I got 250- 1/4 inch or 6.35mm steel slingshot ammo from canadian tire for 4.99
For the the rods I used the shafts from aluminum arrows also bought there
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Just my thoughts. 
Presumably the unit should aim for mnimum friction and rolling resistance.
How smooth are carbon fibre shafts? can they be smoothed and polished?
Prehaps 1000 grit wet & dry then polish with car paint cutting compound.
Rolling resistance and inertia on the ball bearings
steel is heavy so more inertia
in an ideal world ceramic would be lighter and better. (I think)
What about the diameter? Bigger = less rolling resistance but greater inertia.
Where is the compromise?
Dust and grease from the air will increase rolling resistance so what about a cover?
Presumably the unit should aim for mnimum friction and rolling resistance.
How smooth are carbon fibre shafts? can they be smoothed and polished?
Prehaps 1000 grit wet & dry then polish with car paint cutting compound.
Rolling resistance and inertia on the ball bearings
steel is heavy so more inertia
in an ideal world ceramic would be lighter and better. (I think)
What about the diameter? Bigger = less rolling resistance but greater inertia.
Where is the compromise?
Dust and grease from the air will increase rolling resistance so what about a cover?
Materials
Hello Everyone
I'm using aluminium tube for the runners and carbon fibre tube for the rolling carriage-just because I had them to hand. Steel balls-add so little in weight as to be insignificant. It all works perfectly. All you need is a small artist's brush to go over the tubes every so often therefore I don't see a cover as being a requirement.
Chris
Hello Everyone
I'm using aluminium tube for the runners and carbon fibre tube for the rolling carriage-just because I had them to hand. Steel balls-add so little in weight as to be insignificant. It all works perfectly. All you need is a small artist's brush to go over the tubes every so often therefore I don't see a cover as being a requirement.
Chris
Hi Mortron,
Here is something to consider in your choice of balls. Depending on humidity in your house and climate and how clean you can keep the balls it is possible that steel balls could pick up moisture and fingerprint acids etc making rust a possibility which will increase your rolling friction. So far I am using plain old steel balls in 4mm size and dry polishing before transferring them to the track. I hold them with a piece of dry tissue. My suggestion is to use ceramic or silicon nitride coated ones but keeping them as clean as possible. As Chris says, "all it has to do is roll".
BillG
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Thanks BillG, that's some good advice. I'm in a basement and would probably benefit from the silicon nitride balls. Nothing worse than your balls getting rusty in damp conditions and affecting how performance... I assume even the smoothest shaft in the world can't compensate for funky balls. 
I was looking for parts at the surplus today and saw some nice steel linear shafts but am not sure they were 6mm. They had black looking balls as well and wondered if they were nitride and the right size... May have to return when I've more time.
Pursuing a simple aluminum tubing may be easier than using solid rod as the electronics shop I frequent has a hardware store above with aluminum and brass tubing. The tubes can be filled or damped to taste. The balls I will have to Ebay.
ChrisG139: do you have any intention of experimenting with an aluminum top carriage instead of the CF? If so, what are you hypothesizing? I am wondering if the CF has some damping properties that are beneficial in this design.
I was looking for parts at the surplus today and saw some nice steel linear shafts but am not sure they were 6mm. They had black looking balls as well and wondered if they were nitride and the right size... May have to return when I've more time.
Pursuing a simple aluminum tubing may be easier than using solid rod as the electronics shop I frequent has a hardware store above with aluminum and brass tubing. The tubes can be filled or damped to taste. The balls I will have to Ebay.
ChrisG139: do you have any intention of experimenting with an aluminum top carriage instead of the CF? If so, what are you hypothesizing? I am wondering if the CF has some damping properties that are beneficial in this design.
Hi Mortron
I will be experimenting at some stage but I've got other projects on at present which are taking up my time. However, the likely experimentation is going to be around the wand and the bottom carriage. People have commented about supporting it from both ends and this is something which I believe would improve rigidity and reduce resonances.
Regards
Chris
I will be experimenting at some stage but I've got other projects on at present which are taking up my time. However, the likely experimentation is going to be around the wand and the bottom carriage. People have commented about supporting it from both ends and this is something which I believe would improve rigidity and reduce resonances.
Regards
Chris
Interesting... the wand you use now is C.F.? I am tempted to use some aluminum extrusion as an arm. Just thin stuff... but my idea in my head and what I can realistically fabricate may not be the same haha.
I have been trying to find some Tubing to build this arm in my area but have come up less than successful. I am in the West End of Toronto.
Trying to find 6mm or 1/4" aluminum tubing that is in 36" or 1m in length. There are a few places that have 12" pieces, but it seems that many people are using 340mm or longer for their bottom rails. I am thinking 12" isnt enough. I have my tonearm wire and balls here... never thought the tubing would be such a challenge.
Trying to find 6mm or 1/4" aluminum tubing that is in 36" or 1m in length. There are a few places that have 12" pieces, but it seems that many people are using 340mm or longer for their bottom rails. I am thinking 12" isnt enough. I have my tonearm wire and balls here... never thought the tubing would be such a challenge.
Thanks PDR.
I have called a few hobby shops but most either dont stock the length im looking for or are quite a way out of the downtown core. I may plan a day one weekend to take a car trip to a few places like Parts Connexion and grab some things I cant downtown. Plus im sure the good shops have plenty of other interesting materials.
The glass blower - great suggestion... I see one around the corner from me. Though I may be less inclined to go with the glass now (maybe some art tho) if this design works well.
Them GRs are super sexy btw.
I might be stating the obvious but try eBay. Most of the materials for my arm were sourced there. Also all of the glass found in art shops is lime glass, the ideal type of glass for this application is borosilicate. It is much harder, has vastly better surface smoothness and is dimensionaly more consistent. It is unfortunately harder to source and is costlier. Try laboratory glass supplies.
EBay is also a great source for balls of all sizes and materials.
Niffy
EBay is also a great source for balls of all sizes and materials.
Niffy
Another Incarnation!!
Hello Folks
I've been working on another version. The testing today was very successful. Many people are concerned about the ability of the arm to track warps effectively-in my view it is a fruitless obsession! However, this new design addresses the (potential) issue-and then some. And sound quality-impressive!
I'll be posting pictures hopefully at the weekend...................
Chris
Hello Folks
I've been working on another version. The testing today was very successful. Many people are concerned about the ability of the arm to track warps effectively-in my view it is a fruitless obsession! However, this new design addresses the (potential) issue-and then some. And sound quality-impressive!
I'll be posting pictures hopefully at the weekend...................
Chris
NO??? NO??? You're killing me! (in a good way)
HAHA.I was having trouble picking between 7/32 (5.556mm) and 1/4 (6.35mm) tubing because of my inability to source standard size metric tubing. I wasn't sure if I would have enough clearance with these 5mm balls. Still want to try this one, but I am definitely staying tuned.
Not so.....
All the tubing at the glass blowers are borosilicate.
Maybe I was not clear.....not art shops.....glass art shops.
The place where glass artists.....you've seen them at the mall making
small figurines....get their supplies. They have a large inventory of both
borosilicate type tubes and rods. The borosilicate rods used on my version were approx 6mm x 600mm long. I bought 4pcs for $3.99....under a buck a piece. Dont think youll get a deal like that on e-pray.
As a side note, I live in a city of 1 million people. I could not source
glass rods or tubes at any of the at least 15 suppliers of lab glass suppliers I tried. They are reluctant to sell them as theyre used for drug use, or your not buying in large lots, like 200pcs or more.
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