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View Full Version : TRAV-A-DIAL DRO question



halac
11-03-2005, 09:02 PM
I noticed this type of DRO on eBay. My question is how does this type of unit interface with the machine. I see that the encoders are a rotary type, not linear like other types I have seen.

Can anyone out there explain how these function?

nheng
11-03-2005, 09:14 PM
Appears to be made by the same people as Trav-a-dials.

The image of the encoders shows wheels that look just like the ones in the Trav-a-dials. The wheel is pressed against the side of lathe ways, mill tables, etc. Under pressure, it creates a fine, micro indentation (similar to a knurl) in the contacted surface which forces the wheel to repeat its track over subsequent passes.

Den

halac
11-03-2005, 09:20 PM
Thanks nheng.

Now my next question is how reliable is this system. I see they are spec'd at +/- 0.005". I've been looking for a DRO for my Bridgeport and I'm hoping this might work out for me. Any information will be appreciated.

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No matter where you go, there you are!

Hal C. , www.teampyramid.com (http://www.teampyramid.com)

[This message has been edited by halac (edited 11-03-2005).]

nheng
11-03-2005, 09:37 PM
Southwestern specs out the dial version at 0.0003" accuracy and "near perfect" repeatability after calibration. The DRO has resolutions from 0.0002" to 0.001" but I didn't see an accuracy spec.

These units need calibration which is done by adjusting how the crown of the wheel contacts the machine surface. You effectively alter the diameter of the wheel very slightly.

I have not used a DRO version nor used on a mill so will have to leave that for someone else to comment on.

added - I noticed that you're involved in Team Pyramid robotics. Wish we had that in this area. We've done Legos and progressed into US First, taking NE regional rookie of the year last year. The US First entry bar is raised way to high ($$) IMHO.

[This message has been edited by nheng (edited 11-03-2005).]