VN 12 5c to jacobs taper for drill chuck.
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    Default VN 12 5c to jacobs taper for drill chuck.

    For drilling small holes on the VN 12, I am limited to finding a lot of odd collets, or using a drill chuck with 1/2" straight shank in a 1/2" VN collet.

    I have a couple spare blanks made up from 1144 stress proof, with the VN taper , threads, keyway and drive lugs already cut- I am thinking about putting one on the the lathe and turning a Jacobs taper for a drill chuck.

    Any advice on this, like what size drill chuck to use and what Jacobs taper to turn? I don't know a thing about the Jacobs taper,angle, size, etc, except that they fit drill chucks.

    Is there a size chart around for the Jacobs taper?
    Any brand of moderately price chucks ya'll like? (moderate-$75-$200)

    Thanks, Stoneaxe.

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    The Jacobs taper dimensions are in the Machinery's Handbook.

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    There were VN OE collet-like adapters that had an inner Morse Taper #2, which would allow you to then have multiple MT2 inter-adapters for different Jacobs chuck sizes. Downside would be that you would have one more intermediate interface to contribute to 'tolerance stacking.'

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    Frankly, you're better off using a center drill in a collet to locate the holes, then drill the holes on a drill press. By the time you put a chuck and a drill of any size in a Van Norman, you have very little space for the part. Especially if you're using a vise.

    Cal

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    Quote Originally Posted by Cal Haines View Post
    Frankly, you're better off using a center drill in a collet to locate the holes, then drill the holes on a drill press. By the time you put a chuck and a drill of any size in a Van Norman, you have very little space for the part. Especially if you're using a vise.

    Cal
    Cal, I can see that working well if the part is simple and easy to re-index- and I get the part about the vn having little clearance under the head. For horizontal drilling it is not too bad, as the ram can be retracted.

    I am actually rethinking this once more, and considering using a VN5C to ER 20 setup, to shorten the chuck length. I will probably buy a set of screw machine length drills also.
    I called Hardinge today to see if they would make one, as they are all set up for collets, they must have the dimensions. Or maybe use a ER20 to 5/8" straight, I have a very short 5/8" VN endmill holder it could go in.
    Just playing around with ways to hold smaller drills, etc.

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    Another option is to make a 5C to MT2 adapter and buy a set of MT2 collets. You can get a set on Amazon for $42 (link). That would also allow you to use an MT2-shank ER chuck.

    Cal

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    Cal, on the MT collet to VN5c- the collets would need a separate drawbar, yes? So the MT collet drawbar would either go through the hollow VN drawbar, opr replace it entirely, or the MT collets would use a short screw drawbar to the back or the VN arbor? (this would mean the VN 5c would need to come out for every tool change)

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    stoneaxe, just to clarify, when you say "VN 5c" are you talking actual industry standard 5C, or the VN "C" collet that Hardinge calls the "5V"? I didn't think there was enough meat in a VN #12 spindle to rebore for actual 5C, as the "C" taper is pretty small.

    The Chinese make a wide range of ER collet holders with straight shanks, and they are pretty well made for the (very little) money. I've gotten a couple off eBay with stubby shanks to use in sharpening jigs. My experience is that bodies are well ground, including concentricity, but the caps can be a bit sloppy. So I think using one with a VN body is a fine idea.

    I would make a blank "C" holder (or whatever fits the mill spindle) and bore it to fit one of these ER holders. Make it a slip fit (finger push fit) with minimal clearance, then relieve all but the front 3/8"-1/2" of the bore by 0.002"-0.005" on radius. Put the collet holder as far into the bored blank as it will go and still allow the cap to be fully tightened, then braze or silver solder the collet holder shank into the blank from the rear.

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    Quote Originally Posted by sfriedberg View Post
    stoneaxe, just to clarify, when you say "VN 5c" are you talking actual industry standard 5C, or the VN "C" collet that Hardinge calls the "5V"? I didn't think there was enough meat in a VN #12 spindle to rebore for actual 5C, as the "C" taper is pretty small.

    The Chinese make a wide range of ER collet holders with straight shanks, and they are pretty well made for the (very little) money. I've gotten a couple off eBay with stubby shanks to use in sharpening jigs. My experience is that bodies are well ground, including concentricity, but the caps can be a bit sloppy. So I think using one with a VN body is a fine idea.

    I would make a blank "C" holder (or whatever fits the mill spindle) and bore it to fit one of these ER holders. Make it a slip fit (finger push fit) with minimal clearance, then relieve all but the front 3/8"-1/2" of the bore by 0.002"-0.005" on radius. Put the collet holder as far into the bored blank as it will go and still allow the cap to be fully tightened, then braze or silver solder the collet holder shank into the blank from the rear.
    VN 5c/ Hardinge 5V.
    Now there is an interesting idea! I was figuring on clamping the ER16 toolholder in a 1/2" collet or endmill holder. Never thought of silver soldering it in. I could also just turn an interference fit , toss the VN blank in the oven and the collet shank in the freezer then shrink them together. Suppose that would work?

    I also bought a ER 25 collet nut and am going to turn a VN collet body for it- so 1/2" tooling can pass through -

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    Quote Originally Posted by stoneaxe View Post
    Cal, on the MT collet to VN5c- the collets would need a separate drawbar, yes? So the MT collet drawbar would either go through the hollow VN drawbar, opr replace it entirely, or the MT collets would use a short screw drawbar to the back or the VN arbor? (this would mean the VN 5c would need to come out for every tool change)
    Not to be picky, but there's no such thing as a "VN5c" collet. Van Norman called them "C" collets; Hardinge called them 5V (the V is presumably for Van Norman) since several other companies, including Cincinnati-Milicron have "C" collets. 5C collets are commonly used on lathes and were, if I'm not mistaken, developed by Hardinge for their Cataract lathes. The 'C' suffix is for "Cataract" and there were a whole series of different sizes.

    You could use a drawbar to pull in the MT collet if you like, but an MT2 taper has incredible hold and a drawbar is not normally needed for retention. As a rule, drill presses quills and lathe tailstocks with an MT taper don't have an sort of drawbar for retention. Regardless, I would use a drawbar just in case. A piece of all-thread, a washer and a wingnut is probably all you need.

    The advantage of the MT2 collet route is that you don't loose any space due to the tool holder. Even an ER-25 collet holder will cost you about an inch, due to the height of the nut.

    As far as reamers go, there are "Jig Reamers" with MT2 shanks. I have a set for my Hauser 3BA, which has an MT2 spindle. The reamers stick out of the end of the spindle an inch or two and come with a set of matching stub drills, which are under-sized just the right amount for reaming. Another option is a "Stub Reamer" with a straight shank. They are pretty pricey new, but you could watch for them on eBay.

    Rather than crank the table down for a tool change, why not tip the head?

    Cal

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    Quote Originally Posted by Cal Haines View Post
    Not to be picky, but there's no such thing as a "VN5c" collet. Van Norman called them "C" collets; Hardinge called them 5V (the V is presumably for Van Norman) since several other companies, including Cincinnati-Milicron have "C" collets. 5C collets are commonly used on lathes and were, if I'm not mistaken, developed by Hardinge for their Cataract lathes. The 'C' suffix is for "Cataract" and there were a whole series of different sizes.

    You could use a drawbar to pull in the MT collet if you like, but an MT2 taper has incredible hold and a drawbar is not normally needed for retention. As a rule, drill presses quills and lathe tailstocks with an MT taper don't have an sort of drawbar for retention. Regardless, I would use a drawbar just in case. A piece of all-thread, a washer and a wingnut is probably all you need.

    The advantage of the MT2 collet route is that you don't loose any space due to the tool holder. Even an ER-25 collet holder will cost you about an inch, due to the height of the nut.

    As far as reamers go, there are "Jig Reamers" with MT2 shanks. I have a set for my Hauser 3BA, which has an MT2 spindle. The reamers stick out of the end of the spindle an inch or two and come with a set of matching stub drills, which are under-sized just the right amount for reaming. Another option is a "Stub Reamer" with a straight shank. They are pretty pricey new, but you could watch for them on eBay.

    Rather than crank the table down for a tool change, why not tip the head?

    Cal
    Cal, thanks for the info- I have a lot to learn!


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