Maplenoll platter stability question

this is usually a result when the teflon pin is worn on the bottom plate allowing a little flutter. This can be exaggerated with a slightly out of balance lead platter. I wrestled with this issue on my first maplenoll ariadne reference (white one with 40 lb platter) because of shipping damage and the worn pin. it is very difficult to find replacement parts for this so i ended up making a replacement. The platter balance is not as critical but for flawless performance is does help. I had the platter turned by a machine shop and balanced. Then repainted with a good grade of acrylic paint. The bottom pin can be pressed out and replaced but you must remove the plate using the three bolts. You can buy stock rods of teflon that will perfectly fit into the bottom plate then machine top so that it fits snug into the brass sleeve in the top airbearing plate. Carefully lube the brass sleeve with the supplied lube or high grade graphite grease. it sounds very difficult but its not really that tough if you are a little handy. I got pretty good at this while getting that table perfected. after that one, i moved up the the ariadne signature (beast of a table with a 90-100 lb platter). i currently own 3 maplelnolls including a heavily modified apollo that was the precursor to lloyd walker's current table. This one was modified by him and has an external drive vs the one attached to the plinth. the VTA adjustment is an engineering marvel.

Back to your other question. Yes on both accounts and yes on leveling the arm. Not sure about what model you have but i am a firm believer in getting base perfectly level. Usually the platter air bearing bottom plate is level, but if not, you will have a level base and the platter is slightly off. this can result in the platter bottoming out as it rotates and force higher pressure on the platter thus robbing vital air pressure to the arm. check them both. I spent a lot of time getting level right on platter. you will know you have it right when you spin by hand (with air on but belt not hooked up) and the platter spins for 3 or 4 minutes. You have not mentioned the arm so I am assuming its properly tuned and does not create a problem. If you level properly, provide clean, consistent pressure the the arm and platter, the maplenolls will produce some of the sweetest sound you will ever hear from a table in this price range.

I sent in a detailed response last nite, not sure what happened but in a nutshell, one significant possibility for your problem is a worn centering pin (teflon) on the bottom base plate of the air bearing. I had a similar problem that i corrected by replacing that pin. If the moderator does not release the my response, you can PM me and i will help you diagnose the table to see if that is the problem

Hello Oilmanmojo,
Thank you for your kind response. Am I correct that a proper, unworn, center pin allows no side-to-side movement when fitted to the opening of the top plate? Or, does the pin act as a centering point and the spinning lead platter completely floats with no contact between pin and top plate? I hope this is understandable.

Great question and hopefully i can answer correctly. The centering pin (teflon i believe is the material if i remember lloyd right), serves the purpose of ensuring as the platter floats on the air between the plates (very small clearances) that it stays centered and does not move side to side as the platter turns. Remember the belt will put a slight force on the platter so sufficient friction exists to spin the platter. This means the platter pulls slightly towards the pulley attached to the motor. Now if the pin is slightly worn, but the platter is perfectly level and balanced, no major problem because the force is parallel to the platter and does not cause wobble. But if the platter is not perfectly balanced, then as the heavy side spins, the clearance will be lower on that side versus the light side. Again if the center pin is perfect, and the imbalance is low, then you do not see much if any deflection because the imbalance is just offset by a little friction on the pin. Since teflon has very low frictional properties, you do not see much impact. in fact you will be able to determine this if you carefully reduce the platter air pressure just to the platter just rubs. I found that if you listen carefully the imbalance will be an rhythmic sound and not continuous. if the platter is perfectly balanced the sound will be continuous. I know this sounds a little black magic but it works. If the platter is off balance you compensate by adding more air pressure which lifts the platter a little higher thus offsetting the imbalance Again you will see this by looking at the top of the spindle. It wobbles.

Now there is one other possibility and that is the spindle is bent slightly. If that is the case, the spindle will wobble but your tone arm will not move up and down. Look at it carefully. You also can get a carpenter square to determine if the spindle is bent.

hope this helps

tomg

I believe I can have a friend make a replacement center pin for me. I also think I can find a Teflon rod at US Plastics. I've recently replaced the belt and the increased pulling has caused the side-to-side movement to be more apparent. I have noticed the periodic rubbing when the air pressure is reduced. I don't have a source to balance the platter, unfortunately. I have read the owner's manual and have "trued" the top plate's spindle by lightly tapping on it. I finally have a good source of high enough air pressure. So the centering pin is the last hurdle.
Thank you, very much, for the information.