I'm sure there is a marketing component to this - especially in any of the free-for-all type places like ebay or amazon.
However if you look through the catalogs of the companies that sell to manufacturing and production shops, a lot of the stuff that's designated "CNC" is specifically designed for high volume / automated production. Time is money, automated machines run as fast as the can be run etc. So any cutting tools mills, drills taps etc - have features and designs that make them well suited for feeds and speeds way beyond what you are going to do with a small, manual bench mill or even most mills that the typical hobbyist will have. Some of the roughing mills are useful and might work better - but again a lot of them do not offer any advantage at lower spindle speeds and hand cranked feeds, or they just won't do the job on a really light cut that your machine can handle.
Other stuff like CNC vises or hold downs may or may not make sense for you - depending on what you are doing. A low profile vise designed to be used in gang setups on a CNC mill bed, might be just what you need. However there are likely better more versatile options that are cheaper.
I ended up getting a a 1/2" shank ER11 or ER16 collet "chuck" really a holder, the shank is about 4" long and it has a low profile collet nut. it really is designed to let someone use these small collets in a bigger CNC machine where the reach (4" shank was the shortest) and clearance (low profile nut) can be an advantage. I also got a set of collets to go with it - have a tiny desktop CNC machine that uses the same collets, so I can now use a variety of drills in it. The spindle on the desktop CNC tops out at 24K RPM.
The 4" shank chuck is not for my CNC, it allows me use the same collets in my bench top mill with a half inch mill holder AND it also in my Deckel D-bit grinder so I can handle a wider range of shank sizes (sharpen drill bits etc.). I work with small stuff so it made sense.
If I didn't have the Deckel and the desktop CNC my precision drill chuck would be just fine for my mill.
The collet holder with long shank was marketed as "CNC" ER11 collet chuck.
I am by no means an expert on this stuff and I'm still learning. When I was just getting started, I stuck to the most common cheaper "traditional" manual tooling - figuring that I had much more to learn before trying more exotic stuff.
So use common sense, don't spend more than you need to (there's always more to buy!)
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Question
Most of our collets for our CNC are what you call range collets, where each one can be used for a variety of bits. (12-13mm range for 1/2" and 6-7mm for 1/4".) Recently a tooling salesman was insisting we should have dedicated collets (1/2" collet for a 1/2" bit). Supposedly this will be easier on the spindle, and increase tool life, among other things. Can anyone confirm this, or is it just another pitch?
Forum Responses
(CNC Forum)
From contributor M:
From my experience, range collets should not be used. Buy either metric sizes for metric shanks, or inch sizes for inch shanks.
We use both range and size collets. Haven't had any problems.Why are you using collets in the first place? You should start thinking about hydro chucks, Tribos, shrink fit chucks. No collets to replace; run out on these tool holders is extremely low. They also last a lot longer. My operators love the hydro chucks because tool changes are very quick and very little cleaning is required. Changes are in seconds, not minutes.First, the tooling salesman was right. I would go into the technical aspects of this, but I can simplify it by asking you one question... Given how much you paid for that router, do you really want tools and tool holders that are "close enough"? If it were my machine and my money, I would not take a chance on something that might work out, might not... and might tear up my equipment.
Contributor A hit on something. The PS chucks that we [Leuco Tooling] carry as well as the Tribos chucks are simplicity in action, as well as being highly precise. These not only make setup a great deal faster, but also have running tolerances that are greatly superior to the standard collet chucks.
Hydro chucks? A bit more info, please. I took a quick look at the Techniks site, so have a general idea. Seemed they were specifying use in wet or oily environments, though. Is general wood cutting overkill for these? Cost?A hydro chuck is simply a chuck that uses hydraulic pressure to mount the tool. It works the same as hydro lock moulder heads, but somewhat backwards.
You will have a tool holder (for specific sizes only, the "close enough" approach will not work here) and when the tool is set to a specific height, you turn a lock screw which will create pressure in a chamber surrounding the bore in which the tool is set, the bore will contract, thereby locking the tool in place very securely.
Physics dictates that the pressure applied will be evenly distributed if given even points of distribution. This means that the same amount of pressure will be applied over the entire shank of the tool, thereby holding it with equal amounts of pressure as well as centering the tool as accurately as possible.
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Just as a note: If one were to try to mount a 12mm shank tool in a 0.500" (12.7mm) hydro chuck, it may return to its pre-pressurized state, but most likely, it will go beyond the locking point and not return to a useable state, at least as far as the 0.500" tool is concerned.
There are a few other options as well. Keep your applications in mind when shopping for tool holders. Standard collet chucks do have a place, but you really need to make sure you use the right collets for the tools you are holding. I wouldn't use anything that was close enough unless I had a real production emergency.
Before this thread I'd never heard of hydraulic tool holders. Between your explanation and my quick look at the Techniks site, I now at least have an introductory understanding of the concept... and it's pretty slick. I do like the idea.
I use ISO30 tool holders with ER32 collets specifically sized to the bit shank (typically 1/4", 3/8" and 1/2" along with a scattering of other sizes). I cut solid wood typically held in place with vacuum pods. My primary tools are a 3/8" downcut spiral 2-flute HSS bit on a 1/2" shank and the same in carbide as an upcut spiral with a 3/8" shank. Both have a 1 1/4" cutting length. I also frequently use a HSS upcut spiral 1/2" bit with a 1/2" diameter x 1 1/2" long cutting length. We rarely break bits... They usually wear out first.
So, do the hydraulic holders work with ISO30 setups? If not, then that is the end of this for me.
If they do, though, then what would be the typical comparison cost to a tool holder, collet and nut? What is the longevity factor? I know I at least am delinquent in disposing of collets, holders, and nuts that may be beyond their useable life, and probably others out there tend to do the same.
Finally, in a standard collet and nut system, the idea is that as the collet tightens, it becomes perfectly parallel with the shank of the bit as it closes in, thus properly holding the bit in place. What is the oil in the hydraulic holder pressing against that then presses against the bit shank? It would seem there must be some sort of pressure plate involved that matches the bit shank radius.
It sounds like you have your bit requirements in hand and know what you need and have it in house. Good.
The way it works is the bore where you put the tool is, in reality, a thin steel wall machined to be slightly larger than the O.D. of the router bit. When the bit is inserted, you turn the locking screw and it pressurizes the grease chamber, forcing that thin steel wall to compress inward. The only moving part is the screw itself. When the screw is released, the pressure is released, and the wall flexes back to its original shape.
Yes, is does come in ISO30 style. I won't show pricing here as I think it would be in bad taste, but I can tell you that our ISO30 hydro chuck costs about 40% more than our ISO30 collet chucks.
Thanks. What happens to that thin wall if the bit spins? Or is the hydraulic pressure great enough that a bit could not spin in these chucks as they occasionally can in a standard collet? This obviously isn't an every day thing, but if it can happen, it will happen... as I'm sure you know. I generally understand hydraulics, so your explanation is just fine. It's a simple and neat system.Simple and neat, indeed. And very efficient. What happens if (when) it spins? You buy a new chuck. There is some hope of buffing the bore, but 99.9% of these that come in for inspection have been spun and they are, for lack of a better term, toast. At that point they are non-serviceable.Most of the responses are correct. The more accurate your collet is, the better the overall tool life and quality of cut will be. You can take the hydro one step further and use a shrink fit system. This is even more rigid, which is another thing that you are looking for. Most of the range collets are actually just metric collets. The 1/2" you have is more than likely a 12-13mm collet.
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