3" hole Mild Steel 3/8" thick

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Friend of mine ask me if I could make a hole in a cast steel column sq and 3/8" thick. I immediately thought of my torch. But he would like to have a clean 3" hole and I do not believe i can do that with oxyacetylene.  Would a hole saw and going slow work? He would like a clean cut. ThanksGeezerPower Mig 255C185 TIGBlue 175 MIGRanger 8 Kohler 20HP1974 5K Lincoln/Wisconsin Powered (Cherry)Victor/Harris O/AK 487 Spool Gun
Reply:A slow hole saw and cutting fluid should get you there.  Should be able to get it done in 30 min's max.Sent from my XT1635-01 using TapatalkLincoln 175Monkey Wards 230v.  Stick
Reply:Should work.  Take a scrap piece of 3/8 and try it.  You'll find out if the result is to his liking.
Reply:A really good bi-metal hole saw will make quick work of that job. I usually cut thick stuff dry with an air jet keeping the kerf clear, cutting oil just gums up the chips and binds things up. Oh, pre drill the pilot hole, you bend fewer pilot bits when it doesn't have to drill through and catch the cutter when it breaks through. Before everybody screams about the dry cutting, get a Lenox cutter with highspeed teeth, I have some that have cut hundreds of holes and still cut well. Even up to 5" through 3/4" plate. Air and safety glasses are the key.
Reply:.geezer

Originally Posted by geezer

. . . if I could make a hole in a cast steel column sq and 3/8" thick - . . . thought of my torch . . . he would like to have a clean 3" hole and I do not believe i can do that with oxyacetylene . . . Would a hole saw and going slow work? . . . clean cut . . .
Reply:They make a torch circle attachment for cutting torch. I works very good. I just drill 3/16” hole for the attachment and cut the hole.Later I used a magnetic pattern torch. The best was electric eye  pattern torch Today they have cnc pattern torch'sDave

Originally Posted by geezer

Friend of mine ask me if I could make a hole in a cast steel column sq and 3/8" thick. I immediately thought of my torch. But he would like to have a clean 3" hole and I do not believe i can do that with oxyacetylene.  Would a hole saw and going slow work? He would like a clean cut. Thanks
Reply:Here are the choices I would suggest:Either carbide tipped hole saw (first choice) orplasma cutter with a template.Circle cutting guide will be awkward for a small diameter such as 3”.

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Reply:

Originally Posted by 12V71

A really good bi-metal hole saw will make quick work of that job. I usually cut thick stuff dry with an air jet keeping the kerf clear, cutting oil just gums up the chips and binds things up. Oh, pre drill the pilot hole, you bend fewer pilot bits when it doesn't have to drill through and catch the cutter when it breaks through. Before everybody screams about the dry cutting, get a Lenox cutter with highspeed teeth, I have some that have cut hundreds of holes and still cut well. Even up to 5" through 3/4" plate. Air and safety glasses are the key.
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Originally Posted by Lis2323

I do the same with air

even with annular cutters.
Reply:

Originally Posted by ronsii

I thought for sure you were going to post up a pic with a couple cold air guns working with the magdrill!!!!

https://www.vortextube.co.uk/cold-air-guns
Reply:

Originally Posted by Lis2323

That’s out of the budget for my farm /retirement/hobby shop


Reply:Thanks for all the replies, much appreciated. Obviously many of you have experience using hole saws in metal, I just never had a reason.Apologize for not listing why a 3inch clean hole. It is more appearance than function. So if I have it correctly,  purchase a good quality by metal hole saw, hold the rpms down and drill slow and steady, pre drill pilot hole.  No air jet so lubricate well and clean hole frequently.We will run a test piece.thanks for taking the time to replyLast edited by geezer; 09-10-2020 at 09:49 AM.GeezerPower Mig 255C185 TIGBlue 175 MIGRanger 8 Kohler 20HP1974 5K Lincoln/Wisconsin Powered (Cherry)Victor/Harris O/AK 487 Spool Gun
Reply:[QUOTE=Lis2323;8767361]Here are the choices I would suggest:Either carbide tipped hole saw (first choice) orplasma cutter with a template.Circle cutting guide will be awkward for a small diameter such as 3”. Thank you very much, I have seen many test pieces you post with your replies. Very thoughtful. What type hole saw is that please?????GeezerPower Mig 255C185 TIGBlue 175 MIGRanger 8 Kohler 20HP1974 5K Lincoln/Wisconsin Powered (Cherry)Victor/Harris O/AK 487 Spool Gun
Reply:Not necessarily from this seller, but I bought mine off eBay. https://www.ebay.ca/itm/174130409771Edit. Just noticed this set doesn’t have a 3” (75mm) cutter)You will need to search for the individual one(s)  you require.Last edited by Lis2323; 09-10-2020 at 10:51 AM.:
Reply:A lennox hole saw will cut thru that no problem. As mentioned predrill your center hole. I use cutting oil and lots of it. Probably more for coolant than anything.
Reply:A photo would help and what the hole is used.A 3" hole is not hard to do.But it is cost if just welding or electrical maybe something else.I have used torch for welding to milling machine for ball bearings but I had look at cost.Dave

Originally Posted by geezer

Friend of mine ask me if I could make a hole in a cast steel column sq and 3/8" thick. I immediately thought of my torch. But he would like to have a clean 3" hole and I do not believe i can do that with oxyacetylene.  Would a hole saw and going slow work? He would like a clean cut. Thanks
Reply:

Originally Posted by ronsii

LOL!!!   I remember when I first saw the cold air guns show up in the catalogs!!! I really wanted one

but they were pretty expensive

... never did get one...  now I see they're a lot cheaper!!! must be the patent ran out or something????P.s. I think you're taking this whole retirement/downsize thing too far


Reply:

Originally Posted by davec

Vortex cooling has been used for decades.  I recall it was used in tanks in WW2 to cool the crew some, so no way there are patents on it anymore.  They are quite loud and use a ton of compressed air...
Reply:A circle cutting guide will do a 3" inch hole. A really clean tip is essential and the cut could be cleaned up with a flap disc in a die grinder or hand drill. Cut hole slightly smaller to allow for polishing it. Not too hard to make a simple circle guide. Kind of crude but makes a nice hole in thicker plate. Last edited by Welder Dave; 09-15-2020 at 04:34 AM.
Reply:I think it hasn't been mentioned yet but it is recommended to drill one or two holes (say 10mm holes) on the inside of the circumference (just touching the hole saw cut line) to chips to evacuate so the teeth can keep on cutting. Otherwise you will clog the teeth and just creat heat. It prevents you from having to stop, blow chips, drill again, etc.If the hole is in the flat, it is pretty much mandatory. For the vertical, maybe not so much.Post a few pictures of the results of the operation!Mikel
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Originally Posted by Mikel_24

I think it hasn't been mentioned yet but it is recommended to drill one or two holes (say 10mm holes) on the inside of the circumference (just touching the hole saw cut line) to chips to evacuate so the teeth can keep on cutting. Otherwise you will clog the teeth and just creat heat. It prevents you from having to stop, blow chips, drill again, etc.If the hole is in the flat, it is pretty much mandatory. For the vertical, maybe not so much.Post a few pictures of the results of the operation!Mikel
Reply:3" TUNGSTEN CARBIDE TIPPED HOLE CUTTERBM-THC300_10.0 star ratingWrite a review$109.99Dont think my friend will spring for this, we will try carbide tip conventional hole saw first. This is a one time project, if we had a series of these then a more substantial cutter would be justified.GeezerPower Mig 255C185 TIGBlue 175 MIGRanger 8 Kohler 20HP1974 5K Lincoln/Wisconsin Powered (Cherry)Victor/Harris O/AK 487 Spool Gun
Reply:I worked for an old blacksmith back in the 70's. He used water & dish soap as coolant for drilling. Works pretty good & is easier to clean up afterwards than cutting oil, just blow it off & coat with wd40.Just don't let the bit get hot before you start cooling it. Hot bit/saw + water = cold quench.
Reply:I just use a regular bi metal hole saw in the drill press. I usually use air nozzle to help cool and remove chips. Go slow and wear earplugsMillermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:for one, Torch and template.I'on kno wat hapent?
Reply:me ther..???
Reply:I'll let you borrow this, but you need to record video of it.


Reply:Well i want to apologize to all who posted recommendations/suggestions. Indeed we cut holes in the sq tubing with carbide tipped hole saw and 1/2 inch drill.  Took our time and it worked fine, nice clean cuts. I will try and post pick or two. Much obligedGeezerPower Mig 255C185 TIGBlue 175 MIGRanger 8 Kohler 20HP1974 5K Lincoln/Wisconsin Powered (Cherry)Victor/Harris O/AK 487 Spool Gun
Reply:A 3 inch hole saw can get stuck.

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Reply:cutting horizontal is good, chips fall out and I am not against using a little water and fully grasp the concept of this being one off in nature.  Even if the saw was disposable the cost isnt a deal breaker.www.urkafarms.com
Reply:

Originally Posted by bubmiller

A 3 inch hole saw can get stuck.

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Reply:

Originally Posted by Weldalittle

you would think they could have come up with a better emergency operator safety system.
Reply:Back to topic, I don't have the resources of a machine shop, so I use hole saws regularly in heavy metal. I usually drill a hole in a block of wood first, then clamp it in place as a guide instead of using a pilot bit. Sent from my SM-A115AZ using Tapatalk
Reply:A regular quality bi metal hole saw will easily do it fairly quickly if there is only one to do no problem. Slow and clean chips out often. Maybe use air to blow it clean and keep teeth clean. Cutting oil will help keep teeth clean, cool and cutting. Good steady pressure at slow speed and keep saw making chips. Any hint of loading up stop and clean it again.Anytime I use a hole saw the arbor drill bit has been replaced with solid rod. Never use bit in hole saw to make the pilot hole. Use a separate bit to drill pilot hole then the solid rod in hole saw will keep hole saw guided straight and not woller out your pilot guide hole. The diameters are more accurate and cut is straight and clean.Last edited by danielplace; 4 Hours Ago at 11:01 PM.
Reply:Nice drill 2 piece type.Dave

Originally Posted by Weldalittle

you would think they could have come up with a better emergency operator safety system.