One more thread on a homebuilt RCM! Yay! Well, first I want to say that my willingness and knowledge to delve into this is largely due to all the info collected under DC's consolidation thread on all the various RCM projects, and by extension to the many members here who have shared their experiences. So thank you all.
Nothing I'm doing here is going to break any ground, but it's a bit of a different combination of features than I've seen on other RCMs. First, in many ways this RCM will be a shameless copy of the VPI concept. It seems like a time-proven design, and I am not in possession of a junker turntable to convert into an RCM. So I figured I might as well try to emulate one of the standard bearers. I'm planning to prototype this on scrap wood at first, and then build a nice(ish) cabinet after I have it sorted.
In fact I decided to use two key parts straight from them: the well known 3015 mod kit (vacuum tube and base assembly) and the 16.5 version of the arbor (they call it a platter hub, btw, and were really confused when I asked to purchase an "arbor"). I don't have the mod kit yet - it seems to be taking a long time to obtain. I'm also using a Dayton gearmotor similar to the one in the 17, model 3M154. The motor is geared numerically higher than the VPI 17 motor, so it turns at 10rpm instead of 16 or 18, which should still be pretty good (maybe preferable?). It also uses permanent split capacitor design like the 17's, so it is easily reversible. And with a 5/16" shaft, it will fit the 16.5 arbor. I got this for $29 on Ebay brand new, including the run cap and free shipping. So that was a good deal! The big difference that I didn't notice right away is that the mounting holes are much closer together. This probably rules out the shock mounting that VPI uses for its standoffs, because I'm afraid the whole thing would sag at the heavy end and then the platter wouldn't be flat.* I admit I'm a bit perpelexed as to why VPI felt the need to use isolation mounts, because I can't imagine there will be tons of vibration and noise from this motor (especially compared to the vacuum!). However, I might try using rubber mounts under the motor plate if I decide they are necessary. Here is the motor with arbor attached, along with the run capacitor:
The wiring of the motor is bog simple: connect the black wire to neutral, and connect the yellow and gray wires to opposite terminals on the run capacitor. Then connect the hot power lead to one terminal on the capacitor to run it one way, or to the other terminal to reverse the rotation. A simple SPDT switch with a center "off" will determine which of the two terminals on the run cap gets the power, enabling me to switch the direction of rotation (or neither gets power for "off"). The ability to do this, btw, is an upgrade from a 16.5.
Here are two platters I'm going to try:
I went around and around in thought about how to mount a platter. I still believe the ideal design would use a large thrust bearing (like a lazy susan style or something fancier using needle bearings) to bear the platter weight and any forces of installing a clamp, etc. The challenge with this would be to connect the motor with a coupling that allows some vertical flex along the shaft's length, or else the motor would still end up bearing some of the platter's thrust forces due to tolerances. I found jaw couplings from Lovejoy that would have fit the bill. Then I would have to figure how to make a threaded spindle (for a clamp) and attach a homemade platter to that. One could also probably still use the VPI arbor, but then we're talking about $50-70 just in parts for the arbor, coupling, and thrust bearing parts. That was all making my brain hurt, so I took the easy route and bought the VPI arbor. I was concerned that the gearmotor wouldn't be designed for thrust loads, but VPI doesn't seem worried about that and I've never heard of a Dayton gearcase failure in an RCM, so I'm going to save hours of work and stop worrying. I didn't like paying $20 for the arbor, but I have to say that it's a nicely machined piece in aluminum and they included the three stainless (I think) screws and that cute little red condom to protect the threads. So I believe it was totally worth it, and it will alleviate a ton of work.
I have made two platters out of 1/2" mdf, which I believe is the same thing VPI uses. I will finish them with something waterproof, and bond something grippy on top so they can grip the records tightly. I made one platter of 11" diameter, the same as the VPI design. I am also going to try a 4" platter that just covers the label, like Nitty Gritty does it. The idea here would be to prevent any contamination of a clean record side after it's flipped over to clean the second side. It was easy enough to make it while I had the tools out, and no extra cost. So why not try it?
I cut these out using a Dremel rotary tool with the spiral cutting bit and the circle-cutting jig with router base. I'd never used that attachment before, and it worked out pretty well. Just remember to cut the circle clockwise (like the directions say), or it will be a mess! These are both very concentric around the center hole. I used the arbor to mark and drill the three small attachment holes, and I used the dremel with cutting bit and router base to counterbore each of those holes (like countersinking, but with flat shoulder instead of flared base because the screws are flat headed). This routing wasn't done with a guide, so the counterbores aren't perfectly round; but the smaller screw holes are and they line up with the threaded holes in the arbor perfectly and all of this will be covered with a mat anyway, so perfect looks aren't important.
Finally, here is the MDF plinth or base that I am using just for the prototype build:
Ugly as hell, but it was free. It was left over from the previous owners of my house - one of the only good things they left behind (but I'm not bitter). I am sizing it at 16x14 for now, a bit larger than a 16.5's size. But I will evaluate the layout and finalize dimensions for the final build later. It's 3/4" MDF - not sure what thickness VPI uses. The cutout is for the motor, of course. It's ugly because I was experimenting with the Dremel cutting bit on it. Not my best work, but that won't keep me from mounting the motor for the prototype. Rather than fashion a whole motor plate like VPI does, I might just use the flat strips of aluminum. It's all going to be covered by the larger platter anyway, and if I end up using the small platter then I'll make a plate and make it prettier so that the exposed end looks good.
EDIT: Oh yeah, forgot the vacuum! Minor detail. So the plan for now is to use a small shop vac that I already have, and make a fitting for the VPI arm base. I want to keep the vacuum as a separate, detachable piece for now because I use it for other things. This is how the KAB EV-1 does it, as well as a number of other DIY projects. The plan for now is that even the final version of this will be sited in the unfinished portion of my basement. That means I can keep the vacuum right by it and handy. If the time comes that I move the whole thing into the finished side (where my hi-fi system is), then I'd probably build in a vacuum. Or, my house actually has a central vac system and maybe I could connect that, using a separator tank to keep the water out of it.
I guess one could call this project a VPittyKAB. So this is where I am until I get the mod kit from VPI. I'll update with progress.
*If anyone wants the standoffs VPI uses, you can buy almost identical ones from JEGS, which they sell for mounting racing ignition boxes (note that these are 10-32 threads). Amazon also has really cheap mounts in a couple thread sizes that are almost the same, but they are male threads on both ends.
Nothing I'm doing here is going to break any ground, but it's a bit of a different combination of features than I've seen on other RCMs. First, in many ways this RCM will be a shameless copy of the VPI concept. It seems like a time-proven design, and I am not in possession of a junker turntable to convert into an RCM. So I figured I might as well try to emulate one of the standard bearers. I'm planning to prototype this on scrap wood at first, and then build a nice(ish) cabinet after I have it sorted.
In fact I decided to use two key parts straight from them: the well known 3015 mod kit (vacuum tube and base assembly) and the 16.5 version of the arbor (they call it a platter hub, btw, and were really confused when I asked to purchase an "arbor"). I don't have the mod kit yet - it seems to be taking a long time to obtain. I'm also using a Dayton gearmotor similar to the one in the 17, model 3M154. The motor is geared numerically higher than the VPI 17 motor, so it turns at 10rpm instead of 16 or 18, which should still be pretty good (maybe preferable?). It also uses permanent split capacitor design like the 17's, so it is easily reversible. And with a 5/16" shaft, it will fit the 16.5 arbor. I got this for $29 on Ebay brand new, including the run cap and free shipping. So that was a good deal! The big difference that I didn't notice right away is that the mounting holes are much closer together. This probably rules out the shock mounting that VPI uses for its standoffs, because I'm afraid the whole thing would sag at the heavy end and then the platter wouldn't be flat.* I admit I'm a bit perpelexed as to why VPI felt the need to use isolation mounts, because I can't imagine there will be tons of vibration and noise from this motor (especially compared to the vacuum!). However, I might try using rubber mounts under the motor plate if I decide they are necessary. Here is the motor with arbor attached, along with the run capacitor:
The wiring of the motor is bog simple: connect the black wire to neutral, and connect the yellow and gray wires to opposite terminals on the run capacitor. Then connect the hot power lead to one terminal on the capacitor to run it one way, or to the other terminal to reverse the rotation. A simple SPDT switch with a center "off" will determine which of the two terminals on the run cap gets the power, enabling me to switch the direction of rotation (or neither gets power for "off"). The ability to do this, btw, is an upgrade from a 16.5.
Here are two platters I'm going to try:
I went around and around in thought about how to mount a platter. I still believe the ideal design would use a large thrust bearing (like a lazy susan style or something fancier using needle bearings) to bear the platter weight and any forces of installing a clamp, etc. The challenge with this would be to connect the motor with a coupling that allows some vertical flex along the shaft's length, or else the motor would still end up bearing some of the platter's thrust forces due to tolerances. I found jaw couplings from Lovejoy that would have fit the bill. Then I would have to figure how to make a threaded spindle (for a clamp) and attach a homemade platter to that. One could also probably still use the VPI arbor, but then we're talking about $50-70 just in parts for the arbor, coupling, and thrust bearing parts. That was all making my brain hurt, so I took the easy route and bought the VPI arbor. I was concerned that the gearmotor wouldn't be designed for thrust loads, but VPI doesn't seem worried about that and I've never heard of a Dayton gearcase failure in an RCM, so I'm going to save hours of work and stop worrying. I didn't like paying $20 for the arbor, but I have to say that it's a nicely machined piece in aluminum and they included the three stainless (I think) screws and that cute little red condom to protect the threads. So I believe it was totally worth it, and it will alleviate a ton of work.
I have made two platters out of 1/2" mdf, which I believe is the same thing VPI uses. I will finish them with something waterproof, and bond something grippy on top so they can grip the records tightly. I made one platter of 11" diameter, the same as the VPI design. I am also going to try a 4" platter that just covers the label, like Nitty Gritty does it. The idea here would be to prevent any contamination of a clean record side after it's flipped over to clean the second side. It was easy enough to make it while I had the tools out, and no extra cost. So why not try it?
I cut these out using a Dremel rotary tool with the spiral cutting bit and the circle-cutting jig with router base. I'd never used that attachment before, and it worked out pretty well. Just remember to cut the circle clockwise (like the directions say), or it will be a mess! These are both very concentric around the center hole. I used the arbor to mark and drill the three small attachment holes, and I used the dremel with cutting bit and router base to counterbore each of those holes (like countersinking, but with flat shoulder instead of flared base because the screws are flat headed). This routing wasn't done with a guide, so the counterbores aren't perfectly round; but the smaller screw holes are and they line up with the threaded holes in the arbor perfectly and all of this will be covered with a mat anyway, so perfect looks aren't important.
Finally, here is the MDF plinth or base that I am using just for the prototype build:
Ugly as hell, but it was free. It was left over from the previous owners of my house - one of the only good things they left behind (but I'm not bitter). I am sizing it at 16x14 for now, a bit larger than a 16.5's size. But I will evaluate the layout and finalize dimensions for the final build later. It's 3/4" MDF - not sure what thickness VPI uses. The cutout is for the motor, of course. It's ugly because I was experimenting with the Dremel cutting bit on it. Not my best work, but that won't keep me from mounting the motor for the prototype. Rather than fashion a whole motor plate like VPI does, I might just use the flat strips of aluminum. It's all going to be covered by the larger platter anyway, and if I end up using the small platter then I'll make a plate and make it prettier so that the exposed end looks good.
EDIT: Oh yeah, forgot the vacuum! Minor detail. So the plan for now is to use a small shop vac that I already have, and make a fitting for the VPI arm base. I want to keep the vacuum as a separate, detachable piece for now because I use it for other things. This is how the KAB EV-1 does it, as well as a number of other DIY projects. The plan for now is that even the final version of this will be sited in the unfinished portion of my basement. That means I can keep the vacuum right by it and handy. If the time comes that I move the whole thing into the finished side (where my hi-fi system is), then I'd probably build in a vacuum. Or, my house actually has a central vac system and maybe I could connect that, using a separator tank to keep the water out of it.
I guess one could call this project a VPittyKAB. So this is where I am until I get the mod kit from VPI. I'll update with progress.
*If anyone wants the standoffs VPI uses, you can buy almost identical ones from JEGS, which they sell for mounting racing ignition boxes (note that these are 10-32 threads). Amazon also has really cheap mounts in a couple thread sizes that are almost the same, but they are male threads on both ends.
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