Beogram 8000: Adjusting Horizontal Parallelism and Glueing the 3D Printed Plastic Tabs to the Carriage

The Beogram 8000 seems to like its new 3D printed plastic tabs that I implemented a few days ago. So I decided to epoxy them in place for long term stability. To be able to clamp them I needed to remove the tonearm carriage from the rail that I could turn it up to apply the clamps:

After applying epoxy to the remaining 'stumps' I clamped the new tabs in place:

After 5 min the epoxy had settled, and I took the opportunity to also adjust the horizontal tonearm parallelism. The adjustment screw can only be accessed from underneath the carriage, so this was the moment:

After adjustment the tonearm was at the same height as the sensor arm:

Lovely!

Beogram 8000: Repair of Broken Off Plastic Tabs on Tonearm Carriage with a 3D Printed Part (II)

Allright! After fixing the broken off tab on the rear of the tonearm carriage of the Beogram 8000 that I am restoring right now, I came up with a similar fix for the broken off tab on the front. This one was a bit easier to access:

I decided to design a 'cap' that would fit on the remaining stump and hold the carriage down on the steep rod on which it travels:

This part was more challenging to print since on one side it had to be very thin to not alter the 'home' position of the carriage, and due to the oval orifice for the rod. Such structures are difficult to print due to th unavoidable gravitational forces that make it difficult to bridge voids with the printer. That is why the part looks a bit 'wobbly'. These pictures show the part installed. Here without steel rod:

And with steel rod in place:

The rod is easily taken out from the plastic receptacles that clamp it in place on either side, i.e. the part can be installed by removing and then inserting the rod into the part, and then clicking the rod back into its receptacles.

I ran the mechanism a few times and it seems to work very nicely...the part does not obstruct anything in the motion path of the carriage. So potentially this is fixed. Like with the tab in the back I had to iterate the part a bit until a good fit was obtained:

I will epoxy the part into place once I am certain it performs well. Without clue it would probably not stay in place during transport. 

Beogram 8000: Repair of Broken Off Plastic Tabs on Tonearm Carriage with a 3D Printed Part (I)

I finally got back to the Beogram 8000 that recently arrived from Japan. After fixing the spindle rotary encoder issue, I had to put this project on hold to complete a Beomaster 8000. One of the remaining major restoration tasks was the repair of the broken off plastic tabs that hold the arm carriage to the metal rods on which it rides. They must have broken off during a rough transport experience or a similar stressful moment. Anyway, there was not much choice other than replacing the carriage with one from a donor 8000 or going creative on this issue with a 3D printer. I chose the latter since I usually cannot accept Beograms being parted out.

This picture shows the broken off tab in the back of the carriage:

and the photo below shows the other broken off tab in the front of the carriage. The white stuff is evidence that someone tried to glue the broken off part back into place, but it must have come off again:

The repair of this one will be the topic of my next post. Here is a picture of the second tab in the back that was still in immaculate condition:

It was immediately clear what was missing from the broken off tab: The part that swings underneath the rail rod on which the carriage travels. This keeps the carriage on track even if gravitational forces are briefly suspended during transport etc...

Gluing the broken off parts is futile in such cases. There is no plastic glue that can be strong enough to fix this type of issue. There is just too much torque on the part, while the contact surfaces are really skimpy and no match for the acting forces. So I set out to design a creative solution based on a 3D printed part. This is what I came up with:

The small tab clamps into the gap below the tone arm counter weight and holds the part in place. The bent section of the part goes underneath the rail holding the carriage in place. Here are two pictures of the part installed:

The part clips into place with a solid click and pretty much holds itself in place without the need of glue etc...I will nonetheless glue it once I am confident that it does its job well, to make sure that the Beogram survives its return journey to Japan. It is a pretty interesting process to design such a custom part since it needs to fit an already existing part precisely. This required a number of trial and error iterations until a satisfactory fit and a happy 'click' were achieved. Here is a picture of all the iterations that I printed before I had the one that is shown installed above:

If you look real close, every one is different. A lot of effort, but now the carriage of this Beogram is again held in place safely! At least in the back, the repair of the broken tab in the front will be the topic of my next post.