Seeking a knob/dial - Page 1
Forum section: electronics / general

author: TimFox
author_rank: Super Contributor
timestamp: November 03, 2022, 09:18:55 pm
content: I'm trying to locate something that used to be normal.Specifically, I'm looking for a skirted knob, where the skirt has numbers 0 to 100 spread out over 180 degrees (for a tuning capacitor).The only knobs and dials I can find in catalogs are either 270 degrees (for a pot), or integers on 30 degree increments (for switches).Preferably, this would be for a 1/4" shaft (with set screws), skirt diameter between 2 and 3 inches.Besides Mouser, etc., I've looked in my sources for surplus electronics, but apparently WW II was a long time ago.Anyone have a source?

author: Psi
author_rank: Super Contributor
timestamp: November 03, 2022, 10:00:55 pm
content: I dunno if this is for a one-off or for production.But.Assuming you can't find one, and don't want to pay china for 1000 pcs to make a custom order for them.Then one way you could do it would be getting some round PCBs made up which have the numbering correct. Either using silk or using ENIG for the text.Then epoxy those PCBs to the underside of an existing knob without a skirt.

author: TimFox
author_rank: Super Contributor
timestamp: November 03, 2022, 10:03:58 pm
content: It's a one-off.McMaster has some self-adhesive dials, but they all cover 360 degrees.Leeds has an ancient G-R knob that is exactly what I want, but it does not have the numerical dial on the skirt.I was hoping to find a surplus General Radio knob, or similar.

author: Psi
author_rank: Super Contributor
timestamp: November 03, 2022, 10:07:25 pm
content: Another option is to find a pot with a skirt but no numbers and then use wet letter transfer to put numbers on the pot where you want them.Then then it dry and spray it with lacquer to secure everything.

author: srb1954
author_rank: Super Contributor
timestamp: November 03, 2022, 10:07:38 pm
content: Quote from: TimFox on November 03, 2022, 09:18:55 pmThis type of dial used to be quite common when built into a reduction drive for tuning VFOs. These were used a lot on old ham gear but appear to quite expensive now.https://www.amazon.com/Philmore-S38-Vernier-Control-Knob/dp/B00A9HHTCQ

author: Psi
author_rank: Super Contributor
timestamp: November 03, 2022, 10:09:52 pm
content: Just a note, that one above has a gear set inside. Which may/may-not work for your application.The knob rotates a lot and the scale moves slowly with the pot. 1:8So the scale and pot are not one piece.270deg pot * x8 = 2160 / 360 = 6 full rotations.

author: TimFox
author_rank: Super Contributor
timestamp: November 03, 2022, 10:18:45 pm
content: Quote from: srb1954 on November 03, 2022, 10:07:38 pmThose friction-planetary-drive vernier dials used to be ubiquitous in different sizes.I'm looking for a direct drive.I'm probably stuck with making a dial and using a pointer knob for my 180-degree rotation requirement.

author: srb1954
author_rank: Super Contributor
timestamp: November 03, 2022, 10:29:16 pm
content: Quote from: TimFox on November 03, 2022, 10:18:45 pmTake one of the reduction drives and disable the reduction mechanism to make it into a direct drive.As I remember these drives used ball bearings rotating in a cage to provide the reduction mechanism. You could possibly fill the cage with epoxy to seize it up.

author: TimFox
author_rank: Super Contributor
timestamp: November 03, 2022, 10:52:43 pm
content: The cheap drives that are still available used friction between a thin disc and pinch wheels to effect the planetary drive.The old National "Velvet Verniers" were better--probably used balls.I have found one antique knob, but it is a bit larger than I wanted.Still looking.

author: Benta
author_rank: Super Contributor
timestamp: November 03, 2022, 10:59:25 pm
content: Quote from: TimFox on November 03, 2022, 09:18:55 pmUnrealistic, unless you place a microscope in front of the knob.A 1...10 scale with tenth lines between the numbers is realistic.Anyway, the company offering the most comprehensive portfolio for this is Odenwälder or OKW,www.okw.comThey do NOT have a 180 degrees skirt, but they do have an almost blank skirt (one line). If you can find someone to engrave it you should be good.The largest you'll get is a 31 mm knob with 50 mm skirt. Look at "COM-KNOBS" and "COMBINATION KNOBS" plus accessories.https://www.okw.com/en/Products/Tuning-knobs-with-collet-fixture.htm

author: TimFox
author_rank: Super Contributor
timestamp: November 03, 2022, 11:49:10 pm
content: Quote from: Benta on November 03, 2022, 10:59:25 pmClarification: I don't expect every integer from 0 to 100 indicated, just a range from 0 to 100 spread around 180 degrees.I have located one antique bakelite knob (about 3" diameter), which is similar to what I want.I could also use an appropriate dial plate.Again, these are very common for 270 degrees, corresponding to a potentiometer, but I have a variable capacitor.

author: Benta
author_rank: Super Contributor
timestamp: November 04, 2022, 12:02:37 am
content: Perhaps you missed this sentence:"but they do have an almost blank skirt (one line). If you can find someone to engrave it you should be good."There are lots of shops doing engraving for doorbell signs etc. and they will probably jump at doing something out of the ordinary. At least, that's my experience over here (front panels etc.).Did you even look at OKW?

author: james_s
author_rank: Super Contributor
timestamp: November 04, 2022, 12:11:50 am
content: Maybe you can get somebody to 3D print one on a resin printer? This seems like a good application for one of those.It's hard to find knobs like this because hardly anything uses them anymore. Large variable capacitors themselves are hard to find these days, everything is digital.

author: Ian.M
author_rank: Super Contributor
timestamp: November 04, 2022, 12:46:38 am
content: No. the skirt is better done on a laser cutter in clear Acrylic. Cut the OD, shaft hole and fixing holes with the laser, and use it to engrave the numbers and lines, mirror imaged, on the underside of the skirt, then fill the engraved markings with a paint marker in a contrasting color to the panel it will mount over.

author: floobydust
author_rank: Super Contributor
timestamp: November 04, 2022, 01:32:37 am
content: Knob dial skirts for Tektronix scope, any vintage ones are quite brittle and the press-fit tends to make them break in two.I drew it up in AutoCAD, really the only way to get precision and deal with the angles and shape.Then had some custom made laser cut, a bit thicker acrylic. OD around 29mm.First build, the text is a bit more difficult, painting in laser cut text did not work. I would not get in that mess again.

author: james_s
author_rank: Super Contributor
timestamp: November 04, 2022, 01:35:08 am
content: That Tek knob looks great. I washed one of those once and it came out very clean, so clean that all the printing came right off

author: floobydust
author_rank: Super Contributor
timestamp: November 04, 2022, 01:53:27 am
content: It's missing the bevelled edge and I should really do a Rev. 2 and sell them for restoration. But the laser cut tolerances/belt slop for the precision press fit were no fun either.OP could maybe print the dial on paper and laminate that, or transparency, take it to Staples or a place that does photo's and see what formats they offer.I've seen photos printed on aluminum backed media are common and look OK for a large dial.Old school was using Letraset for knobs and dials, pic related.

author: TimFox
author_rank: Super Contributor
timestamp: November 04, 2022, 02:08:13 am
content: After lots of googling, I finally found this dial.It is designed for use with antenna tuners, which is a similar application to mine and doesn't require any custom fabrication.https://www.palstar.com/mm5/merchant.mvc?Session_ID=d7322ac3a2497f80f68d06cf747fb874&Screen=PROD&Product_Code=7350200s

author: RJSV
author_rank: Super Contributor
timestamp: November 04, 2022, 05:05:53 am
content: (Sorry if this doesn't relate...still might help. -Rick B.)See picture, the 'House' Tektronix '465 Scope shown has a dial, I think it's called a 'vernier dial knob':The inner knob, 0 through 9, causes the outer skirt to move, 1/10 the way in it's dial, for each time the inner dial completes a run past top center, positive clockwise, or decrease by counterclockwise.So I guess that's a 100 step vernier altogether.But elsewhere the special knob I remember has a little rectangular window cut-out, where another dial underneath had it's scale partially showing. So the scale rotated, underneath that opening in the outer stationary skirt.Yeah, WWII salvage and historical items, and the small electronics surplus places,...some of those business owners, dead now, (sorry). Anybody rememberQUINTRONICS in West Berkeley industrial area?And hey...; Maybe try get that question in, to Computer History Museum (?)

author: RJSV
author_rank: Super Contributor
timestamp: November 04, 2022, 05:07:02 am
content: 100 part Vernier dial

author: Psi
author_rank: Super Contributor
timestamp: November 04, 2022, 06:27:50 am
content: You can also make your own resin ones with a backing plate and some clear resin

author: tooki
author_rank: Super Contributor
timestamp: November 04, 2022, 07:32:47 am
content: Quote from: floobydust on November 04, 2022, 01:32:37 amGreat result! Though I am triggered (yes, pun intended) that you didn’t use the original font!(The original is almost certainly Univers condensed.)

author: Ian.M
author_rank: Super Contributor
timestamp: November 04, 2022, 10:34:30 am
content: Quote from: floobydust on November 04, 2022, 01:32:37 amAutocad is far from the only way to get the required precision and deal with the complexity, and any parametrically scriptable CAD or vector drawing software could be used. e.g. its fairly easy to model the O.P's knob with its far more complex markings in OpenSCAD, in about 40 lines of activecode for the skirt and markings.Try a low VOC paint or India Ink for painting in the markings as many paint solvents craze Acrylic, leading to unwanted adhesion and staining outside the etched areas and the poor results seen.

author: TimFox
author_rank: Super Contributor
timestamp: November 10, 2022, 10:47:44 pm
content: Closure to my search.I appreciate the useful suggestions about making my own, but since it's a onesie application I was looking for a reasonable purchase.I now have two choices (both delivered today), and I will decide based on the detailed panel design.One is an antique bakelite knob (National brand) from eBay, 3.5 inches diameter (which might be too large for my application).The other is a dial plate (in production from Palstar in Ohio, who make antenna tuners along with other RF products), 2.5 inches diameter (probably a better size) that I can attach to a normal knob.Both are photographed against a 0.5" grid.

author: Benta
author_rank: Super Contributor
timestamp: November 10, 2022, 11:43:32 pm
content: Wow! I like the knob. Good find.

author: scopeman
author_rank: Frequent Contributor
timestamp: September 12, 2024, 11:19:06 pm
content: Quote from: floobydust on November 04, 2022, 01:32:37 amFloobydust,I have 4 Tek scopes (465 and 465B's) that have Vertical attenuator knob skirts that are damaged and either broken or they all have the lettering worn off. Any chance you could make skirts for me? I could do the paint part. I have looked everywhere for these. They go from 5mV to 50V and I believe that the text spacing is 22.5 degrees. Obviously if I had a PDF of the text layed out I could confirm that but if you have a 465/465B you could confirm that yourself.At one point (when I didn't need them of course) I thought I saw someone on eBay that sold these but now that I need them I can't find them.Thank you for your time,SamW3OHM