@andrew said in CNC PCB milling:
@niallain it is 3020T which uses trapezoidal screws. "Z" uses ball screws.
you can check the "official" technical details on the item's specification (scroll down to the description then click on the "specification"):
declared specs for mine were in the same ballpark as your's 3020T, modulo 8mm trapezoidal screw. But in reality that wasn't true at all, in my case cuplrit of the biggest error is the flex from the way screw nuts are attached to carriage, and the second/third are nonlinear screws (+-0.060mm) and backlash.
I'm ordered a 1204 ball screw kit for Y axis, to test how much it would reduce error.
As for testing, I just used regular digital calliper with 0.01mm resolution.
I'm planning to use this:
for rising with acetone
I plan on using this:
for rinsing with IPA.
I'm sharing the info because it's not always easy to find spray bottles with the right kind of chemical resistance. From what I've read, the usual advice for mechanical sprayers is to empty the container immediately after use because even with Viton seals and gaskets, very often "resistant" does not equate to "unaffected." For instance, LDPE ziplock bags may be able to withstand acetone for a while, but eventually the acetone will break through.
Likewise, I used to think that nitrile gloves were fairly resistant to most chemicals, but then I noticed that acetone passed through them quite quickly. Likewise, nitrile gloves would be a poor choice for handling methyl alcohol. According to this handy chart, the best type of glove for both acetone and methyl alcohol (as well as IPA) are butyl gloves: https://www.augusta.edu/services/ehs/chemsafe/PDF files/gloveselechart.pdf
As it happens, I picked up a pair just recently as PPE for use with, before, or after an ultrasonic PCB cleaning. However, last week I visited one of the big box hardware stores and their entire inventory of chemical resistant gloves was wiped out, so be sure to plan ahead.
Chapin International 10027 48-Ounce Industrial Acetone and Acetone Dye Hand Sprayer (1 Sprayer/Package), White, Full Size
Wash Bottle for Acetone, 500ml - Labeled with Color Coded Chemical & Safety Information (2 Color) - Wide Mouth, Self Venting, Low Density Polyethylene - Eisco Labs
LiBa Spray Bottles (4 Pack,16 Oz), Refillable Empty Spray Bottle for Cleaning, Essential Oils, Hair, Plants, Adjustable Nozzle for Squirt and Mist, Bleach/Vinegar/BBQ/Rubbing Alcohol Safe
$11.99 ($11.99 / Count)
Karter Scientific 210P3 Safety Wash Bottle, Narrow Mouth, 500 mL Capacity, Polypropylene/Plastic