PDA

View Full Version : First go-round with a rotary table



gizmo2
10-28-2012, 04:26 PM
Bought one about six months ago, today afforded the first opportunity to throw it up on the mill and give 'er a go. The BEST news is, nobody got hurt, the body in question being mine... The learning curve was rather steep today. The part has a bad case of the uglies but will be usable, and I can make another when I get sick of looking at it. Also need to make some gizmos to speed centering, facilitate clamping, and adapt it to my particular machinery, but I think it's going to be a nice addition to the shop.

winchman
10-28-2012, 05:01 PM
What can possibly go wrong when using a rotary table?

RLWP
10-28-2012, 05:21 PM
What can possibly go wrong when using a rotary table?

You are welcome to come and spend some time in my workshop - bring lots of safety equipment, it's a steep learning curve

It always amused me that CNC mills were equipped with bullet-proof glass

Richard

justanengineer
10-28-2012, 05:29 PM
It always amused me that CNC mills were equipped with bullet-proof glass


Since when? All of the cncs Ive ever used had some form of relatively thin plexiglass, Lexan, or other composite, not the 3"+ glass/composite layering found in bulletproof glass.

RLWP
10-28-2012, 06:53 PM
I worked with CNC machines a long time ago, when head crashes, table gouges and flying tools were more common, early 1980's. Things are much better now, if less exciting

Richard

bob ward
10-28-2012, 07:26 PM
Also need to make some gizmos to speed centering, facilitate clamping, and adapt it to my particular machinery, but I think it's going to be a nice addition to the shop.

For rough and ready centreing I have a double ended adaptor, one end drops into the centre hole of the rotab, the other goes into a mill collet.

gizmo2
10-28-2012, 08:07 PM
Yep Bob, that's the ticket. The only thing I made for it before I tried to use it were some t-nuts, I should have thought about it a bit more and made some more niddlys. Bet I coulda made a spud in the time it took me to cobble up the dial-in!

metalmole
10-28-2012, 11:56 PM
No making ones skin leak is a good thing, once you get some time on your R table you will start making some nice looking parts...

winchman
10-29-2012, 01:30 AM
The problem with making centering thingies that fit into the center hole to align a part with a hole in it is that the center hole in the RT is often not centered very well. The ones I've seen have been off by several thousandths.

Paul Alciatore
10-29-2012, 12:51 PM
The problem with making centering thingies that fit into the center hole to align a part with a hole in it is that the center hole in the RT is often not centered very well. The ones I've seen have been off by several thousandths.

I measured the run out on the center hole of my RT and found it to be quite good. I made a plug to fit with a reamed center hole for centering:

http://img.photobucket.com/albums/v55/EPAIII/RotaryTableCenterFinder.jpg

I think the drawing is wrong in that it is a MT3, not MT2. A bit of luck was that my RT's center hole matched my lathe's HS taper, both being MT3. Otherwise I would have needed an adapter.

The center hole is used with a electric light center finder with a 0.200" diameter probe so I made it exactly 0.400" with a reamer. You then just need to add/subtract 0.100" from the reading when contact is made. You have to touch X, back up 0.100", then touch Y and back up 0.100". Repeat this several times until no further changes occur. Do remember to compensate for backlash when backing up.

The 1/4-20 threaded hole at the bottom of the center hole allows a removal tool to be used. The removal tool is a long 1/4-20 bolt with a sliding weight on it. Screw the bolt loosely into the hole and strike the bottom of the bolt's head with the weight and the tool pops out easily.

The OD of this tool was machined to quickly center some gears I was working on.