Hi,
I don't want to run this topic off track and the only reason I posted that was as a compliment to ARC, as their scales are close in accuracy to what the expensive magnetic scales are at a fraction of the price. Fair enough that might not be as durable, but that comes at a cost of glass or magnetic scales. If you added covers similar to what the glass scales have, they would be able to stand up to a fair bit of abuse from swarf etc without any worries.
From what I have read on a lot of forums, is guys that are wanting something cheap and accurate, and the ARC scales fit the bill. A lot of people just cant afford, or don't want to spend the money on an expensive DRO system.
The off topic bit
With the glass V's magnetic, I was just surprised to see less accuracy, but at a higher price. I have been running glass scales for 4-5 years now and I have not had one problem, even with flood coolant.
If they are mounted properly and protected with the factory covers they are fine. There are those installations where a glass scale wont fit and magnetic are great for that, but you do loose accuracy.
On a lathe cross slide that 0.015 mm accuracy of the magnetic scale ends up 0.03mm on diameter. A fair way away from the Sino/Meister 5um glass scale accuracy of plus or minus 0.01mm on diameter in the same situation, or 0.002mm on diameter for the 1um scales at only $20-$25 each extra an axis, which is still under the magnetic price.
If you have a lathe that a glass scale wont fit on the cross slide, you will need to go with a magnetic, or if you want the accuracy of glass a lot of people with confined space are making a extended bar off the back of the cross slide to mount the scale out of the way.
I am not knocking any system here, I only brought this up for the reason I said above, and also that I was surprised to see these latest model expensive magnetic scales being advertised as 1 and 5 micron, when their accuracy is only 0.015mm, sort of makes paying the extra for the 1 micron scales useless in my opinion.
Sorry for the OT bit, I think if we are going to discuss these scales any more we need to start our own thread.
Jonny you have the axis's mixed up their, the X is the cross slide and the carriage is the Z.
Dave