Rotary table questions.

[Arich0908]

Im new to the whole seen and with from lots of help form forum members Ive learned allot.
I have one question. This has been puzzling me for the better part of a week . Why do they have MT2 MT3 attachments on rotary tables . How and why would you need to use that on your mill?

Also what do you need a power drawbar for?

[Pressfit]

The tapered center hole on a rotary table is to accept a pin...tapered on one end which fits precisely into the hole, and the other end is usually ground as a straight shaft several inches long. If you mount the Rotab to a Horizontal Boring Mill (HBM) and don't have this pin you may have a hard time finding centerline.

There are other ways to do it but the pin makes it quicker and easier.
Generally you can tram both sides of the pin with a test indicator. But you don't need the pin if it's a tilting Rotab and it's face can be tilted perpendicular to the machine spindle. In that case the first thing you have to do is square the Rotab face using the table travel in X and Y axis. Then you go back to tram the hole.

The power drawbars are mostly time saving devices.

I hope I understood the question.

[Arich0908]

Thank you.

[jalessi]

Arich0908,

You can purchase accessories for your rotary with morse taper such as a collet chuck, a mini 3 jaw chuck or even a larger 3 jaw chuck.

The power draw bar makes doing a tool change less work.

YouTube- bdrmfg.com Power Drawbar for Milling Drilling Machine RF45

YouTube- bdrmfg.com Power Drawbar for Milling Drilling Machine RF45

Jeff...

[Arich0908]

Well isnt that the bees knees!!
Jeff I figured thats what they where for and Im not going to lie . I did not understand one bit of explanation 1.
But I can see adding collets chucks and 3 jaws to a rotary table.

[knudsen]

I have a backing plate for my lathe's 3 jaw that centers on the taper, so I don't have to center it by hand. For really small stuff, like making some scale machine pulleys or mag wheels for modeling, I just drop a Jacobs type chuck mounted to the appropriate taper into the hole. I've also dropped a lathe center in it for rough centering the RT to the spindle (I use a pointed tool in a collet in the spindle, then line them up by eye). Usually I use a DTI (dial test indicator) spindle mounted, measuring the RT's taper, to center the RT, as it's much more accurate. As you can see, the taper is very important and useful. IMHO, an RT with no center hole at all is pretty much useless.

LMS provides us with a couple of really good, free documents on RT's:

http://littlemachineshop.com/instruc...otaryTable.pdf

http://littlemachineshop.com/instruc...otaryTable.pdf

This information is actually better than what I have found in books on machining. Many of us, self included, have barely scratched the surface of the capabilities of a good RT.