universal tonearm mounting template needed

steveblezy · « **Reply #40 on:** 13 Jun 2010, 03:06 pm »

I have a rather unique tonearm that is based off of the RB arm-tube. The vertical bearing have been installed in the bearing carrier with a 2mm offset. Makes my life so much easier now that I have 4mm of total adjustment. it has been very nice when I want to try a few different setups. I like to tinker around so I do find it useful.

Steve

neobop · « **Reply #41 on:** 13 Jun 2010, 03:10 pm »

Quote from: Wayner on 13 Jun 2010, 12:07 pm

What planet are you from? I just got done proving that your statement is totally false and you still keep on. Do you not understand geometry?

If rcag_ils gives me his spindle to tonearm distance that he wants to drill, I can give him the exact overhang to achieve any Baerward or Lofgren's null point locations. The 5 drawings I submitted above have 5 different spindle to arm spacings, yet all achieved the same null points.

I see you added something to your post after I responded. What I said was correct. If someone wants to change their alignment from Loefgren A to Loefgren B, it will necessitate moving the cartridge further forward in the headshell and probably changing the angle slightly. This is assuming the pivot is in a fixed position. The overhang will also change. This is a known fact, according to the laws of geometry. The arc of a Loefgren A will be different from a B.

Your statement about your CAD program is very misleading. The equivalent alignments you suggest, if it gives you nulls at 70,29 and 116.6 can either be achieved with a Loefgren B protractor, or it's not a true Loefgren B alignment.

Overhang is often difficult to measure and is not necessary to achieve 2 nulls. If the cartridge, headshell slots, and eff length will not allow a particular alignment, then no "equivalent" alignment will be the same. The distortion figures that you think justify that choice will differ.

I'm trying to help the OP get it going. If he misses the mark by a couple of mm, or can't measure overhang exactly, it's not a problem really. He can get a good alignment. You, on the other hand are trying to promote yourself, by offering something for free, that is inappropriate in this case.
neo

neobop · « **Reply #42 on:** 13 Jun 2010, 03:31 pm »

Overhang and getting an alignment are related, but not the same. Overhang is the distance the needle is in front of the spindle. That is on the arc, that winds up out in front of the spindle. In a traditional set-up, overhang is only good for the manufacturers alignment. If you want to change your alignment, you would also change overhang. Getting the nulls on a particular alignment does not mean that you have the "right" overhang, unless it is the same as the factory alignment, and your arm is mounted at exactly the specified distance.

Most of the confusion about this results from some programs that are based on a set overhang and S to P distance. Those 2 figures remain as constants, and all else falls into place. I'm not commenting on the effectiveness of those programs.
Neo

steveblezy · « **Reply #43 on:** 13 Jun 2010, 03:43 pm »

Very true, any change in the alignment would probably require a change in the overhang.

regarding neobop's comment (I'm trying to help the OP get it going. If he misses the mark by a couple of mm, or can't measure overhang exactly, it's not a problem really. He can get a good alignment. You, on the other hand are trying to promote yourself, by offering something for free, that is inappropriate in this case.) maybe we should start offering tips and hints regarding how to locate the mounting location before he/she drills. Yes, a couple of mm will have an effect.

If the op knows what arm that they wish to install, the manufactures information regarding the S-P distance is available. Cool, so we know what distance is required. Now what is the most accurate way to locate then distance so the drilling is on the exact spot?

Any ideas? I would look at a metal gig that sits on the spindle with a small pilot hole at the manufacturers spec so an arc could be traced showing all suitable location for dropping the drill.

Any other ideas or have a missed the original purpose of this thread? (If I am completely off base of confused I will remove this post to help keep the conversation focused)

Steve

rcag_ils · « **Reply #44 on:** 13 Jun 2010, 05:00 pm »

Quote

If the op knows what arm that they wish to install, the manufactures information regarding the S-P distance is available. Cool, so we know what distance is required. Now what is the most accurate way to locate then distance so the drilling is on the exact spot?

Any ideas? I would look at a metal gig that sits on the spindle with a small pilot hole at the manufacturers spec so an arc could be traced showing all suitable location for dropping the drill.

I am thinking just draw a line of the S to P distance on a cardboard, cut the cardboard to length, punch a small hole on cardboard and put it over the spindle, then swing the other end of the cardboard over to the armboard, find a spot that the arm wouldn't interfere with the dustcover, then drop the drill. Did I miss anything?

What I've learned from this thread is where to find the S to P distance, and it determines where the hole should be.

neobop · « **Reply #45 on:** 13 Jun 2010, 05:16 pm »

Rcag_ils,
At the start of this thread I described a Dennesen arm hole locator. It is the only gauge of its kind, that I'm aware of. It makes it relatively easy to mark the exact right spot.

Your idea of using the cardboard is a good one. But you'd have to check your results a number of times to make sure you're at the right distance. A steady hand and a good ruler helps.

On some decks, you could pop the platter and have a nice flat surface to measure from. If that is the case with whatever deck you're working with, then you might want to try that. A number of points, will make up an arc.

neo

Wayner · « **Reply #46 on:** 13 Jun 2010, 05:20 pm »

Quote from: neobop on 13 Jun 2010, 03:10 pm

I see you added something to your post after I responded. What I said was correct. If someone wants to change their alignment from Loefgren A to Loefgren B, it will necessitate moving the cartridge further forward in the headshell and probably changing the angle slightly. This is assuming the pivot is in a fixed position. The overhang will also change. This is a known fact, according to the laws of geometry. The arc of a Loefgren A will be different from a B.

Your statement about your CAD program is very misleading. The equivalent alignments you suggest, if it gives you nulls at 70,29 and 116.6 can either be achieved with a Loefgren B protractor, or it's not a true Loefgren B alignment.

Overhang is often difficult to measure and is not necessary to achieve 2 nulls. If the cartridge, headshell slots, and eff length will not allow a particular alignment, then no "equivalent" alignment will be the same. The distortion figures that you think justify that choice will differ.

I'm trying to help the OP get it going. If he misses the mark by a couple of mm, or can't measure overhang exactly, it's not a problem really. He can get a good alignment. You, on the other hand are trying to promote yourself, by offering something for free, that is inappropriate in this case.
neo

Wow. Now my CAD is evil. OK, good luck.

neobop · « **Reply #47 on:** 13 Jun 2010, 10:26 pm »

Evil? As in bad, wicked, iniquitous, immoral, sinful, base, unprincipled, sinister, malevolent, malicious, malignant, vile, villainous, vicious, nefarious and heinous?

Nah.

It might be good actually, I haven't really checked it out, except to get an idea how it works. At any rate, I think it might be inappropriate under the circumstances. There is more than 1 way to skin a cat.
neo