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Spotting Drills
Centre drill are often used as spotting drills in the lathe
but there's a pretty wild mismatch between center drill point angles and the the usual jobber drill that follows. Special spotting drills are produced for NC use at about three times the price of similar centre drills. How do the special features work and are they worth the premium price? Some seem to be single flute designs and the included angle is usually less thqn 118 deg jobber drill angle. What's the experience in using these items and what's the reasoning behind the design differences? Jim -- Posted via NewsDemon.com - Premium Uncensored Newsgroup Service -------http://www.NewsDemon.com------ Unlimited Access, Anonymous Accounts, Uncensored Broadband Access |
Spotting Drills
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Spotting Drills
wrote:
Centre drill are often used as spotting drills in the lathe but there's a pretty wild mismatch between center drill point angles and the the usual jobber drill that follows. Special spotting drills are produced for NC use at about three times the price of similar centre drills. How do the special features work and are they worth the premium price? Some seem to be single flute designs and the included angle is usually less thqn 118 deg jobber drill angle. I use them a lot on the mill, seldomn on the lathe. I like them! The keep long, because you won't drill deep holes, and you can't and should not drill holes. Just the conical part. Mine are two-fluted. Buy them! Nick -- Motor Modelle // Engine Models http://www.motor-manufaktur.de DIY-DRO // Eigenbau-Digitalanzeige http://www.yadro.de |
Spotting Drills
In article , Nick Müller
writes wrote: Centre drill are often used as spotting drills in the lathe but there's a pretty wild mismatch between center drill point angles and the the usual jobber drill that follows. Special spotting drills are produced for NC use at about three times the price of similar centre drills. How do the special features work and are they worth the premium price? Some seem to be single flute designs and the included angle is usually less thqn 118 deg jobber drill angle. I use them a lot on the mill, seldomn on the lathe. I like them! The keep long, because you won't drill deep holes, and you can't and should not drill holes. Just the conical part. Mine are two-fluted. Buy them! I have never used a spotting drill - and don't know what their construction is. However, just an alternative idea for pentagrid: have you tried stub drills. I almost always use these for starting holes, especially in small sizes. They are about half the length of a normal jobbers drill bit, and hence much stiffer, but only cost about the same or a little more. I do often spot with the very tip of a centre drill, but I'm not sure it is necessary. David -- David Littlewood |
Spotting Drills
You can buy whole drill sets (w/ the case) in the stub length, even the 115
pc set. A little pricey, tho. Stub drills can often save you a tool change, altho I'm sure the purists out there are clenching and grinding their teeth. :) The silver lining to breaking a jobber's length: Now you got a stubby! -- Mr. P.V.'d formerly Droll Troll "David Littlewood" wrote in message ... In article , Nick Müller writes wrote: Centre drill are often used as spotting drills in the lathe but there's a pretty wild mismatch between center drill point angles and the the usual jobber drill that follows. Special spotting drills are produced for NC use at about three times the price of similar centre drills. How do the special features work and are they worth the premium price? Some seem to be single flute designs and the included angle is usually less thqn 118 deg jobber drill angle. I use them a lot on the mill, seldomn on the lathe. I like them! The keep long, because you won't drill deep holes, and you can't and should not drill holes. Just the conical part. Mine are two-fluted. Buy them! I have never used a spotting drill - and don't know what their construction is. However, just an alternative idea for pentagrid: have you tried stub drills. I almost always use these for starting holes, especially in small sizes. They are about half the length of a normal jobbers drill bit, and hence much stiffer, but only cost about the same or a little more. I do often spot with the very tip of a centre drill, but I'm not sure it is necessary. David -- David Littlewood |
Spotting Drills
"David Littlewood" wrote in message ... In article , Nick Müller writes wrote: Centre drill are often used as spotting drills in the lathe but there's a pretty wild mismatch between center drill point angles and the the usual jobber drill that follows. Special spotting drills are produced for NC use at about three times the price of similar centre drills. How do the special features work and are they worth the premium price? Some seem to be single flute designs and the included angle is usually less thqn 118 deg jobber drill angle. I use them a lot on the mill, seldomn on the lathe. I like them! The keep long, because you won't drill deep holes, and you can't and should not drill holes. Just the conical part. Mine are two-fluted. Buy them! I have never used a spotting drill - and don't know what their construction is. However, just an alternative idea for pentagrid: have you tried stub drills. I almost always use these for starting holes, especially in small sizes. They are about half the length of a normal jobbers drill bit, and hence much stiffer, but only cost about the same or a little more. I do often spot with the very tip of a centre drill, but I'm not sure it is necessary. David -- David Littlewood What David said, but insist in a split point to insure free cutting without deflection. The web of a drill has extreme negative rake and doesn't cut worth a damn. By splitting the point, the negative rake is eliminated, replaced by a cutting edge that cuts instead of plows. The difference in starting and drilling is remarkable. Folks that came up in the shop the old way did *not* routinely use spotting drills. That's what center drills were for, along with actually drilling centers. Don't ask me how I know this-----it's hard enough getting old without someone bringing it to your attention. Spotting drills are really a tool of the CNC age, where it's important to have a device that will start a hole where it's desired and not worry about breaking the tip off, which is common in center drill use, particularly when you get down to a #1 or smaller. By virtue of the grind design, spotting drills have virtually no web, so they behave much like a split point drill. Their short length provides rigidity and insures that the hole you drill will be where desired, and the grind permits easy evacuation of the chips that are generated. The tip is far more robust than that of a small center drill. Because of my training, and the era in which I spent my time in commercial shops, I do not use them, nor have I ever. Harold |
Spotting Drills
"David Littlewood" wrote in message ... In article , Nick Müller writes wrote: Centre drill are often used as spotting drills in the lathe but there's a pretty wild mismatch between center drill point angles and the the usual jobber drill that follows. Special spotting drills are produced for NC use at about three times the price of similar centre drills. How do the special features work and are they worth the premium price? Some seem to be single flute designs and the included angle is usually less thqn 118 deg jobber drill angle. I use them a lot on the mill, seldomn on the lathe. I like them! The keep long, because you won't drill deep holes, and you can't and should not drill holes. Just the conical part. Mine are two-fluted. Buy them! I have never used a spotting drill - and don't know what their construction is. However, just an alternative idea for pentagrid: have you tried stub drills. I almost always use these for starting holes, especially in small sizes. They are about half the length of a normal jobbers drill bit, and hence much stiffer, but only cost about the same or a little more. I do often spot with the very tip of a centre drill, but I'm not sure it is necessary. David -- David Littlewood I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! |
Spotting Drills
In article , Tom Miller
writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? David -- David Littlewood |
Spotting Drills
"David Littlewood" wrote in message ... In article , Tom Miller writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? David -- David Littlewood They are ground to a sort of a cusp - centre point and also cutting edge at the periphery of the flutes AWEM |
Spotting Drills
In article , Andrew Mawson
writes "David Littlewood" wrote in message ... In article , Tom Miller writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? David -- David Littlewood They are ground to a sort of a cusp - centre point and also cutting edge at the periphery of the flutes AWEM Thanks. David -- David Littlewood |
Spotting Drills
Keywords:
In article , "Andrew Mawson" wrote: "David Littlewood" wrote in message ... In article , Tom Miller writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? They are ground to a sort of a cusp - centre point and also cutting edge at the periphery of the flutes I've been looking for a supplier for these for decades, ever since I tried some a friends father had. None of the drill vendors I've spoken to have even heard of them. I even checked with several of the major US manufacturers at the Eastech machine tool show a few years back. Doug White |
Spotting Drills
edge at the periphery of the flutes I've been looking for a supplier for these for decades, ever since I tried some a friends father had. None of the drill vendors I've spoken to have even heard of them. I even checked with several of the major US manufacturers at the Eastech machine tool show a few years back. Doug White Plenty of them here in Auz |
Spotting Drills
Andrew Mawson wrote:
"David Littlewood" wrote in message ... In article , Tom Miller writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? David -- David Littlewood They are ground to a sort of a cusp - centre point and also cutting edge at the periphery of the flutes Are spot-weld removing drills the same? Lots of them on ebay (spot, drill). -- Peter Fairbrother |
Spotting Drills
"Peter Fairbrother" wrote in message ... Andrew Mawson wrote: "David Littlewood" wrote in message ... In article , Tom Miller writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? David -- David Littlewood They are ground to a sort of a cusp - centre point and also cutting edge at the periphery of the flutes Are spot-weld removing drills the same? Lots of them on ebay (spot, drill). Black and Decker do the sort of drills Andrew is describing, under the Piranha name. They work well in sheet metal (at least up to about 10mm) but are expensive. Our workshop guys at work call them crown-point drills. They are similar to the lip and spur drills used by woodworkers. Same basic idea - cut the rim of the hole before removing all of the support. |
Spotting Drills
In message , Andrew Mawson
writes "David Littlewood" wrote in message ... In article , Tom Miller writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? David -- David Littlewood They are ground to a sort of a cusp - centre point and also cutting edge at the periphery of the flutes AWEM Perhaps look at ............. http://www.centerdrills.com/CNCspot.htm Mike -- Mike Whittome - Frequently wrong; seldom without opinion! |
Spotting Drills
Mike Whittome wrote:
In message , Andrew Mawson writes "David Littlewood" wrote in message ... In article , Tom Miller writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? David -- David Littlewood They are ground to a sort of a cusp - centre point and also cutting edge at the periphery of the flutes AWEM Perhaps look at ............. http://www.centerdrills.com/CNCspot.htm After reading this thread I bought some spotting drills to try (from ebay), and I have only one comment - wonderful!! Centre drills are good for drilling centers where you need a pilot hole and a 60 degree "countersink" for the center, but for getting a hole in the right place without hassles or the drill bit wandering all over, spotting drills are unbeatable. I just drilled a cross hole in a bit of hard shiny 8mm round stainless with a rickety old pillar drill, and I didn't even use a centre pop to mark it - nae fuss nor bother, and it just started in the right place! I don't know how they work, because they don't look too different, but I am convinced - apart from centers, I'll never use a centre drill to start a hole again. OT, how does one spell the word? Is it optional, or another case of two countries divided by a common language? -- Peter Fairbrother |
Spotting Drills
On Fri, 28 Apr 2006 01:03:01 +0100, Peter Fairbrother
wrote: Mike Whittome wrote: In message , Andrew Mawson writes "David Littlewood" wrote in message ... In article , Tom Miller writes I tend to use sheet metal drills for hole starting. They are very short and are double ended. you can break twice as many for the same price! Sheet metal drills? David -- David Littlewood They are ground to a sort of a cusp - centre point and also cutting edge at the periphery of the flutes AWEM Perhaps look at ............. http://www.centerdrills.com/CNCspot.htm After reading this thread I bought some spotting drills to try (from ebay), and I have only one comment - wonderful!! Centre drills are good for drilling centers where you need a pilot hole and a 60 degree "countersink" for the center, but for getting a hole in the right place without hassles or the drill bit wandering all over, spotting drills are unbeatable. I just drilled a cross hole in a bit of hard shiny 8mm round stainless with a rickety old pillar drill, and I didn't even use a centre pop to mark it - nae fuss nor bother, and it just started in the right place! I don't know how they work, because they don't look too different, but I am convinced - apart from centers, I'll never use a centre drill to start a hole again. OT, how does one spell the word? Is it optional, or another case of two countries divided by a common language? You spell centre, I spell center. You say tomato, I say tomato. It all works. I do find it interesting that so many words, and so many accents, that should be the same are so different after a couple hundred years. Even though we have been talking to each other the entire time. Not just England and the USA. England, Australia, Canada, and the USA. All different. And across each country big differences. Not just class differences in the way we speak, but even in the same class. Blue collar workers sound much different in different parts of the country even though they use much of the same slang. ERS |
Spotting Drills
"Peter Fairbrother" wrote in message ... snip---- I don't know how they work, because they don't look too different, but I am convinced - apart from centers, I'll never use a centre drill to start a hole again. The one big difference is rake angle. Center drills are zero rake, do not cut to center, and have little chip relief. Those conditions do not lend themselves to easy machining. Harold |
Spotting Drills
In rec.crafts.metalworking Harold and Susan Vordos wrote:
The one big difference is rake angle. Center drills are zero rake, do not cut to center, and have little chip relief. Those conditions do not lend themselves to easy machining. --Soooo they're good for thin materials but not for drilling to depth? -- "Steamboat Ed" Haas : I'll have the roast duck Hacking the Trailing Edge! : with the mango salsa... www.nmpproducts.com ---Decks a-wash in a sea of words--- |
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