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Hi! I've been out of commission for a while from the group, but now that I'm on the mend, I have some projects to do. The first one is turning a .170 pin down to .154, and I need to instal a precision chuck that will grab something that small (It's about 1.5 inches long, and I have to turn all but about a quarter inch of it down. Where could I find somewhat inexpensive chucks that will do this, or adapters and a chuck, and what are the spindle dimensions, nominally. I'm measuring the outside of the threads with a mitutoyo dial caliper and getting 1.240, the register is 1.250, and the threads appear to be 1.250 (gotta find my thread counter), but I know this is a rough way to do this.
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Might be easier to turn it on centers. Or maybe with a collet...
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On May 21, 2021, at 11:13 AM, Joseph Difusco via < josephdfco@...> wrote: Hi! I've been out of commission for a while from the group, but now that I'm on the mend, I have some projects to do. The first one is turning a .170 pin down to .154, and I need to instal a precision chuck that will grab something that small (It's about 1.5 inches long, and I have to turn all but about a quarter inch of it down. Where could I find somewhat inexpensive chucks that will do this, or adapters and a chuck, and what are the spindle dimensions, nominally. I'm measuring the outside of the threads with a mitutoyo dial caliper and getting 1.240, the register is 1.250, and the threads appear to be 1.250 (gotta find my thread counter), but I know this is a rough way to do this.
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Use a precision drill chuck on a half inch shank. Mount and indicate in a 4 jaw chuck.? Turn part a quarter inch at a time to reduce part deflection. This turns my monster Lodge & Shipley into a jeweler's lathe. Another alternative is to mount the chuck direct in the spindle via the Morse taper but that doesn't allow for adjustment Good luck
Larry
On Friday, May 21, 2021, 6:24:00 PM EDT, glenn brooks <brooks.glenn@...> wrote:
Might be easier to turn it on centers. Or maybe with a collet...
On May 21, 2021, at 11:13 AM, Joseph Difusco via < josephdfco@...> wrote: Hi! I've been out of commission for a while from the group, but now that I'm on the mend, I have some projects to do. The first one is turning a .170 pin down to .154, and I need to instal a precision chuck that will grab something that small (It's about 1.5 inches long, and I have to turn all but about a quarter inch of it down. Where could I find somewhat inexpensive chucks that will do this, or adapters and a chuck, and what are the spindle dimensions, nominally. I'm measuring the outside of the threads with a mitutoyo dial caliper and getting 1.240, the register is 1.250, and the threads appear to be 1.250 (gotta find my thread counter), but I know this is a rough way to do this.
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Unfortunately, I can't find a collet in that size.
Can you explain how you would turn that on centers to me? It's been a while since I've been engaged in this, and I'm a bit rusty.
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I've got a 4-jaw chuck, but unfortunately it has a solid center. I'm guessing that the 1/2' shank would have to go into the lathe's spindle a bit? A collet to hold the work seems like an option, but the MT3 doesn't come in minor decimal sizes like something like a chucking reamer does. Also, like you mentioned, adjustment would surely be needed considering the size of the part (0.169"). For future reference, do you know what the spindle size and TPI is?
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I just looked at the collet; it's definitely not an MT3. Anybody know what it is? Also, I was looking on Amazon, and they had some 4-jaw chucks, including some that were self-adjusting (which I suspect has the same problem as 3-jaw chucks: jaws are not independent, so you're stuck with whatever inaccuracy was built into it. Any recommendations? If I spindle-mount, what's the thread specs? What Morse taper is the bore?? How do I turn between centers a part like this?Thanks!
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there is also 6 jaw chucks ?? ?but like 3 jaw they are self-centering
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On May 23, 2021, at 7:01 PM, Joseph Difusco via < josephdfco@...> wrote:
I just looked at the collet; it's definitely not an MT3. Anybody know what it is? Also, I was looking on Amazon, and they had some 4-jaw chucks, including some that were self-adjusting (which I suspect has the same problem as 3-jaw chucks: jaws are not independent, so you're stuck with whatever inaccuracy was built into it. Any recommendations? If I spindle-mount, what's the thread specs? What Morse taper is the bore?? How do I turn between centers a part like this?Thanks!
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I may have missed it, but is this a lot 4? If it is you may be looking at an abreviated spindle/collet adapter. My lot 4 has such a short adaptor in it and I'm not sure how to get it out, but it shouldn't be difficult. Here are two photos, the first is a MT4/3-C adapter and the second a 3-C collet.
Now that I'm back in the house I wish I'd taken a photo of the adapter stuck in the spindle. (Gotta figure out how to send pics)
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Got both photos through; Now, imagine that the collar on the adapter is busted off or turned off, could that be what you have?
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The collet looks a bit like what I have, but is more of an abrupt diameter change just before the mouth (like a trumpet. I don't recognize the other thing. My collet just goes right into the spindle, and the drawbar has a round handle on the left side of the lathe.
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Very nice, but Ouch! I'm an "MSC dreams with Chinese crapware means" kinda guy. I did just spend almost $300 for a drill bit from MSC recently, though. I've got a Thompson SMG bolt made of 4140, hardened to 55 Rockwell, and everything I've tried so far (drills and centercutting endmills) just kinda polishes the surface.
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You have a 3C collet.? Thread OD = .642? Pitch = 26. "3 C collet specs" search will brink up the info
Larry
On Tuesday, May 25, 2021, 09:13:24 AM EDT, Joseph Difusco via groups.io <josephdfco@...> wrote:
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Your spindle looks just like mine when the collet is out, why do you believe that the little lip at the end cannot be part of a shortened collet adapter?
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I just went to look, and yes my spindle nose looked just like yours, so I found a rod long enough to go through the HS with extra left over, then slid that as a hammer a few times and yup, the adapter popped out. It clearly had a thick lip on the outer edge that was removed at some time. BTW, I dribbled a bit of Kroil on the adapter first before hitting the back edge of it.
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That's not what I was implying. I honestly have no idea how this is set up. I'm sure that you know this machine a great deal more than I do, and definitely need help & guidance in figuring it out.
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Kroil ! I was trying to remember the name of that stuff!? I remember using that to get the barrel out of a Colt Single-action Army revolver I had a few years ago. Nothing I did or used worked until I soaked it in Kroil. Now I've got to order some before I forget again.
Does having the adapter out give us some more flexibility? If I'm reading your earlier post correctly, theres a 3 Morse taper underneath, and I've got lots of those. Also, it seems like you can get a 4-jaw independent chuck (if I ended up using that route) with an MT3 on its back, and lots of precision drill chucks with that taper as well, though I like the idea of a 4-independent-jaw chuck and a precision drill chuck with 1/2" shank a lot better, as L. Leonard mentioned.
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I just measured the spindle itself. The OD I'm getting on the threads is 1.225, and 1.250? where the thread ends. I just ordered another 3-wire set so I can get the pitch diameter.? I also ordered a tpi gauge set.? Does anybody know offhand what info I would need to look for a backplate that's already drilled and threaded for this, if one exists? If not, I'll wait for the pins & gauges, and get a blank backplate and bore & thread it.? What did you all do for chucks (sources, etc)?
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Joseph,
?I have two Daltons, one a lot 4 and one a lot 6, and I haven't restored either one although that was my original intention. The lot 6 had no adapter but the lot 4 did, as I said, abbreviated at the RH end and stuck in the spindle without a spindle nose protector. Perhaps using collets without a spindle nose protector is not a good idea.
?I also joined a British wood working forum because I saw a machinist section and mentioned there that I wish I could? find a MT3 (OR is it MT4?) to 4-C adapter, and a black pastor in Africa contacted me somehow years later and sent? a NIB adapter to me out of the good of his heart.
?So I can't speak much beyond that about the adapters or the spindle thread protector, which I also think is used to help remove the adapter when one wishes to reinstall a chuck.
?For the adaptor that fits the lot 4 somehow I got a MT3/3C adaptor which is complete, the one in the photo, and in fact the thick rim is too thick such that the MT3 does not seat because it holds it forward a few thousandths of an inch, so I need to find a way to remove a bit from the back side of that rim. I've speculated that removing the adaptor using both the spindle nose protector AND a rod and hammer through the spindle would make sense and be less dangerous to the old lathe.
Thank you,
Glen
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Wow! That's some incredible luck, and all-too-rare kindness.
I wonder: What's the advantage of using a 3C instead of the original MT3 collet? Are they more plentiful? More accurate? I suspect accuracy is the wrong answer, because then the inaccuracy would still be in the system. The drawbar?
Well, I just ordered an?Albrecht 3/8 Keyless Chuck With 1/2" Arbor, 0-3/8" range, and a new 1/2" 3C collet. The old one had stripped threads.? I'm going to plug everything in, and measure runout with a dial test indicator or dial indicator, and hopefully I can put off the 4-jaw temporarily and thus take my time and do it all properly, for a minimum amount of money.
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glenn brooks
