- Joined
- Jul 28, 2017
- Messages
- 2,368
I've been fighting an intermittent noise issue with my Igaging DROs since the time I installed them on my benchtop mill. I've done all kinds of things -- shielding braid over the cables, single-point grounding, isolating the scales from the mill (using home-made plastic mounts) etc. The problem would disappear for awhile, then come back, usually when I was trying to sneak up on the final dimensions of a part I'm working on (Murphy strikes again!). I started thinking the problem was in fact an intermittent of some kind, so did some additional experiments.
Long story short, I found that the noise problem disappeared when I connected the aluminum scale to the DRO's internal ground. I had previously ohmed things out and found that the scale was connected to ground. Since the sensor must move along the scale, this meant the connection was through a sliding connection. Aluminum is notorious for building up an oxide layer, so it seemed like a good idea to hardwire the scale to the sensor's ground -- and it worked.
Since my experiment involved attaching an alligator clip to the scale, I "hardened' the connection by drilling a hole through the far end of the scale and installed a spade connector, then hardwired the scale to its DRO ground, making sure to make the wire long enough to accommodate the full range of sensor motion.
If there are some out there who are looking at the Igaging DROs at this point I can't recommend the aluminum scales. The stainless ones should be much better in this regard (assuming the sensor circuit is the same). If you're fighting noise problems with your aluminum Igaging scales and don't want to spend any more money than necessary, you may want to try this to see if it helps. Temporary connections with alligator clips are an easy way to see if it will. You may need to "scrub" the jaws across the aluminum to make connection.
I've read that some capacitive DROs put V+ on the scale, so you definitely want to check that possibility with a DVM before you make this mod!! I ohmed out both battery connections from V+ just to be absolutely certain I wasn't going to short the two CR2032 Li-ion batteries to ground.
Long story short, I found that the noise problem disappeared when I connected the aluminum scale to the DRO's internal ground. I had previously ohmed things out and found that the scale was connected to ground. Since the sensor must move along the scale, this meant the connection was through a sliding connection. Aluminum is notorious for building up an oxide layer, so it seemed like a good idea to hardwire the scale to the sensor's ground -- and it worked.
Since my experiment involved attaching an alligator clip to the scale, I "hardened' the connection by drilling a hole through the far end of the scale and installed a spade connector, then hardwired the scale to its DRO ground, making sure to make the wire long enough to accommodate the full range of sensor motion.
If there are some out there who are looking at the Igaging DROs at this point I can't recommend the aluminum scales. The stainless ones should be much better in this regard (assuming the sensor circuit is the same). If you're fighting noise problems with your aluminum Igaging scales and don't want to spend any more money than necessary, you may want to try this to see if it helps. Temporary connections with alligator clips are an easy way to see if it will. You may need to "scrub" the jaws across the aluminum to make connection.
I've read that some capacitive DROs put V+ on the scale, so you definitely want to check that possibility with a DVM before you make this mod!! I ohmed out both battery connections from V+ just to be absolutely certain I wasn't going to short the two CR2032 Li-ion batteries to ground.