floating tool holder - can we actually talk about metal working

rk vs turning the
l to the center
same benefit from
On my old lathe the drill bit obviously tries to center itself but can't always overcome the handicaps of age and infirmity (the machine's). Before reaming I run a boring bar in and usually can hear some eccentricity and taper in the cut.
I've found combinations of chuck and tailstock position that drill straighter than others. The best is a Collis center drill holder with the tailstock almost fully retracted.
formatting link
If your tailstock has a keying slot maybe you could pop the chuck off the adapter and see if you can find a new position for it that counteracts other arbor and tailstock spindle errors like droop or not being exactly at headstock spindle height.
jsw
Reply to
Jim Wilkins
Loading thread data ...
partially right Wes, but if the reamer is off center, it has outward pressure on the hole as it enters and so it makes a slightly funneled hole, plus (this is a hobby, remember) it annoys the BEEEP out of me. There may be some additional wear on the jaws of this unit - the error is angular, not centering - a center drill held in the chuck drills in the center of the work, but a reamer that extends out from the chuck does not.
Jim W - there may be some combo of rearranging the chuck (which is the biggest of the Jacob's ball bearing chucks, the one that holds 3/4 inch) on it's JT to MT adapter that would make it better, but I doubt it. My conclusion is "don't bother trying to fix it, get the right tool" - I'm just trying to figure out what the right tool actually is - maybe a holder with the rubberflex collets?
Reply to
Bill Noble
[ ... ]
As someone else posted yesterday, the chucking reamers have a long fairly skinny shank, so even if the chuck is introducing errors, the shank will allow the cutting forces to re-center the reamer -- as long as you don't shorten the shank for convenience. :-)
You can probably get away without the floating holder given the flexibility of the long shanks.
Not sure what an automotive shank is on a reamer. Perhaps something for reaming bearings (such as ones for a camshaft) in line?
:-)
Keep asking questions and maybe we can outnumber the political postings?
Enjoy, DoN.
Reply to
DoN. Nichols
">
thanks Don.
1. "automotive shank" applies to the holder, not to the reamer - it is apparently some kind of shank used on special tools used for automotive engine work - it is an acme thread of several diameters, one of them being 1 1/16" - for example, this one
formatting link
2. so, your recommendation is to just ignore the offset and let the flex in the reamer shaft take it up - that's what I've been doing - but it annoys me - for those cases where I use a drill bit held in the chuck (as opposed to a drill bit with an MT taper shank), this same offset comes into play, and of course the larger bits (and the larger reamers) are pretty stiff. I'd like to fix this somehow because, if nothing else, it's unaesthetic - but I don't' want to end up with another drawer full of tooling.
I guess I don't understand those flex collets with the rubber - is the point of the rubber to give a wide holding range or to allow some degree of floating of the tool being held?
what about these things - I have some ER series collets and a holder for my mill so maybe a matching holder with an MT-3 shank instead of a 40 taper would be right?
Reply to
Bill Noble
...
Rubberflex collets have thin tapered metal jaws like the ones in a Darex Drill Doctor chuck, but embedded in rubber.
The Jacobs #36 is the least accurate of my tailstock chucks because it droops. A 3/4" drill bit in it jumps up about 1/16" when it enters a center-drilled starting hole.
jsw
Reply to
Jim Wilkins
Understand on the collets - the don't float. And, your comment on the #36 is exactly my issue - it annoys the heck out of me, which is why I'm looking for a solution
Reply to
Bill Noble
[ ... ]
O.K. A strange tool holder, with what appears to be a socket for Morse taper holders. Whether it has a self-centering feature is something which I can't tell just from photos. I would need it in my hands.
That is exactly what the Jacobs Rubberflex collets are for. Nothing to do with allowing a reamer to self-align with the hole in the workpiece. Just an earlier idea for the same purpose as the ER collets (and with an even wider range). They happen to be a royal PITA when trying to chuck up something really short, BTW.
> what about these things - I have some ER series collets and a holder for my > mill so maybe a matching holder with an MT-3 shank instead of a 40 taper > would be right? >
Reply to
DoN. Nichols
thanks - today, I was rearranging tooling and low and behold I have a self centering (floating) collet chuck thingie - it is for taps - it has a tap collet (with the square bottom) and a 3/4 inch shank - But, I don't see a convenient way to use it to hold anything except taps, and I only have the one collet (1/4) for it - it doesn't look like it could hold anything much larger. So, I moved it from its previous hiding place to a new hiding place near the taps, so at least if I need it, I have some small chance of finding it.
next step is to figure out which size ER collets I have - maybe tomorrow.... Meanwhile, I am learning something from this thread - perhaps some others are also.
Reply to
Bill Noble
I went out to the garage to see what collets I used with the Mill - it turns out I have two holders, one that is NMTB to R8 and so I can use R8 collets, and one that is this one
formatting link
which apparently uses TG-100 collets (I have a range of collets for it) And, of course, I have 5C collets for the lathe so, now to see what I can find.....
suggestions?
Reply to
Bill Noble
[ ... ]
Which kind of tap collet? The one used on TapMatic tapping heads uses a small version of the RubberFlex collet -- two sizes cover all the taps which fit that size.
Or is this the kind where you have a Morse Taper 0 adaptor to hold a tap by the square and the shank OD?
Measure the maximum outside diameter -- in millimeters -- to get the ER-?? number (or close to it. :-)
Enjoy, DoN.
Reply to
DoN. Nichols
Hmm ... I would expect that adaptor to consume a lot of the space between the spindle and the table. Assuming that you mean the spindle is NMTB 40 and the colle you wish to hold is R8.
Probably a better grip than the R8 collets. They have a reputation for letting the endmill walk down into the workpiece (and sometimes the table) under heavy cutting loads.
Good Luck, DoN.
Reply to
DoN. Nichols
The floating holder I have is W.M Zeigler Tool Co, Detroit, no numbers or model info, 3/4 inch shank is 1.65 long, - the collet is unlike others I've seen, steel, vaguely like a double angle collet, but with a square base so it won't turn, and inside, it has a square section to grab the tap. I think what I have is an early version of the 0-SA variant in the catalog that is on-line here
formatting link
- see page 27 for a good view of the collet - I guess I'll have to be on the lookout for more collets too
Reply to
Bill Noble
O.K. Once I turned on enough things so it would let me *see* the catalog. It wanted both JavaScript and Flash turned on to allow me to see it.
First -- this seems to be overkill for your work, and looks as though it is for powered spindles, not non-rotating tailstock spindles.
Second -- it corrects for lateral offset, but not for angular errors such as your drooping tailstock ram. (Assuming that it *is actually drooping.)
If it *
is* drooping, it is wear in the bore in which the ram moves, and it will droop more the more it is extended.
However, another likely problem is wear on the carriage, so the whole ram is below center -- whether extended or not.
The fix for the second problem (which can be verified by a Blake centering indicator or other ways which are less convenient) is to determine how low it is, and to add shim stock between the tailstock and the carriage along the parting line which allows for lateral offset.
Most serious lathe makers make the tailstock just a little *
above* center, so as it wears through its life, it will get better before it starts getting worse.
The Blake is also convenient for tuning the tailstock back on center horizontally, too.
Good Luck, DoN.
Reply to
DoN. Nichols
Thanks Don - In my case, I know that it is the drill chuck, not the tailstock - an MT drill or reamer put into the quill directly aligns accurately (well, within a few thousandths), a drill blank held in a collet aligns accurately also, as does a live center - but a drill rod or a reamer held in the Jacob's chuck is misaligned. The reason I went down the path of getting one of these floating holders in the first place was that I couldn't see a practical way to hold a range of chucking reamers without a chuck, and if chucks aren't accurate, then I need the float - did I go off track with this reasoning?
Reply to
Bill Noble
[ ... ]
Hmm ... does the tailstock ram engage the tang, or can you rotate the arbor (and the chuck with it) to any possible position?
You might see what the drill rod does with the Morse taper arbor rotated 180 degrees.
Second -- it is possible (especially if you have an old chuck and arbor) that the arbor has been bent by crash. When I get chucks via eBay, even if the come on the right sized arbor, I buy a new arbor from MSC -- either Jacobs brand, or Albrecht -- so I don't have to deal with a bent or poorly made arbor.
Hmm ... also -- do you have a Morse taper gauge for that taper? If so -- blue the arbor and trial fit it into the gauge to see whether it is making full contact. It might have a ding which is causing it to fit off center, and you can simply stone off the ding until you get full contact around the arbor (except where you have stoned too deep, of course. :-)
Usually, drill chucks are a lot better than the specs say, especially the high end Jacobs and the Albrecht ones. Those specs say that it won't be *worse* than this -- not that every one will be this bad. :-)
Hmm ... also, how good are the jaws in the chuck? A drill spinning in the chuck (e.g. trying to use a Silver & Demming 1" drill bit without shank flats in a 1/2" chuck) can damage the jaws of the chuck as well as the shank of the bit.
You can get rebuild kits from Jacobs (if a genuine Jacobs chuck), and you can find instructions on the Jacobs web site if you have never taken a chuck apart before. Before you start, you will need to make two sleeves on your lathe -- one for pressing the chuck apart, and the other for pressing it back together. Aluminum works fine for this, and you need a different set for each size of chuck. You also need an arbor press of some sort.
I think that it is overkill in this case. Your consideration of the ER collet chuck in the tailstock should work quite well -- especially since your other collets and such have tested good. You don't need a standard drill chuck to hold a chucking reamer -- but you *can* use one if that is what you have -- and the chuck and arbor are in good condition. It is called "chucking" to distinguish it from the ones with flats on the end for a tap wrench. :-)
Enjoy, DoN.
Reply to
DoN. Nichols
dwolfhope had written this in response to
formatting link
: Kennametal makes a double angle fully floating straight shanks holder 3/4 to 1 3/4 on the shank sizes. They use a DA180 collet to hold the reamer shank.You can contact us at snipped-for-privacy@kennametal.com or call 1-800-835-3668 for more information on these holders.
Dave W. Kennametal Application Support ------------------------------------- Bill Noble wrote:
##-----------------------------------------------## Delivered via
formatting link
Forums Web and RSS access to your favorite newsgroup - rec.crafts.metalworking - 210937 messages and counting! ##-----------------------------------------------##
Reply to
dwolfhope

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.