Re: Widening an existing hole with a drill bit: how to guarantee concentricity?
¿ªÔÆÌåÓýIt¡¯s taken me a long while to learn this, but there are times when it is best to buy rather than make (and this is one of those times). ?You want the run-out on your collet chuck to be as small as possible, and unless you are experienced at working to close tolerances, buy a manufactured M14 collet chuck.? That way you will still have your undamaged M12 collet chuck to use at a later time or to sell or give away. ?? ? As many others have already stated, drilling to enlarge the mounting hole will likely lead to frustration and a ruined part; the opening has to be bored and then carefully tapped (and for that you need a working lathe).? To mount the collet chuck for machining you would probably want to use an independent 4-jaw chuck and center the opening of the collet chuck using a dial test indicator.? ?If you want to do this as a teaching exercise for yourself, you may want to first practice on a piece of steel rod. ? Best of luck, ? Jerry F. ? From: [email protected] [mailto:[email protected]] On Behalf Of james Pineda via groups.io
Sent: Thursday, April 20, 2023 11:20 AM To: [email protected] Subject: Re: [Unimat] Widening an existing hole with a drill bit: how to guarantee concentricity? ? Hi, I would second the boring option, if you want any hope of achieving any sort of concentricity.? If I understand you, you want to take a 12mm mount ER16 collet chuck, and convert it to a 14mm mount, yes?? And to be able to use it as originally designed, or at use it and maintain the tolerances you were able to achieve?? ? Using a drill press for this job seems an exercise in frustration. As pointed out by others, neither the drill press nor drills are designed for this type of work.? ? I'm sure there are other ways to do this, but here's a couple of suggestions, all of which involve mounting the ER16 chuck and collet and performing a boring operation ? You could make bore and tap a rod and mount that onto the headstock spindle. Turn to diameter with a shoulder. If your headstock is properly aligned, you should have a concentric rod/cylinder to mount the ER16 collet/chuck to. Then bore. ? Or, a la Joe Pie on youtube - make a bushing to hold a precision ground rod? ?
? Or, you could just buy a new chuck collet with the 14mm threads...because you still have to thread it. ? hope this helps ? james ? ? ? On Thursday, April 20, 2023 at 08:57:12 AM PDT, Bill in OKC too via groups.io <wmrmeyers@...> wrote: ? ? Steve pointed out to me that not all of my messages are going to the group, and he thought at least this one should, so here it is! ? Bill in OKC ? William R. Meyers, MSgt, USAF(Ret.) ? Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Improvise, Adapt, and Overcome. Expect in one hand, expectorate in the other. See which one gets full first. ? ? ? ----- Forwarded Message ----- From: William R. Meyers <wmrmeyers@...> To: Steve Johnson <steve@...> Sent: Thursday, April 20, 2023 at 10:23:25 AM CDT Subject: Re: [Unimat] Widening an existing hole with a drill bit: how to guarantee concentricity? ? I have been known to make mistakes about what the OP was looking for, so I went back and looked at the original message. He has a chuck with a pre-drilled hole. I'm guessing that he didn't drill it, so doesn't have the drill. Besides, depending on the the drill, the setup, and how tight the chuck was tightened can all affect how big a hole a drill bit drills when it's used, so getting a accurate hole would be a crap-shoot. Sets of adjustable reamers are relatively cheap, so OP could ream the hole to size, Still be better done in his lathe, which he says is not all together right now... ? Maybe we need to find someone near him who can help him out! :)? ? Bill in OKC ? William R. Meyers, MSgt, USAF(Ret.) ? Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Improvise, Adapt, and Overcome. Expect in one hand, expectorate in the other. See which one gets full first. ? ? ? On Thursday, April 20, 2023 at 10:06:42 AM CDT, Steve Johnson <steve@...> wrote: ? ? Good point Bill. ? Still, providing the M12 hole had never been tapped, use the original bit for centering and bore with the new tap drill size.? On Apr 20, 2023, at 9:03 AM, Bill in OKC too via <wmrmeyers@...> wrote: ? Are you sure about that? The tap drill for an M12x1 tap is 11mm. That is what I used making the collet chuck and faceplate that I worked on. Both fit the Unimat SL spindle. See the Metric fine thread chart here:??I am a bit math-challenged, but that should make the minor diameter 11mm or perhaps a bit more. If it were M12x1.5 or M12x1.75 you'd be closer, but probably not enough to get good concentricity.? ? Bill in OKC ? William R. Meyers, MSgt, USAF(Ret.) ? Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY! Improvise, Adapt, and Overcome. Expect in one hand, expectorate in the other. See which one gets full first. ? ? ? On Thursday, April 20, 2023 at 09:54:10 AM CDT, Elliot Nesterman <elliot@...> wrote: ? ? Without a milling machine or a lathe, achieving perfect axial alignment ? |
