Jumping in with a turntable project...

[Jim Leach]

Hello everyone!

I've been a bit quiet here lately.. Waiting for my D/A board to arrive and my drive gear(s) for my Theta Data.

BUT, I had an idea: I'm going to make a turntable!

I have read several threads on here (some QUITE long) and have a pretty good idea of what I'm going to do.

Bearing: I will probably make this myself. A beefy stainless shaft (1/2"-1" OD) running on a ceramic or sapphire ball in a brass sleeve (with Redline D4 ATF oil bath). The large diameter is for stability of the bearing yes; however it is also to allow me to close a collet on the shaft and use the actual shaft as the axis for turning the platen once the rough platen is attached to the shaft. This will ensure the platen is perpendicular to the shaft within 0.0005" or so, which I think will be good enough. I wish I had access to a dynamic balancing machine like the one used by the other shop next door to us in West Virginia!

Motor: I want to use a hall-effect servomotor. The quietest one I can find (as of now) is this one: http://www.teknic.com/files/product_info/1726_V3.3.pdf at $160.00 it is pretty cheap as well. I am open to any suggestions to alternate motors!

I think the platen should be MDF/Carbon fiber laminate. Looking now for carbon sheet (baked) as well as loose cloth, as I think wrapping the chassis with carbon will look cool. Possible paring with Cocobolo, but that is WAY down the road.

Drive pulley will be simple brass. I can make it whatever diameter I need.

"belt" will be a nice o-ring

I am going to try and get some sink cut-outs of granite- black with some luck- and use that for the sub-base.

I am toying with the idea of suspending the mid-chassis with small air springs. They look like little shock absorbers. Three of those should isolate the top well, and it will be easy to adjust level with two of the three on some kind of threaded posts.

I am currently trolling eBay for tonearms, as I am not at a level to be making that! An RB300 would be fine; but certainly open to any and all suggestions!

So, let the games begin! I want to get the motor at least in hand before I go crazy making other items, only to find out the motor won't fit my intended design... So that is the priority right now!

Thanks in advance to all you big black disc players!

[c2cthomas]

Hi Jim! Good luck with this. I keep thinking about doing a TT but seeing as how my vinyl collection is rather small I think my time is better spent playing around with a music server. Once upon a time I repaired TT's and still have a fascination with things that go round and round, especially when done well.

Watch out for cutting and grinding the carbon fiber materials - it can be nasty stuff to clean up and you will want some proper breathing gear.

[Jim Leach]

Actually, my small vinyl collection is one of the main driver's for this, believe it or not!

I would be quite happy with a Rega P3, but for the money, I thought I could make something quite nice- a true piece of art to behold while listening to CD's for example.

And, as to the carbon, I have worked with it before. It is VERY nasty stuff. Equally nasty is the epoxy used to hold the stuff together (I use West System). Good advice for those who have never worked with it however!

The cloth is a real pain to work with as it wants to stretch in every direction. I may stick with inlayed sheet pieces to complement the wood (or maybe aluminum) for the other components.

I suppose I will need a very stable power supply circuit with some adjust ability to 'dial in' the speed. I was thinking a momentary switch with a strobe would be neat- how many marks do I need around my platen to give a 60hZ strobe at 33.3 RPM? I think we have a Haas dividing head in the model shop, so I can rig that up once I turn the OD...

I have a lot of projects going on right now (wedding, house reconstruction etc.) but I want to do this. I am looking forward to any and all input as I get going on this!

[Jim Leach]

UPDATE:

I have done the plinth in MDF/birch ply laminated. The very core will be Lexan, which I hope to back-light so the table 'glows' when it is on. Should look cool!

I am designing my main bearing now. Probably another 3-4 hours designing, and then I can cut material.

I have found a DC motor that I like WAY overkill for this use, but better too big than too small. Should be ordering that this week or next.

I am going to make my tonearm 14.2" long, so an off the shelf arm will not do much other than give mt specific dimensions and design ideas. BUT, I am still looking for any and all unwanted tonearms (in any condition!)

It is going slow, but it is going. I hope to have this done by the end of the summer.

[c2cthomas]

Good progress Jim!! Would luv ta see sum photo's when you get things sorted out.
A couple of good sites to visit

The Crossover Network http://www.thecrossovernetwork.co.uk/forum/index.php

The Vinyl Engine Vinyl Engine | The Home of the Turntable

[Jim Leach]

Thanks for those links!

I am registered and have a similar thread going over at the engine already. But, thanks for the link! To anyone else considering this project, that site has a TON of great information, and a lot of DIY table builders. Plus some very smart guys (not that we don't) who know more about table design and design considerations that I would have ever found otherwise!

Here's some pictures too!

First one is the first idea for the look. I cut some scrap material at 30 degrees back-angle to have the lexan recessed into the plinth. It looks cool, but the resultant sharp top edges seem too fragile, and will end up breaking off over time.

So, I have a new design I will mock up tonight.

Second photo is just the 20 X 20 pieces ready for additional work...

[Jim Leach]

Almost a year later...

So the plinth has not progressed beyond what is shown above. Big surprise.

I have found and read more on turntable and tonearm design considerations than any human should have to endure. BUT, I have finalized the drawings of my (scratch built) tonearm- Version three- and I'm having parts made now (well, when he has time anyway). The arm will be carbon and OFC. It should look pretty nice!

The platen bearing was also scrapped in favor of a complete redesign (yet to be done). I want to use an inverted bearing, but recently learned quite a bit about proper platen design and intend to follow that. I also want it to be an oil-bathed inverted bearing, and making all that happen is a bit difficult with gravity being what it is and all (damn physics!)
So that's the update. Not much of one really, but I easily have 60-80 (part time) hours into the tonearm design, with a few components left to design.


So, sorry I've been away... I'm married now (almost a year already!) and have done a lot on the house (with no end in sight) It seems the more I fix, the more I find messed up. (climbing into the attic tonight to see what's up there...

[c2cthomas]

Originally Posted by Jim Leach

So, sorry I've been away... I'm married now (almost a year already!) and have done a lot on the house (with no end in sight) It seems the more I fix, the more I find messed up. (climbing into the attic tonight to see what's up there...

NOOOOOOOOOOOOOOOOOOOOOOO - NOT THE ATTIC!!!!

Goooooood ta see ya back Jim! Ahhhh.......... your progress speed matches mine nicely - still have a amp I built a year ago and need to get around to putting it into a case.............

[Jim Leach]

He He.. The wife is a bat-a-phobic (not sure what that is) and is SURE there could be BATS in the attic!

Anyway, the access was sheetrocked over so this will be a messy job (did I mention she's a germ-a-phobe too?)

[kevinkr]

Congrats on getting married. Did that myself almost 5yrs ago (second time around though). Can't wait to see more of your TT project.

Know all about household projects, my 100yr old house keeps me quite busy at times. Attic... <Shudder>

I'm less ambitious, restored a TD-124/ii a few months back. Listening to it now.. Amazing..