JMW 10.5 vs SME V

OK I serviced the "dashpot" on my SME V. There is a design issue on the dashpot that I take issue with: the width of the piston is wider than the lengtth of the side of the piston that articulates with the dashpot well. Any mechanical engineer will tell you that this is a formula for "canting" (that thing that happens when you try to close a drawer and it gets cocked to the left or right and won't push in until you pull it out and carefully align it before closing).

So in my case - I had to use molybdenum grease on the piston in order not to get it to cant. I used silcone "stopcock" grease which was way too light for this purpose. I removed it and then I used silicone lube for my Walther Lothar Air Pistol lube (don't ask). And this is better. However I still have to order the sticky grease. I will try to source it here, I am told it is Rocol Kilopoise 0868S which can be sourced here in the US (looking for it now).

I also had to pull apart the spring while trying to align it so that the faces of the spring were parallel to each other. Here they used a conical spring (wide end on the piston, narrow end against the fixed ceiling) and I think they should have used a narrow spring all the way. But I haven't been able to see what would fit in there. A cylindrical spring may not have sufficient clearance.

At any rate working on the spring also seemed to help prevent canting.

The queuing lever works great now - but it is instantaneous. I will have to get the viscous fluid in order to get it to slow down a bit.

Jkorten,

Impressive report. I don't even have an SME arm, but it was still a good read.

Wouldn't a conical spring (wide end on the piston) or a full-width spring somewhat mitigate the possibility of canting? I'll bet that's what SME thought. (Of course a higher height:width ratio for the piston would have been best, as you noted.)

One piece of follow up information for you folks. According to the very helpful customer service people at SME:

SME V has always had only one revision of bearings since the beginning of production. The only change that has been made has been to the internal arm wiring. There is a modification available for this wiring for early production arms. That is all.

In addition they have made a version of the arm with gold stenciling instead of the original silver. They also have a gold plated version of the arm (makes the sound a bit too brilliant IMHO... KIDDING!)

Anyhow - I've decided to keep the arm as the wiring investment is little compared to a new price for this tonearm. And I have yet to be convinced this is not still one of the best tonearms available. Of course I would need to listen to the other arms in this category on my system, but I cant, so I won't, and will remain blissfully ignorant.

Enjoy the tunes!

Jerry