Spindle Tapers

[itsme]

Hi there,

I'm looking at new mills around the Sieg X3 size, and was wondering about spindle tapers.

It seems that most machines around this size come with either an MT3, or an R8 spindle taper. Which is the better taper to choose (assuming you get a choice...) and what are the reasons behind that choice?

Thanks
Warren

[warpedmephisto]

I would definitely choose R8 over MT3 if you're given a choice. MT3 is just kind of a "push in" taper where nothing more than the taper locks it in place. R8 you have a threaded draw bar hole where the taper holds the tool tight and the drawbar holds the collet up in the spindle. Plus there's a TON of R8 collets out there for just about any kind of tooling requirements.

[mxtras]

R8 without a doubt. If for no other reason - the collets are just way too easy to find and obtain and you have a much larger variety to choose from.

Scott

[Ken_Shea]

Warren,
Ditto on the replies, R8, don't even consider the MT a choice for mills, I doubt that if it is a mill of any size that you will even have that choice to make.

Ken

[phil burman]

The MT tooling for a mill also has a draw-bar thread. The two main differences are the R8 has a wider diameter at the business end so it is stiffer (unless you have an MT4 spindle or above). It also has a key-way slot that fits on a key in the spindle and eliminates any risk of slippage.

I agree that the R8 is a better overall choice, unless you already have a lot of MT tooling or also want to use the same tooling on a lathe. It’s also not so easy to obtain R8 tooling in Europe.

Regards
Phil

I would definitely choose R8 over MT3 if you're given a choice. MT3 is just kind of a "push in" taper where nothing more than the taper locks it in place. R8 you have a threaded draw bar hole where the taper holds the tool tight and the drawbar holds the collet up in the spindle. Plus there's a TON of R8 collets out there for just about any kind of tooling requirements.

[romteb]

I would definitely choose R8 over MT3 if you're given a choice. MT3 is just kind of a "push in" taper where nothing more than the taper locks it in place. R8 you have a threaded draw bar hole where the taper holds the tool tight

My Sieg mini-mill has MT3 And also has a Threaded draw bar to hold it in place.

[Ken_Shea]

That is interesting that the R8 is not common in the UK but very common here in the US, I was not even aware that a MT was available with a draw bar for keeping it in place, you just do not see that here.

[itsme]

Hi,

Thanks for the replies - it seems that the R8 is the more popular choice. I'll check here in the UK though, to see what tool availability is like.

At the moment I have got a Sieg X1 which uses an MT2 with a drawbar. Seeing that most of my MT2 tooling won't be transferable, I may as well start again with whatever is cheapest/easily available.

Thanks again
Warren

[phil burman]

I think you will find the availability of R8 tooling in the UK is not to bad. At least at the hobby end of the market. However judging by some recent reports some of the cheap R8 tapers being supplied are bordering on unacceptable, even for the hobbiest. Main land Europe R8 it is less common.

Regards
Phil

Hi,

Thanks for the replies - it seems that the R8 is the more popular choice. I'll check here in the UK though, to see what tool availability is like.

At the moment I have got a Sieg X1 which uses an MT2 with a drawbar. Seeing that most of my MT2 tooling won't be transferable, I may as well start again with whatever is cheapest/easily available.

Thanks again
Warren

[MIKE JEFFERS]

hello warren
r8 tooling is far easier to find here in the uk than mt2/3 etc and cheaper
also when you upgrade further to say a bport or similar chances are it'll be r8
mt stuff tends to be older and big stuff uses int30/40 etc
you can also machine your old m/t stuff to fit a r8 collet
mike