Around five years ago, I decided that I wanted to put together a disk cutting system. I started collecting and reading all related literature I could get my paws on, from the very beginning of disk recording to the present, in the form of books, manuals, journal and magazine articles, websites, and so on.
Eventually, I located a Fairchild model 199 lathe in the USA, which seemed like a decent start for the project. It started life many decades ago (late 30's as far as I could figure out) at the Fairchild Aerial Camera Corporation in New York. Fairchild Recording came a bit later than that. It was sold to a radio station in Grand Rapids, Michigan, where it saw plenty of use until it was considered obsolete. It then spent decades in storage at the radio station, until it was eventually sold some years ago to a man in Grand Rapids who sold it to a man in Florida, who sold it to me in 2015.
S/N 769
I got the lathe in the form of the mechanical assembly in a sort of crate, with a DIY cutterhead adaptor. There was no head or electronics with it. The drive to the platter comes from a big 60 Hz synchronous hysteresis motor, coupled to a gearbox/drive unit, on top of which the platter is bolted.
The motor is suspended on springs with damping material in them, and employs a rubber flexi-coupling to transmit the drive to the gearbox. I am located on the 50 Hz side of the pond, so the first thing I did was to put together a quartz-controlled, extremely stable and precise 60 Hz supply for the motor. This, along with the two-speed gearbox, can drive the platter at 33 1/3 rpm and 78 rpm. Changing the 60 Hz line frequency up or down can also derive 45 rpm, 16 rpm, and so on. Have not implemented this yet, but it is on my to-do list. For now 33 rpm is adequate for testing and further development.
I then got myself an RCA MI-4896 magnetic monophonic cutterhead to get the project going.
It unfortunately arrived broken. The coil seemed fine, but it was evidently out of whack mechanically. This could have been shipping damage, or just someone attempting to replace a blown coil and not knowing how to put it back together properly. Moral of the story, and advice to ebay sellers: Do not assume a cutter head is in working condition just because you can measure some DC resistance in the coil with an ohm-meter! If you are not able to properly test it, then it is safer to assume it is not functional.
I took it apart and rebuilt it. All the bits were there, but it needed a careful alignment. After that it worked great. These are nice little heads if you're into the vintage sound of the early days of electric recording. Think of early blues up until the 50's or so, rock'n'roll, etc.
I had some choice of power amplifiers to try out, but needed the RIAA pre-emphasis. I built some simple passive units based on the Lipshitz and Hagerman articles.
My playback equipment and Mastering chain put out very high signal levels, while several of my power amplifiers expect a 0.7Vrms input level. The attenuation from the passive RIAA pre-emphasis circuit does a great job of matching the levels.
I built a big, heavy and beautiful wooden cabinet for the lathe, put together a heat lamp assembly and a microscope, and not having a chip suction system ready yet, I started off with impressing (embossing) on polycarbonate blanks.
Of course, to properly align the stylus with the centerline of the record, I had to make a new adapter to compensate for the drastic change in angle of cut.
Although this lathe is around 80 years old and saw heavy use in its youth, it is in remarkably good condition. This is due to the exceptional design, use of high quality materials throughout, and excellent machining. A lot of parts are made of stainless steel, which prevented corrosion during the decades in storage. There was plenty of grime that had to be carefully cleaned away, and the entire machine was in a desperate need of proper lubrication.
Then I started noting down the problems. The first serious problem was a terrible noise coming from the gearbox and the second problem was a massive platter run-out.
I started by removing the platter and realising that the noise source was inside the gearbox! Horror! No service manual there, no pictures online, nobody I could find with experience working on these gearboxes! All I knew was that it is a fairly complicated machine with helically cut gears, worm-gear drive, numerous oil seals, a gear change and a clutch. In the service manual of a similar Fairchild lathe there was mention of a ball-race step-up... The drive unit is Fairchild model 824, by the way.
Luckily, I have plenty of experience working on old machines, as I used to maintain, repair, modify and convert vintage tour vans for bands, mobile studios and so on. I also drive, maintain and repair this 1979 Bedford, which has driven me and other musicians all across Europe for several years...
So I took a deep breath and pulled it apart! I was going completely in the dark, trying to figure out the multiple adjusters, bearings, ball races, seals, etc. I was glad to see that the over-engineering extends into the gearbox and that nothing was broken or worn too bad. The problem was that one of the previous owners neglected the bothersome routine lubrication procedure and damaged some races and thrust washers. I measured them carefully, got replacements and put it back together.
I'm not good at shooting pictures while I'm working on something because I get absorbed in what I'm doing, so there's no pictures of the insides of the gearbox. The surgery went well and the noise is gone. I re-aligned the motor and rubber coupling and it runs nice and smooth.
Next up was the run-out.
The gearbox shaft was the first point of call. All good there, so the next tricky part was mounting the flange for the platter on the shaft. This flange has an unusual adjustment, with a half-circular key floating in a half-circular slot on the shaft, with an allen screw on the side to secure adjustment
I managed to get the flange aligned to the point of no visible deflection on the dial gauge in any direction.
Then came the platter, which is a 16lbs cast alloy affair. For some reason, it was not straight on the straight flange. It appears the the top face is not 100% parallel to the bottom face, causing a run-out there too. While planing the faces accurately and then cutting a new spiral on top would be an option, I decided to proceed with a different idea. Inspired by the adjustability of the platter on more modern lathes, I drilled and tapped three equidistant threaded holes for adjusters on the platter!
This did the trick and I got the run-out to +/- 0.9 mil at 16".
The rest is due to an uneven top face, so machining the platter in the future might be a good idea. Most blanks, especially plastics, exhibit far more run-out though, not sure if it is really worth the effort to improve the platter further. More soon....
Fairchild/Magnetovolt Custom Disk Cutting Lathe
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~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Excellent work, resurrecting the dead takes some time indeed, well done,
Best
Best
Chris
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Nice work mate keep it up!!!
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
While doing all this, I also started putting together a vacuum suction system for the chip, so I could actually cut with a heated stylus.
My first few attempts were far from ideal. I used a vacuum cleaner which was too loud, did not provide enough suction for plastic blanks and overheated. I also made the suction lines unnecessarily long and used a rubber hose from an automotive vacuum line which was too stiff, resulting in problems with the suspension movement. The suction tube at the side was also not the best position for it and it often failed to pick up the chip or just got too easily clogged.
So, I rebuilt the system with shorter lines using mainly copper gas line, replaced the rubber hose with a medical silicon hose, moved the vacuum gauge to the top of the chip jar instead of the inlet where I initially placed it, and built a suction nozzle which sits behind the stylus.
I also replaced the vacuum cleaner with a proper rotary vane vacuum pump. Much stronger and much quieter. I got a cheap one though, and the oil separator at the exhaust was as good as not having one at all, so as soon as I started it up it started smoking like a steam engine and spitting out all the oil. Obviously not a unit for indoor use!
I installed it in the pneumatics hut, next to my air compressor, with a filter at the inlet and a long hose to the chip jar in the cutting room. I built a crude but very functional oil separator from a domestic water filter housing and replaced the chip fat they shipped it with, with some real hydraulic oil, suitable for a rotary vane pump (needs to resist vaporisation). Works great and no longer spits oil out!
The rotary vane pump does actually induce some pulsing at some low frequency, which at times can cause a noticeable effect on the groove. Not audible, but visible. I will install a pneumatic low pass filter which will essentially be an air tank, which would do pretty much what a reservoir capacitor does in a power supply circuit, to get rid of the pulsing.
I have also designed a really sturdy, current regulated DC supply for the heater wire on the stylus, and built a prototype which I have been using extensively. This will soon become a Magnetovolt product which will be available for sale. We are waiting for some custom parts and will assemble the first complete units as soon as we have all bits together for the housing.
I also installed a fairly crude heater wire retainer assembly on the RCA head and I have been happily cutting 8-10 sides per day since then (several months ago already) while improving things further.
Somewhere along the line I also tested the leadscrew for run-out but it was perfect and straight.
By the way, these domestic water filter housings are perfect for so many different uses, highly recommended!
More soon...
My first few attempts were far from ideal. I used a vacuum cleaner which was too loud, did not provide enough suction for plastic blanks and overheated. I also made the suction lines unnecessarily long and used a rubber hose from an automotive vacuum line which was too stiff, resulting in problems with the suspension movement. The suction tube at the side was also not the best position for it and it often failed to pick up the chip or just got too easily clogged.
So, I rebuilt the system with shorter lines using mainly copper gas line, replaced the rubber hose with a medical silicon hose, moved the vacuum gauge to the top of the chip jar instead of the inlet where I initially placed it, and built a suction nozzle which sits behind the stylus.
I also replaced the vacuum cleaner with a proper rotary vane vacuum pump. Much stronger and much quieter. I got a cheap one though, and the oil separator at the exhaust was as good as not having one at all, so as soon as I started it up it started smoking like a steam engine and spitting out all the oil. Obviously not a unit for indoor use!
I installed it in the pneumatics hut, next to my air compressor, with a filter at the inlet and a long hose to the chip jar in the cutting room. I built a crude but very functional oil separator from a domestic water filter housing and replaced the chip fat they shipped it with, with some real hydraulic oil, suitable for a rotary vane pump (needs to resist vaporisation). Works great and no longer spits oil out!
The rotary vane pump does actually induce some pulsing at some low frequency, which at times can cause a noticeable effect on the groove. Not audible, but visible. I will install a pneumatic low pass filter which will essentially be an air tank, which would do pretty much what a reservoir capacitor does in a power supply circuit, to get rid of the pulsing.
I have also designed a really sturdy, current regulated DC supply for the heater wire on the stylus, and built a prototype which I have been using extensively. This will soon become a Magnetovolt product which will be available for sale. We are waiting for some custom parts and will assemble the first complete units as soon as we have all bits together for the housing.
I also installed a fairly crude heater wire retainer assembly on the RCA head and I have been happily cutting 8-10 sides per day since then (several months ago already) while improving things further.
Somewhere along the line I also tested the leadscrew for run-out but it was perfect and straight.
By the way, these domestic water filter housings are perfect for so many different uses, highly recommended!
More soon...
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~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
While cutting PVC blanks with a heated diamond, I came across a weird intermittent vertical oscillation problem. It sometimes appeared and sometimes went away. It was a function of angle and depth of cut, which was further excited by the vacuum suction. Definitely didn't make a reliable cutting system like that, so I bought one of the air dashpots sold by KisstheGroove on lathetrolls. I built a bracket to attach the cylinder to the carriage and another bracket to attach the piston rod to the cutterhead adapter, close to the cutterhead itself. I had to drill the cast aluminum carriage and tap threads in the blind hole, where the top bracket sits. Same with the cutterhead adaptor.
This is an adjustable dashpot, so the damping can be fine tuned to match each setup. Very handy little gadget!
Stephen also single-handedly wins the BEST PACKING EVER award for his blast-proof packing! I really regret not making detailed pictures of me unpacking this thing! The dashpot was in a small plastic bag with foam around it, which was placed inside a THICK (really thick, like, REALLY thick) walled pipe, with extra foam on the sides, and more foam around the whole thing, which was placed in a very solid cardboard box... I could run it over with a fully laden semi and it would most likely survive.
I asked him when ordering to make sure it can survive being thrown off the airplane at flight attitude directly into my garden, which is what they seem to do with packages around here...I always ask for this when ordering anything fragile. But, Stephen has been the only person to really manage doing quite literally what I asked for thus far!
It makes me want to order more things from him, even if I don't actually need them, just to demonstrate to others how packing should be done! Pictures and video next time.
The packing issue has been a constant source of frustration throughout my entire professional life. Thanks Stephen!
More soon..
This is an adjustable dashpot, so the damping can be fine tuned to match each setup. Very handy little gadget!
Stephen also single-handedly wins the BEST PACKING EVER award for his blast-proof packing! I really regret not making detailed pictures of me unpacking this thing! The dashpot was in a small plastic bag with foam around it, which was placed inside a THICK (really thick, like, REALLY thick) walled pipe, with extra foam on the sides, and more foam around the whole thing, which was placed in a very solid cardboard box... I could run it over with a fully laden semi and it would most likely survive.
I asked him when ordering to make sure it can survive being thrown off the airplane at flight attitude directly into my garden, which is what they seem to do with packages around here...I always ask for this when ordering anything fragile. But, Stephen has been the only person to really manage doing quite literally what I asked for thus far!
It makes me want to order more things from him, even if I don't actually need them, just to demonstrate to others how packing should be done! Pictures and video next time.
The packing issue has been a constant source of frustration throughout my entire professional life. Thanks Stephen!
More soon..
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~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
So, the pneumatic low pass filter worked a treat, and now I've got pulse-free suction.
It's just another domestic water filter housing, placed between the chip jar and the vacuum pump.
I'm also half way through building the sixth 45U rack in the studio. This one will live in the cutting room next to the lathe, and will hold the lathe-related electronics:
1. Quartz Motor Supply
2. Heater Supply
3. Cutting Amplifiers
4. RIAA Pre-Emphasis/Preamplifier
5. Pitch System Electronics
6. Metering
7. HF Limiter
8. Anything else that may come up later...
Now, this is where things get rather interesting! I have finally received the first version of the pitch motor and assembled it on a bracket with shockmounts. I did some tests with it directly coupled to the leadscrew and it went well! I need to make a flexi-coupling for it. I am using it with a very simple fixed pitch controller for now, but a Magnetovolt Analog Variable Pitch System is underway.
I have also fitted the Caruso head with an integrated, heavy duty, machined aluminum, Fairchild mount. This makes the Caruso cutterhead fully compatible with the Fairchild suspension, used on a variety of Fairchild lathes.
It is an extremely rugged construction with practically no flexing, which is directly attached to the Caruso body and has the right dimensions to bring the stylus along the centerline of the record with a base angle of 8 degrees, as it would originally sit on a Neumann suspension.
Furthermore, the angle of cut is fully adjustable on the Fairchild suspension, so I could also make variations of this mount for radically different angles of cut. I still need to add the angle of cut adjuster plate and dashpot piston rod bracket to this, and then maybe make it anodised black to match the Caruso body.
We will be making these available soon through Magnetovolt for anyone who would like to use a Caruso head with their Fairchild lathe. It will fit Model 199, 539, 523, and possibly more!
It's just another domestic water filter housing, placed between the chip jar and the vacuum pump.
I'm also half way through building the sixth 45U rack in the studio. This one will live in the cutting room next to the lathe, and will hold the lathe-related electronics:
1. Quartz Motor Supply
2. Heater Supply
3. Cutting Amplifiers
4. RIAA Pre-Emphasis/Preamplifier
5. Pitch System Electronics
6. Metering
7. HF Limiter
8. Anything else that may come up later...
Now, this is where things get rather interesting! I have finally received the first version of the pitch motor and assembled it on a bracket with shockmounts. I did some tests with it directly coupled to the leadscrew and it went well! I need to make a flexi-coupling for it. I am using it with a very simple fixed pitch controller for now, but a Magnetovolt Analog Variable Pitch System is underway.
I have also fitted the Caruso head with an integrated, heavy duty, machined aluminum, Fairchild mount. This makes the Caruso cutterhead fully compatible with the Fairchild suspension, used on a variety of Fairchild lathes.
It is an extremely rugged construction with practically no flexing, which is directly attached to the Caruso body and has the right dimensions to bring the stylus along the centerline of the record with a base angle of 8 degrees, as it would originally sit on a Neumann suspension.
Furthermore, the angle of cut is fully adjustable on the Fairchild suspension, so I could also make variations of this mount for radically different angles of cut. I still need to add the angle of cut adjuster plate and dashpot piston rod bracket to this, and then maybe make it anodised black to match the Caruso body.
We will be making these available soon through Magnetovolt for anyone who would like to use a Caruso head with their Fairchild lathe. It will fit Model 199, 539, 523, and possibly more!
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~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
I can see this working without any issues, are you using a rubber belt and pulley to drive the lead screw ?
I really like the way you mounted the motor with he rubber feet Looks neat !
Nice work Jesus !
I really like the way you mounted the motor with he rubber feet Looks neat !
Nice work Jesus !
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Thanks Dimi. No rubber belt/pulley, the motor is coupled directly to the leadscrew using a rubber coupling.
In a direct drive fashion, the motor seems capable of driving the leadscrew with enough torque over a range from 250 lpi to 10lpi for the lead outs. I was worried about needing more torque but it seems that this motor and gearbox combination produces more than enough torque. It works a treat with absolutely no noise being transferred from the motor. Or at least, it is lower than the rumble from the platter motor and gear box. It is a low-noise brushed DC motor coupled to a low-noise planetary gearbox. In the picture above I am driving it from a linear regulated DC supply which I normally use as bench DC supply. I am also experimenting with PWM circuits, but so far, I have been able to get more reliable running at very slow speeds using the linear DC supply. I have replaced the piece of wood under the motor that you can see in the picture with a kork base to provide an extra layer of decoupling and when I figure out the exact driving requirements I will install a custom pitch box which will cover the motor and contain the driving electronics. Modulating the supply to the motor with an audio preview signal is the next step, which will give me a nice and simple analog variable pitch system.
This is what the original Fairchild pitch box looks like. Strictly fixed pitch, which can only be changed by swapping out gears. No provisions for spiraling, lead in or lead outs. I was doing these manually by disengaging the half nut and moving the carriage by hand...! But the nice thing is that by removing the gear from the leadscrew you are left with an excellent surface to attach the rubber coupling for a directly driven leadscrew with a separate motor. In the original arrangement you can change the direction of cut by moving the lever in the gearbox up or down, which engages the forward or reverse gear with the leadscrew gear. With the direct drive motor, you can change the direction of cut by changing the rotational direction of the motor.
In a direct drive fashion, the motor seems capable of driving the leadscrew with enough torque over a range from 250 lpi to 10lpi for the lead outs. I was worried about needing more torque but it seems that this motor and gearbox combination produces more than enough torque. It works a treat with absolutely no noise being transferred from the motor. Or at least, it is lower than the rumble from the platter motor and gear box. It is a low-noise brushed DC motor coupled to a low-noise planetary gearbox. In the picture above I am driving it from a linear regulated DC supply which I normally use as bench DC supply. I am also experimenting with PWM circuits, but so far, I have been able to get more reliable running at very slow speeds using the linear DC supply. I have replaced the piece of wood under the motor that you can see in the picture with a kork base to provide an extra layer of decoupling and when I figure out the exact driving requirements I will install a custom pitch box which will cover the motor and contain the driving electronics. Modulating the supply to the motor with an audio preview signal is the next step, which will give me a nice and simple analog variable pitch system.
This is what the original Fairchild pitch box looks like. Strictly fixed pitch, which can only be changed by swapping out gears. No provisions for spiraling, lead in or lead outs. I was doing these manually by disengaging the half nut and moving the carriage by hand...! But the nice thing is that by removing the gear from the leadscrew you are left with an excellent surface to attach the rubber coupling for a directly driven leadscrew with a separate motor. In the original arrangement you can change the direction of cut by moving the lever in the gearbox up or down, which engages the forward or reverse gear with the leadscrew gear. With the direct drive motor, you can change the direction of cut by changing the rotational direction of the motor.
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~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
I finally got around to fitting the custom pitch box on the Fairchild. Still testing the operating limits of the motor. So, the control panel and the electronics are not in there yet but at least there is some steady progress. I can now do decent looking lead-ins, spirals and lead-outs, and I can cut around 25 minutes on a 12" side at 33 rpm. That's still on fixed pitch. Will get to variable pitch soon.
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~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
That looks fantastic Jesus, I like the way the lead screw motor is mounted did you try and do some silent cuts To hear if any of the motor noise was coming threw?
Dimi
Dimi
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Thanks, Dimi!
I did plenty of silent cuts at coarse pitch (fast motor speed) and long lead-outs (fastest motor speed) and there is absolutely no noise from the lead screw motor that can be heard above the rumble of the main motor and surface noise. The rumble and surface noise are both pretty damn quiet too. So, I would say its a complete success up to now. I used a long rubber coupling between the motor shaft and the lead screw shaft and rubber feet on the motor, so it is practically floating. I tried a few different drive couplings until I found the ideal hardness to not have any grouping, while still rejecting any vibration. It also helps that it is a low noise motor.
I did plenty of silent cuts at coarse pitch (fast motor speed) and long lead-outs (fastest motor speed) and there is absolutely no noise from the lead screw motor that can be heard above the rumble of the main motor and surface noise. The rumble and surface noise are both pretty damn quiet too. So, I would say its a complete success up to now. I used a long rubber coupling between the motor shaft and the lead screw shaft and rubber feet on the motor, so it is practically floating. I tried a few different drive couplings until I found the ideal hardness to not have any grouping, while still rejecting any vibration. It also helps that it is a low noise motor.
~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
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inspector77
- Posts: 78
- Joined: Mon Nov 17, 2014 10:59 am
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Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Hello Jesus what motor are you using for the pitch control?
regards
regards
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Nice one Jesus, not bad results considering your using that beefy motor.
The pitch box looks like it's got some room for a couple of VU meters and other functions, besides the
Pitch control, will you also be adding in other functions to this box? by the way nice job on the metal work As well.
The pitch box looks like it's got some room for a couple of VU meters and other functions, besides the
Pitch control, will you also be adding in other functions to this box? by the way nice job on the metal work As well.
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
The motor is a low cost, low noise, brushed DC motor, coupled to a low noise planetary gear box, with a reduction ratio appropriate for the Fairchild.
I plan on making these motors available along with the drive electronics at reasonable cost, along with the rubber isolators and rubber coupling.
I could also make complete pitch boxes for Fairchild lathes if there is enough demand. The motor and control can be adapted for a variety of lathes and custom projects.
The pitch box was my own design, manufactured by a local metal working firm. There is indeed plenty of space in it, which will mostly be occupied by the motor control electronics and variable pitch system, along with the power supply and enough space so the whole thing would not overheat.
The front panel that is missing on the picture will have all the controls plus an lpi meter. Most of the electronics will be attached to the front panel apart from the power supply which will be on the rear panel. That would make it very easy to install and remove for adjustment/maintenance.
The heater supply and the rest of the electronics will be made in 19" rack format and fitted wherever the user sees fit.
The heater supply is also ready, we are just waiting for the first complete silk screen printed poxes to be assembled.
I plan on making these motors available along with the drive electronics at reasonable cost, along with the rubber isolators and rubber coupling.
I could also make complete pitch boxes for Fairchild lathes if there is enough demand. The motor and control can be adapted for a variety of lathes and custom projects.
The pitch box was my own design, manufactured by a local metal working firm. There is indeed plenty of space in it, which will mostly be occupied by the motor control electronics and variable pitch system, along with the power supply and enough space so the whole thing would not overheat.
The front panel that is missing on the picture will have all the controls plus an lpi meter. Most of the electronics will be attached to the front panel apart from the power supply which will be on the rear panel. That would make it very easy to install and remove for adjustment/maintenance.
The heater supply and the rest of the electronics will be made in 19" rack format and fitted wherever the user sees fit.
The heater supply is also ready, we are just waiting for the first complete silk screen printed poxes to be assembled.
~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
I'm very interested with this project Jesus
How's the pitch box build going ?
How's the pitch box build going ?
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Similar, yes, in the sense that it is a DC motor coupled to a planetary gearbox. That's about where the similarities end. Although any similar motor like that would probably work, as long as you figure out the correct operating range for the lathe it will be used on. It doesn't take much torque to keep the leadscrew spinning, but you need a bit extra to keep it smooth. The most important thing is to make sure the motor is adequately decoupled to not transmit any noise, especially during faster rotational speeds. Also, it is especially important to not put any load on the leadscrew bearings from the weight of the motor or misalignment between motor and leadscrew, which could damage the bearings.
rsimms3 wrote:Is your pitch motor similar to this one?
http://www.ebay.com/itm/Trident-0196-0050-12V-DC-70-RPM-Gear-Box-Speed-control-Electric-Motor-/141874897707?hash=item210867232b:g:og0AAOSwp5JWZk5R
~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Great work Jesus ,getting dad to help ,the suction etc and the whole look of it ..keep it up..
i am also amazed at how many Greek people are into this whole art..
biglove
i am also amazed at how many Greek people are into this whole art..
biglove
Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
Second Fairchild 539 Overhead &cutterhead in Athens,Greece but my project is not ready yet. I'm working to construct a powerful and stable turntable. More infos coming soon... http://lathetrolls.com/viewtopic.php?f=1&t=4663#page-bodyMEGAMIKE wrote:Great work Jesus ,getting dad to help ,the suction etc and the whole look of it ..keep it up..
i am also amazed at how many Greek people are into this whole art..
biglove
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Re: Fairchild/Magnetovolt Custom Disk Cutting Lathe
There has been a lot of progress here lately, but I have had no time to post, what with recordings, mastering and upgrading the lathe all the time...
I have mounted the Caruso, done all the wiring, built the suction system for it, made bracket for the dashpot, and built the amplifier rack. For the time being, I am using the Caruso preamp boards, built with decent components, and a regulated 15VDC supply, some high quality resistors and capacitors for the series RC network, as well as a unit that converts the high level balanced signals that come from the signal processing and tape playback into low level unbalanced signals, to be used by the Caruso preamp board. I had some custom audio transformers made for the task, which now give me a ruler flat response between 10 Hz and 35kHz with excellent transient response.
I experimented with different amplifiers and found that it is extremely important to use a decent amplifier for best results. A variety of different amplifiers I had here all had questionable stability with 26dB of feedback applied. Each channel individually could get to 30-32dB of feedback with most amps before oscillation, but when both worked together things didn't look that good. I eventually finished up an old project I had, an old NAD amplifier which I heavily customised. With this amplifier, not only am I getting excellent stability with 26dB of feedback, but I am also realising I am not really needing to get up to 26dB of feedback to get a good sound. I am now cutting with around 25dB of feedback, and getting very good results. Some of the cheaper amplifiers I tried had weird peaks and resonances even with around 28dB of feedback.
I had a few other problems along the way, since the increased weight of the carriage due to the Caruso brought my pitch motor to its knees, so I am currently experimenting on that side again...
All the wiring on top of the head make the suspension very stiff so I have to get used to the adjustments with this setup. Angle of cut was adjusted fairly close to 15 degrees. I am still fine tuning the whole system but I am now very happy with the cutting electronics and the Caruso head.
Here are some photographs of the process:
I have mounted the Caruso, done all the wiring, built the suction system for it, made bracket for the dashpot, and built the amplifier rack. For the time being, I am using the Caruso preamp boards, built with decent components, and a regulated 15VDC supply, some high quality resistors and capacitors for the series RC network, as well as a unit that converts the high level balanced signals that come from the signal processing and tape playback into low level unbalanced signals, to be used by the Caruso preamp board. I had some custom audio transformers made for the task, which now give me a ruler flat response between 10 Hz and 35kHz with excellent transient response.
I experimented with different amplifiers and found that it is extremely important to use a decent amplifier for best results. A variety of different amplifiers I had here all had questionable stability with 26dB of feedback applied. Each channel individually could get to 30-32dB of feedback with most amps before oscillation, but when both worked together things didn't look that good. I eventually finished up an old project I had, an old NAD amplifier which I heavily customised. With this amplifier, not only am I getting excellent stability with 26dB of feedback, but I am also realising I am not really needing to get up to 26dB of feedback to get a good sound. I am now cutting with around 25dB of feedback, and getting very good results. Some of the cheaper amplifiers I tried had weird peaks and resonances even with around 28dB of feedback.
I had a few other problems along the way, since the increased weight of the carriage due to the Caruso brought my pitch motor to its knees, so I am currently experimenting on that side again...
All the wiring on top of the head make the suspension very stiff so I have to get used to the adjustments with this setup. Angle of cut was adjusted fairly close to 15 degrees. I am still fine tuning the whole system but I am now very happy with the cutting electronics and the Caruso head.
Here are some photographs of the process:
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~~~ Precision Mechanical Engineering, Analog Disk Mastering ~~~
Agnew Analog Reference Instruments: http://www.agnewanalog.com
Agnew Analog Reference Instruments: http://www.agnewanalog.com