eHam

eHam Forums => Mods And Repairs => Topic started by: W9WD on January 25, 2013, 04:36:30 PM



Title: Big knobs with 360° markings ???
Post by: W9WD on January 25, 2013, 04:36:30 PM
I'm looking for some big knobs to replace the two that are on the tuning capacitors on my Murch. The markings don't go all the way around so I have to resort to pencil marks....

The existing knobs have a metal skirt that is 2" diameter and they fit on a 1/4" shaft.

I'd sure like to find some to replace them with 360° markings.
Or..... if I could find some metal disks (?) with markings all the way around that could stick to the metal chassis, I could use big pointer knobs.

Clues? Resources?

Thanks for looking
Greg

 ???


Title: RE: Big knobs with 360° markings ???
Post by: WB6BYU on January 26, 2013, 08:36:27 PM
What about a protractor?  That would have 360 degree markings.  You can secure it
under the nut against the front panel to make it stationary, or glue it to the back side
of the knob.  They are available in a variety of sizes in school supply and stationery
stores, as well as those that handle professional drafting supplies.

I've also seen clear plastic stick-ons with a full compass rose that are used for
plotting on navigation charts - some place that sells charts for boaters or
pilots might carry them.  Otherwise you can download a complete compass rose
from the web (somewhere) and print it out to whatever size you want.


Title: RE: Big knobs with 360° markings ???
Post by: AC5UP on January 27, 2013, 07:21:12 AM
...a Real Ham (tm) would install a small CCD camera liberated from a cell phone inside the tuner with some white LED's for illumination, then connect a flat panel video display to the output. That way one could observe the exact mesh of the plates in real time.

Call it the MurchCam and stream it on the web so we can all watch.   ;D

Or........... A person could use a wire sized drill bit to dimple the skirt of the knob with a series of dots in a pattern maybe 90 degrees apart.  One dot, two dots, three, four, etc. then fill each dot with a dab of white paint.  With a drill press this could be easy.


Title: RE: Big knobs with 360° markings ???
Post by: W9WD on January 27, 2013, 07:59:09 AM
While looking I ran across these at Amazon and bought a couple. The only problem is they got from 0-180 and back down again

http://www.amazon.com/gp/product/B0053DGGDE/ref=oh_details_o00_s00_i00
 (http://www.amazon.com/gp/product/B0053DGGDE/ref=oh_details_o00_s00_i00)
Then I ran across this page.....

http://www.oregonruleco.com/dials.htm (http://www.oregonruleco.com/dials.htm)

If you look real close one of them goes from 0-360. They have sticky on the back already. I'm going to call on Monday
Then a skirted knob with a pointy pointer or maybe a little magnifying glass lens with a line through it like is used on some compasses....

I do like the Murchcam idea though


 ;)


Title: RE: Big knobs with 360° markings ???
Post by: W0FM on January 31, 2013, 12:26:08 PM
There are a number of guys who restore antique radios who will custom make clear plastic radio dials.  Some of them advertise on sites like www.antiqueradio.com (http://www.antiqueradio.com).  I had a new plastic dial made for the Philco cathederal I restored and I think it cost me less than $20.  Just another place to hunt.

Good luck.

73,

Terry, WØFM


Title: RE: Big knobs with 360° markings ???
Post by: W3NR on February 01, 2013, 04:54:29 AM
Let me look in the junk box later today. I just might have what you need.  I looked to see if you had an email address on QRZ, but you don't. I know I have quite a few larger knobs with plates or just plates, not sure if they are 360 or not,  Its 14F outside, so it is not my type of wx to go poking around in the unheated  shop.

Ed W3NR


Title: RE: Big knobs with 360° markings ???
Post by: W3NR on February 01, 2013, 07:19:30 AM
Started to wonder why you need 360  when variable caps only rotate 180 from full open to full closed.

Ed W3NR


Title: RE: Big knobs with 360° markings ???
Post by: W9GB on February 02, 2013, 05:45:48 PM
Metal Monkey (UK) - Dial gauges
http://www.metal-monkey.co.uk/acatalog/
Dial Material: Our dials are manufactured out of solid 304 Brushed Stainless Steel.
http://www.metal-monkey.co.uk/acatalog/Dial_Gauges.html

Dial scales, scanned from many Antique Radio Receivers
http://www.ppinyot.com/Dialscales/dial_scales.htm

fixit-fox (eBay) sells Dial Plates for main tuning knob on Hallicrafters SX-101, SX-101A or SX-88 radios.

CONTACT EB5AGV Jose Gavila about his C-Dial project.  He engraves a CD-Rom for the dial !
http://www.jvgavila.com/cdial.htm

I use a CNC machine (computer controlled mill in this case) along with a conical tool. It is a kind of plotter, but with a mill instead of a pen. It is connected to a PC which sends the data to the controller.
The CDial engraving can be customized to suit your needs in various ways.
The sample has a logging scale from 0 to 99, equally spaced in 360 degrees, but this can be changed to, let's say, 270 degrees and, of course, with other markings and orientation: the CDial sample I made was intended for FIXED dial and movable pointer, so the numbers would be always read fine (not upside down in any case). In case of a MOVABLE dial and fixed pointer all what is needed is to change the dial markings and put all of them facing to the center of the circle, as in a Collins S-line or KWM-2 dial, for example.


Title: RE: Big knobs with 360° markings ???
Post by: W9WD on February 19, 2013, 02:32:53 PM
Found some dials on Ebay being sold as Hallicrafters Tuning Knob Disc 00-100 SX-101,88,SR-400

http://www.ebay.com/itm/360399360852?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 (http://www.ebay.com/itm/360399360852?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649)


They did not have the same hole pattern as the Murch knobs so I added 3 holes
Original Murch dial on the right, modified Ebay dial on the left

http://www.muellersatomics.com/random/2dials.jpg (http://www.muellersatomics.com/random/2dials.jpg)