• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Bent Thorens tonearm

JohnMac

JohnMac

Addicted Member
Good Morning All,

I just bought a TD 145, sight unseen. A "Worked when I put it away 10 years ago" deal. It is generally in pretty good condition but the tone arm is bent downward at the fitting on the head shell end of the tube. No kink, just angled down. Does anyone know of a way to fix this? Thanks in advance.

John
 
Register to hide this ad
I had this happen to an AR many years ago. Take a look at the point where the arm tube enters the pivot block, at the opposite end of the tube from the headshell. You may find a set screw that holds the arm tube in the pivot block. If the down angle of the headshell is due to the arm tube rotating in the block, you can correct it by loosening the screw, rotating the arm tube until the headshell is properly aligned, and tightening the set screw to lock the arm tube in place.
 
Hi Dr Tinear. I don't think that is the issue as it is (or is supposed to be) a straight tube. Rotating it would just change the incorrect angle.
 
Here's pic that might help.

In the pic it appears that the tube arcs but the bend is actually right at the fitting
 

Attachments

  • Thorens tonearm.jpg
    Thorens tonearm.jpg
    65.6 KB · Views: 148
Last edited:
The Thorens has a straight arm. The angle is not caused by the tube rotating, but by a bend in the tube. The fact that it is bent right at the ferrule is problematic. It is going to be tricky to straighten it, and to verify it is straight. You need to be able to grip both sides of the bend without crushing the tube. The good news is, it's un-useable now, so you can't ruin it. Here is my suggestion:
You need to make a support for the arm tube. Buy a piece of aluminum tubing where the inner diameter is the same as the OD of the arm tube. You can get it at McMaster-Carr. Then cut the tubing in half lengthwise with a hack saw or band saw. Place the cut tubing on the arm tube, right at the ferrule for the headshell. Now you can grip the tubing there without crushing the arm tube. Grip the tube with a pliers and grip the ferrule with a second pair of pliers with padded jaws. Bend the tube a little at a time and keep checking it with a straight edge, or set up a jig with a parallel line you can sight against, such that when the tone arm is parallel to the plinth, the top of the headshell is also parallel to the plinth.
Caution: when bending the tube, do not put any stress on the arm pivot or you could ruin the bearings. Hold the arm tube stationary and exert the bending force on the ferrule.
 
That's the approach I was looking at. I tried to find a socket the appropriate size to put over the ferrule and make contact right at the bend but wasn't confortable with that because I couldn't stabilize the tube enough to be sure I wouldn't put stress at the pivot point. When you say to place the cut tubing on the arm do you mean both halves on either side? Wouldn't that still alow the tube to be crushed between the two pieces? Maybe I misunderstood.
 
What is the vintage and make of the tonearm? Is it a TP16? What Mk? I do have a TP16 Mk1 without a headshell that might be a 1:1 replacement if the picture is showing the same vintage tonearm with a different headshell.
 
Do I see a set screw on top of that fitting? If so, try loosening it to see if the tube is bent or if the fitting is simply sitting at an angle.
 
audiodon657 said:
What is the vintage and make of the tonearm? Is it a TP16? What Mk? I do have a TP16 Mk1 without a headshell that might be a 1:1 replacement if the picture is showing the same vintage tonearm with a different headshell.
Click to expand...

I assume it is a tp 16 but don't know for sure. Looks like the same arm as my 160 but the headshell on my 160 is slightly different. How can I identify it?

Just put a straight edge on it and the bend begins about 1 1/2" from the ferrule. I don't understand how the hell it could get bent like that.
 
JohnMac said:
That's the approach I was looking at. I tried to find a socket the appropriate size to put over the ferrule and make contact right at the bend but wasn't confortable with that because I couldn't stabilize the tube enough to be sure I wouldn't put stress at the pivot point. When you say to place the cut tubing on the arm do you mean both halves on either side? Wouldn't that still alow the tube to be crushed between the two pieces? Maybe I misunderstood.
Click to expand...

I meant both halves, one on either side. Even if the cut leaves a gap between the two halves, I think it will spread out the force over a large area and protect the tube. It will be easier if you can remove the ferrule. Then you would not have to cut the protecting tubing in half, just slide it over the arm tube. You could use a second piece of tubing to fit over the end of the arm tube, to bend it with.
 
Sam Cogley said:
Do I see a set screw on top of that fitting? If so, try loosening it to see if the tube is bent or if the fitting is simply sitting at an angle.
Click to expand...

That's not a set screw, it's a nub. Only purpose I can see is to keep the ferrule nut from sliding back on the tube.
 
If you can take it all apart you just might be able to bend it back in shape carefully between two flat surfaces (a couple of sheets of plywood) clamped slowly to force the arm back in shape. It may not be perfect but I think it would work well enough. The biggest problem you might run into is crushing the tube.
 
JohnMac said:
That's not a set screw, it's a nub. Only purpose I can see is to keep the ferrule nut from sliding back on the tube.
Click to expand...

Look at it closely with a magnifying glass. It may be a pin that you have to remove, either by driving it through or pulling it out.
 
You're right. I looked at my 160 and the pin is flush. I was able to pad a pair of pliers and press the pin in, allowing the nut to slide over the tube.

The best and safest way to do this job would be to remove the tube so I could get things in a position that wouldn't damage the bearings. Could maybe even use a flexible tube benderlike the type used for copper tubing. Maybe someone can help me with removing the tonearm???
 
spartanmanor said:
You might also fill the tube with sand before trying to bend it back.
Click to expand...

That's an excellent idea. Brass instrument makers typically fill straight tubes with pitch before bending them into crooks to keep the tubes from kinking as they're bent. One manufacturer (Blessing) uses liquid nitrogen instead of pitch; it works just as well, and cleanup consists of pouring the supercooled liquid out of the tube and letting it vaporize. I expect that sand would work nearly as well as pitch or liquid nitrogen for the job you're trying to do.
 
You must log in or register to reply here.
Back
Top Bottom