DIY Tonearm

[jls001]

Two weeks!!!

I re-sanded the surfaces with lint free cloth (a.k.a. old tee shirt) and removed all traces of the gummy deposits. It was a lot of hard work

Now some of the surfaces have a wet look but there is no stickiness. Though all the wood that I've used are Burma teak, they vary wildly in colour and grain. The arm tube is pale cream and looks more like fir wood (I didn't know teak can look so pale), whereas the tonearm base has a mix of the more usual brownish shade with deep brown streaks. The arm rest support, cut off from another plank, is more uniformly brownish and has uniform grain, and looks closest to the grain and colour of antique teak wood furniture.

I guess I'll have to wait for the wet look to go. Meanwhile, I can refresh my near-nonexistent spraying skills on some dummy surfaces. Need-based learnings do have its pitfalls

 

[keith_correa]

Two weeks!!!

It can take upto a month

It's turned gummy because it is hardening - being a drying oil. The problem is the long time it takes to dry.

Now if you spray lacquer over it before it has dried fully...

 

[jls001]

This is how they look now. Satiny, smooth due to buffing, and dry to the touch. I'm not sure if the pictures convey that. Look at the left portion of the arm tube picture - that's very close to how it looks in real life. The right part of the pic is over exposed as that's the direction from which light falls.

 

[jls001]

Some progress - made counterweights - one about 110 grams and the other about 140 grams.

 

[jls001]

Now if you spray lacquer over it before it has dried fully...

May be you'd like to complete the sentence?
Come on, don't be shy

 

[jls001]

OTOH, lacquer it now and see how things turn out. If the finish is less than satisfactory, sand it off and re-do

 

[jls001]

Did the deed. Sprayed lacquer on bottom surface of arm rest board. First application was an unmitigated disaster - had sprayed too much, and the liquid was dripping copiously

Luckily it wasn't hard to remove it completely with rubbing cloth after it had dried partially for about half an hour. I got it right the second time round. It's nice and shiny and uniform now. Applied second coat and waiting for it to cure.

 

[jls001]

Pic updates:

Waiting for curing

 

[kaushik]

looking very nice ....in DIY we have to do many attempts , and keep looking if failed
I was after a stepped mechanical attenuator fully diyed 2-3 proto failed
over time got another idea with some pin headers ..with a linear movement
i will sit with it and pull some workable model this time

 

[jls001]

After waiting patiently for forty eight hours for the lacquer to cure, I've put it back together.

The portion which rests on the arm rest gains a transparent heat shrink sleeving to avoid ugly scuff marks. The arm rest bracket is also sleeved. I made a fresh arm rest as the previous one gripped too tightly. I used another material for the bracket as the paper clip I was using was too tough to shape properly, and I could not achieve the desired bends. Plus, if over bent, it just snaps.

I also managed to break one cartridge clip. Luckily it was a ground wire so I can get by three wires in my current cartridge.

Below : The counterweight can hit the bottom when the arm is lifted off arm rest. So it will need reworking. During normal play it doesn't foul.

Also pending is a proper arm lift. I've got the parts and need to figure out how best to make it work. Otherwise it is making sweet music.

 

[jls001]

Higher hanging counterweight made. Now it doesn't foul the bottom when lifted.

 

[mahiruha]

Hi Jls,
very interesting project indeed and congrats for making a well functioning arm that is already making music. Just saw the picture of the counterweight you have made and it looks very interesting. You can also try making a counterweight like ISOkinetik ISOweight asymmetric upgrade counterweight fits VPI JMW tonearms 143g | eBay so that you can push it straight into the tonearm and you can easily adjust azimuth by rotating it.
In this particular arm how you are tackling the problem of VTA and anti skating ?

Thanks.

 

[jls001]

@mahiruha: if you see the last pic, notice the vertical brass pipe. It has an 8 mm diameter brass rod passing through it. The brass pipe is fixed to the rectangular white metal piece. The brass pipe can be moved up or down to adjust height. There is a 4 mm grub screw that fastens the brass pipe to the rod inside (after adjusting desired height). Adjustability is 3/4 inch.

There is no antiskate arrangement as this is a medium to heavy mass 12 inch arm. It works well without applying AS.

I had thought about the counterweight you suggested but went in favour of something that is suspended well below the axis of the arm tube, to lower the overall CoG. My design for counterweight bracket allows azimuth adjustment.

 

[Hiten]

Tonearm looking nice joshua.

 

[jls001]

Since this is a DIY tonearm, I wanted to DIY even the arm lifter. The initial version was too simplistic, and it had no damped drop. Also, more grievously, it could not drop the stylus to the exact desired groove position.

So I had to rethink a better one that will do vertical lift and drop and also provide some amount of damping. I ruled out silicon oil damping as the housing becomes too stringent for my limited knowledge and skills. All orifices need to be leak proof.

So I carefully studied an arm lift I tore out from a non working TT that fellow forumer Shafic was kind enough to donate. I got additional ideas from the Nanook 219 thread over at diyaudio.

After many half successes, this is the outcome.

The black barrel is cannibalised from yet another luckless pen I had to design the internal mechanism to fit the limited volume of the barrel. For a first timer like me, it was quite a challenge. The above picture shows prototype number three.

Will fit it in the arm and see if it works as designed. Here's hoping it work on the arm. It seems to be working OK at least on the test bench.

For those who might be interested, I'll post build pics later.

 

[Record Player]

Great going Joshua. Everything is being planned and executed perfectly.

Any chance of posting a video of this arm singing?

 

[Sumanta]

I am not clear how it is going to work, so a photo of the system in working will help me a lot.

 

[jls001]

I'll build a proper barrel to replace the pen barrel. The pen barrel is quite a bit thinner than ideal. I plan to use screws to the fix the arm lifter barrel to the wooden plank, like I did for the bearing support. For this, the wall of the barrel needs to be much thicker than the pen barrel's so that it doesn't deform under the pressure of the screws. Need to make a new wood plank as the location of the hole I already drilled for the arm lift is not really ideal.

 

[jls001]

New barrel:

Need to rework the cam shaft. Drop action is nearly where I want it to be, but it can be more deliberate. It needs a fine balance of friction and spring action.

 

[Sumanta]

You are putting brands under shameful condition and inspiring us to follow you the way you follow your passion!