Painting binding posts  - Page 1
Forum section: electronics / general

author: Simenhs
author_rank: Contributor
timestamp: March 30, 2023, 09:58:59 am
content: Hi, I am making a battery powered "benchtop" power supply and it has two binding posts.I would like to paint a red and black ring on each of these two binding posts. Se picture below.My problem is that I haven't found a type of paint that stick well to these stainless steel binding posts.I have tried with acrylic paint, but does come off if i scratches it with my nail. I have also tried a few types of tape, but that's not any better.Do you have any suggestions to a type of paint that would be well suited to this application?More info on the project can be found here:https://github.com/Blue-Smoke-Electronics/Ember/wiki

author: wilfred
author_rank: Super Contributor
timestamp: March 30, 2023, 11:28:46 am
content: You could try nail polish. I use it for marking metric and imperial spanners. Not sure if black is a standard nail polish colour though. You could ask a passing Goth I suppose.

author: Kean
author_rank: Unknown
timestamp: March 30, 2023, 12:16:17 pm
content: Heatshrink is another option

author: SMTech
author_rank: Frequent Contributor
timestamp: March 30, 2023, 02:31:36 pm
content: teeny tiny nerd pots of enamel paint

author: jpanhalt
author_rank: Super Contributor
timestamp: March 30, 2023, 02:51:46 pm
content: If you are adventuresome, there are several YT and DIY posts on "anodizing" (i.e., coloring) stainless steel.

author: Simenhs
author_rank: Contributor
timestamp: March 30, 2023, 03:14:50 pm
content: Nail polish is a good idea. I stole some from my wife and is testing it out now. It is not sticking to well after a few minutes, guess it needs longer to fully dry and harden.I did also try with heat shrink, but I'm having problems. There is nothing for the heat shrink to grab onto, and it slides down into gap between the two parts of the binding post. Guess I could try to find heat shrink with stronger glue.Is this the kind of enamel paint you are talking about ?https://www.revell.com/products/colors-accessories/email-color/

author: jpanhalt
author_rank: Super Contributor
timestamp: March 30, 2023, 04:15:13 pm
content: Stainless (at least the alloys with which I am familiar) is easily etched in strong acid with a high chloride concentration. HCl is an obvious choice, but battery acid (sulfuric acid) with salt would probably work. Even ferric chloride for etching PCB's works. A little etch will probably help the paint adhere. You could mask off the knurled areas to keep them from etching. Wax is a good etch resist and is easily removed afterward.

author: thm_w
author_rank: Super Contributor
timestamp: March 30, 2023, 09:20:38 pm
content: Quote from: jpanhalt on March 30, 2023, 04:15:13 pmCan you even buy stainless steel binding posts? Surely these are nickel plated or something similar.Some sandpaper might be an option as well.

author: Bud
author_rank: Super Contributor
timestamp: March 30, 2023, 09:23:40 pm
content: Cant you simply paint +/- symbols on the case ?

author: Stray Electron
author_rank: Super Contributor
timestamp: March 30, 2023, 09:29:21 pm
content: It might be worth trying paint made for plastic models but nail polish should also work. Both are available in a wide variety of colors.

author: Stray Electron
author_rank: Super Contributor
timestamp: March 30, 2023, 09:31:57 pm
content: Quote from: thm_w on March 30, 2023, 09:20:38 pmI don't know why someone would even want stainless for this application. I don't see any benefit and it's not a very good electrical conductor.

author: Stray Electron
author_rank: Super Contributor
timestamp: March 30, 2023, 09:36:26 pm
content: Quote from: Simenhs on March 30, 2023, 03:14:50 pmThat should work but I've never seen the Revell brand paint. The hobby shops around here all carry (carried?) Testor's brand paint and it used to come in little tiny glass bottles that held 1/2 oz of paint. The last time I bought some (many years ago!) it cost 19 cents per bottle and they had a huge variety of colors.

author: tooki
author_rank: Super Contributor
timestamp: March 31, 2023, 07:00:18 am
content: Why not just use standard plastic-insulated binding posts, rather than the (usually audio-focused) in insulated ones??

author: Simenhs
author_rank: Contributor
timestamp: March 31, 2023, 08:30:45 am
content: Quote from: Bud on March 30, 2023, 09:23:40 pmThat is definitely a possibility. I just liked the design where the case is clean. Also, the binding posts has this nice flat area that look like it's meant to be painted. Black paint on a black case could also be hard to see. I like the idea of using +/- symbols, someone might not be familiar with the red/black convention.

author: Simenhs
author_rank: Contributor
timestamp: March 31, 2023, 08:33:46 am
content: Quote from: thm_w on March 30, 2023, 09:20:38 pmYou are right, checked the datasheet and turns out it is nickel plaited brass. Thanks for pointing this out, I do not know why I was sure it was stainless steel

author: Simenhs
author_rank: Contributor
timestamp: March 31, 2023, 08:50:13 am
content: Quote from: tooki on March 31, 2023, 07:00:18 amThe reason I'm using these binding posts is that they are small, most other binding posts I have looked at is sticks out from the case far longer.They also have a hole all the way through them, which means that the tip of the banana plugs can go inside the case.And, they feel very nice giving the power supply a more premium feel.What i don't like about them is the price, the cost of two binding post is like 1/4 of the total cost of the bom.They do not come in black and red versions.If you have a suggestion to another type of binding posts that would fit I would be very grateful, or a good place to look for them.

author: Stray Electron
author_rank: Super Contributor
timestamp: March 31, 2023, 09:33:01 am
content: The reason why most binding post extend out so far is because they can also be used as sockets for banana jacks. If you don't want that feature and you want something that doesn't stick out as far, then you should probably look for insulated terminals with or without a thumb screw or thumb nut. Would an old fashioned terminal barrier strip suit your purpose? Or if you want to use banana jacks then you can can get banana jack sockets (without the binding post) that are quite shallow. Take a look at Ebay item #394415280991, for example. They do accept banana plugs but the socket is recessed into the front panel and only sticks out about 3/16".

author: Simenhs
author_rank: Contributor
timestamp: March 31, 2023, 12:58:32 pm
content: Quote from: Stray Electron on March 31, 2023, 09:33:01 amI definitely want it to be connectable with both banana jack and the thumb screw. The way the binding post I use now solves this is with a hole all through the device. I have not been able to find any other terminals that does this.

author: Ian.M
author_rank: Super Contributor
timestamp: March 31, 2023, 01:36:34 pm
content: If the flat area was meant to be painted, it would be slightly recessed with a bead-blasted finish for better paint adhesion. Its smooth and goes right down to an edge with the clamping face of the thumb-nut so paint on it is invariably going to chip with use and end up looking messy.Paint a filled circle of the required color round the mounting hole for the post, don't paint the post itself. Alternatively cut thin hard plastic washers of the required colors, a bit bigger than the mounting post diameter and trap them between the posts and the case.

author: tunk
author_rank: Super Contributor
timestamp: March 31, 2023, 02:08:29 pm
content: Is it a 3D printed case?If so, maybe you could print some red+black press-fit covers (the whole heigth)?

author: David Hess
author_rank: Super Contributor
timestamp: April 01, 2023, 02:21:03 am
content: Quote from: Kean on March 30, 2023, 12:16:17 pmThat is what I would do.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 18, 2023, 09:13:27 pm
content: Put some glue around it, and then wrap colored yarn around it. Tie it off with some knots until the yarn dries.I've been using this with great success for years. You can for example also use it for repairing stiff ends on shoe laces.It also works with plastic caps of tubes and such. the glue does not even have to stick to the plastic, it just has to keep the yarn together.

author: Simenhs
author_rank: Contributor
timestamp: July 03, 2023, 02:26:33 pm
content: This is what I ended up doing. I add a groove in the 3d print that I fill with paint. This sticks better, and is not in contact with the user whenever they tighten the nuts.I also was able to barrow a lathe form my father in law, which I have been using to make my own custom binding posts out of brass. The new binding posts are easier to solder to the pcb and feel a bit more premium because they have a bit more weight to them.

author: TimFox
author_rank: Super Contributor
timestamp: July 03, 2023, 03:57:51 pm
content: I believe that that particular style of metallic binding post with through hole is popular for a chassis-ground connection, where the color does not matter.

author: Ian.M
author_rank: Super Contributor
timestamp: July 03, 2023, 05:46:10 pm
content: Since you are now making your own binding posts, you could turn a wide groove in the knurled area, and color code them with a ring of heatshrink sleeving. If the groove is a bit deeper than the heatshrink thickness, it should be pretty resistant to wear from normal handling. Some experimentation will be required to allow for longitudinal shrinkage of the heatshrink so it fills the groove width.

author: ajb
author_rank: Super Contributor
timestamp: July 03, 2023, 10:22:39 pm
content: Your solution looks great! I would be concerned about the risk of something coming into contact with those that shouldn't given the exposed metal, personally, but that's just me. Going back to the original question, one thing I don't see mentioned is the importance of surface prep with any kind of paint. Warm soapy water and a toothbrush, water rinse, then a rinse in acetone would be a good start. Then make sure you aren't touching the area to be painted with bare hands until fully painted. Etching/scuffing with sandpaper to provide some 'tooth' on the surface first will help as well, but cleaning is even more important after doing that.