Further thoughts
The stylus drag will want to extend the arm which will want to move the arm to the left (as this is the direction the arm moves in as it extends). Skating torque will want to move the arm to the right. If the design of the arm gets the two forces in balance then there will be no net force. This should mean that the arm is as free to move to the right as to the left. This will result in an arm with no residual skating force. I might have to recant my previous statement that all pivoted arms will have a skating force (though technically this arm does have skating force, it's just balanced by another force) Furthermore if drag increases then skating will also increase keeping the balance. So not only does this design have built in antiskate it also compensates for variation in stylus drag.
A truly remarkable design.
Niffy
The stylus drag will want to extend the arm which will want to move the arm to the left (as this is the direction the arm moves in as it extends). Skating torque will want to move the arm to the right. If the design of the arm gets the two forces in balance then there will be no net force. This should mean that the arm is as free to move to the right as to the left. This will result in an arm with no residual skating force. I might have to recant my previous statement that all pivoted arms will have a skating force (though technically this arm does have skating force, it's just balanced by another force) Furthermore if drag increases then skating will also increase keeping the balance. So not only does this design have built in antiskate it also compensates for variation in stylus drag.
A truly remarkable design.
Niffy
No way. Think of the string probe. The arm would travel to the left, if pulled with a string.
Think of the magnetic guide as a rail. The pull of the stylus is aligned straight down the armtube. The rail is angled relative to this pull. This will generate a force to the left. There is a pivot between the magnet and the cartridge, the resultant force at the cartridge will be to the right. This is the skating force part, the direct pull does result in a pull to the left. Hopefully these balance.
Niffy
Niffy
At first, I was not sure why the guiding pivot has to be at the headshell area when you can avoid it. Oh yeah, the Esperado arm places all the guiding mechanism under the platter. Still, I would still prefer to install the active sensor system or passive guiding parts behind the main arm to avoid having bearings above the headshell like the Garrard Zero so I agree with Niffy's below statement.
Walter, Niffy. can be useful ? (my 2018 simulation of an LT like PLT - the black trace is the magnetic guide).
More than his remarkable construction, more than smart antiskating devices, for me the great merit of the LT is the geometry itself, that allows a guide pattern singularly aligned with the cantilever, then significantly immune to skating.
About forces distribution on PLTs, i'm less optimistic (i've made 3), but, with my bad english, explaining will take some time. Meanwhile i can't see a reason to modify your (and other's) statement, because
Having a 0 sum skating is not like being skating-free.
This too will take some time (and another thread?) to be explained, except to linear TAs builders.
carlo
Congratulations for your cables, mine are much more relevant - i'll ask to some spider for thinner ones.
The stiffness of the air tubes comes from the pressure itself, even more than from the material: worrying but not enough to prefer the Ladegaards.
More than his remarkable construction, more than smart antiskating devices, for me the great merit of the LT is the geometry itself, that allows a guide pattern singularly aligned with the cantilever, then significantly immune to skating.
About forces distribution on PLTs, i'm less optimistic (i've made 3), but, with my bad english, explaining will take some time. Meanwhile i can't see a reason to modify your (and other's) statement, because
Having a 0 sum skating is not like being skating-free.
This too will take some time (and another thread?) to be explained, except to linear TAs builders.
carlo
Congratulations for your cables, mine are much more relevant - i'll ask to some spider for thinner ones.
The stiffness of the air tubes comes from the pressure itself, even more than from the material: worrying but not enough to prefer the Ladegaards.
Last edited:
Hi Carlo.
My arm cables are made of 4 strands of 0.06mm magnet wire twisted together, 2 for positive and 2 for negative. I use a separate run for each channel that are not twisted together. Twisting the two channels together makes for a single cable that is much stiffer than the 2 separate. I did try just a single pair of the 0.06mm wire but felt that the sound was a bit thin. I also tried using 6 strands twisted together. I could discern no sonic improvement over the 4 strand but it was notably stiffer. The cables are very thin to look at. The first time my mother saw my turntable she said "ooh, you've got a hair on it" and tried to pluck the arm cable off the deck. I almost had a heart attack.
Niffy
My arm cables are made of 4 strands of 0.06mm magnet wire twisted together, 2 for positive and 2 for negative. I use a separate run for each channel that are not twisted together. Twisting the two channels together makes for a single cable that is much stiffer than the 2 separate. I did try just a single pair of the 0.06mm wire but felt that the sound was a bit thin. I also tried using 6 strands twisted together. I could discern no sonic improvement over the 4 strand but it was notably stiffer. The cables are very thin to look at. The first time my mother saw my turntable she said "ooh, you've got a hair on it" and tried to pluck the arm cable off the deck. I almost had a heart attack.
Niffy
It is a legitimate concern for all the commercial moving bearing arms including Kuzma's. But for my arms, it is so insignificant that the resistance from silicone damping is stronger than the resistance from the tubing with air pressure at 65 psi. I have done many experiments.
Non magnetic bearings
Hi to all. In the pursiut to m yown design of PLT I need to find non-magnetic ball bearings, those not be attracted by magnets. Attraction will influence proper work of magnet guide (my design is very different from that of Frank). As far, as I know, evem ceramic bearings still use steel parts, which will be attracted. At the same time, some sorts of stainless steel are almost non-magnetic. Are such bearings available?
Niffy, with your experience with different ball bearings, any suggestions?
Walter
Hi to all. In the pursiut to m yown design of PLT I need to find non-magnetic ball bearings, those not be attracted by magnets. Attraction will influence proper work of magnet guide (my design is very different from that of Frank). As far, as I know, evem ceramic bearings still use steel parts, which will be attracted. At the same time, some sorts of stainless steel are almost non-magnetic. Are such bearings available?
Niffy, with your experience with different ball bearings, any suggestions?
Walter
Hi Walter,
The best ball race bearings I have tried are the hybrid-ceramics from boca bearings. These use silicon nitride balls in 440 stainless Steel races. I believe the retainers are also 440 stainless. Unfortunately I think that 440 is slightly magnetic. When I get home from work I'll dig mine out of my parts bin and wave a magnet at them. I did try some full ceramic bearings from China. These did not perform as well as the bocas in my application but as they are zirconium oxide for both the balls and races and have PEEK retainers they will be non magnetic. Boca do do full ceramic bearings with either PEEK or PTFE retainers that will be non magnetic. I think they are quite expensive but will almost certainly be much higher quality than the Chinese ceramics I used.
Niffy
The best ball race bearings I have tried are the hybrid-ceramics from boca bearings. These use silicon nitride balls in 440 stainless Steel races. I believe the retainers are also 440 stainless. Unfortunately I think that 440 is slightly magnetic. When I get home from work I'll dig mine out of my parts bin and wave a magnet at them. I did try some full ceramic bearings from China. These did not perform as well as the bocas in my application but as they are zirconium oxide for both the balls and races and have PEEK retainers they will be non magnetic. Boca do do full ceramic bearings with either PEEK or PTFE retainers that will be non magnetic. I think they are quite expensive but will almost certainly be much higher quality than the Chinese ceramics I used.
Niffy
Hi all,
My favorite supplier:
https://www.igus.nl/product/460
Ball bearings of resin with glass balls, really non magnetic, don’t know about the sizes though- starts with 3mm
Best
Coolerooney
My favorite supplier:
https://www.igus.nl/product/460
Ball bearings of resin with glass balls, really non magnetic, don’t know about the sizes though- starts with 3mm
Best
Coolerooney
Sorry Walter,
The boca hybrid bearings were strongly attracted to the magnet I put near them. Scrub the "a bit magnetic" from my previous post and replace with highly magnetic.
The main advantage of fully ceramic bearings is that they tend to have lower levels of friction than their steel counterparts. Although plastic and glass bearings will be non magnetic they will probably have higher friction than equivalent steel bearings. As it's a tonearm you're building I assume that keeping friction to an absolute minimum is important. You could experiment with making pin bearings from non magnetic materials. These will probably be lower friction and have less play than even the best ball race bearings. And bearing chatter is much less likely to be a problem.
Niffy
The boca hybrid bearings were strongly attracted to the magnet I put near them. Scrub the "a bit magnetic" from my previous post and replace with highly magnetic.
The main advantage of fully ceramic bearings is that they tend to have lower levels of friction than their steel counterparts. Although plastic and glass bearings will be non magnetic they will probably have higher friction than equivalent steel bearings. As it's a tonearm you're building I assume that keeping friction to an absolute minimum is important. You could experiment with making pin bearings from non magnetic materials. These will probably be lower friction and have less play than even the best ball race bearings. And bearing chatter is much less likely to be a problem.
Niffy
I bought these from Boca for a project I've set aside. The bearings weren't the problem.
Boca Bearings - Search Results for sr3c-yzz #5 nb2
They came lubed and normally I would clean them and run them dry, but these spin so well right out of the package that I left them as they came.
I just tested them with a magnet to see if they might be helpful for walterwalter, but unfortunately, they are strongly attracted and effected even at approx. 30 mm.
The project involved trying to separate the horizontal and vertical functions in a PLT and the deeper I got into it, the more difficult and unsatisfactory it became. I've learned to appreciate all the rotary movements in PLTs and the way that makes any given part capable of at least two functions.
Boca Bearings - Search Results for sr3c-yzz #5 nb2
They came lubed and normally I would clean them and run them dry, but these spin so well right out of the package that I left them as they came.
I just tested them with a magnet to see if they might be helpful for walterwalter, but unfortunately, they are strongly attracted and effected even at approx. 30 mm.
The project involved trying to separate the horizontal and vertical functions in a PLT and the deeper I got into it, the more difficult and unsatisfactory it became. I've learned to appreciate all the rotary movements in PLTs and the way that makes any given part capable of at least two functions.
Niffy, Doug, thank you, now I see that stainless steel is not an option.
Carlo, I'll think of shielding, your idea seems to be worth trying. However, completely non-magnetic bearings I would like to try first.
Coolerooney, igus looks really good, I just have no glue about prices. They seem not to provide small scale sales. Closest their retailer to my country is in Poland, that isn't too bad.
Walter
Carlo, I'll think of shielding, your idea seems to be worth trying. However, completely non-magnetic bearings I would like to try first.
Coolerooney, igus looks really good, I just have no glue about prices. They seem not to provide small scale sales. Closest their retailer to my country is in Poland, that isn't too bad.
Walter
Hi Walter,
If you like I can make some enquiries, let me know what you’re looking for
You’re in the Ukraine?
Found these guys
https://www.igus.com/Contact/Sales/UA/iglide
https://www.igus.com/Contact/Sales/UA/igubal
But it can be they don’t carry that product range in your area
Worst case, you buy em through me, at cost, no worries- but no returns -hahaha
Btw, They are quite generous with samples/sample boxes -check it out
https://www.igus.com/info/company-sample-request-com
Have some lying around, but are bigger ones- see pic- you’re welcome to em
Best
Coolerooney
If you like I can make some enquiries, let me know what you’re looking for
You’re in the Ukraine?
Found these guys
https://www.igus.com/Contact/Sales/UA/iglide
https://www.igus.com/Contact/Sales/UA/igubal
But it can be they don’t carry that product range in your area
Worst case, you buy em through me, at cost, no worries- but no returns -hahaha
Btw, They are quite generous with samples/sample boxes -check it out
https://www.igus.com/info/company-sample-request-com
Have some lying around, but are bigger ones- see pic- you’re welcome to em
Best
Coolerooney
Attachments
Last edited:
Hi Walter,
Found in my email a recent price list, product codes are same
The prices are per piece, per 25, 100 etc- see the tiers
There is a significant minimal charge, which I usually avoid by picking the stuff up myself, the’re close by
have no clue on pricing in PL or UA, but it gives you a ball park idea— ———sorry, file size is to big, 4,7 mb -if you want send me your email, can’t attach on IM’s
Best
Coolerooney
Found in my email a recent price list, product codes are same
The prices are per piece, per 25, 100 etc- see the tiers
There is a significant minimal charge, which I usually avoid by picking the stuff up myself, the’re close by
have no clue on pricing in PL or UA, but it gives you a ball park idea— ———sorry, file size is to big, 4,7 mb -if you want send me your email, can’t attach on IM’s
Best
Coolerooney
Last edited:
Plastic bearings seen by my retailer (no brand - sold for food machinery) run very well, but with evident chatter; Not so small too.
Found this for Igus - seems that here they sell single bearings i.e. 20 eur a 3mm bearing
https://www.igus.it/info/ball-bearings-xiros-a500#section_6
A doubt - with hybrid bearings just the races can be attracted, and the races are round - if they are not going to be magnetized (magnet not always near them) where is the problem?
carlo
440 not only is "a bit magnetic", they tend to get rusty with salted water - pity they don't make with 316, like everything else on boats - winches must be greased so often ..
I've used very thin silicon steel scavenged from a burnt TX to shield an MC battery operated pre pre, put inside an octal phono, with high currents all around: works great
Found this for Igus - seems that here they sell single bearings i.e. 20 eur a 3mm bearing
https://www.igus.it/info/ball-bearings-xiros-a500#section_6
A doubt - with hybrid bearings just the races can be attracted, and the races are round - if they are not going to be magnetized (magnet not always near them) where is the problem?
carlo
440 not only is "a bit magnetic", they tend to get rusty with salted water - pity they don't make with 316, like everything else on boats - winches must be greased so often ..
I've used very thin silicon steel scavenged from a burnt TX to shield an MC battery operated pre pre, put inside an octal phono, with high currents all around: works great
Last edited:
Coolerooney, thank you, a bit too expensive for experimental prototype arm. I'm not yet sure it will work as expected, so I'll rather try with chiper Chinese from Aliexpress, and if arm is as good, as I hope, I will use IGUS for final version.
Carlo, problem with magnetic bearings is in my design. I need at least two of them to be non-magnetic, because as they pass near magnets, the distance between magnets and bearings change, and in doing so, it will affect tracking ability of the arm.
Carlo, problem with magnetic bearings is in my design. I need at least two of them to be non-magnetic, because as they pass near magnets, the distance between magnets and bearings change, and in doing so, it will affect tracking ability of the arm.