Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Oct Tue 20, 2020 4:23 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 8 posts ] 
Author Message
 Post subject: Variable capacitor mounting
PostPosted: Jun Tue 23, 2020 7:39 pm 
Member

Joined: Feb Thu 19, 2015 1:49 pm
Posts: 80
I have quite an abundance of tuning capacitors from scrapped radios mostly aa5's . I would like to use them for my different regen.projects but the problem is most of them were circuit board mounted. They have the nice triangular pattern of holes but they are not threaded. It would be quite hard to get a screw and nut in there,close clearance ! Would a thread cutting screw work and what size do you think?


Top
 Profile  
 
 Post subject: Re: Variable capacitor mounting
PostPosted: Jun Tue 23, 2020 7:53 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 26542
Location: Detroit, MI USA
A thread cutting screw, or a tap carefully used. You have to take precautions to keep the chips out of the plates and the ball bearings.

Most were either 6-32 or 8-32, you can tell by the size of the unthreaded hole which it was intended to be.

_________________
Dennis

Experience is what you gain when the results aren't what you were expecting.


Top
 Profile  
 
 Post subject: Re: Variable capacitor mounting
PostPosted: Jun Tue 23, 2020 8:28 pm 
Member
User avatar

Joined: May Wed 18, 2011 2:40 am
Posts: 4969
Location: Littleton, MA
You may need a bottoming tap, depending on the amount of clearance between the hole and the stator:
https://en.wikipedia.org/wiki/Tap_and_die#Tap

McMaster-Carr is one source:
https://www.mcmaster.com/bottoming-taps ... teel-taps/

_________________
Steve Byan https://www.byan-roper.org/steve/steve-at-play/


Top
 Profile  
 
 Post subject: Re: Variable capacitor mounting
PostPosted: Jun Tue 23, 2020 8:59 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 8676
Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
If you buy a tap, (from my experience) buy the absolute best quality taps you can afford (or better). Also buy a properly fitting tap handle .... emphasis on "properly fitting". The first time you break a cheap tap off in an attempt to cut threads and you are stuck with broken tap in a good capacitor, and it happened because you had a cheap tap or were driving it with the wrong tool, that's when the better quality tap and handle set would have paid for itself.


Top
 Profile  
 
 Post subject: Re: Variable capacitor mounting
PostPosted: Jun Wed 24, 2020 6:50 pm 
Member

Joined: May Tue 30, 2006 4:46 pm
Posts: 10186
Location: Santa Rosa, CA
Yes, tap the holes for 6-32. I think the correct drill bit is #35. Use a little bit of machine oil and go slow. 8-32 may be overkill.

Rich


Top
 Profile  
 
 Post subject: Re: Variable capacitor mounting
PostPosted: Jun Thu 25, 2020 1:48 am 
Member
User avatar

Joined: Aug Tue 21, 2012 1:19 am
Posts: 173
Location: Southern Ontario
I have made brackets that I bolt or screw to new holes I drilled on the back or front of the capacitor then fastened the bottom of the bracket to the chassis or board.
The new holes are made where they will not interfere with the capacitor plates.

_________________
Lee

If you can't figure it out, cool the iron and start your day over.


Top
 Profile  
 
 Post subject: Re: Variable capacitor mounting
PostPosted: Aug Thu 06, 2020 7:02 am 
Member

Joined: Oct Fri 11, 2019 3:03 am
Posts: 40
Location: Seattle, WA 98122 (from Hungary)
Thread is 6-32. I bought a tap and tap the hole as long as the tool goes. From experience, the hole is able to receive a screw with this initial thread - actually the screw does the rest of the job. You can try buying a second tap and snap off its tip, so that you can use it to finish off the thread.

Attachment:
tap.jpg
tap.jpg [ 272.19 KiB | Viewed 461 times ]


Top
 Profile  
 
 Post subject: Re: Variable capacitor mounting
PostPosted: Aug Thu 06, 2020 12:18 pm 
Member
User avatar

Joined: Oct Sun 15, 2006 12:57 pm
Posts: 7218
Location: Liberty, Missouri
Quote:
...You can try buying a second tap and snap off its tip,...

NOW, you have a bottoming tap.

I refer you to Steve's WIKI LINK. Good info for those who haven't used taps before.

========

Taps, by necessity, have to be quite hard, and are thus brittle. Machine screw taps, by virtue of their small size are therefore fairly easily broken. So, when using them be aware of how much torque you are applying, AND make sure you don't "wobble" as you're rotating it.

I have one of these I bough probably 40 years ago and it is still a handy tool. By being a screw driver format as opposed to the typical lever handle type, it reduces the danger of you breaking a tap.

TAP DRIVER

========

For those who do a lot of building I've found that using small battery powered drill drivers is a real step up. The Fwd/Rev bar which is usually conveniently located, makes the in/out of tapping quick and easy, while the clutch minimizes, and for #6 and larger, eliminates the possibility of breaking a tap because of torque.

_________________
Pics, Bold & underlined text, are usually links.

https://mikeharrison.smugmug.com/

Mike


Top
 Profile  
 
Post New Topic Post Reply  [ 8 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 12 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB