Newall DRO Adjustment

[MetalhackerParticipant @metalhacker]

I have a Newall dp700 fitted to my Boxford VSL. It has never given accurate readings on diameter. If I move the cross slide 10mm inwards to give an overall cut of 20mm dia, it reads 17.68. This was measured with a mitutoyo dial gauge so should have been accurate. I have followed the recalibration instructions to no avail. I have tried earthing the output screen to the lathe, which has not improved things. Does anyone have any ideas about how to resolve this. While I work in metric it is less of a problem but it makes imperial dimensions rather difficult!

Andries

[Peter Cook 6Participant @petercook6]

Is the error consistent, i.e. every time you move 10mm you get the same 17.68 reading? Does the error vary depending on the starting point? If it’s consistent it would seem to rule out noise/earthing issues. Those would tend to give more random  errors. Is the Error linear, i.e. if you move the cross slide only 5mm is the error halved?

When you say you have followed the recalibration instructions, have you checked that the encoder choice is correct? Have you looked at the linear compensation screens to make sure that no corruption has crept in.

The fact that it has never worked correctly points to either a faulty or mismatched encoder.

What happens if you swap over the channels so that the other channel sees that encoder. Do you get the same errors?

Edit – there is what appears to be a fairly detailed user manual here

[ZanParticipant @zan]

I’ll check mine in the morning. but just a current thought, is the resolution of the controller set to the same as the scale.? I seem to remember that is one of the  important early setting during “set up”

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