Lets Erode Those Pesky Eroded Edges
Saturday, January 3, 2009
I experienced this problem when I raised the voltage to 10 v from 5 v.
Tomorrow I will run the following experiments:
1. I will use the calculations recommended by Cedric Green. I established today that my set up offers a resistance (R) of 7 ohms. From the etch time discussion:
T = F x R/V ; where T = time in minutes; R = resistance obtained by
calibration with 100 sq.cms., and V = volts; F is obtained from the
table
So for this project T = 40* X 7/5 = 56 minutes.
*I used the F factor of 40 from the table as an estimate of a .3mm bite.
This will yield a lower voltage and longer etch time which should "cool" things down in the etching process and better protect the Puretch ground.
2. I will make sure that my PosJet film is firmly adhered to the Puretch mylar so I can position the plate perpendicular to the sun without the sliding around problem. My thought is that a shadow or other exposure irregularity caused the resulting erosion problem. Since my film was sliding around I exposed the plate flat but the sun was at a 2:00 angle.
3. I will also try an experiment using the orientation of the plate in the etch tank as a variable. If rising bubbles are a cause then this test should quickly identify that issue.
4. I will try an experiment with decreased anode/cathode plate distance to increase the amps at 5 volts.
I plan to separate the effects so I can determine the effect of each on the erosion problem being discussed. I’m hoping that reduced voltage is going to do the trick
