Maplenoll platter stability question

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.

If you have a good machine shop where u live they may do it for u. Good luck and let me know how it comes out

Hello Oilman,
My friend did a great job and made a couple of center pins that fit perfectly. Now I want to clean some of the lower platter mounting parts and touch up the paint around the mounting area. I try and restore as much as possible when things are torn apart. My friend thought that the upper and lower plates might have been made of magnesium. They have a very smooth surface where they touch when no air is between them.

Excellent. You should see the difference pretty quick. Couple of points. As you reassemble, please note the bottom plate has the holes that are threaded. As you probably figured out, the long bolt screws into these. Not sure if they are sealed on the bearing surface side but the three tables i have all are sealed. If they are sealed, i would just tighten until they are hand tight. Not sure if you have the white table (lot of plywood that is sealed on sides and top with white corian or the grey table (mostly corian though i believe there is a plywood core. The white table is a little tougher to deal with because with 20 year old plywood, it can be a little brittle. There is a string online where a fellow maplenoll owner completely refurbished the white one and sealed the plywood exposed surfaces with a pliable material that hardened similar to corian. The grey signature table is a lot easier to deal with.

Concerning the material, it is an alloy that i believe has some aluminum and magnesium but it is a special alloy that could be highly polished to extreme tolerances. I have been warned by several experts that you want to leave it alone and do not try to alter it. It is very hard but brittle and was specially polished and each of the plates were matched. I have a few spare platters and spindles that i purchased from the guy i got my ariadne signature. One of those platters is ruined where a person tried to polish it to "improve" it. I know anything can be polished with the right materials but i am a firm believer in leaving that to people who understand how to handle this material. My understanding is that Dilger had a number of these plates made and that was one of the "expensive" components that made the table pretty expensive at the time. i have been very successful just cleaning about every 6 months with an alcohol pad and very soft microfiber cloth. By the way, make sure you put a little lube (the blue stuff if it was provided) in the brass fitting that the teflon pin fits in.

I am excited to hear how this works out for you.