Search found 188 matches
- Sun Dec 24, 2023 7:18 pm
- Forum: Experimenters' & Innovators' forum
- Topic: Recommended DC motors for turntable
- Replies: 2
- Views: 4190
Re: Recommended DC motors for turntable
I am playing with a Yaskawa coreless direct drive servo motor SGMCS-05B3C11 as a direct drive on a 14 inch platter, 5nm =~ 50kgcm of torque which should be fine. One thing I did find is that the servo driver seems to chop at 6kHz, which given the very low running torque can wind up audible in the ai...
- Sat May 20, 2023 7:38 am
- Forum: Experimenters' & Innovators' forum
- Topic: Need Help and Direction for Building a Lathe
- Replies: 12
- Views: 6653
Re: Need Help and Direction for Building a Lathe
Yea doing it from scratch is a serious LEARNING experience, especially if mech eng of the fairly serious sort is not really your thing. Lots of precision parallelism over annoying distances and fun with vibration management (I am on Rev 3 of my build, hint epoxy granite is your friend for stiff, wel...
- Sat May 20, 2023 6:54 am
- Forum: Secrets of the Lathe Trolls
- Topic: VR T-560 Back Angle Contradictions
- Replies: 14
- Views: 10445
Re: VR T-560 Back Angle Contradictions
Don't forget that the material you are cutting is plastic and so deforms under the cutting forces and then springs back to some extent. This argues that for a 15 degree RIAA standard rake on the disk you probably want more then that on the cutter and this is usually a mix of the angle of the torque ...
- Mon Feb 13, 2023 9:52 am
- Forum: Secrets of the Lathe Trolls
- Topic: Room Humidity / Static Issues
- Replies: 16
- Views: 3709
Re: Room Humidity / Static Issues
An ioniser might help.
You want one that makes both kinds to reliably to this, but they are tried and tested technology in the electronics industry for static control of insulating surfaces.
You want one that makes both kinds to reliably to this, but they are tried and tested technology in the electronics industry for static control of insulating surfaces.
- Fri Feb 10, 2023 5:37 pm
- Forum: Secrets of the Lathe Trolls
- Topic: how to determine cutting head max power?
- Replies: 12
- Views: 2985
Re: how to determine cutting head max power?
I think the RF present in the output of (particularly NOS) R2R DACs when combined with the bipolar inputs on something like a 5532 sometimes has rather 'unfortunate' effects, mostly down to slew rate that possibly explains some of the dislike of that part in this application, as well as why such DAC...
- Thu Feb 09, 2023 7:01 am
- Forum: Secrets of the Lathe Trolls
- Topic: how to determine cutting head max power?
- Replies: 12
- Views: 2985
Of opamps, slew rates and settling times.
That's jfet input isn't it? Probably better from an RFI perspective if the inputs lack solid filtering, but the noise impedance is also going to be way higher then the bipolar parts, so it will want a different feedback network for best performance. I certainly don't want to be designing audio that ...
- Wed Feb 08, 2023 10:31 am
- Forum: Vinyl Mastering, Lacquer cutting, Pro's and others
- Topic: Radius of cutting stylus' edge
- Replies: 13
- Views: 6467
Re: Radius of cutting stylus' edge
There are some detailed drawings in the AES Disk cutting anthology of the (IIRC) Capps styli, and I think there is at least one drawing in "Basic Disk Mastering" by Boden.
You got someone able to make these?
You got someone able to make these?
- Sun Feb 05, 2023 6:21 am
- Forum: Secrets of the Lathe Trolls
- Topic: how to determine cutting head max power?
- Replies: 12
- Views: 2985
Re: how to determine cutting head max power?
Are you sure those opamps were properly stable? I have heard some weird things from such (You always have to listen, it is a critical part of testing a design), but it always seems to come down to instability or running the thing into clipping (Recovery from this is often NASTY, just a trade off wit...
- Fri Feb 03, 2023 6:14 am
- Forum: Secrets of the Lathe Trolls
- Topic: how to determine cutting head max power?
- Replies: 12
- Views: 2985
Re: how to determine cutting head max power?
The noise of the semiconductors is all too often dwarfed by the noise of the resistors! You have to be very careful if you want the noise of a decent opamp to dominate over the Johnson noise of the resistors that surround it. Possible to bollox it? Sure, anyone can screw it up, and most designers wi...
- Thu Feb 02, 2023 6:24 pm
- Forum: Secrets of the Lathe Trolls
- Topic: how to determine cutting head max power?
- Replies: 12
- Views: 2985
Re: how to determine cutting head max power?
Loose the old mercury relay, we got better ways to skin that now. Skyworks have an isolated gate driver that is made for switching a pair of back to back mosfets, and will do it in microseconds that is just ideal for speaker protection applications, which is really what we are discussing here, cheap...
- Tue Dec 20, 2022 8:22 am
- Forum: Experimenters' & Innovators' forum
- Topic: Holographic recording of analogue-continuous signal.
- Replies: 19
- Views: 4029
Re: Holographic recording of analogue-continuous signal.
So modulating laser power while maintaining SLM with good coherence length operation? Sounds frankly gnarly, unless you do something like use an AOM or Pockels cell to do the modulation with the laser itself running at constant power with the usual precision thermal management. Even then, holography...
- Tue Nov 22, 2022 5:33 am
- Forum: Plating and Pressing
- Topic: Thermal Fluids instead of Steam?
- Replies: 9
- Views: 6453
Re: Thermal Fluids instead of Steam?
Just remember that heat pump efficiency drops as delta T increases, and Carnot was a right bastard. Might be something to be said for lowering the mass that is cycled to lower the energy transferred from the steam to the cold water? We don't have to use 1970s steels today! Just thinking I don't actu...
- Sun Nov 20, 2022 11:58 am
- Forum: Plating and Pressing
- Topic: Thermal Fluids instead of Steam?
- Replies: 9
- Views: 6453
Re: Thermal Fluids instead of Steam?
The phase change gets you very rapid heating (Steam into a cold heat exchanger will condense and that give up a LOT of energy) which is kind of what is wanted for a fast cycle time, with a thermo fluid you only get the energy from the temperature drop, not the (far greater) energy from the condensat...
- Tue Nov 01, 2022 7:42 am
- Forum: Experimenters' & Innovators' forum
- Topic: Rails & stepper motors
- Replies: 19
- Views: 20497
Re: Rails & stepper motors
One thing I found is that any kind of recirculating ball linear bearing is the kiss of death, you really want something more in the line of a linear cross roller slide, but getting one long enough can be a challenge. Same goes for ball screws, good for precision machining, but NOT the right thing in...
- Wed Oct 19, 2022 7:52 am
- Forum: Secrets of the Lathe Trolls
- Topic: Line Output Converters
- Replies: 4
- Views: 3249
Re: Line Output Converters
You can eliminate a lot of the gain stages in eq and limiting by going digital for that, but the power amps sort of need to be actual amplifiers, and anyone running a feedback head needs to close that loop in the analog domain simply because the group delay thru a set of ADCs and DACs will destroy a...
- Sun Sep 04, 2022 6:12 am
- Forum: Vinyl Mastering, Lacquer cutting, Pro's and others
- Topic: Frequency range of harmonics found on records
- Replies: 2
- Views: 5032
Re: Frequency range of harmonics found in vinyl.
CD4 was cut at half speed IIRC, which does of course nothing to help with the geometric limits but does significantly reduce the current required in the cutting head coils. There are three limits on the amplitude you can cut up there: One geometric imposed by the back angle on the cutting sapphire (...
- Mon Aug 22, 2022 5:13 am
- Forum: Experimenters' & Innovators' forum
- Topic: Horizontal Lathe CNC into phonographer
- Replies: 25
- Views: 4904
Re: Horizontal Lathe CNC into phonographer
It was NOT a CNC Lathe, it was an old school manual toolroom machine (And frankly rather knackered). Look up Hardinge HLV for a picture of the kind of thing. I cut a small disk (hence the limitation due to centre height), could have done a cylinder I suppose, but I have nothing to plat those back. T...
- Wed Aug 17, 2022 4:56 am
- Forum: Experimenters' & Innovators' forum
- Topic: Horizontal Lathe CNC into phonographer
- Replies: 25
- Views: 4904
Re: Horizontal Lathe CNC into phonographer
For shits and giggles I cut a record on a Hardinge HLV, turned up a mandrill to take the blank with a stub to fit in a collet, and mounted the cutting head in a tool holder, then use the power facing mode to cut the groove. Speed was a bit 'iffy' and the headstock belt on that machine is showing its...
- Fri May 13, 2022 11:59 am
- Forum: Experimenters' & Innovators' forum
- Topic: Platter and bearing design
- Replies: 5
- Views: 2675
Re: Platter and bearing design
There is a bit of a trap with bronze self lubricating bearings, they only really work if the surface speed is high enough, which is possibly not the case here, you might do better to organise lubrication of the bearings rather running them dry. I got stuffed good and proper trying to use a sintered ...
- Fri May 13, 2022 8:14 am
- Forum: Secrets of the Lathe Trolls
- Topic: Desk Vibration Dampening
- Replies: 6
- Views: 2933
Re: Desk Vibration Dampening
The old school approach when setting up playback decks on rather 'mobile' surfaces in raves might work well here. What you do is use 3 or 4 sorbothane hemispheres (Squash balls cut in half) under a paving slab with the deck placed on the slab. Your basic mass/spring/damper sort of thing really. The ...