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The Talyvel 4 was designed to run off either wall power or off a pair of internal rechargable NiCd batteries. These batteries are obsolete, and the internal charging circuit is primitive, so I've...

0.2 arcsec is 1 micron in a meter. So if you want to calibrate a reasonable-sized plate at the micron level, you need 0.1 arcsec accuracy and resolution.

I initially mapped out my surface plate...

Hi Mark,

I was thinking about making a plaster-and-tile lap like those used for telescope mirrors. I can cast them on my smaller (300 x 450) surface plate, which is good to 2um.

I was planning...

I want to make my surface plate more accurate by lapping away the high areas. The first step in this was to get a good map of the topography. I have finally gotten the Taylor-Hobson software...

I'm going to continue extending this thread with info that might be useful to others with Talyvel4 meters. This post concerns the computer interface. The manual provides good detail of what is...

Here's what the display unit looks like (turned off, sorry).

https://www.practicalmachinist.com/vb/attachment.php?attachmentid=262501&d=1564961928

I spent some time this weekend going through...

NiMh and Li batteries are so much better that NiCd batteries are only used for "legacy" applications. If I needed to replace these I would modify the charger circuit and install a pair of 3300mAh...

One of the cables from read head to display unit was missing a connector. For the next person who has to fix or make a Talyvel 4 cable, here's the details.
...

The Talyvel4 arrived yesterday and I've started checking it out. Starting to add some information here that might be useful for others in the future.

BATTERIES

There are two Ni-Cd batteries of...

Hi Paul,



I find that hard to understand. The bridge circuit used to sense pendulum position operates in the audio band at a few kHz. When the Talyvel4 was designed and being produced (mid...

When the batteries are charged can you run without mains power? I have not understood if the batteries are always needed, or just when running off the grid.

Sure, happy to share. Github, search for "moody surface plate".

Thanks. If you can compile and run a C program you are welcome to use my code. I've sent you a link to it offline.

Hi John,



Yes, that's right.

Some time ago I calibrated my surface plate (800 x 1200mm) with an autocollimator using Moody's method. I was surprised to see that Moody's paper never...

Hi Paul,



I have another question. According to the manual, the main Talyvel 4 display unit contains a set of NiCad batteries. Do you know if these are needed if the unit is connected to...

Hi Paul,

Thanks for responding. Glad I'm not alone.



I read the procedure in the manual (first setting the balance, then setting the gain) and it seems straightforward. I'll do this first...

Hi Richard,

Thanks for the links. The latest model (Talyvel 6) appears to use exactly the same read heads as the model I am getting (Talyvel 4) but modern electronics has been grafted to the top...

I've just purchased a old Taylor-Hobson Talyvel 4. The seller described this as "ancient, but in good working order".

For those who are not familiar, this is a precision differential electronic...