Cartridge torque wrench

[Solypsa]

A lot of posts on tightening screws

My small amount of experience with torque specs ( in a former life as a Mercedes Technician ) tells me Dietrich's comment is based in truth ( different metals require different torque ) but is an oversimplification as @tima points out ( diameter, pitch, etc. ) as well as the capacity and makeup of the receiving threaded body.

I like nice tools and have been thinking of getting a mini torque driver. Most have 10% or more variance in accuracy...

For this application you can also apply the angle torque method. Seat both screws ( may take a little practice to feel when they are seated but not tight ) and tighten a specific amount as seen in degrees of rotation. Once you decide what is 'good' this is repeatable if using same screws and same receiving cartridge body. A cheap and efficient way to repeatable results. Any washer used will have a crush factor and this can change for a new never used washer and one already crushed. For that matter a new screw has a stretch factor versus one already torqued...

 

[terry9]

One of the Linn people wrote quite a bit about this, suggesting ranges for different cartridge body materials. Sorry, don't have the link.

The engineering tables which I have seen relating to screw or bolt materials and tightening torques indicate maximum torques, not optimal torques. It seems to me that the only valid approach must be trial and error, under the maximum, or course.

I use a precision Stahlwille 775/12 torque screwdriver (TBS tools in Aachen), and not just because I like nice tools. I want the torques on the mounting screws to be pretty much equal, and I trust Stahlwille to deliver that. In these parts, Mercedes uses Stahlwille tools almost exclusively, so Solypsa should be right at home with this.

For what it's worth, my Koetsu Diamond Rosewood likes about 3.0 cNM , the Mayajima Zero likes about 2.0 cNM, tightening very lightly lubed brass screws. Small differences is torque seem to yield noticeable differences in sound - but that could be psychosomatic. The big improvements in sound seem to come from equalizing torques which were unequal.YMMV

 

[tima]

For what it's worth, my Koetsu Diamond Rosewood likes about 3.0 cNM , the Mayajima Zero likes about 2.0 cNM, tightening very lightly lubed brass screws.

Pardon my metric ignorance: what is 'cNM' ... something newton meter ... ??? cubic? centimeter? I'm seeing no references to cNM by name.

I see your German torque screwdriver (made in Japan) measures in those units. Must be a size 3? 2-30 cNM, size a/3 for inch-lbs.

Nice tool - it's an investment:

Stahlwille 51460003 Torque screwdriver TORSIOMAX 775a/3, 0.2 - 3 in lb

Torque screwdriver for inserts and adaptors with external hex E 6.3 (1/4") DIN 3126/ISO

hfg-na.com

 

[howiebrou]

AnalogMagik Torque Wrench for Cartridge Headshell Screws

Determing the proper torque for headshell screws. The AnalogMagik Torque Driver Kit provides drive bits, Teflon Washers, as well as a precision calibrated Torque Wrench, so you can accurately optimize the torque level for your headshell to deliver the best possible performance.

www.analogmagik.com

 

[Yeti]

I originally posted this in another thread, mainly because the OP aslo used a Schröder tread bearing arm, though the thread dates from some years ago.
I bought a torque driver that claims a range from 5 to 60cNm (0.05 - 0.6Nm, ~0.44 - 5.3lbinch ) and even came with a calibration certificate for the points at 60, 36 and 12 cNm.
My usual cartridge is an Ortofon SPU Royal N which comes with its own screwdriver and peg wrench and brass screw and nuts. Using either of these against the torque driver I couldn’t even get to 5cNm, more like somewhere between 2 and 3. Assuming Ortofon know their cartridge’s robustness I forbore to apply a grip stronger than fingers and just used what I could achieve comfortably.
I’m using a Schröder Reference arm and a brass cartridge mounting plate, to achieve a suitable mass for the cartridge, the plate attaches to the wooden “head shell” of the arm with a single screw and here the tightness really matters. Too tight and though the music has a swing to it the dynamics are subdued and there’s no excitement, to get this cartridge to play rock music convincingly requires this screw and also the counterweight grub screw, which bears on a plastic sleve, to be barely tight enough to hold their positions. A bit of Dio era Black Sabbath happened to be at hand when setting this and was quite telling. The angle of an allan key and listening was the only way to gauge these in the end, the torque driver was well below its useful range. Canan even lighter torque driver be accurate enough in practice?
Where this torque driver does come in handy is the screw that locks the arm height adjustment. The actual adjustment is by a hidden screw inside the pillar with a left hand thread but the setting is locked by another grud screw and 21cNm was about there and at least I’ve removed any inconsistency from this when adjusting arm height but it’s effect is quite marginal compared to the two key screws who’s torque I still can’t measure.
The Dynavector 17D3 I used while my SPU was rebuilt seemed to want a tighter setting on the mounting plate to arm screw but this was pre torque driver and just my impression.

 

[Solypsa]

I tend to think the 'angle torque' approach as you describe is fine, based on your post. Close tolerance and ultra light range torque drivers aren't too common...

 

[Kcin]

Nothing is that simple and I know Mak is very meticulous.

In reality it means testing different screw types with different cartridges and listening and making notes along the way.

If that's not complicated enough, brass isn't brass and SS is isn't SS etc as most of this stuff is now out of China and I have found a lot of inconsistency in the metallurgy.

A torque screw driver gets you to try various combinations with some consistency or measure of where you have been.

Its not the fun part of the hobby for me anymore yet there is no substitute for listening for these minute changes.
I do use the software to see if I can find any correlation between my ears and empirical results...

 

[Bonesy Jonesy]

One of the Linn people wrote quite a bit about this, suggesting ranges for different cartridge body materials. Sorry, don't have the link.

The engineering tables which I have seen relating to screw or bolt materials and tightening torques indicate maximum torques, not optimal torques. It seems to me that the only valid approach must be trial and error, under the maximum, or course.

I use a precision Stahlwille 775/12 torque screwdriver (TBS tools in Aachen), and not just because I like nice tools. I want the torques on the mounting screws to be pretty much equal, and I trust Stahlwille to deliver that. In these parts, Mercedes uses Stahlwille tools almost exclusively, so Solypsa should be right at home with this.

For what it's worth, my Koetsu Diamond Rosewood likes about 3.0 cNM , the Mayajima Zero likes about 2.0 cNM, tightening very lightly lubed brass screws. Small differences is torque seem to yield noticeable differences in sound - but that could be psychosomatic. The big improvements in sound seem to come from equalizing torques which were unequal.YMMV

For your Koetsu 'terry9' requiring 3.0 cNm of torque to the cartridge mounting screws / bolts you would need the 'Stahlwille 775/3' (range of 2 to 30cNm) not the 775/12 (which is 20 to 120cNm) ! i.e. ;

CODE	SIZE	W	X	B MM	L MM	G

51060003

3 1)

2–30 cN·m

0,2 cN·m

F 6,3

105

55

Stahlwille Torque screwdriver TORSIOMAX No. 775 – Aircraft Engineers Store | UK

aircraftengineersstore.com

CODE	SIZE	W	X	B MM	L MM	G

51060012

12 2)

20–120 cN·m

1 cN·m

F 6,3

157

180

Stahlwille Torque screwdriver TORSIOMAX No. 775 – Aircraft Engineers Store | UK

aircraftengineersstore.com

1) with a swivelling handle-end to improve tool control; and with a clamping screw for locking the preset
2) with an additional locking mechanism to prevent the selected torque being inadvertently adjusted