2. analog
  3. 159642-124530

Have a Victor UA-7045 tonearm coming

I've been searching for either a Victor UA-7082 or a UA-7045 tonearm ever since I purchased my Victor CL-P2 plinth with two arm boards.
The rear arm is almost ready to go, it's a Audio Technica ATP-12T mounted in a custom aluminum armboard. I also had to machine a bracket to add a Jelco JL-45 tonearm cueing device and a tonearm rest. This should be perfect for my low compliance DL-103.I have been looking at both models of the Victor arms and have posted WTB on several forums, watching Ebay but nothing nice has come up. So for the past month I have been keeping an eye out on the Japanese website Yahoo Buyee and finally saw something I liked. It's a clean looking UA-7045 that should work out nicely.
https://buyee.jp/item/yahoo/auction/v741873067?_=cnZxVG5GZVlFQTA3VEZVTDBjQnRCS1RGYWtnTW1ZOTZORUVmb2R...=I won the auction this morning for $202.81, way cheaper than I've ever seen one of these go for. estimated shipping is around $50.00 via DHL. It takes up to two weeks for the seller to get the arm shipped to Buyee and they will inspect and repackage it for shipment via DHL. So in several weeks I'll have this in my hands.
Since I know the spindle to pivot distance I will machine an armboard for it in advance.
Anybody familiar with this series of arms knows all about the rubber damper in the counterweight stub that degrades and causes the dreaded tonearm droop where the weight starts hanging down.
There are two types of this series of arms, those that have the droop (most) and those that will develop it soon. Aging rubber and gravity never let up. Every arm will eventually have this problem.
I've talked to my friend Elliott about this as he had one of these arms for a short time. He sent me a sketch of a rubber piece that he made from hardware parts that he used to fix his. Between Elliott and the internet I found enough info to figure out how this comes apart but I'm not entirely happy with the fix. Since Victor can't supply the rubber dampers I've been thinking about possibly making a mold and casting them out of urethane. I have samples of urethane coming to me from a supplier so I can compare the hardness of the rubber bushing to the urethane samples to find a close matching durometer value.
The mold will be a simple affair, machined out of aluminum. I need to dig out a vacuum pump buried in my garage to see if it works and I found a vacuum chamber on Ebay for 50 bucks.
Once I get the arm I'll pull the stub off and get some critical measurements and work from there. I can even do a temporary fix on the stub until I have a decent result as I have never cast urethane before.Anyway, I'm very excited to be getting this tonearm and at least one member here (chakster) talks very highly of it.

BillWojo




billwojo
elliottbnewcombjr
5,699 posts
 
Bill,

Congrats,

I was very impressed with the workings when I took the one I had apart before sending it back.

Not to send bad vibes, however, don’t be drilling any holes yet,

the thing could get destroyed, and even if perfect, you might find a great 7082 an hour from now.

Patience, until you have the bird in hand.

billwojo OP
397 posts
 
Your absolutely correct Elliott, it is an easy job to machine the hole in the armboard plate anyway. I need to find some more material to make a few extra armboard plates for the future. I DO want to find a UA-7082 arm down the road.
BillWojo
lewm
13,386 posts
 
Bill, in my opinion, you are way overthinking this. I would just go to a good hardware store and find a tiny O-ring of the proper size that does the job. Although I have never yet replaced the rubber donut in my own 7045, I have seen that most good hardware stores have O-rings that would work. I see no need to be anal about casting a perfect replica.
billwojo OP
397 posts
 
lewm, o-rings won't fix the problem if the rubber is deteriorated to the point that it is falling apart. You can add all the rubber you want to the exposed section of the tonearm and make the stub stick straight out but if the square head of the bolt touches the small collar that holds the assembly in place  than you have lost the damper effect. Might as well epoxy it in place as a rigid unit at that point.
I would like to develop a permanent solution that fixes it forever. Urethane doesn't degrade like rubber.
When new the square head of the bolt when tightened deforms the end of the rubber bushing and pushes it into the notches of the collar, there is no metal to metal contact.

BillWojo
lewm
13,386 posts
 
Bill, Now I am not sure what it is you want to replace. I had assumed you are talking about the rubber (I used the word "rubber" as a catch-all; I did not mean to insist on rubber in the formal sense) donut that provides decoupling of the CW assembly. So what are you referring to when you say, " if the square head of the bolt touches the small collar that holds the assembly in place than you have lost the damper effect"? Obviously you would choose a replacement part that does the job right. Incidentally, these days you can buy O-rings made from just about any variant on rubber that makes sense. Just go on-line to McMaster-Carr or there is another site that specializes in O-rings per se. Neoprene and urethane and etc are probably available. In fact, it would probably be more difficult to buy an O-ring made of conventional "rubber", if you wanted to.

By the way, I have written this elsewhere many times in the face of Chakster’s insistence that the CW has to stick out the back like a full-blown erection, there is some mechanical advantage to having a slight droop such that the center of mass of the CW lies in the plane of the LP. If you notice the design of modern tonearms, like the Triplanar and the Reed and etc, that’s how they do it intentionally.
More to discover