I would say the advantages of leaving it out outweigh the disadvantages of having one. Having read some of the replies below, there seem to be two kind of people: Those that do everything by the book and those that take risks.
I bet you the ones that do everything by the book and claim to be "good" engineers, will still make the mistake of trying to do up the drawbar with the pin misaligned at least once, possibly causing damage. Also, I doubt that they are the "innovative" type. They are generally great at doing things to plans, but crap at coming up with anything new. I would say that a "good" engineer is one that comes up with accurate and innovative engineering regardless of the quality of the tools. A "good" engineer also minimises the risk of f*ck-ups. I would therefore leave the pin out for tooling that does not need it because:
1) You'd have to be a complete imbecille not to be able to tighten the drawbar correctly without the pin in.
2) The collet is only likely to slip if you make a bad mistake, and then it's safer if it does slip.
3) The advantages posted by others.
Yes -- *drive* keys -- not index pins to keep the collet from spinning while you tighten the drawbar. :-)
The Bridgeport BOSS-3 (Series I) has the 30-taper Erickson spindle. The holders have the slotted flange, and this is used (in place of a drawbar) to both index (with 180 degree out possible) and to draw the taper up firmly. (A set of rotating ears fit through the slots as well as the keys. When you rotate the locking collar, the rotating ears swing over the flange and tighten against it to draw it in.
There are times (like with a boring/facing head) when I would feel more comfortable with a drawbar. :-)
The Nichols mill (40-taper) is a bit different. What it has is a pair of threaded holes for large Allen head cap screws to act as drivers, and the official 1" arbors (and presumably other sizes) are cross-drilled with about a 0.300" drill rod inserted through it, with a set screw at right angles to keep the two ends equidistant from the surface of the arbor. However, the Allen head cap screws will serve as driving lugs for the slotted flanges as well -- and even for CAT-40 end mill holders -- once you heat them to soften the Loctite, unscrew the draw stud, and machine up a replacement neck with internal thread to accept the standard drawbar. (I have done this with a couple of them from eBay auctions in sizes which I could not find with the standard flange.
Of course -- these *are* drive flanges, while the index pin for an R8 has nowhere near the strength if you manage to overcome the taper's friction drive. It will probably shear off in a hurry.
Thanks, DoN. It's been so many years that my memory is a bit foggy, but you've described them exactly as I remember them. I am not familiar with the smaller tapers aside from the quick change that I own. The real popularity of the smaller tapers seems to have hit the market big time when NC's and CNC's became popular, but by then I was well steeped in what I was doing and didn't change. At that time there was no reason to do so. Today I doubt I could get a job if that was my desire.
The quick change that I own is a Bridgeport product that has a Jacobs type keyed head and end mill holders that have a small taper, much in keeping with the large ones, although these are quite small. In looking at the head, one could easily conclude that Jacobs made it for Bridgeport. From your description of The Bridgeport BOSS-3 (Series I), I gather this system is similar, if not identical.
The q/c head extends the length of the spindle considerably and you can feel the difference on a Bridgeport, so I don't use it much. When doing a production job that required a few different end mills, though, it was a real time saver, so long as the demand was light duty.
I guess my entire point about the R8 is that the key is not intended to drive the cutter, although there are times when it probably does. I'm of the opinion it is there to prevent the collet from spinning when the thread on the drawbar and the collet don't fit up well, be it from chips or other reasons. Personally, I enjoy having the key in place and don't find it difficult to install the collets properly. I guess it's all in what one gets used to. I can see how easily a person could make the mistake of installing a collet not lined up with the key when they were used to not working with one. That in and of itself is pretty good reason to have the key in place. Helps prevent learning what I consider to be bad habits when running machines. The mileage of others is likely to vary.
And the BOSS-3 was the first of the Bridgeport CNCs. (Apparently the BOSS-1 and BOSS-2 were so bad that they never made it out of the factory. :-) The BOSS is the software (or firmware) name, while the machine hardware is Series-I or Series-II, depending on size.
I've seen (and used) one for an earlier Bridgeport clone converted to CNC by Anilam. That one had an R8 shank, and the quick-change holder on the end.
The differences between that and my Bridgeport with the Erickson quick change is:
1a) Erikson uses a full 30-taper NTMB style. Thinkness of flange, and distance of the far side from the gauge line are critical to it properly locking.
1b) The other quick-change adaptor which I mentioned above was smaller than 30 taper (close to 20 taper, if such exists), and instead of having a flange with two opposed notches, it has two fairly narrow ears -- about the width of the notches in the 30-taper if scaled down to match.
2a) The Erickson quick-change head must be spun closed with the hand followed with a special wrench.
2b) The other system is designed with a spring to spin the head closed, and a pair of pins to lock it open until the ears depress them. So you stop the spindle, spin open the collar, and the old tool in the collet assembly drops out. (You hopefully catch it, instead of allowing the end mill to bash into the workpiece, the milling vise, or the bed. :-) You then slap the new one in place, and the collar spins to a lock position on its own -- no wrench needed.
3a) The Erikson will accept any of the various 30-taper NTMB end mill holders, and various flavors of collet holders.
3b) The other system has two sizes of collet holders, and two series of collets to fit them. I've not seen anything else to fit them -- although it could well exist.
The BOSS-3/Series-I has a special spindle package with the socket for the quick-change made as part of it, and with a hollow ball screw surrounding the quill, for the CNC to drive the quill directly on-axis.
That sounds like what I experienced at work, and attempted to describe above. The BOSS-3/Series-I extends perhaps and additional inch beyond where the end of a R8 collet would be in the standard spindle. (Another interesting thing is that the 30-taper and the taper part of an R8 collet are identical -- just that the final drawbar shank on the
30-taper is smaller (more griping taper), and, of course, it has the driving keys.
Yes. The real place where a quick-change system of any sort wins is in CNC, every time you install a tool, the distance from the gauge line to the cutting end is the same (until you re-sharpen the end mill, or shift it), so you don't have to edit the program to reference the new position.
There are also fixtures to allow you to adjust the extension of a replacement tool to a constant extension from the gauge line, so you can replace or re-sharpen tools without having to modify the program. (Although most programming systems have provisions for clustering the tool dimension definitions right at the beginning of the program.) The Compact-5/CNC lathe, however, is not so nice. You have to re-enter the tool offsets in the program *each* time you call up a given tool, even if it is in a turret. This makes it rather important to perform as many operations with a given tool before changing it as possible -- especially if you are hand entering the programs, as I normally do. :-)
And there are probably times when it *attempts* to drive it, and fails. :-)
Let me put it this way. If I had gotten a manual Bridgeport with R8 shank, and found that it was missing the key -- or that it was sheared off -- I would by now have made and installed a replacement. As I understand it, the key is simply a dog-point Allen head set screw, backed by another Allen-head setscrew short enough so the socket extends through it, to allow a single Allen wrench to loosen the lock setscrew, and then back both out at the same time.
I *do* appreciate the index pin in the 5C collet adaptor in my Clausing 12x24 lathe.
So now folks, I admittedly havent read but a handfull a replys on this one.....
.....BUT.....
If your running some ganged wheel cutters having some diameter to em inna R8 spindle in back gear onna Brigeport type mill at 78 rpms or such, you might wanna make sure your drive pin is engaged.
I just took a look at mine, and it sure looks like it's exactly as you describe. A dog point set screw. On the back side of the quill there's a screw that my money says will allow access to the key (screw) so it can be either changed or adjusted for length. It would require aligning the spindle with the quill to do so, however.
I bought my first Bridgeport in '67 and the second one in '77. I still have the second one, and in all those years I have not destroyed the key, nor have I had any incidences of tightening the collet when it was not aligned properly. The minor amount of time it takes to align the collet doesn't appear to me to be significant, but I get the idea that if you don't do it routinely, it is likely somewhat troublesome. I think I understand those that don't feel the key is necessary, I just don't agree with them. It appears you don't, either.
I read your comments earlier, about installing your collets while you're at the opposite end of the headstock tightening the drawbar. I, too, have run such machines and can't imagine not having the key to keep the collet from spinning. I not only appreciate the key, I more or less demand it. Seems it would be quite awkward without one.
The last job I held before I started my shop back in '67, I ran a small Clausing, likely a similar machine to yours. It was a 6" machine on which I ran a lot of close tolerance work. I liked the variable speed drive it had, but it was a bit noisy. To be honest, I was quite spoiled from having had an EE at my disposal for years prior to leaving Sperry. Still, I was quite impressed with the ability of the little Clausing to perform. I recall a month straight of various low volume production parts with a +/- .001" tolerance. No problem. It was equipped with a KDK tool post, which has never been a favorite of mine. I prefer a square toolpost (OK Rubber Welders, specifically), although they tend to be limiting for complex setups.
Hi Chuck, When I got my used Bridgeport clone, I couldn't afford the tooling, so I made some R8 blanks up at the local tech colledge as part of a cnc course I was taking. The instructor asked me how I was going to mill the slot for the drive pin. I told him my machine didn't come with one. He told me I'd better get it back in there, as he had seen an accident where the R8 arbour had slipped, and tightened the draw bar to the point where it had broken, shooting it out of the top of the machine.
One of the blanks became a 6'' dia fly cutter, and I've always wondered if I should have taken his advice, or if he was pulling my leg. Seems to me that as the arbor slips it will tighen the draw bolt, and I imagine this will stop the slip well before the UTS of the drawbolt has been reached. Also, if that much torque was present, I couldn't see how the pin would hold it either, so I didn't replace it. So far no problems in 15 years.
Agreed. I guess that you could lock down the collet drawbar and use one of those three-finned wrenches to spin the collets into it from the spindle nose end, but it is one extra tool to find someplace to keep, and the fine adjustment would be a bear since any workpiece would get in the way of the wrench.
6" Are you using the UK spec -- center height above bed, instead of the US maximum diameter swung above bed? Mine is 6" by the UK standards, or 12" by the US ones.
O.K. That is one notch above mine -- even it it is the same size. Mine has five step pulleys in the pedestal, and back gears to give a total of ten speeds. (At least until I swap in a three-phase motor and connect up a VFD for the purpose.)
The variable speed pulley assembly is noisy compared to the standard step pulley -- and a Monarch 10EE is even more quiet.
Those can certainly spoil one. :-)
Is that the one with the ribbed post and matching ribs on the tool holders, which can lock up at 15 degree intervals? I've seen them, but never used one.
I really like the Aloris style quick change for everything that I do. I picked the BXA size, since the AXA stops at 12", and the BXA runs from a bit smaller to something like 15", so it is the more rigid of the two.
The square toolposts (four-way) have to be shimmed for each tool (unless you grind the tool to a precise height for the cutting edge), and one for boring or facing eliminates the adjacent slot for turning, so it is really only three-way under those conditions.
With the Aloris style, you have two dovetail stations, one for turning tools, and one for boring and facing tools. And as long as you have enough toolholders, you can set each to put the tool edge on center height *once* so you don't have to tune the height each time you change tools. (And working in combination with the bed turret, you don't have to worry about indexing when you change tools beyond the four stations of the four-way.
But -- I got a chance to use a good quick-change fairly early on, after using mostly a lantern style before, so I got hooked. :-) I only had a couple of weeks of experience with the four-way before the quick-change appeared.
Another idea would be to disturb anyone near you and have them hold the collet while you turn the drawbar. On the other hand, maybe you could just use the damned key as it's intended to be used. I'm completely baffled how some people can go so far out of their way to make things more difficult, and then justify it as if they've made some great discovery. :-)
No, US specs, but I may be wrong on the size of the lathe, it may have been an 8" machine, although I remember it as a 6". It was a small machine, bench mounted, so low that you sat to run it. Considering we worked five
12's and one 6 hour day each week, sitting wasn't all that bad of an idea. It had been used as a polishing and junk machine until I came along. It had been poorly cared for, almost never wiped or oiled. I was quite surprised to have it turn out as well as it did. Once it got wiped and oiled routinely it had a pretty nice feel. A far cry from the first time I ran it, when it was stiff as could be.
I had a thing for doing small work, so when they found out I was willing to do it, they started heaping it on me. I was the one to decide to use the little Clausing, I could have used a larger machine, but if you've done much small work, you know how dreadful that is. Speed is essential, and nothing in the place had the same speed capability. Can't even remember how fast the spindle ran, but it had the collet setup and also a Buck 6 jaw chuck, so it was quite nice to use for the small work I did with it. Interestingly, I had left Sperry (Univac by then) only 18 months earlier, and it was sub-contract work from them that I was running where I was employed. As a result, I was very familiar with the type of quality that they expected. All the work was defense oriented, something I had trained to do.
Still a nice machine, for sure, but variable drive is really the way to go. I miss it on my Graziano, although I've run it for so many years now that I don't remember just how nice it is to be able to changes speed while cutting. The Graziano does that, but by steps, like a gear change. I like the infinite controls, especially when facing and trying to keep up a good surface finish. I've not run anything equipped with VFD, but understand that's what you gain. Super nice way to go, especially if you don't sacrifice torque at low speed. The EE was famous for not losing power at low speeds.
Unless you've run one, I'm not sure you can really understand just how nice they are. I've always coveted one, but couldn't come to terms with the cost. Not that they weren't worth the money, for I feel they were. It was just one hell of a lot of money for a guy that was starting out, secure in his ability, but insecure as to his ability to secure work enough to pay the bills. Looking back, I would have done just fine. Should have bought the EE, but I sure do like the Graziano. In a way, it's a better choice for a guy with only one lathe.
No, and I'm not familiar with the one you describe. The KDK was similar to the typical insert type tool post, only it had a small handle that was thrown (vertically) to lock or unlock the tool blocks. As I recall it had a dovetail type lock, and the handle operated the gib, so to speak. At any rate, when the handle was thrown, the dovetails tightened up. Sorry to be so vague, but I left that job back in '67. Small wonder I'm a bit puzzled.
As I recall, the (short) handle was (is) located on the right hand side of the holder, knob end towards the operator, and had a pivot that was parallel to the ways. It did not index, but like the other quick change holders, it was adjustable vertically. For a small lathe it wasn't all that bad, but the shop had a 42" DSG lathe with a KDK holder. The tool blocks weighed in at roughly ten pounds each, so changing them wasn't a fun job, especially when one worked 12 hour shifts, which was the norm. The one advantage was that when using the lathe to capacity, the cuts were relatively long lived, so you didn't change often.
I get the idea that the KDK line isn't available any longer. You, of all people, seem to be very familiar with machine tool accessories, so I'm somewhat surprised that you aren't familiar with them.
I guess our first experiences are quite influential. It was on the EE that I became familiar with the OK Rubber Welders head, and then once again I ran a machine briefly that was equipped with one when I left Sperry. I got used to having a small box of shims near, and still do, so it's really easy to set up a tool when you're familiar with the system. For the most part, when I was actively machining I could almost guess the right shim combination to find center. Usually one try, then an adjustment by adding or removing a thin shim and it was done. That can be a real PITA if you don't have a supply of shims on hand, though.
The OK Rubber Welders square head is unique in that it indexes by detent every 15 degrees, but has serrations at 3 degree intervals that allow the head to lock down precisely on location. You can make setups and mark dials and trust the head to repeat. Without the serrations, it's no different from any other square indexing block, though. It does not self index, you must index manually, but that's actually a good feature for me because I often used tools in random sequence, occasionally using a tool for more than one function. That way you could index in either direction when the handle was unlocked. No big deal.
In a nut shell, I like the advantage of having unlimited tool holders, which makes a machine much more flexible. I guess the one thing I don't like is having to handle them. You do get used to it, though, and it would be dead easy to go from a lantern type toolpost to *any* device that allowed you to actually make a setup. In all honesty, there's no way in hell you'd catch me running with a lantern toolpost. I like the flexibility, but they suck when it comes to any kind of repetition, as you well know.
Since it is a hobby shop at this point, I would have to go upstairs, talk my wife into leaving her anti-spam research (or whatever else she is doing on the computer) and come downstairs to hold it. And she really does not *like* to come into the shop that much. :-)
Amen!
:-)
O.K. A very different machine, then. It may well have been 6", though I haven't seen one that small.
I'll bet. Did it have the flame-hardened ways? Mine does, and I suspect that is one reason that it shows so little wear. (The bed turret is a second contributing factor, of course.)
For certain small work, I use either the old Unimat SL-1000, or the Taig -- usually with the WW (watchmaker's) spindles and collet sets. Those both give me plenty of speed, and the ability to hold really small parts accurately. The "collets" for the standard Taig spindle are far from what I would prefer, but with the watchmaker's spindle, things are quite nice.
What size collets? Perhaps 3C? (good up to 1/2" or perhaps 5/8" I guess.) Mine handles the 5C comfortably, and has the lever style closer.
Very nice!
:-)
It is, indeed. It should even be possible to set up a rack gear turning a potentiometer to automatically change the spindle speed as you are facing, for lots of repeat cuts.
The EE had a very interesting way of doing that, with a DC motor and separate control of field and armature to maximize both speed at the high end and torque at the low end. Several different techniques were used over the years, and now they are selling rebuilds with oversized induction motors and VFDs to maintain the low-end torque.
I have. One of the ones with a motor-generator in the right pedestal to power the DC motor. I always wondered why I had to turn it on and hear this big motor spinning up while nothing visible moved. :-) This one was where I worked, and the only thing wrong with it was that the spindle tach was dead, so I had to set speeds by feel. :-) If it were mine, I would have pulled that tach and tried to repair it, but it belonged to the government, and was on someone else's property list.
I'm quite happy with my Clausing most of the time. There are times when I would like to have the continuously-variable speed (which I will get when I put the three-phase motor and the VFD into it), and there are times when I would like a bit more swing, but most of the time it is quite satisfactory. And I have the little Compact-5/CNC for things like metric threads, and other repetitive small work, and the Taig and the Unimat SL-1000 for the very small work. Each has its benefits.
Did it have two dovetails -- one for turning and one for facing/boring? The location of the lever suggests that it has only the one dovetail.
The Compact-5 has yet another style of quick-change. There are two male 'V's on the turning and the facing/boring sides of the post, and corresponding female 'V's on the tool holders. Between the 'V's on the post there is a T-head on a cam which engages a T-slot in the tool holder. When you operate the cam, the tool holder is pulled firmly against the toolpost, so you get a good rigid setup. Of course, each holder has its own height adjustment, so you can change tools without having to worry about center height.
:-)
This is what makes me think that it used a single dovetail. I've seen some on eBay (which may be what you are describing) which have some tool holders in an 'L' shape to wrap around the post to provide a facing/boring holder.
I've never actually *used* these (or even seen them other than in the eBay auctions) so the name does not stick.
That sounds as though a counterbalanced crane for changing toolholders would have been helpful.
There is that. For a given number of horsepower fed to the spindle, there are only so many cubic inches of steel which can be removed per hour. :-)
I haven't had hands-on experience with all of them. I think that I have seen them in eBay auctions (if the L-shaped tool holder for facing and boring is right), but I've never used them.
And the name does not inspire confidence in their rigidity, though I suspect that they in reality are very rigid. :-)
[ ... ]
One regular on the newsgroup keeps each tool with the associated shims in a pill bottle. That makes for fairly quick setup.
Agreed -- and when I was using the machine at work with the
4-way toolpost -- the shop was new, and we didn't have shims around, so I had to cut some out of aluminum and whatever else was near the right thickness, using the DiAcro metal shear. :-) When the machinist in charge of the shop ordered and got the Aloris quick-change toolpost, I fell in love with it. :-)
O.K. -- with the Aloris style, I normally don't change the setting of the post (unless I change the compound angle, in which case I re-square it with the ways and chuck face). For different angles of cut, I use different tools, pre designed for that angle. I do have one tool holder with multiple rows of setscrews which would allow mounting a tool at a strange angle, though what I intend it for is next time I go into production mode on the microphone adaptors. I should be able to mount two tools in it -- one to groove the runout groove for the external threads, and the other to part off the previous workpiece, all in a single pass.
Agreed -- though you are still limited to a maximum of four tools at a given setup. With the Aloris style post, I can have any length sequence of tools I need. Let's see:
1) Parting (and grooving)
2) Turning OD to shoulder
3) OD threading
4) beveling edge
5) facing end
6) Boring ID
7) ID threading
I can picture using all of these on a single project -- and making multiples of a given workpiece. And that is ignoring project-specific form tools.
But I guess that you could have two bodies for your four-way, and swap them in mid project, so you could handle up to eight tools at once. I would probably put all the boring/facing ones on one turret, and the OD turning/threading and parting ones on another one.
Indeed so. They also have the *dis*advantage of flexibility too. They are not nearly as rigid as a good block form toolpost. (Though I guess using a raw HSS tool ground to shape without a holder might offer a bit more rigidity.
My mistake, I should have mentioned that all of their mills had power drawbars. I agree that in the absence of same that anyone abusing a machine by pulling a collet past the index pin should be fired on the spot for total incompetence.
I don't think that CNC can really be blamed on the decline in skill levels. The blame lies partly with the education system. How many schools do you know of that still offer any training in "hand arts"?
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.