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Nakamura TMC20 Turret Proxy


Aug 14, 2014
Wollongong, Australia
Hi Gents

Have a new to me Naka TMC20, with Fanuc OT control. 1986/1988 approx age. She’s old but was cheap and has been belting out parts for me since I bought it.

My issue started as a nuisance situation where after a tool change mid program, it would hang there at toolchange position and would not continue the program.

When I reset the turret, and manually index the tool, it won’t move for the first click, but will actuate the turret clamp/unclamp solenoid which can be heard.
After that the turret would index fine and you could re run your program without bother until it would happen again 3/4 parts later.

This issue went away for a while and I made a lot of parts and a lot of indexes.

Well finally today it has done the same issue 2/3 times and now the turret won’t index at all.

When you hit index turret, you can hear a solenoid valve open to attempt to move/unclamp/clamp the turret but no movement.

In MDI, calling up a toolchange will not work either.

And after restarting the machine and attempting to “home” the turret won’t work either - and if the turret isn’t homed in T1 after starting up, the spindle will not run, programs will not run - however strangely it is stuck in tool 1 as it is.

So leading me to think it’s a proxy switch for the turret to say it’s clamped which has failed or needs adjustment.

Tech is coming to look next week, but thought I’d ask anyway.

Thankyou Gents

Tuff Luck Tom

Feb 14, 2010
Asheville, Nc, Usa
Could it be that your turret may be between positions? I've had experience with my turret being in-between positions. I'm not sure about the best method for your nak if it is. My lathe I am able to force the turret clamping solenoid off, force the unclamping solenoid on through the i/o diagnostic (centroid retrofit). And then manually dog the contactor for the turret motor till I am back in position and reverse the i/o process. Also if it is really close to position you may be able to rotate it with a little force by hand. Being between positions could have the curvic coupling not lining up (think meshing face gears) and would make the turret not clamped as described.