Hi EC, and everybody else, any suggestion about process to get aluminum surface more frictional to get equal rough finish?
Drain cleaner? Not a terribly good suggestion, but the best I can think of. I assume you're thinking of your motor pulley?
you can also try adding a idler pulley on the other side of the platter, directly opposide the motor. then loop the belt so that it just touches the sides of the platter. you could run a tighter rubber belt, without it overstressing the platter bearing. the platter bearing is thus only acted on by opposing belt force, with zero pull towards the motor.
a couple of turntable makers use that approach, like below:
a couple of turntable makers use that approach, like below:
I tried drain cleaner, dipped piece overnight, it actually works. Of course there is problem; it foams on surface and leaves ugly ring on metal piece where it enters liquid. If possible to completely submerge pulley it would be very good, like this I need to think how to do it.
Thanks for suggestion Jayme, if you see the size of my platter bearing (D20mm x 65m) you like me wouldn't be worried that this will be over-stressed or move anywhere 🙂. I would be more worried about motor bushings wear. I can already put even tighter belt, so far as motor shaft allows.
Earlier I was thinking of similar solution but with different purpose: to use 3 miniature HDD motors around the platter to drive it, but did not made it further than paper sketch.
In any case, this is now real finding the last possible micro improvement as far as this classic TT concept is concerned. One of these days I will put it in operation and start listening again. Only things to do is etch the pulley (if I do it at all) and finish the cover. Ill report on this and make thread summary.
Most important is that Supaspin + 4 channel chip amp for cars + 12V wall brick PS + VCR capstan motor make excellent drive for TT capable of achieving 0.03% wow. And all this at total cost of about 25 Euro + cost of making PCB , pulley and mounting for motor. I don't think any other solution can beat this.
Thanks for confirming that drain cleaner actually works; I'll make a mental note. Yes, platter bearings tend to be pretty substantial and perfectly capable of taking a sideways force, but motor bearings aren't. Except of course for capstan motors that were designed to have a pinch roller pressing against them.
Im looking at the way to avoid foam, or to reduce its effect.
Here is again a catch. Capstan motors take pinch force on long shiny shaft between 2 bearings , see example picture below. That is the place where lot of side force can be placed harmlessly, but no way to install pulley there (for Lenco people, this could be very good place to drive idler wheel).
So I installed pulley on top of the rotor directly (on picture on small brass cup). Now side force is aside of bearings and top bearing has many times more load (actually takes all side force load) .
Than again, what I'm saying is probably discussion about 50 years of continuous run, if lubricated it will probably never wear regardless of belt tension 🙂
By the way, here are results of overnight dipping random piece of aluminum in drain cleaner. It is clearly etched and surface friction can be easily observed by finger.
But there is messy area where foam was created . On picture is also my pulley - rotor- shaft assy. I'm thinking how to etch driving part of pulley without making too much mess by foam.
In process I did, it is not possible to etch pulley alone as to get it within tolerances I had to assemble it in motor and than finally grind to dimensions. Think I will experiment with protection paint to avoid foam mess.
But there is messy area where foam was created . On picture is also my pulley - rotor- shaft assy. I'm thinking how to etch driving part of pulley without making too much mess by foam.
In process I did, it is not possible to etch pulley alone as to get it within tolerances I had to assemble it in motor and than finally grind to dimensions. Think I will experiment with protection paint to avoid foam mess.
HI,
To me seems this TT have 2 motors and not one motor and a idler pulley.
Best regards
Adelmo
By the way , by looking at Acoustic signature TT that Jayme posted above, it is clear it is 2 belt 2 motor execution, so far looks good.
What I noticed that pulleys are anodized , that I believe is done separately, not mounted on motor shafts. What was here discovered by EC and myself is that lathe is not good enough to finish pulley (later to be mounted on motor shaft), it needs to be attached and fixed to motor and than finished for perfect roundness.
In short search, also couldn't find specifications of precious Acoustic signature TT's???
What I noticed that pulleys are anodized , that I believe is done separately, not mounted on motor shafts. What was here discovered by EC and myself is that lathe is not good enough to finish pulley (later to be mounted on motor shaft), it needs to be attached and fixed to motor and than finished for perfect roundness.
In short search, also couldn't find specifications of precious Acoustic signature TT's???
I wonder what is resistant to drain cleaner? A plumber would probably know. Enamel paint resists ferric chloride (PCB etching fluid), but only experiment will tell if it resists drain cleaner. It's quite possible that leaving the cleaner overnight is too long. Temperature is also a factor. When I've etched PCBs, I warm the ferric chloride solution to perhaps 40C and it cuts the etching time by a factor of two or more. You really want just the right amount of etching time. It's quite possible that a pulley requires just the right amount of (supervised) time. And I suspect that (just like a PCB), it's important that there isn't any finger grease on the pulley before immersion in drain cleaner - get it properly clean.
Your point about the supports and where the sideways motor load is applied is taken.
Your point about the supports and where the sideways motor load is applied is taken.
I decided that I started to over complicate things. Now after dinner just ditched pulley in sump cleaner. It is tall enough for solution to attack important parts without eating rotor... Will show result in hour or 2.
Well, things are getting interesting, it turned black
Black is washing away with rag, but not completely. On extruded aluminum it was not changing color, but than again this is also extruded alu rod, than machined. Im confused.
In principle it does not look bad, surface is getting rougher, but I need to refurbish my memory of metallurgy classes. Thing for tomorrow...
Black is washing away with rag, but not completely. On extruded aluminum it was not changing color, but than again this is also extruded alu rod, than machined. Im confused.
In principle it does not look bad, surface is getting rougher, but I need to refurbish my memory of metallurgy classes. Thing for tomorrow...
Yuck. There are lots of different aluminium alloys, and your extruded angle was clearly different to the pulley. Unless that axial hole allowed the cleaner to attack something different inside?
did you try out the post-cleaner pulley on ypur table with the belt? was the friction better? and did speed stability improve or decrease?
Hi Jayme, it is mixed bag and I still did not draw any conclusions.... Generally it looks slightly worse.
Hi EC8010, there is nothing in that center hole except epoxy glue, so no idea where black is coming from...
First, this is pulley after approx 2 hrs in cleaner, washed with soap, than with alcohol. It is clearly etched a bit. Got kind of gunmetal shades which is not to ugly. Picture is high resolution enough so you can see where I was modifying eccentricity with sand paper, and where not.:
With pulley like this and best (tight belt) , I hardly get 0.03% any more , it is 0.04 and 0.05% , not much but clearly worse.
This was more of a lucky shot, one out of ten:
Coming back to main purpose of modifying surface to get higher friction: which is a loose belt. Every belt will loosen with (short ) time of use and I wanted to see if life can be extended.
So with loose belt and etched pulley picture is slightly improved (think I had 0.22 % before, now it is repeatably 0.18 -0.19 %) . However something showed up in many measurements, dips (or peaks) almost exactly every 0.5 second. This is what I struggle to interpret as such frequencies cant be neither platter neither motor related..... Here is picture; loose belt and etched pulley:
With different (but also more loose) belt I get also the same 0.5 second issues, but now profile is kind of every second is deeper..... Interesting...
Seems I made myself unnecessary extra work, but than again it is ok to get closer to the bottom of the issue. Stupid thing, rotate an cylinder at exact speed,, well not so simple...
Two things that can be concluded; 1 With such set up belt has big role and 2. this phone app is great!
Hi EC8010, there is nothing in that center hole except epoxy glue, so no idea where black is coming from...
First, this is pulley after approx 2 hrs in cleaner, washed with soap, than with alcohol. It is clearly etched a bit. Got kind of gunmetal shades which is not to ugly. Picture is high resolution enough so you can see where I was modifying eccentricity with sand paper, and where not.:
With pulley like this and best (tight belt) , I hardly get 0.03% any more , it is 0.04 and 0.05% , not much but clearly worse.
This was more of a lucky shot, one out of ten:
Coming back to main purpose of modifying surface to get higher friction: which is a loose belt. Every belt will loosen with (short ) time of use and I wanted to see if life can be extended.
So with loose belt and etched pulley picture is slightly improved (think I had 0.22 % before, now it is repeatably 0.18 -0.19 %) . However something showed up in many measurements, dips (or peaks) almost exactly every 0.5 second. This is what I struggle to interpret as such frequencies cant be neither platter neither motor related..... Here is picture; loose belt and etched pulley:
With different (but also more loose) belt I get also the same 0.5 second issues, but now profile is kind of every second is deeper..... Interesting...
Seems I made myself unnecessary extra work, but than again it is ok to get closer to the bottom of the issue. Stupid thing, rotate an cylinder at exact speed,, well not so simple...
Two things that can be concluded; 1 With such set up belt has big role and 2. this phone app is great!