Tool for measuring pivot to spindle distance?


My new cartridge is on its way. I am making sure I have all the necessary tools for setting up the tonearm and cartridge, and realized that I don't have a decent tool for measuring the pivot to spindle distance for the tonearm. All I have is a plastic ruler with mm measurements - not ideal to say the least!

I would love to get something like the Clearaudio Protractor or the Dennisen/Nerve Audio Protractors, but such tools are beyond my budget. Is there a less expensive alternative? For example, would a set of 12" digital calipers (with mm readings of course)work?

I see some calipers costing around $35 - great price - are they accurate enough at that price point? No doubt most of these are made in China, which may or may not be a problem.

My budget is not much - less than $50 would be ideal. Any advice would be appreciated.

Holly
oakiris
Holly,
Do you have a table/arm set-up that might differ from arm specifications, or a vintage arm of unknown mounting distance?

If you use a traditional 2 point protractor or something like a Geodisk, you don't need mounting distance. They are based on the actual location of the pivot not where it theoretically should be. If you want to use an arc protractor you need the exact distance. In that case calipers seem like a good idea.
Regards,
I've been using a straight ruler w/o sonic penalty (I think). But recently I've been thinking along your lines, Oakiris. For $40 this caliper would surely be good enough. It's allegedly good to a hundredth of a mm, but even if not exactly true, I take that it's better than eyeballing it with a ruler?
Holly has a Teres 160 table with a few upgrades. The
armboard on that table swivels and when you move it, it
changes the pivot to spindle distance. I was the one that
moved it several times when we were trying to figure out
what was wrong with her system. The armboard was very
loose, so I wasn't really to blame, (that's my story and I'm
sticking to it) :-)

I told her the first thing that she would need to do is
remeasure the pivot to spindle distance, (she knows the
correct distance), then lock down the armboard very tightly
before she installs her new cartridge. I think the armboard
loosened up over time and she hadn't used it for quite
awhile.

I think a good solid, thin metal ruler would be fine, but a
digital caliper would work too.