YADLB - Yet Another Desktop Lathe Build

[electronrancher]

Ok, I've got the frame structure finished so I'd like to post some pics and get feedback (hopefully not the screeching kind, lol!). This "1200-powered" desktop jig is built from laser-cut acrylic and uses 5/16 allthread as the spine. Carriage rides on LM8UU bearings on 8mm linear rod.

I was originally going to go Presto style, but the worm gear and designing a wiggle-free vertical axis was making my brain hurt. Then, I saw Ciuens' 3D printed lathe (http://lathetrolls.com/viewtopic.php?f=15&t=3027&p=31621#p31615) and the full overhead span looked like a really great way to go. Thanks Cieuens! I planned on using a 16-microstep stepper to drive the leadscrew, but Cuiens warned me of vibration issues with that plan. I am currently waiting for some geared down DC motors to arrive to run the leadscrew. And plus, I need to build up a PCB for the DC motor driver anyway.

I am using the "other" Dayton exciter http://www.daytonaudio.com/index.php/loudspeaker-components/loudspeaker-drivers-by-series/exciters/daex25shf-4-steered-high-flux-25mm-exciter-20w.html, mainly because it has mounting tabs. Linkages will be thin aluminum rod, with a hacked aluminum hex standoff as stylus holder.

I am currently scratching my head over suspension of the cutterhead - these drivers are HEAVY, and my counterbalance is quite touchy from the imbalance in pivot lengths. Maybe a spring? Spring and dashpot? I'm interested in any thoughts on that.

Side View - The two side panels are mirror images, so the lid holder cutout serves double duty to help the user level and align the deck. The small back panels help square everything up to the deck.

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Carriage - Rides on 4 LM8UU's in a multi-rib box. Tab/slot keeps things square, then the seams are bonded with weldon. Awful stuff, but gives an incredible bond. Feedscrew will run down the center.

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It doesn't look like it here, but centerline of stylus travels perpendicular to the center of the record

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[ROLANDJAYS]

I don't like the acrylic, but then I do like the acrylic.... ya know

[Ciuens]

Very good. Its design is very similar to mine. My system was printed in 3D. Acrylic is visually beautiful, but I find it very fragile. I made some upgrades, and soon I will post the results. Good job.

[Ciuens]

I'm using this small stepper motor, it is small, but with enough torque to move my whole system.

http://www.aliexpress.com/item/Board-ULN2003-5-Line-4-Phase-5V-Stepper-Motor-28BYJ-48-With-Drive-Test-Module-Best/32265285152.html

The control is done by an Arduino Uno and a small software designed in Labview.

Initially I had problems with this kind of counterweight. My head weighs nearly 500g, now use a spring system.

My last test recording. Need to buy a diamond stylus to cut polycarbonate.
https://vimeo.com/125253506

[electronrancher]

Yes! Our lathes are at least cousins, if not brothers. The overhead span is a nice sturdy design, thank you again for posting your work.

I'm interested in collaborating if you are.. I don't have labview, but I have an arduino here, it would be no problem for me to set mine up to use a stepper - then we could share code. With an op-amp envelope detect it might be possible for the arduino to do a simple type of variable groove pitch. And at very least the leadin/leadout stuff.

What thread pitch is your leadscrew?

[Ciuens]

The stepper motor is connected to the larger gear to reduce the force applied to the leadscrew. This gear system also eliminates any incident vibration in the cutter head.
My Little labview program does all the necessary speed control, lead in / lead out and play/stop.

[electronrancher]

Looking forward to hearing about your upgrades! I'm waiting for some DC motors, but actually this project may go on the back burner for a while - I'm getting a presto!

I will learn on that, and plus - it will give me a reference to what kind of performance I SHOULD be getting. Then I will be able to better evaluate thew build of this guy.

[EpicenterBryan]

My last test recording....

Hey Ciuens,
Did you ever do any testing with those drivers before going with your printed spring / pushrods? Did you cut the existing 4 point spring and attach your assembly, or is it still in there with your plastic parts attached to it?

Bryan

[Ciuens]

Hello Bryan,
I did several tests with several different configurations. using the transducer with metal springs had much resonance in the range of 500Hz / 700Hz. Decided to employ printed in 3D, and the resonance was for the range of 1khz. The level of high frequencies increased by 20% and have more control over equalization. The following image of the two options, note that the fully printed in 3d has a coil made by hand, was not perfect as the Todd, but it worked perfectly.