DIY Schroeder Tonearm???

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Renron

Renron

Member
Joined 2007
Sourdingue,
Very nice lifter, did you make it? or purchase it? Achete?
Here is one on Flea-Bay for $55.
This is the one I purchased, fluid filled works perfectly.
Ron
 

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bcdhifi

Member
Joined 2007
bgruhn said:
Shaking? Hopefully not, my Schroeder clone, is quite stable. It has been quite a while since I last posted on this topic, but over the past few weeks I've been listening to some LPs again and playing with a passive linear tracker design and browsing in the audio forums. Saw a few postings that I can't find again in another (???) forum one of which was a reply by Frank Schroeder in which he mentions the thread he is using to suspend the arm wand. He says that there a lots of lines available now that can be used and that he is using a braided line which has a nearly square cross section. I found some braided fishing line of 65 pound test and nearly square cross section. It was thin enough to use without modifying the arm parts.

Back when I put my arm together about the only consideration was that it be non-stretch. Kevlar fly tying thread was what I chose and it has held up well, but it is exceeding fine and flexible with strands that are loosely twisted and which don't give me good control of anti-skating forces. Another thing that never worked to my satisfaction was the Allen head screw recessed in the anti-skate wheel which serves to anchor the top of the thread and set the magnet gap. At least in my implementation there was too much interaction between the gap screw and the skate wheel no matter how carefully I tried to set them. I had to bias the skate force by way too many turns and that was changing the magnet gap so to get a good gap setting the anti-skate force was reduced too much. So this got me to thinking. The braided line being some bigger in section and being braided would probably give the torque needed and with fewer turns of twist from the old Kevlar thread. The next step was to implement a change that I been thinking about. A way to adjust the gap which doesn't change the twist rotation. I drilled the top gallows member center hole to accept a press fit cylinder having about a 1/2" diameter and a larger 3/4" diameter, Each of the 2 cylinder diameters were about 1/4" high. Then I drilled this out for easy clearance of the center drilled #6-32 screw the line passes through. Next I cut a smooth channel in the side of the screw. Made a pin and pressed it into the new part just far enough to prevent the screw from turning but allow it to go up and down by turning a nut threaded onto the screw. This screw is drilled for the line and is about 3/4' long. Raising or lowering the screw by turning the nut tensions the line and sets the gap dimension.

In operation one sets the length of the line so the knot gives a bit of gap between the magnets to allow for settling in of the overall line length. Then the anti-skate force is set about where you think it should be. Then use the nut to select the appropriate magnet gap. A few iterations will be required to get it where it should be but where the two motions required of the line, radially and axially, are independent, the whole process becomes far more precise and controllable.

The final look is not quite as attractive as the recessed screw but it looks quite finished and nice. I'll append a picture in a day or so. Maybe on a real Schroeder arm the problem I solved doesn't happen, but I've not seen the real thing. BTW, I've set up the arm and it was easy and fast. Been listening for a couple of evenings and for the first time ever tracking across the record was quite good with skating being not obvious.

BillG
Click to expand...
There are some braided Kevlar fishing lines on the market that might be suitable.
 
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gaborbela

Member
Joined 2005
Hello
I just received my material from EPay for my tonearms suspension.
Any opinion about wood tonearm VS carbon fibre or metal..Please!
Did someone com pared them.
I have several material for the arm, I will test them and give some info.
I have aluminium arrow shaft, titanium tube (these only 6mm and 0.4mm wall thickness) but very solid also very light.
I ordered carbon fibre tubes 3K version 9mm with 1mm wall thickness and 13mm with 0.5mm wall thickness.
I would like to get some opinion about the wood arm. Also some info, have to be hard wood or half hard etc.
I have a long 12" drill bit less than 5mm thick I can try to drill some wood and after machined to the right size.
Al do I don't have source (friend) who work or has those machines required.
Because of that I have to make arm suspension on the kitchen table.
Probably will not be so professional I sow some of you done but I use what I have. Cordless drill, jig saw, hacksaw so on...
Some picture, the aluminum for the suspension, the brass 2" diameter 1/2 thick for counter weight.
Greetings Gabor
 

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berlinta

Member
Joined 2003
Hi Gabor,
Even though the suitability or sonic merits of various armwand materials have been discussed here and elsewhere, I'd like to remind you that the bearing design does "drain" (a poor metophor) the mechanical energy generated during playback per rigid coupling to the arm base(board). Almost all of the energy dissipation needs to take place in the armwand/counterweight assembly. Merely relying on a rigid material(Titanium, CF...) will allow for both standing waves and strong resonances to be exited.
Suitable woods combine high enough a rigidity with excellent internal damping(further aided by oil or laquer treatment). CF and particularly Titanium requires some form of damping(i.e. CLD) .
Lastly, a 5mm bore diameter in wood(or any other material) calls for the wiring running though it to be fixated. You don't want it to "flop around" or rattle inside the wand.

Good luck with your project,

Frank
 
kenev

kenev

Member
Joined 2002
berlinta said:
Hi Gabor,
Even though the suitability or sonic merits of various armwand materials have been discussed here and elsewhere, I'd like to remind you that the bearing design does "drain" (a poor metophor) the mechanical energy generated during playback per rigid coupling to the arm base(board). Almost all of the energy dissipation needs to take place in the armwand/counterweight assembly. Merely relying on a rigid material(Titanium, CF...) will allow for both standing waves and strong resonances to be exited.
Suitable woods combine high enough a rigidity with excellent internal damping(further aided by oil or laquer treatment). CF and particularly Titanium requires some form of damping(i.e. CLD) .
Lastly, a 5mm bore diameter in wood(or any other material) calls for the wiring running though it to be fixated. You don't want it to "flop around" or rattle inside the wand.

Good luck with your project,

Frank
Click to expand...

What's CLD?
 
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gaborbela

Member
Joined 2005
Hello
Thanks for the answer!
So I leave out the wood armwand for now. From your answer I understood rigid materials are the favorite with these type of suspension.
My titanium tube is a soft type compare to the regular titanium alloy materials.
These is 99.5% titanium and 0.5% aluminum.
All do soft still rigid enough (like low carbon iron) for armwand and of course light.
About the inside hole in the armwand all the tubes has larger than 5mm hole that is why I taught that can be good if I use wood armwand.
About damping material, silicon gel or oil etc would ad a lot of weight what we do not want here.
How I know I must use dumping material or with out my tonearm still OK?
Can I hear it?
Thanks one more time.
Greetings Gabor
 
Nanook

Nanook

Member
Joined 2004
gabby:

I don't think trying to bore through a dowel will be successful. without a drill press or some sort of precision machinery. I've snapped drill bits trying to do that through 4" thick material. You might consider notching a channel out along the length (if careful a Dremel Tool can be used). Then glue some heat shrink or similar tubing into the notch . As long as you use large enough heat shrink, wires should be easy enough to push through the tubing.

You can use theatrical makeup (pure latex) to paint the tonearm shaft. Sumiko sold something called the "analog survival kit", they still might.
 
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gaborbela

Member
Joined 2005
Hello
I want to do these way.
First drill a hole with my 12" long drill bit in a piece of 1" X 1" wood. When I'm done after shaved done to the right size with machine.
I think these could work fine.
I use that drill bit many time, and if you go slowly it is possible to use it all the way (12") .
Probably I will try it on some oak wood before I spend on exotic wood.
Let see what happen. I know it take a lot of time but that is why wee call it DIY.
Nannok actually you have a good idea to.
Greetings Gabor
 
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