reply to post 172
Bins,
If you are going to attempt a single string bearing I think the N35 magnets are not strong enough for a really successful design. K&J Magnetics Inc. has N52 magnets 5/16" x 1/8" (PN D52-N52) $0.43 each. I bought 8 for a total of $10.44 including $7.00 for shipping, USA. I think that was priority mail service.
If you want to try the N35 magnets I think you will be more successful with a split string/inverted Y bearing design. My first attempt was with similar N35 magnets and the inverted Y suspension and was very successful. Even now after completing a single string tonearm I think I like the inverted Y designs better. Please see photos of my inverted Y design at www.apricot.com/~bgruhn/turntable/magarms.html
Bill
Bins,
If you are going to attempt a single string bearing I think the N35 magnets are not strong enough for a really successful design. K&J Magnetics Inc. has N52 magnets 5/16" x 1/8" (PN D52-N52) $0.43 each. I bought 8 for a total of $10.44 including $7.00 for shipping, USA. I think that was priority mail service.
If you want to try the N35 magnets I think you will be more successful with a split string/inverted Y bearing design. My first attempt was with similar N35 magnets and the inverted Y suspension and was very successful. Even now after completing a single string tonearm I think I like the inverted Y designs better. Please see photos of my inverted Y design at www.apricot.com/~bgruhn/turntable/magarms.html
Bill
binspaul said:Hello Bill,
Thanks for the suggestions. I will try to implement the 2 string version first. Once, I gets the N52, I will try the single string version.
What is the main platter/spindle bearing you use ? I was not able to find a suitable one yet.
Best regards,
Bins.
Hello Bins,
Odd that you should ask about the bearing today. Just last night I got around to dealing with the bearing design. As I mentioned in another post I have been using ABEC class 7 shielded ball bearings selected for low noise. Stashed away in my materials collection there has been a rod of bearing type nylon and a ~2mm diameter saphire ball left over from my days in the aerospace industry. So I made up nylon replacement inserts to replace the ball bearings. These nylon parts are simple plugs sized to be a tight press fit into the bearing housing. The upper one is drilled for the spindle and reamed to fit smoothly with a hand reamer. The bottom one has a shallow depression made to accept the saphire ball. The spindle is 1/4" dia steel drill rod (USA) aka silver steel. It too has a depression made with a small center drill or countersink bit. I put a small very small amount of cyanoacrylate adhesive into the depression in the spindle chiefly to make the ball captive for easy assembly. Years ago there were great arguments against using anything the least bit compliant in the bearing system of turntables. But now we see increased use of teflon as in the Welltempered TT.
So I am giving it a shot. Only been using the new bearing system for one day now, but the results are far better than I had been expecting. With the stylus resting on the plinth I can turn the amplifier up to full gain and hear nothing from the bearing. This is with the belt removed and spinning the platter by hand. playing records is a pleasure with the noise floor way way down. I think there is some from the motor. Next step is to decouple the motor from the base plate with its own free mounted lead base. I don't feel any great need to push ahead with that project yet.
Go for the nylon/teflon bearing. It could be even longer living than conventional metal based designs. BTW, if you can't get saphire balls, I am sure you will get great results with a steel ball bearing ball.
Bill
binspaul said:
Hi Bins,
I just reviewed the Altmann DIY TT article. I must say that Mr. Altman deserves credit for a well thought out project well carried out. His choice of a motorcycle valve for the spindle is a great idea. The valve guide will work very well for the upper sleeve bearing. I like the idea of using the valve head for the platter support. You should have no trouble with runout of the platter if the valve is properly machined. I don't know what your degree of skill is with tools and materials etc. as well as what your goals are for a turntable and tone arm. If you are striving for a fully completed analogue front end built to rival one of the high priced units, then I would suggest looking for materials and designs different from the Altman project. If you will be pleased with the home workshop look and a TT/arm that performs very well indeed, then follow through with as much of the Altman design as you are comfortable with.
Regarding where to get teflon or nylon:
The web is loaded with suppliers and information on these materials. It comes in plain and filled varieties enough to boggle the mind. I used an unfilled material. For starters look at Industrial Plastic Supply Inc. They have a price of $15.84 for 2 feet of 3/4" nylon rod. You could use the nylon bearing instead of the motorcycle valve guide. I think you can get a quieter bearing this way especially if you run the lower ball in a nylon or teflon seat.
Also, see if you can buy small quantities from local machine shops or engineering firms. There are great numbers of firms making or selling saphire and ruby balls on the web.
Please read up on Bill Firebough,s Amadeus design where he discusses running his round spindle in a square hole in the upper teflon bearing. This is what I will implement soon. I chose the round hole in the nylon as an interim design while I figure out how to make the square hole thing. I believe we can have better performance (rumble etc) with the plastic materials. Possibly at the expense of some bearing life. So after 10 years put in a new bearing.
Best wishes in your endeavour.
Bill
I have been thinking about the magnets. It seems to me that the one string approach is better executed by having the magnets pulling at each other. The string keeps the arm suspended above. With magnets oriented to reject, there are forces that will tend to not only lift but move to the side thus requiring the two string approach. Correct me if I am wrong.
Hello Bill,
Thanks for your guidance. Without your suggestions, I would have gone void. Farnell (www.farnell.com) is having a good stock of nylon rods. What is the best diameter for the bearing rod - 15mm/20 mm ? By the way, what is your suggestion on bearing guides ?
Still waiting for my neodymium magnets to arrive....
Best regards,
Bins.
Thanks for your guidance. Without your suggestions, I would have gone void. Farnell (www.farnell.com) is having a good stock of nylon rods. What is the best diameter for the bearing rod - 15mm/20 mm ? By the way, what is your suggestion on bearing guides ?
Still waiting for my neodymium magnets to arrive....
Best regards,
Bins.
binspaul said:Hello Bill,
Thanks for your guidance. Without your suggestions, I would have gone void. Farnell (www.farnell.com) is having a good stock of nylon rods. What is the best diameter for the bearing rod - 15mm/20 mm ? By the way, what is your suggestion on bearing guides ?
Still waiting for my neodymium magnets to arrive....
Best regards,
Bins.
Hello Bins,
Sorry to have taken so long to reply. I have been very busy with home improvement projects. I hope I am guessing correctly on the parts names you are using for the bearing assembly You say "bearing rod", I understand that to be "spindle". You say "bearing guides", I understand "sleeve" or "bushing" or "journal" as in Journal bearing.
If we are talking about the same parts, then I can answer your question with the dimensions I used on my TT. Nothing sacred here, I used these dimensions because they looked reasonable and were sizes of stock I had on hand.
1- Nylon rod diameter = 5/8"
2- Bearing rod diameter = 1/4"
> material = silver steel
3 - Bearing housing = Aluminium, diameter = 2" Not critical.
Next week I will draw a sketch and post it if you need to see something. I wonder if we should start a new topic?? This is way off the subject of Schroder tone arms.
BIll
Hello Bill,
I think it is better to create a new thread. Can we use the following as the main bearing ? Please suggest.
http://export.farnell.com/jsp/search/productdetail.jsp?sku=7035822&_requestid=33984
Why do we need to use the aluminium section in the tonearm (for the rear end where the magnets are attached) ? What advantage do we gain in doing so ? Is there any disadvantage if we use the wood for the entire tube ?
Regards,
Bins.
I think it is better to create a new thread. Can we use the following as the main bearing ? Please suggest.
http://export.farnell.com/jsp/search/productdetail.jsp?sku=7035822&_requestid=33984
Why do we need to use the aluminium section in the tonearm (for the rear end where the magnets are attached) ? What advantage do we gain in doing so ? Is there any disadvantage if we use the wood for the entire tube ?
Regards,
Bins.
binspaul said:
Bins,
The chief reason I see for using the aluminium section in the tonearm is to make fabrication easier to do and more precise. (You
could design an all wooden model but it would look quite different from the typical Schroeder designs.) The aluminium section where the counterweight goes makes counterweight adjustment easier and there is much less chance of damage from locking screws. The thing to remember is that there is no ONE way of building the tone arm and that any given choice may require some modification somewhere else to compensate for some parameter that gets upset with the change.
Frank Schroeder mentions that his designs take advantage of EDDY CURRENTS for additional damping. I have not fully analyzed what is taking place here, but without the aluminium sections I think there would be no conductor material to allow Eddy Currents to be generated or to support the flow of such currents. This could be the single most important reason to use aluminium.
Best regards,
Bill
Hi Bill,
"Frank Schroeder mentions that his designs take advantage of EDDY CURRENTS for additional damping. I have not fully analyzed what is taking place here, but without the aluminium sections I think there would be no conductor material to allow Eddy Currents to be generated or to support the flow of such currents. This could be the single most important reason to use aluminium. "
Right on the money...
I have built several arms with armwands made entirely out of ( a single piece of ) wood. Without special treatment, the end stub will "sink" or bend downwards over several years. Although the counterweight typically weighs only between 170 and 250gr, many woods cant take this constant bending pressure. The again, one can put a metal or Cf rod or screw through that section.
Counterweight impedance matching is another issue....
Have fun,
Frank
"Frank Schroeder mentions that his designs take advantage of EDDY CURRENTS for additional damping. I have not fully analyzed what is taking place here, but without the aluminium sections I think there would be no conductor material to allow Eddy Currents to be generated or to support the flow of such currents. This could be the single most important reason to use aluminium. "
Right on the money...
I have built several arms with armwands made entirely out of ( a single piece of ) wood. Without special treatment, the end stub will "sink" or bend downwards over several years. Although the counterweight typically weighs only between 170 and 250gr, many woods cant take this constant bending pressure. The again, one can put a metal or Cf rod or screw through that section.
Counterweight impedance matching is another issue....
Have fun,
Frank
I have just started with this thread and construction of the arm. I first looked at the Well Tempered arm and bought materials for that build. I then switched to this one and decided to keep the arm the same. That is a carbon fiber tube. Once the wires are in place it will be filled with sand and sealed. I will probably fill the short length were the counter weight is located with a more dense ballast? Not as nice as a wood arm, but perhaps as good?
length
Hey everyone....
For those that are building up their own DIY Schroeder tonearm... what length are you making yours?
I'm going back and forth between 9 and 12 inches. Both geometries are doable as I have yet to build a plinth for my deck. A 12 would be better sonically, but the longer tube has me thinking about potential long term arm warpage and a larger footprint for the plinth to take up. The wood I'm using is nice and stable, but being an instrument builder I know the potential is there, especially when seasonal humidity does it's thing, and it does get very humid in the summer and very dry in the winter in Atlanta Ga.
I'm starting to accumulate the raw materials right now.. I have a nice pieces of air dried Ebony 2" x 3" x 28" that I'll cut up and turn to make up a few arm tubes. I have some Vectran chord, even less strech and stronger than Kevlar, I have some N52 magnets and a Jelco arm lift.
This week I'll be sketching up some preliminary drawings. I'm armed with about 100 photos of all the DIY and genuine Schroeder ams. I have a compy of the patent and copies of the arms instruction manuals, plus links to a lot of forum threads about the arm.
I do have a background in musical instrument building and mechanical engineering and industrial design. This looks to be a fun project.
I'll eventually mount this arm on a Garrard 401.
Jeff Davison
Hey everyone....
For those that are building up their own DIY Schroeder tonearm... what length are you making yours?
I'm going back and forth between 9 and 12 inches. Both geometries are doable as I have yet to build a plinth for my deck. A 12 would be better sonically, but the longer tube has me thinking about potential long term arm warpage and a larger footprint for the plinth to take up. The wood I'm using is nice and stable, but being an instrument builder I know the potential is there, especially when seasonal humidity does it's thing, and it does get very humid in the summer and very dry in the winter in Atlanta Ga.
I'm starting to accumulate the raw materials right now.. I have a nice pieces of air dried Ebony 2" x 3" x 28" that I'll cut up and turn to make up a few arm tubes. I have some Vectran chord, even less strech and stronger than Kevlar, I have some N52 magnets and a Jelco arm lift.
This week I'll be sketching up some preliminary drawings. I'm armed with about 100 photos of all the DIY and genuine Schroeder ams. I have a compy of the patent and copies of the arms instruction manuals, plus links to a lot of forum threads about the arm.
I do have a background in musical instrument building and mechanical engineering and industrial design. This looks to be a fun project.
I'll eventually mount this arm on a Garrard 401.
Jeff Davison
Hello Jeff,
Nice to see you also in the same direction. You can have a look at the suggestion made by Stew at: http://www.diyaudio.com/forums/showthread.php?postid=1832428#post1832428
Do post your ideas and observations as it will be really helpful for us also.
Best regards,
Bins.
Nice to see you also in the same direction. You can have a look at the suggestion made by Stew at: http://www.diyaudio.com/forums/showthread.php?postid=1832428#post1832428
Do post your ideas and observations as it will be really helpful for us also.
Best regards,
Bins.
binspaul said:
Bins,
1- I don't know if it is necessary to fill the arm tube with sand or anything else. All the arms I have built so far have been filled with very fine and dry sand right from the start. Will that increase the weight? Come on now, answer your own question.
2- I am still, at just a tad under 80 years, active in the repair and restoration of fine antique clocks. So I have extremely good fine muscle control and eyesight. So, I just pick it up and put it down where and when necessary.
Regards,
Bill
Hi Bill,
That's nice, but risky. Sand will be having some amount of magnetic particles, right ? Are you using any process to filter that out ? What about chalk powder or wood dust ?
Can we use the dimension values given in the attached image for this implementation (at least some) ?
Regards,
Bins.
That's nice, but risky.
Sand will be having some amount of magnetic particles, right ? Are you using any process to filter that out ? What about chalk powder or wood dust ? Can we use the dimension values given in the attached image for this implementation (at least some) ?
Regards,
Bins.
