Do all R8 collets have keyways?

[slashmaster]

My spindle has a keyway. Are they all like that? I just want to make sure I don't get the wrong collets.

[djr76]

I believe so. 5C, 16C, and 3J do aswell

[slashmaster]

Thanks Djr76,

Do I have to worry about wether the collets are metric or standard thread or are they all the same?

[djr76]

same thread whether it be metric or standard.

http://www.shophardinge.com/default.aspx has some dimensional references for many collets.

[One of Many]

R8 is R8 as far as a key way, spindle taper and draw bar thread.

Where they differ is in the space between the taper and threaded end.

Some collets and arbor adapters are necked down in this region more than others, which reduces the strength of the key way. No big deal on collets under 5/8" or light use. If the key in the spindle is not out far enough and the collet is soft or gets over loaded/spun, the key MUST be removed in order to extract the collet. I've seen some operators beat the collet out with the draw bar.

This becomes more critical IMHO as the cutter gets larger. Say like on an import R8 shell mill arbor, boring head arbors etc. Even drill chuck arbors. Try to avoid buying that style. If at all possible, buy what fits above and beyond the application. Then make sure it is tightened to fit that purpose.

Technically speaking, the key is not there to keep the tool holder from spinning while running. It is there to keep it from turning for tightened/loosening purposes. If it was there for running, it would be a much larger key to transfer horse power to the cutter.

DC

[slashmaster]

Originally Posted by One of Many R8 is R8 as far as a key way, spindle taper and draw bar thread. Where they differ is in the space between the taper and threaded end. Some collets and arbor adapters are necked down in this region more than others, which reduces the strength of the key way. No big deal on collets under 5/8" or light use. If the key in the spindle is not out far enough and the collet is soft or gets over loaded/spun, the key MUST be removed in order to extract the collet. I've seen some operators beat the collet out with the draw bar. This becomes more critical IMHO as the cutter gets larger. Say like on an import R8 shell mill arbor, boring head arbors etc. Even drill chuck arbors. Try to avoid buying that style. If at all possible, buy what fits above and beyond the application. Then make sure it is tightened to fit that purpose. Technically speaking, the key is not there to keep the tool holder from spinning while running. It is there to keep it from turning for tightened/loosening purposes. If it was there for running, it would be a much larger key to transfer horse power to the cutter. DC

Thank you very much one of many! That's just what I wanted to know. I guess a noob like me would want to start out with collets and not end mill holders right? I'm having trouble deciding what to get. I need 3/8", 1/2", 5/8" and 3/4". Someone in another post suggested a couple sets but they seemed to have more collets than I need. Not so sure I want to do that but more advice for a noob with an X3 would be great. Thanks

[One of Many]

Here are some tradeoffs for you to ponder.

The one benefit with Weldon style solid cutter holder is with a CNC being able to do a tool change and not lose the Z tool offset like a collet will. Another good selling point of the Tormach set, although I prefer the higher end Royal EZ-Change setup. If you do not have CNC capability then this is not as important for a totally manual machine.

What you have to consider is how much Z height will be lost with end mill holders extending out of the spindle verses collets. The holder also (IMHO) reduce the capacity of small bench mills due to the extended length putting the end of the cutter further away from the sliding head support area with greater mechanical advantage against the smaller Z dovetail. Keeping everything short coupled makes a lot more sense in side load cutting and reducing excess spring in the machine. Spring induces the potential to suddenly grab the part, pulling it into the cutter in a flash besides inconsistent repeatability.

There are lots of collet manufacturers out there. You can judge the imports by whether the sellers are proud enough to advertise their name brand. Buying high quality used is better than poor quality new any day. Just don't buy them sight unseen if you do not know the reputation of who made them. Pretty does not equal precision and used but not abused does not mean junk. Affordable is buying them once and being satisfied with how reliably they hold a cutter on center, with minimal wear and/or runout for hobby use.

1/8, 3/16,1/4 and 5/16 are very common bench mill cutters too. Waiting till you need them is a day too late!

DC