MLMartin Posted February 21, 2008 Share Posted February 21, 2008 i have a plate that is 1 1/2" thick the plate is to big to move into the forge, just not gona happen very well. well i want to place a 1" square hole in the plate and i need it pretty uniform. i have piloted a little hole were i want it. my plan is to drill a much larger hole then heat up around the hole with a rose bud and drive a 1" square drift though. seeing as i want to drift a 1" hole should i go ahead and drill the hole to 1" then heat and drift, or will this force the outside of the hole a little large? if so should i move down and drill a 15/16" or a 7/8" hole? Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted February 21, 2008 Share Posted February 21, 2008 I'm afreaid that if your plate is too big to put in your forge then you will be longer getting it hot enough with a rose bud then you were getting old! 1 1/2" plate if any size will take a LONG time to get that hot. If possible get it in a coal/coke forge to heat. I helped a friend upset the corner of a piece of 2" plate 12" square, took a while to get it hot enough to upset. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted February 21, 2008 Share Posted February 21, 2008 CAn you drill it a lot oversize then make a round bushing with a sq hole in it and weld in place? Quote Link to comment Share on other sites More sharing options...
Frosty Posted February 21, 2008 Share Posted February 21, 2008 Two things come to mind. First is to drill and broach rather than drift. A broach is a cutter that is driven through the hole. While broaching is usually found under machineshop operations it's a fine old blacksmith's technique and can even be done hot if you really want to.Milling: Operations - Broaching The other is to dig a ground forge and attempt to heat and drift. I'd bring lunch though. Frosty Quote Link to comment Share on other sites More sharing options...
Hillbillysmith Posted February 21, 2008 Share Posted February 21, 2008 Try this for making your square hole: iForge Blacksmith Projects go to the bottom of the page to #164 "Square". This should help you. -Hillbilly Quote Link to comment Share on other sites More sharing options...
jimbob Posted February 21, 2008 Share Posted February 21, 2008 I think I'ed drill it out with something like a 3/16 drill bit a series of holes all the way around the inside of the proposed square hole then knock out the plug then use a cold chisel to clean it up and maybe a file after that Quote Link to comment Share on other sites More sharing options...
MLMartin Posted February 21, 2008 Author Share Posted February 21, 2008 yes jimbob i expected as much, i have done that before and i expect ill be doing it again. just though i would ask to see if anyone had tryed and had any luck thanks everyone for the tips Quote Link to comment Share on other sites More sharing options...
habu68 Posted February 22, 2008 Share Posted February 22, 2008 what you need is a Harry Watt square drill bit. It is a special drill for drilling square holes.Reuleaux Triangle -- from Wolfram MathWorld another method would be to use a small drill in each of the four corners to define the radius for the corners, (square inside corners are never good, they are a point for cracks to start). Then with a larger drill remove the majority of the material from along the edges of the square, this will leave a series of wave like cuts when you have the center drop out. The next step would be to use the pre-industrial milling machine (an apprentice with a file) to remove the excess metal to the line of the square hole. Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted February 22, 2008 Share Posted February 22, 2008 I have made a 1 inch square hole in 1 inch plate by drilling a series of 1/4" holes around the perimeter, then using a slim chisel to take out the center. Following that, use a file and a lot of elbow grease to square it up. I could have probably punched mine, but I didn't want to change the shape of the original piece (that metal has to go somewhere). If you can get your plate on a drill press, it's a snap (watch bit speed). If not, it's a much longer chore with a hand drill. I doubt you can heat it enough to punch the hole without using a forge, regardless of your preparation. Good luck with your challenge. Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted February 22, 2008 Share Posted February 22, 2008 Anyway............ Quote Link to comment Share on other sites More sharing options...
skunkriv Posted February 22, 2008 Share Posted February 22, 2008 You already have that small hole drilled in it. I would consider torching it out close then heat in a ground forge like Frosty says and drift. Or grind to the line cold. Drilling small holes all the way around then filing and grinding is of course another good option. Quote Link to comment Share on other sites More sharing options...
patrick Posted February 22, 2008 Share Posted February 22, 2008 If you are going to drill and then drift, you probably don't want your drill larger than 3/4 because you won't get flat sides to the hole if you drill it to big. I know because I tried it in some 2.5 or 3" stock I was trying to make into a bolster block for power hammer work. If you have a big enough torch (or torches) you can get the area of the hole up to foring temps, BUT if you don't heat it and cool it uniformly from both side it will warp. Torching a rough square will remove a lot of excess metal, but leave you with a heat affect zone that likely will be difficult to file. You could probably overcome this with a die grinder. Probably the best way is to use the suggestion already posted of a series of drilled holes. Quote Link to comment Share on other sites More sharing options...
saintjohnbarleycorn Posted February 22, 2008 Share Posted February 22, 2008 how about building a fire outside and heating it up real well and then take the torch to it, It would take two people I would guess with the size of the piece you have, a good wood fire can generate quite a lot of heat. you could even set up a tripod with a block and tackle or chain hoist to set it on something to heat and beat with. Quote Link to comment Share on other sites More sharing options...
solvarr Posted February 22, 2008 Share Posted February 22, 2008 Know anyone with an oxy acetylene rig? While back an acquaintance needed to do something similar. He rough cut the hole and then had enough heat because he cut in a spiral to build the heat he was able to finish the hole by drifting. He needed to mount a 3 inch bar to a 1 inch plate so he worked up a tapered mortise on the end. Forced the sucker through the yellow hot glowing hole. Flipped it over and used a rosebud to finish doming the tennon. Seems like you should be able to do something similar. Be sure you get the right tips and gas mix for the thicker steel and do a few practice cuts if you have never done this before. Quote Link to comment Share on other sites More sharing options...
stretch Posted February 22, 2008 Share Posted February 22, 2008 If you can get the plate to a big enough drill press I would use a previous idea and drill a 2" hole, take 4 pieces of 3/4"X2" and weld them together with a 1" hole in the middle, weld them real good and machine that piece down to 2" and put it in the hole and weld it. It also come down to how much strength you need with this hole. You might have to weld it real good or just a good bead around the top and bottom and done. Grind it up nice and everyone will always wonder how you got this square hole in the middle of a plate 1 1/2" thick. This would be alot easier on the body than filing or drifting. The hole in one of my anvils is punched crooked and I tried filing it. It is still crooked:):) Quote Link to comment Share on other sites More sharing options...
welder19 Posted February 22, 2008 Share Posted February 22, 2008 Even if you can't drill a hole that big just torch cut it and then weld the flat stock in to make your 1" square hole, like stretch said. Unless you have a big rose bud and large tanks and even then you'll be a while trying to heat it enough to punch it, torching will take a bit too but no where near as long as just heating it. welder19 Quote Link to comment Share on other sites More sharing options...
Dodge Posted February 22, 2008 Share Posted February 22, 2008 I like Rich Hale's idea. This is similar to the way they repaired 3/4" bolt holes on machine mounts where I used to work. Drill oversize hole. Bevel hole 45 Quote Link to comment Share on other sites More sharing options...
Dan Crabtree Posted February 22, 2008 Share Posted February 22, 2008 If the plate is too big to move around easily I would use an oxy/act torch and get it as close to square as you can. Then take a file or die grinder to smooth out the edges. drilling in thick plate can be very time consuming. If you are good with a cutting torch I would go with this method. Quote Link to comment Share on other sites More sharing options...
MLMartin Posted February 22, 2008 Author Share Posted February 22, 2008 i do have oxy act, have cut 4" before, uggg that was a bear, i may cut it, i have cut holes like this before with this method then filed, but my hand isent to great and spend to much time filing. maybe ill do that then go out and buy myself one of those good little .5" belt sanders, haha ill actually have a good excuse for buying more tools, like you ever need one to begin with. Quote Link to comment Share on other sites More sharing options...
Ten Hammers Posted February 23, 2008 Share Posted February 23, 2008 I haven't seen posted just how large the piece of plate is. You might clamp the piece off the edge of the welding table so to have good place for the torch to exit. Consider this. Take a piece of square tubing about 1 1/2" in diameter and cut a piece off the end about an inch long. Tack this to a piece of scrap 7 guage ( 3/16 ) or so. Stick the torch in the square and pierce the plate ( or drill a hole in it ). Cut the inside of the tubing profile in the plate and see how the hole size comes out. Consider that the tip for the big plate is perhaps a bit larger. Forge ( or weld up ) a piece for your torch to follow ( INSIDE ) and think about using this to make your hole with the torch. Play with it a bit. I use similar technique for plasma and 14 ga for a need I have. If you have cut big plate before then you know the rules of engagement ( serious gloves, eyewear and setup/feed technique ). A nice caffene level and comfortable stance may give you most of the hole you want. A DYNAFILE in the hole afterwards would make a nice sweet finish. I can't imagine using a standard file after a torch cut. I might also practice on another piece before the big show. Good luck. Second thought. If the plate is not exceptionally big ( one man size if you weld some handles on it ) you MIGHT get it in the forge but would be a monster fire. After the torch heat and slug is gone ( which will give you core heat ), if you torch a bit small and THEN have a drift of correct size to drive through, you would then need a place to set the ( now monster big monster hot ) piece out of the forge on something solid ( preferably a bit low like the end of a piece of 6" pipe about 18" long ). You can then strike the sizing drift HARD with a sledge. You need a serious orange to yellow heat for this. I would say you have one chance to start and drive the drift. If you stick it and let it get hot it will mushroom and you will have an issue flipping this over to drive the drift back out. Bruce in the Shetlands might read my suggestions and laugh. Having an assistant hold the welded on handles would be nice but with planning many things work. You will have a by george problem if you don't plan well. This is a team sport project that needs a good team. I have one son in law that is a welder that I might ask for help on something like this and he might turn me down after he saw what I was trying to do ( lol ) Mebbe Rich's suggestion is better. Another suggestion is that if this hole is for a stake, make a hole in some 1/4 plate and set THIS over a wood block and have the bottom of the stake in wood. Use the top steel hole for stability and screw the steel to the wood block. Quote Link to comment Share on other sites More sharing options...
Ice Czar Posted February 23, 2008 Share Posted February 23, 2008 If you have a big enough torch (or torches) you can get the area of the hole up to foring temps, our large rosebud has no problems spot heating even thick plate, provided you have access to both sides, even easier with a hole to heat from the inside out our small rosebud on the other hand.... Quote Link to comment Share on other sites More sharing options...
imagedude Posted February 23, 2008 Share Posted February 23, 2008 I'd drill a 15/16 hole with a Rotabroach drill then add the corners using an electric powerfile. Quote Link to comment Share on other sites More sharing options...
jimbob Posted February 23, 2008 Share Posted February 23, 2008 I think Dodge has the best approach.The savings in time and work would far outweight the cost of the oversize bit to drill the hole for the insert...I think its better than the ole tried and true! you might also try this site http://upper.us.edu/faculty/smith/reuleaux.htm or this one IntegerSpin.com Quote Link to comment Share on other sites More sharing options...
NeatGuy Posted February 23, 2008 Share Posted February 23, 2008 what you need is a Harry Watt square drill bit. It is a special drill for drilling square holes. That is cool! I found very little information about the drill...but the "Watts Brothers Tool Works" still make these niffty devices: 760 Airbrake Avenue, P.O. Box 335 Wilmerding, PA , 15148-1014 Phone: 412-823-7877 FAX: 412-823-4844 As complicated as they seem they are actualy oddly simple. USPTO patent numbers: 1,241,177 1,241,1761,241,175 Quote Link to comment Share on other sites More sharing options...
habu68 Posted February 23, 2008 Share Posted February 23, 2008 For someone with a knee mill this would be a fairly simple milling job, a couple of end mills to hog out the majority of the hole and a smaller one to fine cut the radius for the corners. It is done all the time for tool and die work to make pockets for inserts. Check with your local high school tech school you might find they could do it as a project. It is basic milling. Quote Link to comment Share on other sites More sharing options...
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