma cutter ot OA set up?? Drill a hole big enough for a jig saw blade to fit in, use a metal blade should curt right through it.Donnelly Small Engine & WeldingFoley AlabamaLincoln 225 TigLinoln 215 migHypertherm Powermax 65Ellis 1600 sawEllis 6000 belt grinderJD2 Model 4 tubing benderAtlas  12"X54" metal latheLots of large hammers
Reply:What will sometimes help A LOT when drilling thick metal is to drill a hole in the cut path of the holesaw to give a place for chips to go.  Try drilling a 3/8 hole and give that a shot.
Reply:I have run it to this with hole saws before. Usually its on thicker metals than that but if I had to take a guess. You might want to check the alignment of the teeth on the hole saw. They are susposed to be staggard one is bent in and the other kinda bent out. The ones that are bent in are to keep the slug more narrow than the inside of the hole saw. Some times if you apply to much force they kinda bent out like the others than the material you are cutting gets wedged against the inside of the hole saw not letting you cut any further. The saw is probably still very sharp just out of alignment. You can either get a new hole saw or if your patient enough you can use a small pair of pliars are readjust the teeth. I have had luck doing that remember they dont have to be bent in to much, just a few thou. Hope this helps
Reply:A torch would make quick work of that problem.
Reply:use an 1/8" drill bit and just drill it out with a few hundred holes, sounds like u already have your layout done.I forgot how to change this.
Reply:Aceman is right on relief hole for chips. I drill 4 of them works great.
Reply:I  have make a few of those! I use a cutting torch. If it is a green tank run air in it after you take out a few of the plugs. I have use motor exhaust fume that is the best way. Good luck
Reply:Aceman and 06BlueRamDrilling holes for the chips?  Excellent!!  I have run into the same problem on heavy steel and did not know what the problem was   Dave J.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:I vented my last 250 gallon propane tank by throwing a lit rag at it.  After 5-15 seconds of adrenilane charging blue flame that sounded like a jet engine, about 15 or more feet long, it settled down.  I would like to say I learned my lesson, but it was so much fun we kept trying to put a little propane back in it, but we never recreated the original perfect mix.  I am suprised the hole saw does'nt work, although you would need a slow powerfl drill, like a milwaukee hole hawg.   A plasma or torch would be my first choice, if available.
Reply:Originally Posted by blackbartI vented my last 250 gallon propane tank by throwing a lit rag at it.  After 5-15 seconds of adrenilane charging blue flame that sounded like a jet engine, about 15 or more feet long, it settled down.  I would like to say I learned my lesson, but it was so much fun we kept trying to put a little propane back in it, but we never recreated the original perfect mix..
Reply:Yeah, I know, that's why I didn't post it in the "safety section".  Actually, maybe I'm lucky, but I have worked on many propane tank modifications.  I was under the impression they could vent with a very large flame, but an actual explosion was near impossible. I have worked with the western propane association on fire dept trainings, and the only explosion I ever experienced was due to homemade tanks. Am I wrong? the vent opening should be adequate in my opinion.  I was taught that in a fire it was safer to keep the tank vent burning, because then you know where the gas is. When I did my first tank I threw dry ice in it, to create CO2, but the gas Co told me not to worry about it, they torch tanks all the time.  Maybe the pressure rating and steel thickness make it different than a thinwalled gas tank, or maybe I need to rethink.  I saw them fix a tank once by opening a 2" plug, causing much of the contents to freeze.  They replumbed it (putting in a liquid tap) and after it thawed they found they didn't lose that much product. The local feed supply store cuts tanks all the time for cattle water tanks.  He also does not take any additional precautions. I may be totally wrong, in which case, at least I'll make the front page on my way to outer space!