1219/29 dearing ring repair and more.

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dualcan
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1219/29 dearing ring repair and more.

Post by dualcan » 09 May 2018 19:07

Hi,
Having received a request to repair 1219/29 tone-arm with a broken dearing ring from a fellow V.E. member , I asked him to send me some info and pictures of the afflicted arm. All seemed straight forward from the pictures but as a precautionary measure, I asked that he send me a few extra parts such as the main lever and all the components that make up the arm, minus cart and C weight. Since the Anti Skate spring was loose and missing the supporting half moon, I requested the segment, the spring and its support arm in order to re calibrate the spring as close as possible, without the unit in front of me.
The parts were packed extraordinarily well and no damaged was caused in transit:
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Once I opened the parts, the arm seemed OK without any visual damage as can be seen in my usual check against a chassis edge (note straight/parallel clearance between chassis and TT edge):
DSC00004.JPG
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Things however did not look right with the bearing traverse bracket and the Alu tube, so I inserted a counter-weight shaft which did not enter all the way (first clue!):
DSC00005.JPG
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and now the arm shows it is no longer straight. The bent is not visible because it is right at the edge of the bearing traverse:
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We now see the bent in the arm. I had to pull out the tube from the traverse
If the arm is not straightened, all the adjustment for auto lift height (Start) and cue alignments will be unachievable.
In the next section we will see how to straighten this bent and once the arm is back to form we can proceed to the dearing ring repair plus other work that the arm requires.

To be continued.
k

dualcan
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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 09 May 2018 20:40

To get these tubes straight, I have an assortment of cylindrical rods, starting with Philips screwdrivers for the smaller diameter tubes, right up to heavy 12” nails that fit in the very large arms (1009/1019).
Since North American tools etc. are imperial O.D. measures, they fit like a glove inside the metric I.D. arm tubes.
For the forced insertion, I usually wear a leather glove to get a grip on the alu tube. This prevents damaging/crushing the tube. The spike/ nail etc is coated with some Vaseline or such and held in a vise:
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Final inspection is again on chassis edge (pic is interim straightening stage ..):
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Once the tube is correct, it is re inserted into the traverse, but since we have it out, it's a good time to wash out the bearings in isoprophyl alcohol:
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Once that is done and the Alu tube cleaned, it's time to re assemble. To hold the tube in place, I use Loctite medium strength to allow corrections- if needed:
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The alignment for the arm it is to lay upside down and assure the head and the traverse lay flat on the table. The rear edge of tube must be flush with the bearing traverse (shown in next entry).

To be continued,
k

dualcan
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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 09 May 2018 21:29

Seen here is the back end of the arm which must have the alu tube and traverse flush as outlined previously:
DSC00045.JPG
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The arm is now complete and a visual check against the chassis edge shows this:
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I forgot to mention earlier that the sound cables have to be removed from the arm/tube very early on. This is easily accomplished by lifting the cable pc plate up from the head with the aid of a small screwdriver.

The arm can now be put aside and we can concentrate on the broken dearing ring.

The repair part can be obtained from Shapeways :
https://www.shapeways.com/product/D2RFE ... _content=2
It looks rough to start because of the printing procedure (left= prepped part; right= Shapeways, as delivered) :
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All sides need to be cleaned with files and Dremel tool.
The design of the part has taken into account the finishing procedure and therefore is slightly larger to start. The most important item is to perfectly drill the centre hole with a 5mm bit. This hole must be precise as it will guide the new part in the helical lift switch. The inter-fit of all the lift parts is very precise and the hole on this part is key to get a smooth"multi/single" lift later on.
A more detailed procedure on this is on my web page/dropbox:
https://www.dropbox.com/home/Dual%20Sha ... 0218%20518

The old dearing ring needs to be “shaved” of its old “ears” and to that end, I use a Dremel with a router bit. This is adjusted to length via the protector sleeve placed over the central shaft. In that way, unnecessary scratches to the upper ring and to the shaft are avoided:
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To be continued
k

dualcan
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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 09 May 2018 21:53

Care must be taken to remove plastic only until the washer is visible:
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Remove excess carefully all around next with a small file:
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and test fit the part many times before epoxying it (!):
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The top central part of the old "ears" must be level with the brass part, as shown. If need be, file down the part's inner floor and side cut-outs, until the fit is as shown (flush with old top).

to be continued
k

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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 09 May 2018 22:17

Clean both parts carefully:
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and mix a drop of each Epoxy component:
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Drop of mixed epoxy is plenty to hold the two parts together.
Spread a film of epoxy inside the new part but avoid getting it on the central shaft/hole. It is a very good idea to coat the shaft with a film vaseline or such (put on/wipe off). This will prevent disaster if epoxy gets on the shaft...
Now seat the two parts but do not remove squeezed out epoxy on top. Let it dry out four hours or more, then trim it. That way it won't be smeared all over the parts.
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Remember, a small drop to two (max) will do the job. Start by coating the bottom washer with a film and then inside the new part. Check that some squeezed out on top and then the glueing is done.
Again, be very careful not to get the stuff on the shaft or the bearing point inside the upper ring!

Next part - the alignment.
To be continued,
k

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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 09 May 2018 22:50

In order for the parts to align and move properly, I found the simplest way was to use the lift switch and the mounting component as a holding device. This ensures that the two new “ears” sit properly in the helical path of the lift switch.
It is vital that no epoxy is near the central shaft or on the outer edge of the new part, otherwise we get a rock....
To help along we can use grease on the shaft and in both helical paths to get the parts seated and moving properly,
For the first four hours or so, the epoxy is still flexible enough for minor corrections. During this time, the helical switch lever can be rotated (as shown below) to see if the lifting is nice and smooth.
With that in mind, place the freshly glued ring into the bushing. I have it loose, mounted on a metal tab, simulating the chassis, but it can also be done on chassis. Don't forget the lifting spring...
Rotate the switch lever to see if it rotates nicely and does not catch anywhere in its travel.
Lock the dearing ring with the nut on bottom so it can't come out. Place chassis up side down similar to the way I place it in the vise. DO NOT place the chassis on the arm.... Use the cardboard service ring as shown in the Motor Service guide above in Dual Service
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The ring now needs to cure for 24 hrs. Once done we can re install. For that purpose this arm will be mounted into my mule 1219 and tested. Once the arm is calibrated, the next step will be to reset the AS spring. That's also a big job, as we will see.
To be continued.
k

tcolegrove
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Re: 1219/29 dearing ring repair and more.

Post by tcolegrove » 09 May 2018 23:39

Wow... Your skills are amazing! Thanks for this thread. It's very informative.

dualcan
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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 10 May 2018 19:33

At this point the dry epoxy that bulged out is removed from the dearing ring:
DSC00048.JPG
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and surfaces filed/sanded back to shape:
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To fill any gaps in the top surface:
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I found that Tamiya putty work well and does not shrink:
DSC00051.JPG
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when filling these cracks:
DSC00052.JPG
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Both putty and the paint (Tamiya TS 29) I will use, can be had at a hobby shop.
Once the putty is dry, the final sanding, prep and final paint can be carried out.
In the meantime we can-
to be continued
k

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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 10 May 2018 20:21

work on the tonearm.
At this stage, cleaning the pc board:
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with a fibre glass pencil eraser or with baking soda/Q tip, will get the contact surfaces clean. Don't overdo it, as this surface is silver coated (hence the black silver-oxide).
Once clean:
DSC00054.JPG
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it's time to shove it back into the arm with the aid of a fish wire. Here I use a telephone solid strand cable 20awg or so, through arm, then soldering it onto end of sound cables:
DSC00056.JPG
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and pulled trough tube and rear oval cut-out in bearing traverse. The pc board is subsequently put back into the head by sliding it into the rails provided:
DSC00057.JPG
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You may may occasionally see a blue translucent insert between the metal head and the pc board.

Each of the four (or five- with the coloured low cap wires) can now be measures for conductivity:
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If one of them is capricious, then it is an easier task to remedy this now, as opposed to when arm is fully mounted.
The reading states 2.9 ohm. Bear in mind that this value also includes the two test leads. If you short these leads then you will find a value (in this case 2 ohms) which should be subtracted to get the actual resistance. Either way, the important thing to remember is that the four (or five) wires exhibit the same, or nearly same value.
At this stage we can clean and polish the arm, tracking force dial and intermediate dearing ring (item 56 / 1219). Do not forget to wash out the two bearing raceways (top / bottom) of the intermediate ring.
If I find no excessive dirt or rust in these raceways during cleaning (bearings are not frozen), I tend not to lubricate but run them run dry. Over time normal oil in these tiny bearings will attract dust and become stiff- normal oil just exasperates this. If I do see some rust during cleaning, then I do lube these sparsely with very thin synthetic ester oil, the same on I use in the motor (Chemlube 201).
The advantage with the ester oil is that it will not thicken but will evaporate over along period of time.
Next, we will mount the arm into the intermediate gimbal/dearing ring, but first-
To be continued,
k

dualcan
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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 10 May 2018 20:51

we need to make sure the tracking dial is set properly. In the tone arm removal instructions, one of the first item prior to removal is the advice to turn this dial back to zero. If this is skipped, then we have a problem setting the dial later on.
To verify that this setting is correct, look at the metal tab on the side of the dial wheel. It must be fully counter clockwise and touch the rest post provided:
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Be careful with other dials as Dual also used dials that spun the other way (704/721 etc.) which would need to have this setting clockwise.

We can now pop the dial onto the arm, making sure the inner spring "hook" is at the top:
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and pop it onto the cut out provided on the bearing traverse.
Carefully insert the arm ino the intermediate ring. I prefer to shove the arm through head first:
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Once the arm is in position, we can line up the tracking wheel with the hole for the bearing screw:
DSC00062.JPG
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And insert the long bearing screw on this side which is LEFT HAND THREAD:
DSC00063.JPG
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The tool required for this unit is a crabeye tool which inserts into the two slots avoiding scratches on the bearing screw.
This screw is carefully turned into the tracking dial until it is seated. With the tonearm perpendicular to the legs of the intermediate gimbal, align the dial wheel's "0" to coincide with the white marker line on the arm. We will revisit this alignment later.
k

dualcan
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Re: 1219/29 dearing ring repair and more.w

Post by dualcan » 10 May 2018 21:30

Here is the view of that previous "0" to line adjustment:
DSC00064.JPG
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Now things get critical. We first insert the left side (and right hand turning) bearing pin /screw with a screwdriver:
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During this procedure the pin must be directed to the centre of the raceway. If it hits the outer edge of the raceway, the bearing will be damaged. I insert this pin just a turn to hold and immediately shift the arm over onto that pin. The arm is now centred onto both pins and the right side pin can be turned in further until it just seats. A very delicate touch is called for here... There will be no discernible play in the bearings at this point. Now slack off the pin by about ten degrees, as seen on the pin slot. This should give just a tiny bit of play, when the arm is moved up and down within the gimbal. Now the bearing tool is used over the screwdriver to tighten the counter nut. As this nut is tightened, the amount of "play" may change, so retesting and resetting is the order here.
Once both bearing pins are placed, we can perform the vertical bearing test which is simply done with a stamp. I use a small vise with rubber caps on the jaw to hold the gimbal/arm.
The cart and counterweight are now added to the arm and all is suspended as shown then balanced out perfectly:
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Note: the stylus is not necessary to be inserted, as long as the arm is balanced

Dropping the stamp on the arm must lower this arm completely:
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At this time, we can revisit that "0" to line adjustment again:
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Providing that the gimbal is mounted in azimuth and the arm is balanced (water level)
the "0" and line need to coincide with the two lines meeting. This is can be corrected by slacking the right hand screw (remember: left hand thread..) a bit and adjusting the dial.

Always re-check the bearing play when working on the bearings and carry out a bearing test afterwards.
To be continued,
k

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Re: 1219/29 dearing ring repair and more.

Post by babadockia » 11 May 2018 05:51

Holly molly! God bless your soul!

dualcan
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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 11 May 2018 17:35

Once the putty is dry, with completed sanding (here using the riffler file as a straight edge):
DSC00071.JPG
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and subsequent alcohol wash, spray painting can begin:
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To protect the needle bearing inside the ring, I use a piece of blue tack, but bubble gum will also work- it's a matter of taste 8) ...
As stated before, the closest paint I found in Tamiya TS 29. It has the right colour shade, sheen, and dries fast. Applying several very thin coats is better than on blob..
Instead of painting my fingers, with age comes wisdom so now I hold the ring using a plastic bag as a glove. Another long tube slipped over the ring's shaft extends it out further enabling a better spray job:
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Once painted and dry, we see that the chrome trim is also covered with paint:
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Luckily the engineers of the day where nice enough to raise this surface , which enables us to clean the area very easily. Use a straight edge (small metal ruler will do) to support 600 paper. Also use a plastic edge which lies on the repair at 90 degrees. The trim ring can now be safely sanded without destroying the lower section paintwork:
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The key to success for a clean paint job as always, is to let the individual steps dry before going on to the next step.
--and next will be remounting the repaired dearing ring onto the prepped arm.
To be continued,
k

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Re: 1219/29 dearing ring repair and more.

Post by mrow2 » 11 May 2018 18:33

This is beautiful work! I have a minor suggestion: At least in N. America there is an epoxy product called JB Weld (Home Depot and the like; others have also mentioned it), comes in package just right for many small jobs. If you examine the package you'll see why it is very strong. Also, as Klaus mentions it can be adjusted well into the setting period and by 24hrs it can be handled. It is gray and has invisible microscopic filings in it which add tremendous strength, once cured. Someone might be tempted (believing that all 2-part glue is the same) to use the dollar-store variety for this job, and something like what Klaus suggests (high quality product) can matter a lot. J-B will file and accept paint as Klaus describes. Could also be used in place of the putty, and while stronger, the putty will be easier to handle. What a repair!

dualcan
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Re: 1219/29 dearing ring repair and more.

Post by dualcan » 11 May 2018 18:46

...and here is the final repaired ring:
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You might have noticed that I did not spray the ring completely. If the original paint is still OK, it is a harder surface than the air-dry respray. Tiny "dings" on the upper surface can be covered easily with a permanent marker instead...

Slip the arm onto the repaired ring by backing it into the ring:
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To seat the bearing pin and counter nut on top, we use the same tools, procedure and caution as before:
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Here is a close-up of the crab-eye tool and screwdriver inserted into pin and counter nut on top of the ring:
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Once the bearing play is adjusted as required, the arm is complete and ready to be re attached into the chassis:
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A note on bearing play: we need play in these fine bearings because of the nature of the metal parts. With varying temperature, the assorted metal rings will contract or expand which can cause a bearing joint to be too tight, thus hindering movement.

As an aside, this is where the later "plastic" dearing ring /arm parts are superior since they are immune to temperature change. The other plus is that the plastic parts are lighter, which reduces the bearing friction again. As well, they are non conductive- a big feature in ground noise/loop issues.

Because the friction of these arm bearings are so low, (0.007 p measured at stylus point), we need to keep that bearing "sloppynes" as small as possible. Only with clean/polished bearings can we expect the arm to perform perfectly in all planes with 0.25g tracking. That's where the precision on these arms start.
Earlier on in this thread, we did a vertical bearing tests with a stamp. For the horizontal test, we need an anti skate force of similar size. This needs to be done with a properly calibrated Anti Skate system. As the client's unit had the anti skate spring removed, I will also recalibrate and set all the A.S. parts and subsequently verify the horizontal bearings.
To that end, the arm and most of the A.S. parts on my mule 1219 will be removed and the client's arm and the required A.S. parts mounted in place. The arm's removal process is covered in the service manual , but I will take a few snaps from this procedure as well. That will be next, so stayed tuned.
Regards
k

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