Dumb question on R8 (i think) spindle

[FanMan]

R8 collets usually don't stick out when tight. They should slip in relatively easily, though sometimes they need to be polished a bit, especially cheaper ones.

Many people remove the key or set screw, it's often more trouble than it's worth. Mine (on a Jet 15) was kinda mashed and made it hard to get the collets in and out; I removed it and never missed it. I just hold the pulley when tightening / untightening the drawbar.

 

[Tozguy]

The measurement you took of the length of the taper on the mystery arbor (1.0665) should be revisited. From the picture it appears that the taper ends (or changes) at around 1/4'' from the shoulder. The length of the mystery taper would be less than what is shown.

FWIW my R8 collets do stick out a bit from the spindle and I would not be concerned about what I see in the picture you provided in post no. 28.

The look of the taper on the mystery arbor leads me to believe that it fit well in the spindle taper. Was that arbor not used by the previous owner in the mill you bought?

 

[Tozguy]

I now believe this non R8 shank tore up the spindle.

What damage are you referring to? Is the inner taper of the spindle in good shape?

Any idea what the arbor is? (and is it not called a shank?)

If the arbor is removable from the chuck its called an arbor. If the shank is an integral part of the chuck, ie can not be separated from it, then its called a shank.

 

[r-mm]

Thanks guys. I can get new, clean R8 collets in place and tightened without too much difficulty. The inside of the spindle is not going to win any beauty contests but its not horrible. A little bit of roughness that you can imagine from looking at the mystery taper. I don't know how to be any more precise about its condition.

Do you all recommend I get a wedge and replace the mystery arbor with a JT33-R8 or get an integral spindle chuck? I was looking at this keyless unit from Shars: https://www.ebay.com/itm/Tegara-1-2...al-Shank-Arbor-13mm-NEW-Taiwan-A/350890798382
I've not used a keyless but always admired them.

 

[Illinoyance]

A lot of machinists remove the screw (key) as a matter of convenience. Mine will go next week. I can't hold the d'Andrea boring head and rotate to find the key. The Volstro rotary head is even worse to install.

 

[Dabbler]

OK guys, I think that I need to show a contrary opinion on this 'removing the set screw in an R8 spindle' thing.

In general it is a very bad idea to remove the key.

Firstly unless you spend $$$ on Hardinge (or better) collets, you can get eccentricity. With a key you always know which way the eccentricity faces.

Secondly, if you ever overtighten the draw bar, it can be a lifesaver when undoing it. That's how the set screw can get bend or damaged... I have experience with this, and on a machine without a set screw.

Thirdly, it is there as part of the fundamental design, and it is shortsighted to remove it unless you understand all the reasons for it being designed into the machine.

so please, unless you are a very experienced machinist, leave it alone!

 

[walz10]

I’d say your machine is has an R8 spindle. Personally I like most others here wouldn’t worry about the pin. If you want it to be there or it bothers you that it isn’t then by all means replace or repair it. For what it’s worth all the power draw bar installation manuals that I have seen instruct you to remove the pin as part of the installation of the power draw bar. The only warning I’d give you is to make sure that your draw bar threads into whatever you put into the spindle easily. Other than that I think you’ll be fine.


Sent from my iPhone using Tapatalk

 

[r-mm]

Guys this mystery persists. Everything seemed fine using the machine with a drill chuck. I only today tried it with a 3/8 endmill in a 3/8 R8 collet (double checked both) and the tool spins as soon as it hits work. Here is what the collet looks like inserted with finger pressure and tightened down with gusto.

All I can think is to buy a new spindle which Grizley sell for $300. Presuming this is an import part, does anyone know where else I may look for similar at lower cost? Other ideas?

SPINDLE

www.grizzly.com

 

[Mitch Alsup]

When properly tightened, R8 collets just barely protrude beyond the nose of the spindel.
Your collet is significantly below the nose of the spindel.

I suggest getting up inside the spindle to figure out what is going on in there.

 

[Dabbler]

Mitch is right your drawbar is not pulling the collet up to seating position.