boring question

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heres my problem. i am currently boring a 1 in hole in a piece of 1-1/2 in solid hot rolled steel round stock (from the end). The depths vary from 2" to 5". I am doing this by putting the drill bit in the tailstock of my lathe and feeding it into the rotating metal.I am going through drill bits a like crazy because i am doing at least 10 of these a day. My question. What is a better method for this? should i be using a metal spade bit with an insert? should i use an end mill and do it on my lathe? I am looking for the most affordable way to do this.ThanksTyler
Reply:I would drill to like a 1/2" or so and use a boring bar with a carbide coated insert on the lathe. It would be accurate as far as the I.D. and the insert would probably last longer than stepping up with drill bits. I would say this would be somewhat affordable compared to using an end mill. But if your doing multiple pieces on a daily basis maybe using drill bits and investing in a bench grinder to sharpen them would be your cheapest way. Just my two cents.
Reply:For boring, you use boring tools/tooling.You are drilling, by using a drill bit.They both make holes, but they are not quite the same tools nor the same operation.That said, double-check your tooling and tools and the machining parameters (feed and speed) and your lube.  But a 1 inch diameter hole should be able to be drilled into plain hot-rolled steel stock with the lathe tailstock.Some possible problem areas:- feed and speed;- lube, or lack of lube;- rigidity/vibration problems;- cheap low-quality drill bits;- combinations of the above;- other  The best laid schemes ... Gang oft agley ...
Reply:An end mill won't help you much.I prefer cobalt alloy bits for drilling into steel.  They last much longer than HSS.That being said, using a drill bit to bore a hole isn't the best way to go.The previous advice about using a boring bar is.Just start with a 1/2" hole, and bore from there.  Then sharpen your 1/2" bit on your drill doctor or what have you.  Using a boring bar will produce a much rounder hole if that matters to you too.
Reply:The question is how precise does the hole need to be.  Obviously not real precise I'm thinking since you have been drilling them so far.  I don't think that ten holes a day would be alot for a "quality" bit.  I have bored far more than ten holes a day and never had to replace the bit.  First, are you drilling a pilot hole?  I would probably pre-drill with a 3/8" to 1/2" pilot then use the 1" bit to finish.  Are you using any type of coolant?  Also as Moonrise mentioned check your speed and feed.  Yes you can drill them and bore them out but using a boring bar that small and boring out a 1/4" of material is gonna be a great deal slower than drilling and if they do not have to be exact I would probably continue to drill them.  Also once the bit starts cutting then be sure to keep a constant steady pressure on the bit keeping it cutting, and clean it out frequently.  A bit that free spins without cutting,  or clogging up the hole with chips will build up heat in the part, and kill a drill bit.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:I've drilled similar holes using a lathe though not that many in one day. I never had to sharpen a bit either. I'm not by any means a machinist, but this is how I did it. I was drilling 1 1/4 holes through 2 inch plate approximately 4 1/2 deep. I first set the lathe to turn pretty slow (can't recall the exact speed but it was only a couple hundred rpm) then drilled a 1/2 pilot, changed bits and drilled to full size. All the time I was drilling I had the white water based cooling (cutting maybe) oil running on the bit. I didn't try to force it just maintained steady pressure and tried to keep a continuous chip rolling out of it. I know the cooling oil is key. All of our bits and cutting tools were strictly top shelf stuff. We had drilling machines that had the coolant blown through the bits coming out of holes in the cutting faces. These machines would punch 3 inch holes through 6 inch plate in a matter of just a couple of minutes with no pilot holes. The bits were very expensive, but they lasted forever with no sharpening. One of my customers has two of the drilling machines that went underwater during Katrina sitting in his yard right now.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Thanks for all the response guys.I am still new to this so you have definitely identified a few major problems with what I am doing. First of all I am not using any type of cutting lubricant at all. What should I be using. And I dont drill a pilot because when i do the smaller bit (1/2) wants to dance on me (it doesnt stay centered as i start to drill it wobles around and starts to cut off center). should i use a countersink style bit or something like that to make a small start and then make the pilot hole or what? Also should i be using a drill bit with a taper to fit my tailstock or should i put a chuck int he tailstock and put the bit in it.Again thanks alot.anytime i ask a question on here i get great response. It is definitely the most helpful forum I have been on.ThanksTyler
Reply:Yes, a countersink bit will definitely help you start on center.  As far as a taper bit vs. a drill chuck.  I use both.  most of my taper shanked bits are larger bits, but if you have a good drill chuck mounted on a taper to fit the tail stock then you should be ok.  As mentioned above drilling is not for precise holes.  It is for rough work.  You will use a reamer or boring bar for precise work.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:wds,IMHO,  go to the hardware store, and buy some mineral oil.  Mix that with water, and use that as your cutting fluid.  Cheap, and most commercial cutting fluids are just that with some preservatives.Use a counter sink to get the center, then go in with a jobbers drill mounted in a Jacobs chuck that has a taper that will fit in your tailstock.  Use a 1/2 inch jobbers drill, and flood the drill.  Don't try to drill through in one move, drill in a little bit at a time, retract to clear the chips, and then drill some more.Then go to a one inch spade drill that is tapered for your tailstock.  You'll eliminate the stackup of tolerances that come from putting a drill in a Jacobs into a taper.  Again, do not try to drill through in one shot.  Get some chips, clear the hole, and keep the cutting fluid on flood.  As long as your tolerance on the hole isn't less than .010", you should get a good hole on size.We do this all the time.I r 2 a perfessional
Reply:why not use 1/4" wall tubing and put a plug in it.  Turning a bar  to size and then cutting it to length would be fast, if it work for your application.  It would a great oportunity to silver braze.Last edited by tapwelder; 07-22-2008 at 11:38 PM.
Reply:Originally Posted by kbnitwds,IMHO,  go to the hardware store, and buy some mineral oil.  Mix that with water, and use that as your cutting fluid.  Cheap, and most commercial cutting fluids are just that with some preservatives.Use a counter sink to get the center, then go in with a jobbers drill mounted in a Jacobs chuck that has a taper that will fit in your tailstock.  Use a 1/2 inch jobbers drill, and flood the drill.  Don't try to drill through in one move, drill in a little bit at a time, retract to clear the chips, and then drill some more.Then go to a one inch spade drill that is tapered for your tailstock.  You'll eliminate the stackup of tolerances that come from putting a drill in a Jacobs into a taper.  Again, do not try to drill through in one shot.  Get some chips, clear the hole, and keep the cutting fluid on flood.  As long as your tolerance on the hole isn't less than .010", you should get a good hole on size.We do this all the time.
Reply:Sorry, wds,A jobbers drill is a standard size drill available from just about anywhere that comes in either fractional, letter, or wire gage sizes.  So, yeah, a standard 1/2 inch bit.If you keep the coolant flowing on the 1" drill, make sure you keep the chips clear, you should get a lot more life out of it.  If you've got any machinery books, look up the preferred speed and feed, and keep to it.Good luckI r 2 a perfessional
Reply:The 'usual' tool to start a hole for drilling is a "center drill".  It is also 'the' tool to use when you are drilling a center hole to put the tip of your lathe center into, when you are turning something between centers.  It's short, has a 'thick' body, and it doesn't tend to walk or skate or dance around when you start the hole with one.  They are only for starting a hole, or for making a center hole (for your lathe center), as they don't go very deep at all.After the hole is started with the center drill, then you use a 'regular' drill.  And maybe you do the operation in a few steps (3/8 or 1/2 inch drill bit, and then your 1 inch drill bit).For lube on steel, you can use mineral oil or kerosene or "cutting oil" of various types.Look up a chart (if you don't already have one) on feeds and speeds for drilling.To me, a "spade drill" is a bit for drilling a quick r-o-u-g-h hole in wood or similar materials.  It is not a bit for precision, nor is it a bit for drilling in metal.  A common brand-name is Irwin SpeedBore ( http://www.irwin.com/irwin/consumer/...rwinProd100185).And if you are removing that much steel, as tapwelder mentioned, maybe start with tube and then plug the end.Also, look up some lathe machining info on the Net if you aren't sure what you are doing.  Or take a machine-shop course at a vo-tech or community college.  Or look around on the web for a forum about hobby machining and see if you can find someone in your area who can give you some hints or instruction or mentor you for a while.  The best laid schemes ... Gang oft agley ...
Reply:Originally Posted by kbnitSorry, wds,A jobbers drill is a standard size drill available from just about anywhere that comes in either fractional, letter, or wire gage sizes.  So, yeah, a standard 1/2 inch bit.If you keep the coolant flowing on the 1" drill, make sure you keep the chips clear, you should get a lot more life out of it.  If you've got any machinery books, look up the preferred speed and feed, and keep to it.Good luck
Reply:Moonrise,There are actually quite a few iterations of spade drills that are used for drilling metals.  They're not made by Irwin, I can't imagine anything that pointy and thin cutting anything but wood.  Metal cutting ones don't have the sharp pointy center, they're actually shaped like a shovel, (spade) since it's assumed that you've already drilled the pilot hole, and the cutting edges are raked and cleared to allow good chip flow.  Acknowledged, they are not a precision cutting device, but I've held .010" diametral in mild steel.I r 2 a perfessional
Reply:Yes there are spade bits for steel. They are inserts that are used to drill deep holes in metal with a lathe or drill press. Since you have a metal lathe why not bore the holes instead of drilling them. You get a better hole and it doesn't take much time. You can make a simple boring bar as in the first pic or buy a fancy carbide one. I have dozens of them for different jobs because it seems like not one size fits all. Just my .02...Bob Attached ImagesBob WrightSalem, Ohio  Birthplace of the Silver & Deming Drillhttp://groups.yahoo.com/group/southbend10k/http://groups.yahoo.com/group/sawking/1999 Miller MM185 w/ Miller 185 Spoolmate spoolgun
Reply:WDS, how large is your lathe, is it old, new, fairly worn or tight? The sloppiness makes a big difference on how well some tools cut; you don't want any chatter. As stated earlier, speeds and feeds also affect that plus determine the heat and load placed on the tool.Regarding spade drills for metal, last month I used a carbide one to open up the back of a "tool steel" safe with 1 1/2" thick walls. Needed a magnetic base drill to drive it; then opened the hole with a  carbide-tipped twist drill. HSS or Cobalt alloys aren't hard enough for this material. I have another such box ('free' on Craigslist!) I have in my trailer at a friends place which I need to work on next. I think it's empty so may use the plasma instead.
Reply:Ahhh, metal-drilling spade bit.  First thing I thought of when I read "spade bit" was the type for drilling in wood or similar.Solid-carbide metal drilling spade bit.  1/2 inch dia, only ~$35 http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3btw, center drill http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32In case you missed it when I said it above, or when several other people have said similar things:Some possible problem areas:- feed and speed;- lube, or lack of lube;- rigidity/vibration problems;- cheap low-quality drill bits;- combinations of the above;- other  The best laid schemes ... Gang oft agley ...
Reply:Drilling without lubricant is a good way to ruin a drill bit in short order. If your lathe doesn't have a coolant circulating pump they are easily and cheaply made. Something for a tank, an evaporative air conditioner pump, a little flex tubing and a valve.You really need to find a drilling chart. It will tell you how many rpm's to turn based on bit size. That is critical to bit life as the larger the bit gets the slower it has to turn. Unless you have one of the machines in my earlier post and I have only seen five of those total over the years.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Originally Posted by Jolly RogerDrilling without lubricant is a good way to ruin a drill bit in short order. If your lathe doesn't have a coolant circulating pump they are easily and cheaply made. Something for a tank, an evaporative air conditioner pump, a little flex tubing and a valve.You really need to find a drilling chart. It will tell you how many rpm's to turn based on bit size. That is critical to bit life as the larger the bit gets the slower it has to turn. Unless you have one of the machines in my earlier post and I have only seen five of those total over the years.