Choiceof DRO

This topic has 10 replies, 7 voices, and was last updated 17 September 2012 at 17:15 by Douglas Johnston.

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15 September 2012 at 23:40 #98449
Andy Freeman 1
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@andyfreeman1
I am looking at fitting a DRO to my Myford Super 7.

I have found two makes, one called 'Electronica' (http://www.electronicaems.co.uk)

and the other is Acu-Rite which have a great display unit but looks very expensive.

Has anyone had experince of using either of these?

Thanks
Advert

15 September 2012 at 23:40 #22215
Andy Freeman 1
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@andyfreeman1
16 September 2012 at 01:30 #98454
Jon
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@jon
Have a look at their Magna S1, the backing and reader look exactly same as Allendale i currently use. Need the finest resolution for repeatability. 1 Micron res http://www.machine-dro.co.uk/magnetic-linear-encoder-reading-head-1-micron-resolution.html + two part backing and tape. Can use cheaper glass for X axis.

I have never seen a decent glass install on an ML7 even from the pros. Its all a compromise and means loosing something greatly needed but the magnetic could solve that on Y axis, glass on X axis at rear.

The readouts i have seen on a certain selling site. Just check zero maintained when powered off and can half Y axis independant of X axis or you would be taking double the cut off the diameter and cant do that with Allendale budget readouts.
16 September 2012 at 11:23 #98485
Douglas Johnston
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@douglasjohnston98463
I have just fitted a 1 micron magnetic scale to the cross slide of a Myford Speed 10, fitting the scale under the slide to keep it out of the way. I was always put off fitting a scale down the side of the slide because it would get in the way of things, but this way works a treat. It is a bit more work to do it this way but well worthwhile. The only downside would be a clash with a rear mounted taper turning attachment (as well as the cost -these magnetic scales are not cheap but you soon forget the expense)

Doug
16 September 2012 at 12:14 #98497
maurice bennie
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@mauricebennie99556
HI Would Douglas please explain a bit more how he fitted his scale , it sounds a good idea.

Maurice B
16 September 2012 at 12:22 #98499
blowlamp
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@blowlamp
Why not go with the Sino/Sinpo etc DROs that are more commonly available and probably much cheaper?

Martin.
17 September 2012 at 09:31 #98575
Douglas Johnston
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@douglasjohnston98463
Hi Maurice, the magnetic sensor is only approx. 5cm long, 1cm wide and 1.7cm high and fits onto an L shaped bracket fixed to the back of the cross slide base. I had to machine a flat area on the base to achieve this. I have a long cross slide on the lathe and I extended this by another 5cm with a block of aluminium bolted to the end, then machined a 1cm wide area about 1mm deep along the underside of the slide and aluminium block, into which the magnetic tape was located using superglue. A thin non magnetic metal plate was fitted over the magnetic strip to protect it from any machining oil or debris.

Careful alignment was needed to achieve the right gap between the magnetic tape and sensor and to avoid conflict with the cross slide screw. The cable from the sensor was routed under the lathe bed and connected to the same digital readout used for the mill. I made a switchover box so that I could select the output from either the mill Z axis or the lathe cross slide sensor.

If anyone is interested I can take some pictures and post them if I can work out how to do it.

Doug
17 September 2012 at 10:37 #98582
Paul Barrett
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@paulbarrett57424
Yes please
17 September 2012 at 15:34 #98616
Douglas Johnston
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@douglasjohnston98463
I've uploaded five pictures of the DRO into an album.

Doug
17 September 2012 at 16:40 #98618
Russell Eberhardt
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@russelleberhardt48058
Posted by Jon on 16/09/2012 01:30:37:

Need the finest resolution for repeatability. 1 Micron res http://www.machine-dro.co.uk/magnetic-linear-encoder-reading-head-1-micron-resolution.html

1 micron!! That's a 25th of a thou in old money. I can only dream of working to such accuracy

Russell.
17 September 2012 at 17:15 #98620
Douglas Johnston
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@douglasjohnston98463
It is not a matter of working to an accuracy of 1 micron, the 1 micron resolution simply makes it easier to get a decent accuracy. Remember resolution and accuracy are two different things.

Doug
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