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23 April 2014

TOS FA3V mill update: Tooling! What I've chosen, what I've got and some basic info on different things.

Well, the start of it, anyway:

 I scored these two Kennametal CAT40 TG100 collet chucks, one 3" gauge and one 4" (or was it 5"?) gauge, for a ridiculously good price on eBay. The seller was even kind enough to combine shipping.

Now, WTF is all the gibberish? Kennametal is a brand, a good one, in fact, of all sorts of metal working tooling, especially indexable carbide inserts and holders.

CAT40 is the spindle specification of my mill. There are several specs, all in even intervals of 10 (10, 20, 30, 40, 50 and larger), with CAT40 being the most common, CAT50 being larger and becoming more common with much higher power machining centers coming onto the market (which needs larger, more rigid tool holders (usually) to transfer the power at every lower runout specifications) and CAT30 used a lot of smaller machines of the imported and cheap variety. CAT40 spindles share nearly all the same specifications as NMTB spindles except that there is no extended tail on the top of the tool holder. (That is the only difference between CAT and NMTB, as you can use CAT40 tool holders in an NMTB spindle, but not vice versa. I am choosing to use CAT40 tooling since surplus and even new tooling is plentiful, readily available and in many cases, dirty cheap.

TG collets are a specification of collets. Collets are holding devices that clamp onto something of a fairly specific diameter, be it a tool or even material to me machined. (Lathes often have collet systems to allow for very low runout, or wobble, workholding and repeatable positioning.) Collets allow for fast tool changes, low runout (which leads to better tool life) and not having to change out the whole tool holder to clamp different size pieces. Changing a collet and tightening the lock nut is way faster, usually, especially with a mill like mine where the drawbar is WAY up on top of the darn thing.

Specifically, TG collets are a single, low angle, high precision collet. The most common collet type is the ER collet system. I chose to go with a slightly less ubiquitous collet system for two reasons:
1. The TG collets' clamping force is much greater.
2. TG collets are better designed, IMO, with a radial bearing integrated into the locknut. There ARE some ER collet systems that have that feature, but ALL TG collet lock nuts should have this by definition. This allows for slightly better centering and more torque being able to be applied, further increasing clamping on the tool.

The two disadvantages of the TG collet system, as far as I can see:
1. The collets are slightly more expensive.
2. The grip range is not as wide, and techincally, you would need a mroe extensive and therefore expensive, set of collets to cover any given range, BUT . . . I won't need more than 5-6 collets, so the grip range is moot and the price for a few collets is much less than for a set of collets.

The TG collets have different size specifications, denoted in multiples of 25, with TG25 being about the smallest you'll find, I think. So, common sizes are TG25, TG50, TG75, TG100 and TG150. Multiply the number by ten and you get the maximum size the collet can accommodate in thousandths of an inch, so my TG100 collet chucks can accommodate 100x10=1000 thousandths, or one inch. So, this means that my collet chuck and the appropriate collet and grip a tool with a shank of up to 1". That's pretty darn large for an end mill. I do have a few of them that are that large, but most endmills that I have that I will use have either a 3/8" or 1/2" shank, and those are the first two collet sizes I will get.

Speaking of endmills:
I'm sorting this lot by size and then further by flute type. Basically, an endmill with more than two flutes is usually used for steel and/or cast iron. Two flute endmills are used for aluminum and other non-ferrous metals.

The ones I don't use are going on eBay to help recoup some of the growing expenses to feed the machine. =)