Wobbly Platter

[waynelectro]

Hello,
I'm cutting on a presto k8 and i've been having a little trouble with the groove depth. It seems like the rubber belt on the platter is a little uneven and when the motor shaft hits a high spot on the belt it pushes the platter at a bit of an angle and the grooves cut too shallow (or too deep).
The belt itself seems to be ok. I've taken it off and it doesn't appear damaged (i.e. no sections are thinner or thicker than others). I can move or reduce the high spots a little by pushing and pulling on the belt, but can't seem to get it even all the way around. Has anyone had this trouble? Is there somewhere to get a replacement? Thanks!

[cuttercollector]

Hello,
I'm cutting on a presto k8 and i've been having a little trouble with the groove depth. It seems like the rubber belt on the platter is a little uneven and when the motor shaft hits a high spot on the belt it pushes the platter at a bit of an angle and the grooves cut too shallow (or too deep).
The belt itself seems to be ok. I've taken it off and it doesn't appear damaged (i.e. no sections are thinner or thicker than others). I can move or reduce the high spots a little by pushing and pulling on the belt, but can't seem to get it even all the way around. Has anyone had this trouble? Is there somewhere to get a replacement? Thanks!

I would be more worried about the platter bearing.
It should have no wobble at all. Placing a finger on opposite sides of the platter and pressing down gently on one side then the other should produce no rocking motion.
Unless I am misunderstanding you, it sounds as if you said the motor shaft is causing the edge of the platter to wander up and down as it presses against the rubber drive ring around the edge.

[waynelectro]

Well, it looks like i've been doing all of my cutting without a platter bearing! I'm surprised it has worked as well as it has. Anyone have an idea where to find a replacement?

[cuttercollector]

Well, it looks like i've been doing all of my cutting without a platter bearing! I'm surprised it has worked as well as it has. Anyone have an idea where to find a replacement?

??????????
I think there should be a metal shaft on the platter and a bushing it should slide into on the deck plate. This should have no play.
Not sure what you mean by missing bearing.
I am going by the construction of other tables including my later K-11 which does not use the same drive system but I think that every portable Presto has a similar turntable support mechanism (as well as most other similar turntables)

[emorritt]

If you're talking about the ball bearing at the bottom of the turntable well, check any hardware store. They usually have an assortment of ball bearings; not sure of the exact size for the K series but I'm pretty sure it's just a little smaller than those used in the 6N & 8N machines with larger turntables. Try one about the size of a pea, maybe a little smaller. If you look at the dimple at the bottom of the TT shaft that would also give you a clue as to the proper size. Yes, it's amazing you get consistent speed much less groove geometry without a bearing...

[waynelectro]

OK, I guess I was mistaken. I do have the bearing. Unfortunately I also have a wee bit of play in the platter. Maybe that platter I have isn't original? Any suggestions as to where to go from here?
Thanks for all the info and advice so far.

[audiocarver]

I had the same problem on my Presto 8N. I am not exactly sure how the k8 is but on the 8N my problem was both the bearing and the shaft itself. It was found that the shaft was worn because of the failed bearing. I ended up taking it to a local machine shop where they checked it out and found it to be at least 0.030" end play on the shaft! Too much wobble! They ended up re-sleeve new bronze bearing stock into the bearing well assembly and then they turned the shaft so it was true again and fit snugly into the bearing well. The end play on the bearing/shaft is now 0.0005."

The shaft on the 8Ns has a flange on the end of it that attaches to the platter with cap screws. I had the machine shop re-true the platter to the shaft as well on their metal lathe while I had them do the other work. If I recall, the whole job cost me $120.00 and they blueprinted the original part.

My suggestion here is find a local machine shop that is willing to take a look at it. Be careful here--as many machine shops do NOT want to mess around with small, less than production jobs.