DIY oak unipivot tonearm

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Hi Cactus

My father was an engineer in materials and electronics and a big music lover.
He was very much a DIYer in a lot of things (cars, furniture, photography etc. not diyAudio though), and I for sure got the make it yourself bug from him and my grandfather who made his own cameras.

"Make your tonearm out of wood son, t'will be much better."

I think I would conceptualy have to agree.

I have at home a set of well made commercial wind chimes.
They have a nice decay to them, but make no audible sound unless struck by the chimes mallet (not strictly true actualy, you can get a slight organ pipe/flute effect if the wind happens to catch them right).

I thought it would be interesting to make some wind chimes with a much lower frequency and longer decay.
Three chimes were made each 182cm long, in 1 1/2", 2 1/4" & 3 1/2" diameter aluminium alloy tube.
With holes for a hanging wire 1/4 way down the tubes, which I figure is a ideal distance to get them resonating nicely, very low, long decay frequencys were produced easily.

Thought I'd have a go at a cowbell and woodblock next, forgeting the cowbell for now, the wood block proved impossible to get any amount of decent resonance or sound from despite trying various shapes deliberately designed to try and promote this.

Anyway to cut a long story short, if you hang a 2x4 a dowel or a log next to the ally tube wind chimes and give them a bash with a mallet, what do you get resonance or sound wise,

THE SWEET SOUND OF NOTHING.

Cheers Simon...:cool::eguitar:

Hello Simon,

My decision to use wood was based on simple practicality. I have an assortment of scrap wood, the basic tools to form it, and it just seemed a good choice at the time.

One thing that struck me about this oak unipivot tonearm is how 'quiet' it is, quiet in the sense that tapping it vigorously produces little to no ill effect through stylus/cartridge/amp/speakers. I think oak was a good choice, but it's got me wondering what properties and potential advantages fir, ash, maple, etc.... might offer.
 
frugal-phile™
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"Make your tonearm out of wood son, t'will be much better."

Grace made 2 very similar unipivots... one with an aluminum girder and one with a chunk of wood. The wood was the preferred arm.

dave
 

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hello all, from the "latest iteration of Nanook's "219" tonearm thread

Great to see other folks doing unipivots.

cactuscowboy:
the arm looks very good, and I am sure it sounds good as well. I do have a minot comment regarding the arm construction. To create a "headshell" that is integral to the arm, it might have been more suitable create a separate "headshell" piece and glue it to the main shaft. The idea there would be to minimize the stress along the grain (I know I'm being anal).

Your re-plinth and arm look excellent.
 
Thanks for the comments Nanook.

I hadn't considered "stress along the grain" and I'm not totally clear on the point you're making? If you're referring to physical strength or integrity of the headshell/tonearm there's no worry there as it's very strong.

I had considered making tonearm wand and headshell separate, and in hindsight wish I'd gone that direction. As constructed, the offset of the integrated headshell did interfere with working the tonearm wand on the planer and router table.

I've been thinking about the next tonearm. I like the idea of continuing with wood, and wonder if a guy could create a wood tube by wrapping/glueing very thin veneer around a round form, say a 3/8" steel rod. Remove the form and you've got a thin-walled and very strong wooden tube. I don't have a wood lathe so that's what got me thinking in this direction. :)
 
Thanks for the comments Nanook.

I hadn't considered "stress along the grain" and I'm not totally clear on the point you're making? If you're referring to physical strength or integrity of the headshell/tonearm there's no worry there as it's very strong.

I had considered making tonearm wand and headshell separate, and in hindsight wish I'd gone that direction. As constructed, the offset of the integrated headshell did interfere with working the tonearm wand on the planer and router table.

I've been thinking about the next tonearm. I like the idea of continuing with wood, and wonder if a guy could create a wood tube by wrapping/glueing very thin veneer around a round form, say a 3/8" steel rod. Remove the form and you've got a thin-walled and very strong wooden tube. I don't have a wood lathe so that's what got me thinking in this direction. :)

Using a veneer wrap over a mandrel has been mentioned before but I'm not sure anyone has actually done it.

Layers of paper and glue might also be used I suppose, they've built canoes with layers of butcher paper and weldwood glue and they turned out pretty sturdy in actual use.

Best Regards,
TerryO
 
Terry,

Moray suggested this to me about 2 years ago, building an arm with paper (preferably some very nice rice paper or such). If foam filled, it could be a very strong composite arm...

Stew,

Instead of filling it with foam, how about taking 2 pieces of foam, cutting a groove down the center for your wires, then gluing both halves together and then tapering it. I suppose it might be possible to mount it vertically on a drillpress (poor man's lathe) and gently turn it down. You could then follow it up with paper & glue (or even thinned shellac) as necessary.

This is just a idea, you're the expert and you will probably see all kinds of flaws in my mindless imageneering.
You know, I might just get off my lazy A** and actually try it when the weather turns cold.
:D

Best Regards,
Terry
 
Terry, I'm no expert...

and just because an idea isn't mine doesn't mean it doesn't have merit. I do however like keeping things simple, and I am a little impatient (it would drive me nuts to wait to use the foam/paper arm). Until the arm was in a final state, I'd probably ruin a bunch of them...

The merit of ultra lightweight and self dampened construction has its own appeal, but having an arm too light can create problems as well. The idea of making an arm using foam as a form to wrap whatever kind of material around it, does make sense, but enough material would need to be added until a particular weight is reached.
 
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Interesting ideas!

I've been thinking about the laminated paper or wood veneer tube concept. I like wood from an aesthetic standpoint, but it would have to be very thin flexible veneer resistant to splitting to work. As for a form or mandrel, perhaps a plastic soda straw would be a good non-stick base, with a steel tube to hold its shape while fabricating.

Also open to ideas and comments regarding aluminum, brass, carbon fiber, fiberglass, bamboo, types of wood, pros & cons of each, etc...
 
Hi Cactus

I've been thinking about the next tonearm. I like the idea of continuing with wood, and wonder if a guy could create a wood tube by wrapping/glueing very thin veneer around a round form, say a 3/8" steel rod. Remove the form and you've got a thin-walled and very strong wooden tube. I don't have a wood lathe so that's what got me thinking in this direction. :)

Hi again Cactus Cowboy

I'm afraid that I might have caught the tone arm making bug from all the great inspiration on the site at the moment.

I'm just guessing, but seeing as you've just made a unipivot arm, then a gimble type arm might be next on your list.

I have recently made a miniature 'steadicam' the simple device patented by Garrett Brown (steadicam photographer on Kubrick's 'The Shinning', still some of the best steadicam stuff ever done I think).

I found that when making the steadicam the brand new ball races I was trying to use were not 'beded in', and whilst the amount of oil/grease they contained is fine for 1000rpm the fact that a steadicam (or a tonearm) never ever does a single whole revolution in it's life, made the unbeded and grease thick bearings unsuitable, due to way too much friction.

Eventualy I thought of using secondhand (and totaly free both in $$$'s and friction) bearings from scrap VHS players which you can literaly find on every street corner.

I have now taken apart 6 VHS players and apart from getting free transformers, capacitors and the like, they are a great source of precision mechanical parts.
Every video head I have taken apart has perfectly worn-in (not worn out) bearings inside it and 6mm dia shafts and bits and pieces to hold and support bearings etc.

The other free source of these types of parts I have also used is busted computer printers of which there are also loads about.

I like your idea of rolled and glued veneer, I would never have thought of that one.

I have also been looking at 10mm id woven carbon fibre tubes, which are extremely light, but rigid, and 18" costs about $15.

I am thinking to make the gimble out of ordinary copper pipe or similar, and fitting the bearings straight is easy, you just put the 6mm shaft through the bearings to hold them straight and run slow set epoxy carefuly round in a fillet between the pipe and bearing sitting in it's hole.

I'm not that great when it comes to wood, but I might have a go, as I think a wooden headshell would be cool.

My idea for a ready made movable weight, is to use 'shaft collars' available in loads of different diameters, in stainless steel & aluminium for $3 a go from engineering suppliers (haven't figured out where to get those for free yet, damn).

Thought I'd bung in a few ideas that have helped me.

Have enclosed some photos of the miniature steadicam, which was made using only a hand drill and a load of files.

There's a cool site called homebuiltstabilizers.com if you want to check out peoples DIY steadicams.
Have also enclosed a PDF paper on 'dynamic balance', it's written for steadicam guys but is just as applicable to tonearms (it's an interesting read and not full of 'Hi-Fi' gobbledegook).

Cheers for now. Simon....:cool::eguitar:

Also you've inspired me to take my Dual TT out of it's existing plinth, and make a new chunky wood one, which I think will suit it. Also taking the old arm off to use as an experimental test bed for the DIY arm. Oh no, not another project, I've got 2 TT refurbs to do now !!!
 

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I'm just guessing, but seeing as you've just made a unipivot arm, then a gimble type arm might be next on your list.

No, actually, I intend to continue with unipivot.

I have a number of high quality turntables (nothing uber expensive) which are all equipped with conventional gimballed arms. I look at my Technics SL-1200 for example and I know that I cannot DIY an arm of that design that comes even remotely close to the quality and performance of the Technics. Keep in mind I don't have a machine shop, so I can't attain high levels of precision in any tonearm I build.

Unipivot is a different story though. It's such a simple design (small number of parts) and the one highly critical part, a super low friction bearing with zero play, is easy to obtain and inexpensive.

Thanks for your detailed post, you've given me some good ideas, the use of "shaft collars" as counterweights for example.
 
Very interesting tread. I have stared working on a Naim Aro inspired tonearm with a carbon fiber tube. I will check out the unipivot bearing you suggest.
Until now I have only used a ballpoint pen and a 6 mm stainless screw for bearing. the project is under construction.
145580d1342775538-diy-unipivot-tonearm-karo.jpg


Since the carbon fiber tube allows at least 4 projects, I have also started on a Well Tempered inspired arm.
 
Wooden arm

Hello cactuscowboy,
Arm looks quite good! (referring to accompanying photos of post #7) I especially like the vta counter stabilizers. I had observed one part which when I build my arm, will implement different. It is the actual 'unipivot' location. I believe the center of gravity could be much lower, negating the use of so much outboard stability weight.

regards, Francis
 
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