Edison Standard Model B feed screw

Share your phonograph repair & restoration techniques here
Post Reply
bartongreg8238
Victor Jr
Posts: 10
Joined: Sat Apr 17, 2021 1:35 pm
Personal Text: Music!

Edison Standard Model B feed screw

Post by bartongreg8238 »

Edison std model B with M8 x 0.5 on it
Edison std model B with M8 x 0.5 on it
I have this rusty feed screw I have been soaking and wondered what type of nut I could use to see if the threads are ok. I found a metric nut that fits pretty good, thought to share. M8 x 0.5

Dave D
Victor IV
Posts: 1105
Joined: Wed Aug 01, 2012 8:43 pm
Location: Port Huron, MI

Re: Edison Standard Model B feed screw

Post by Dave D »

How well does it fit? I think that those feed screws use a different thread shape. I am sure someone like Jerry Van can comment more intelligently.
Dave D

User avatar
phonogfp
Victor Monarch Special
Posts: 6839
Joined: Wed Jan 07, 2009 5:08 pm
Personal Text: "If you look for the bad in people expecting to find it, you surely will." - A. Lincoln
Location: New York's Finger Lakes

Re: Edison Standard Model B feed screw

Post by phonogfp »

Dave is right - the feedscrew uses a buttressed thread, and it isn't metric. A good soaking in Evaporust and perhaps a gentle brushing with a brass wire brush should accomplish all that's possible in its rehabilitation. It might be better to simply replace it with a good one - which should be readily available from several suppliers.

George P.

recordmaker
Victor O
Posts: 99
Joined: Mon Mar 25, 2019 11:50 am

Re: Edison Standard Model B feed screw

Post by recordmaker »

The lead screw is 50 TPI 3/16 inch as far as I can see the 50 TPI lead screws being coarser are not buttress threads like the 100 TPI on the Triumph and Home designs but there is no reason for them to follow any stock thread standard form of the time either.
The M8 fine 0.5 pitch will be a loose fit on the 7.9375mm thread being a little larger than the 8mm core diameter of a M8 screw and has a pitch of 50.8 TPI but on the narrow nut you show this wont really notice.
However it is possibly not the ideal thing to use as a chaser to clean out the threads as the shape of the thread may be at a different angle.

PS
I have looked at my Fireside leadscrew and it does not look as if it is buttressed and i think it is the same as the standard but i will have to get he microscope out to be sure.

bartongreg8238
Victor Jr
Posts: 10
Joined: Sat Apr 17, 2021 1:35 pm
Personal Text: Music!

Re: Edison Standard Model B feed screw

Post by bartongreg8238 »

Evapo rust is awesome! It really did a great job on the feed screw, although there is a significant amount of pitting. This poor feed screw will probably be a display model


Thanks again!
Attachments
Feed screw after evapo rust
Feed screw after evapo rust

Post Reply