DIY linear tonearm

yes, Niffy - that someone is capable of keeping that kind of measures/tolerances with a simple handheld graver is something difficult to accept. Even worse is when, trying to make something like with the usual cross slide you'll break the piece, or the tool, or both - due the lack of sensitivity. That's why ii's done that way.
First years with my lathe were a great school of humility.

Dahlberg- those screws seem very well done: now thread the inside of a 3mm inox rivet with a 2mm or 2,5 tap for the bushings, and you get all you need: exactly what done for Lil Casey parallelogram

carlo
the CNC video hurts me more.
 
Those grub screws look almost like they have the vees already done but I suspect they are the larger size M10 or more. A flat ended grub screw would be an easier starting point. Such as these.
M3 M4 M5 M6 M8 M10 M12 A2 STAINLESS STEEL FLAT POINT GRUB SCREWS / BOLTS | eBay

For the pivots I used these.
Prym 0.80 x 48 mm Glass Headed Pins, White 689828646746 | eBay
They are already shaped most of the way to what we want and they are made of hardened steel.

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I dug out my old steel bearings.

Niffy
 
numbers vs real world
"You sort of get how small these things described are when you see them. The dent I made was ~0,5mm in diameter and in drawing it still looks big. Well, it ain't"

That's the reason for those links of watch making: when you try to get tolerances of a few cents on the lathe (the pieces of my arms are all press or shrink fitted, in order to resonate as a single one) you learn to have a sacred respect for Them, and never take Their name in vain.
As for the Microns it's said They exist, but i've never met one, like unicorns or martians.

carlo
 
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That's the reason for those links of watch making: when you try to get tolerances of a few cents on the lathe (the pieces of my arms are all press or shrink fitted, in order to resonate as a single one) you learn to have a sacred respect for Them, and never take Their name in vain.
As for the Microns it's said They exist, but i've never met one, like unicorns or martians.

carlo


OK I'll bite.

These are photos of the brass inserts for the VTA blocks 11.011 and 11.015 - 4 microns between the bushes, machined on the lathe from12mm brass rod. Block bore was 10.970 for a 40 micron interference fit. To get tighter tolerance you need to polish with emery.
 

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Warren, again all the compliments from one who knows how much skill and effort cost those results: not just due a very good lathe, as popularly thought, but having it set up and used up to those tolerances. We had to learn hardly the meaning of that numbers: i.e. my turntable project was never ended, without a suitable spindle (vibration pattern).
My school, 20 years ago, was this 6x16 panoramic camera (as product photographer I bought the lathe to make special accessories for my Sinars). I had to do it 4 times, but at the end it weighs and measures half of a Linhof 617, and with just 2 cents tolerances on the 55x155mm focal plane (better than hasslblad filmbacks).

carlo
 

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My school, 20 years ago, was this 6x16 panoramic camera (as product photographer I bought the lathe to make special accessories for my Sinars). I had to do it 4 times, but at the end it weighs and measures half of a Linhof 617, and with just 2 cents tolerances on the 55x155mm focal plane (better than hasslblad filmbacks).

carlo


I'm not a photographer but that looks very good to me. It does not matter how many times you have make it to get it right as a DIY. It's about the journey and learning. I was lucky, my father was a toolmaker with his own shop so I learned a lot.


I started gluing up the carriage today, so I can work backwards to get the rail support finished.
 
Searching "Linhof 617" on web gives the reason for building that camera (just try to backpack it...).
Everything started with new clients in jewelry production, since large-format lenses demonstrated not enough sharp with so small objects. So I adapted the Hasseblad lenses that, used for macro, covered the 4"x 5" film at best. Then a lot of gadgets - studio photograpphy was a pretty complicated job before photoshop: no minimal flaw allowed.

I apologize to everyone for my polemical tone, but after the invention of CAD CAM people think that now machining is just a press-button craft, that all is easily feasible. And this gets on my nerves. As if even programming and using properly a CNC machine, would not require great experience and skill.
You had the best possible teacher for sure, Warren. For a diyer it takes a much longer and frustrating path to understand the right procedures.

ciao carlo
 
Hi Dahlberg,

You seem to be getting better results with your dremel than I did when I tried to use mine to make my pivots. My dremel wasn't centered anywhere near accurately enough and it's slowest speed was still way too high.
I ended up using sewing pins as they were already shaped most of the way to what was needed and are made of hardened steel. I rounded the tip by fitting the pin in a hand held pin vice, having cut the head off, and using a sheet of 1200 grit wet and dry paper. I started with the pin lying almost horizontally against the paper then dragged the tip across the paper whilst standing the pin up and rotating the vice between my fingers. I did this whilst applying only the lightest of pressure and rotating the vice between strokes. I also constantly checked both the size and shape of the tip by comparing it to the end of a 0.25mm drill bit.
To polish the tip I first used a polishing pad soaked in Tcut in the dremel and again used the pin vice to constantly change the angle of contact. Final polishing was achieved using diamond paste on a leather pad.
This method proved to be rather easy and effective and made very spherical tips.
The most difficult part of the whole process was drilling a 10mm deep 0.8mm hole in the end of the M3 aluminium axle into which the pins were mounted. I don't own a lathe.

Niffy
 
...hand held tools win cnc lathes hands down ...
in the right hands of course - congratulations to both for your "swiss watchmaker" skill.
Excellent idea, the usb macroscope - mine is just for the eyes, sometimes I've used instead a film scanner (as done for pen tips). I asked if you used the projection on a grid because i've seen a device used by a camera repairman to replicate broken gears.

I don't own a lathe... Cheer up, it's a nightmare even on a lathe - you have to start the hole with the centerdrill, and then to push and pull the drill chuck by hand out of the tailstock. Slooowly, repeatedly. carefully
carlo
 
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Hi Dahlberg,
They are great results especially for a Dremel. Dremels are renowned for having loose bearings.


The most difficult part of the whole process was drilling a 10mm deep 0.8mm hole in the end of the M3 aluminium axle into which the pins were mounted. I don't own a lathe.
Niffy


This is why my plan is to use a 2mm HSS drill for the axle pin. Much easier to drill a 2mm hole. My lathe is 1200rpm max, a bit slow for such a small hole, go slowly.
 
This is why my plan is to use a 2mm HSS drill for the axle pin. Much easier to drill a 2mm hole. My lathe is 1200rpm max, a bit slow for such a small hole, go slowly.

Hi Warrjon,

I set my pillar drill up as a vertical lathe with a second chuck as a tailstock. I made about 8 axles, 20mm long, so I had would have spares for mistakes and experimentation. I actually managed to drill all the way through all of them, starting from both ends, without breaking a single drill bit. Drilling the 1.6mm holes for the tungsten carbide pivots was definitely easier. Taking it slowly is definitely the key, cut half a millimetre max per pass fully retracting the drill between each to clear the bit with a small brush.

Niffy
 
So finally back from work :)
I found out that it worked a lot better if I put the breaks on the dremel with my
index finger having it almost still when it entered and left the honing sharpener.
I also adjusted speed some during honing. I started of by hand grinding away
the rest of the broken 1mm drill so that I was fairly close to start with. The drills
seem to have really good tolerances to start with so that helps. Not sure about
the dremel bearings but I had some problem with a collet (not the dremel
original I think) that was solved using another one.

The software for the microscope is "Celestron micro capture pro", not sure if
the microscope itself is genuine though (it might be).
 
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