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I am restoring my Lambertphone phonograph and need a bolt to fit the baseplate to the lid. It is 1 1/8th long 3/16th diameter and slotted, round head. Can anyone help me with the thread and any offers. I have attached a copy of a bolt required.
Thanks Brian

It is hard to determine from the photo. But the machine screw depicted looks like a 5-40 thread. I know Edison machines used this now obsolete screw.

I picked up 5-40 taps and dies decades ago for fixing machines. I may be able to help you out.

Can you confirm that it has the same thread pitch as the common 4-40 with the shank diameter between the 4-40 and 6-32?

Is the Lambertphone British? If so, I am up the spout and it may be a BA thread.

Governor Flyball wrote:It is hard to determine from the photo. But the machine screw depicted looks like a 5-40 thread. I know Edison machines used this now obsolete screw.

I picked up 5-40 taps and dies decades ago for fixing machines. I may be able to help you out.

Can you confirm that it has the same thread pitch as the common 4-40 with the shank diameter between the 4-40 and 6-32?

Is the Lambertphone British? If so, I am up the spout and it may be a BA thread.

A 5-40 would be way too small.

A 3/16" diameter would equate to a 10-32 or a 10-24 thread. By appearances, you most likely have a 10-24 thread.

Hello Brian,

Have you ever heard the old adage “One measurement is worth a thousand expert opinions” ?

To basic tools for mechanical repair are a dial or digital caliper and a thread pitch gauge or several types of thread gauges.

Anything is possible as some phono manufacturers made custom threaded hardware that was outside of any standard. After taking measurements consult the standard tables to see if there is a match. There are many aspects of the thread shape, for example US Vee threads are cut at a sixty degree included angle with sharp roots and crests, the British Whitworth vee threads have a fifty-five degree included angle and rounded roots and crests. Many options.

Get back to us with your measurements and no doubt some of the board experts will weigh in with a new opinion!

Mark

Here is a low cost thread gauge that combines US, Metric and Whitworth gauge leaves into one tool.

Mark

Thanks Mark for your replies. As I am in the UK I am not sure whether I can buy the gauge on ebay UK. May have to try the USA site.
Brian

Brian, if the bolt uses a separate nut as opposed to threading directly into a hole you can of course use a nut and both combination instead of an exact match. Most of the Victor products attach the motor frame to the motor board with a through-bolt and two nuts that lock together. If you don’t want to buy a thread gauge you can count the number or threads per length with a steel ruler. A thread gauge a handy tool to have around in general and you’ll find other uses for it.

How many of you own measuring tools?

Mark

I became aware of the thread pitch guage a few weeks ago and am awaiting delivery of one I ordered - they are so cheap. I have lots of bolts that I can't match with nuts, and am hoping it will solve some mysteries.

One of the best tools I've bought was a digital caliper, very cheap from ebay/china. I never expected I would use it to the amount I have. Over recent years I've been adding to my toobox, small specialist tools can be found cheaply on ebay/china that are expensive in the local hardware store (eg. thread taps, specialist drill bits, etc). It's so much easier and accurate to use the correct tool.

Things like this are really useful:
https://www.ebay.com/itm/SAE-Inch-Screw ... SwiMBeGXKZ
Dave D