Tool for measuring pivot to spindle distance?
Holly, I've replied to your post on VE. You don't actually need to know the P2S distance if you can easily adjust at the base, just a two point protractor. Simply adjust the board with your protractor to set up the cartridge, like the SME. Just mount the cartridge square anywhere in the headshell and then adjust at the base until the nulls are correct. If you want more tech info as to why this is the case, see point 2 in this link here: common misconceptions about tonearms John |
Well, just saw a Dennesen Soundtraktor on the US Audio Mart site that sold for $39 at the end of December! Darn it! And one that sold on eBay for $120, a more likely price. Sounds as if a good metric ruler is what I had best get for the time being - back to square one. There may be a Soundtraktor in my future, though! Holly |
You already have everything you need to set the Pivot-to-Spindle *and* align your cartridge. 1. Use your ruler to set the Pivot-to-Spindle. Take your time. Tighten the articulated armboard (tight, but not too tight). But what if it isn't perfect? Don't worry, and proceed to Step #2. 2. Go the Conrad Hoffman website http://conradhoffman.com/chsw.htm and download his free cartridge setup protractor. Enter your arms spindle to pivot distance and print out a customer arc protractor template. Pull out that ruler and double check what you print out to make sure your scale is correct. 3. Carefully cut out the hole for the spindle, and begin to align the cartridge per the instructions that come along with Conrad's tool. 4. If your cartridge won't align perfectly at both points on the arc...guess what? Your Pivot-to-Spindle is beyond the acceptable margin of error, and you go back to Step 1. There is only one Pivot-to-Spindle and one Effective Length that will allow the stylus to perfectly touch both points on the arc. If all align, you *know* it's set up correctly. Read the README.TXT that comes along with Conrad's tool. It explains the process far better than I just did (and I tested and gave feedback on many of the early versions of this tool). |
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 |
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. |
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. |
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 |
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) |
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 have a Teres turntable with the original acrylic armboard; my Moerch DP-6 (with a 12" armtube) is already mounted in the armboard. The arm board is loose because the hex screw was not tightened down. The tone arm manufacturer says the spindle to pivot distance should be set at 294.1mm (11 9/16".) 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. Am I going about this wrong? Doesn't the mounting distance need to be basically correct and the armboard secured in the right place before you use the protractor to align the cartridge? Or do you align the cartridge with the protractor and once the null points are correct, that means the tonearm pivot to spindle distance is automatically correct and you tighten down the arm board then? I have been looking at that Neiko caliper, too, Banquo. I would think that it would be accurate enough for use in turntable set up - and the price certainly works for me! |
I have a very old original manufacture Dennesen Protractor. If I need to locate the pivot of a tonearm I want to mount, I take a piece of clean white paper and make two pen marks on it, at a distance from one to the other that is equal to the desired P2S distance. Then I set the spindle hole of the Dennesen centered on one of the two dots and line up the vertical steel pointer at the other end of the Dennesen with dot number 2. Then I lock in the Dennesen at this distance. I then place the Dennesen over the tt spindle, and the vertical steel pointer tells me where the tonearm pivot point needs to be. So, I recommend a Dennesen or Dennesen type protractor to kill 2 birds with one stone, as they say. (Because once you've mounted the tonearm, you can use the Dennesen again to set pivot to stylus distance.) Dertonearm offers an accessory attachment to his protractor, exclusively for setting P2S, but it costs several hundred dollars over and above the cost of the protractor. |
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. |
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, 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, |
We must assume that your tonearm is properly mounted with the correct spindle to pivot distance. If so, go the Conrad Hoffman website http://conradhoffman.com/chsw.htm and download their free cartridge setup protractor. Enter your arms spindle to pivot distance and print out a customer arc protractor template. |
