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Newall DRO question

gear cutter

Cast Iron
Joined
Oct 16, 2010
Location
MO, USA
I want to put a DRO on a Barber Colman #6 gear hobbing machine. The vendor I have talked to about this has recommended Newall. I do not have any experience with this brand. I was told they are better for dirty oily applications. I am looking for any advice or suggestions or feedback about these units. The one that I was quoted is $2,200.00 complete. I will have to install it.
 
I have a newall NMS350 and microsyn scales on a couple of machines and I do rate them highly especially for swarf ingress.

They come in two types of scale, microsyn are carbon fibre tubes and spherosyn are stainless tubes I believe. You can get 2 micron and 10 micron resolution.

The only thing of note is the microsyn scales are a bit fragile and don't take impact well. Mine broke when I cruelly backed my forklift over its box. Replacement was only $120 Australian worthless dollars.

Mounting is pretty easy, I had so make a couple of spot faces with a mag drill for my lathe mounting.

Would reccomend absolutely.

One more thing to note is the NMS readout unit itself is made in china, scales are made in the UK. I think the DP700 and 1200 may still be made in UK. I paid about $850 us dollars for the whole kit with 550mm 400mm 400mm scale lengths.

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If its gonna be a dirty and oily environment, I would go with Magnascale. Better than the Newall both in resolution and accuracy.

I havent heard of Newall doing a 2um scale, they have always been 5 and 10um scales for the Microsyn and 10um for the Spherosyn. The best selling point for the Newall is their warranty. As long as its not the DP500, they have a 3 years no questions asked warranty on their products.

Jon
 
Newall scales are based on inductive scanning principle.

If precision is critical for the application, then optical glass scales are number 1 choice. They provide exceptional accuracy and temperature stability. Draw back of optical linear encoders is that they cannot be used in submerged environments. Correctly installed, they work fine on most metal cutting machines. However if flood coolant is used and the lip seal side of the scale cannot be properly protected from the high pressure sprays, magnetic or inductive options might be a better solution.

Glass scales have lines at 20 micron pitch which translates to 5um native resolution. Magnetic and inductive scales, depending on the model, have pitch between 1mm to 6mm, and then signal gets approximated 100+ times to get down to 5 microns resolution. With approximation come errors. Exposed magnetic scales also attract fine metal chips, which further degrade accuracy and cause random glitches. Inductive scales, if not sealed, could be similarly affected by fine metal dust (e.g. cast iron) and certain EMI frequencies.

P.S. Higher end glass scales typically have air inlets. Using those creates a positive internal pressure inside of the scale and increases protection level from standard IP53 to IP64.
 
I think another big plus for Newall is the ease of fitting. For short Microsyn scales a single end fitting is fine - I have one like this on a lathe cross slide. They are not just resistant to coolant, oil and chips - they just don't notice it. Put a cover over the scale to stop it getting knocked; the Microsyns are carbon fibre (or something very like it).
 
Newall is still pretty old school in that they employ humans that you speak to when you have a question. The human has an 'American' last name and speaks in a foreign tongue they used to call 'English'.
 
Newall scales are based on inductive scanning principle.

If precision is critical for the application, then optical glass scales are number 1 choice. They provide exceptional accuracy and temperature stability. Draw back of optical linear encoders is that they cannot be used in submerged environments. Correctly installed, they work fine on most metal cutting machines. However if flood coolant is used and the lip seal side of the scale cannot be properly protected from the high pressure sprays, magnetic or inductive options might be a better solution.

Glass scales have lines at 20 micron pitch which translates to 5um native resolution. Magnetic and inductive scales, depending on the model, have pitch between 1mm to 6mm, and then signal gets approximated 100+ times to get down to 5 microns resolution. With approximation come errors. Exposed magnetic scales also attract fine metal chips, which further degrade accuracy and cause random glitches. Inductive scales, if not sealed, could be similarly affected by fine metal dust (e.g. cast iron) and certain EMI frequencies.

P.S. Higher end glass scales typically have air inlets. Using those creates a positive internal pressure inside of the scale and increases protection level from standard IP53 to IP64.

The gear hobber does make some fine chips sometimes. And a fan or chip brush can send them flying around. will they stick to the scales? The scale the will indicate hob carraige travel will be where chips may fall.
 
Here is a sample picture of the steel chips sticking to the magnetic scale: http://www.zsinstruments.com/downloads/magnetic_chips.jpg
Actual magnetic tape is a dark brownish strip in a middle, it is protected by stainless steel foil. Typical distance from the foil to the pickup side of the reader head is 40 thous.

And here is an illustration how glass scale should be installed: http://www.zsinstruments.com/downloads/scale_orientation.png
It is OK to have some chips dropping and oil dripping on all but 1 side. Lip seals typically do a good job of keeping minor contamination out. Typical mistake is to clean them with an air gun as it will blow chips right inside.
 
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Here is a sample picture of the steel chips sticking to the magnetic scale: http://www.zsinstruments.com/downloads/magnetic_chips.jpg
Actual magnetic tape is a dark brownish strip in a middle, it is protected by stainless steel foil. Typical distance from the foil to the pickup side of the reader head is 40 thous.

And here is an illustration how glass scale should be installed: http://www.zsinstruments.com/downloads/scale_orientation.png
It is OK to have some chips dropping and oil dripping on all but 1 side. Lip seals typically do a good job of keeping minor contamination out. Typical mistake is to clean them with an air gun as it will blow chips right inside.

This is a picture of where I have to mount the scales.20190718_171937.jpg
 
Here is a sample picture of the steel chips sticking to the magnetic scale: http://www.zsinstruments.com/downloads/magnetic_chips.jpg
Actual magnetic tape is a dark brownish strip in a middle, it is protected by stainless steel foil. Typical distance from the foil to the pickup side of the reader head is 40 thous.

Just for clarification; Newall scales are not noticeably magnetic and my scales do not attract or hold chips of any size. They do operate on an inductive basis but that is not the same as the scale shown in the photo. I would not be too concerned about the location for a scale on the machine shown, provided that they can be protected against knocks from things dropping down on them.
 
261313d1563491036-newall-dro-question-20190718_171937.jpg


That doesn't look any more challenging than the rear of a lathe carriage, and they work just fine there. Newall ships a piece of aluminum angle the same length as the spar that you are intended to use as a chip shield. That angle is enough, but you could add another piece to make it an upside down channel for extra protection if you wished.

I've had several brands of DROs and scales, Teledyne, Anilam, Heidenhain, Accurite, Newall has been the least trouble of any of them, and I've never had a Newall scale problem, or needed to clean a Newall scale.
 
We have a DP700 on a manual lathe, new in 2017. Our issue is it is supposed to have a tool library that we can assign offsets to our QC tooling, and then when we pop in a given tool, we can type in the assigned tool number and the offset for that tool pops up. Also supposed to be able to put in a new job and do a grid shift and all tools will follow, but we get erratic results where sometimes we loose our presets between changeovers.
 








 
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