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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
brf
1,715 posts
 
I am assuming, perhaps incorrectly, that I need to move the armboard until the spindle to pivot distance matches, or gets very close to, the manufacturer's recommendations, then I can tighten down the screw to keep the armboard in place and go on to align the cartridge with a protractor.
Correct. The tonearm must be mounted with the correct S2P distance before the cartridge is mounted using an arc protractor specified for 294.1mm S2P distance.

Also, when using the caliper to measure the S2P distance, take the arm wand off and measure to base pivot point. This will eliminate the possibility of damage, plus you will create a more level measuring distance (if the spindle point and pivot point are not level, your measured S2P distance will be slightly off)
oakiris OP
206 posts
 
Sorry, Mofi and Lewm - for some reason didn't see your posts when I wrote my last one. Mofi has the situation correctly described, and, no, I can't blame him for the unsecured state of the armboard. :-D

Mofimadness has a Dennesen protractor/Soundtraktor, too, Lewm, and I would love to have one, but, they don't seem to come up for sale/auction very often anymore, and the Nerve Audio protractors, which appear to be a copy of the Dennesen Soundtracktor, is almost $200, so out of my reach.

So, I need to get a good metric ruler or an acceptable pair of digital calipers; I may go the Harbor Freight route; their Pittsburgh calipers get decent reviews.

Holly
lewm
13,445 posts
 
Dear Oakris, You wrote, "I think I am confusing folks, or I am confused myself, lol, I know what the spindle to pivot distance is supposed to be, just looking for a tool that will give me a reasonably accurate measurement."

I realized that not everyone was responding to your actual question, and I understand the problem. Which is why I posted about how I use the Dennesen protractor to set P2S (that's the standard abbreviation in these parts for "pivot to spindle"). It works. What I then pointed out is that the Dennesen is really a protractor for aligning a cartridge. So after you've mounted your tonearm at the exact correct P2S distance, then you can use it again, as Mr Dennesen intended.
lewm
13,445 posts
 
My last post was written before your last post got posted.
Scour the for sale sections of this and other audio websites and even eBay, and I think you should be able to find a Dennesen or a Dennesen copy for under $100, with some patience.

Truthfully, if we accept on faith that the P2S should be within +/-1mm of exactly correct (even better than that, according to some), I don't know how you will achieve the goal with calipers. If no Dennesen, you might consider taking a stiff sheet of paper or a very thin sheet of plastic. Then take a very accurate metric ruler and measure out the desired P2S. Then carefully punch a hole the size of your spindle, centered on one of the end marks. Then punch a much smaller hole centered on the other mark. You should do fine with that. No calipers needed, only a good metric ruler.
tketcham
291 posts
 
Holly, you could buy one of these dividers...

Malco spring divider

Otherwise, do a search for "measuring pivot to spindle distance" at VinylEngine or VinylAsylum and you'll find some clever solutions (and an interesting discussion of the need for accuracy and precision in that measurement). :-)

Regards,
Tom
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