DIY Schroeder Tonearm???

[Renron]

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

[Sourdingue]

yes "renron" is my work ,completely from stainless steel

[zeonrider]

Parts of mine :

[Sourdingue]

good job !! the principle is almost identical to mine, how do you do to prevent the cylinder that will lift the arm can not rotate?
On mine to soften the descent I met with the spring chamber of the "silicone grease" that is less bright!

[Sourdingue]

I made another variation on another arm of my design, can a different but equally effective

[bcdhifi]

Originally Posted by bgruhn

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

There are some braided Kevlar fishing lines on the market that might be suitable.

[kenev]

Originally Posted by zeonrider

The latest news :

Sam Gramofon + Schroeder Ru?ka (Klon) - HiFi forumi

Regards zeoN_Rider

Hi zeoN_Rider,

Excellent work!!

I have 2 questions:

1. What are the dimensions of the magnets that you have used?

2. What is the outer diameter of the carbon-fibre tube?

Regards,
Evangelos

[zeonrider]

Originally Posted by kenev

Hi zeoN_Rider,

Excellent work!!

I have 2 questions:

1. What are the dimensions of the magnets that you have used?

2. What is the outer diameter of the carbon-fibre tube?

Regards,
Evangelos

Thanks

1. N magnets diametar 10mm h 5mm
2. 9mm

Now I preparing new one.

N magnets 6 x 3mm





And Sofija, little assistant



Regards zeoN_Rider

[nikolazec]

Sofija is really nice, I must admit
reg

[kenev]

Originally Posted by zeonrider

Thanks

1. N magnets diametar 10mm h 5mm
2. 9mm

Now I preparing new one.

N magnets 6 x 3mm



Regards zeoN_Rider

Thank you for your reply.

I suppose you have/have access to a CNC/milling machine and lathe. I only have a mini lathe.

Regards,
Evangelos