Hi all. This past week I was pleased to receive a recent eBay win of a Rek-O-Kut B-5 lathe and ROK transcription turntable — my second record cutting lathe rebuild/restoration project. I’ve given the lot an initial clean. I’m hoping that from among the ROK community someone could do me the immense favor of sharing some clear shots of the parts for the B-5S or M-5S spiral crank and clockspring overrunning clutch system.
I can’t find anything useful on the Lathetroll site or elsewhere on the internet to illustrate the simple workings of this “deluxe” add-on for the S models. Clearly it is built into the exact same frame as my model and it seems to involve 6-8 basic parts that I could fabricate and add to the “plain” B-5, I believe. (If you disagree, please share you thoughts too! Would be happy to hear experienced insights.) I have scoured the site for other ROK lathe info, but this clutch topic does not seem to have been discussed.
It probably isn’t necessary for other ROK owners, but you can see the attached shot of the lathe. I quite like the bare brass and stainless steel look I discovered after the first-round of cleaning. (The original green crackle paint finish was only 60% intact upon receipt, and the remainder literally fell off with some light brushing.)
Anyway, any detailed shots, diagrams, and descriptions of the workings and makeup of the “S” crank + clutch system from this era of ROK lathe will be greatly appreciated!
John
Machining a spiral crank for an ROK B-5 lathe
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Re: Machining a spiral crank for an ROK B-5 lathe
Just emailed you with some pics. EposLab just did this with his B-5, so you might ask him how he did it. It came out quite nice!
Re: Machining a spiral crank for an ROK B-5 lathe
A follow-up to my previous post. Basplin just kindly emailed me a few clear shots of the exterior of the B5S/M5S crank mechanism. (Again: THANK YOU.) I thought it may be useful for my purposes to share part of my response on-list to hopefully generate more detailed information I might need.
Basplin: I just saw your above/online thread mention of Eposlab's own B5 crank modification. I will try to reach out and see if Eposlab can help here.
For others:
My eBay ROK lot included the B-5 lathe, the core mechanics of a G-1 transcription turntable, a (likely useless) Brush RC-20 crystal cutting head, and a transcription tonearm. At present, I only have an early 1930s RCA MI-4840/MI-4841 cutter head to use from my other lathe rebuild. (I’ll keep trying to acquire a better, more period-appropriate cutter head for the B-5, but I also intend to experiment with DIY head designs – I’ve long hand-built guitar pickups, and these mono cutter designs are just as simple.)
ON THE CRANK MECHANISM:
Based on various lathetroll/internet evidence, there appear to be several 1-3+ generations in the development of the B-5S and M-5S crank/clutch designs. For example, some are embedded in the right-side brass endpiece, and others have the two-gears raised above the surface of the inside of the endpiece. The latter will be the easiest to replicate cleanly.
With the B5/B5S and M5/M5S lathes, all photo evidence I have seen suggests that they are identical on the spindle/post left side of the lathe, hence my query about the crank side.
Among the very few lathetroll discussions of the B5/M5 ROK cranks are the following from grooveguy (https://www.lathetrolls.com/viewtopic.php?f=22&t=6729&p=44355&hilit=rek+o+kut+spiral+crank#p44355): “Very often the one-way 'clutch' that drives the leadscrew uses a coil of spring wire wrapped around an unthreaded part of the screw. One end of this spring is connected to a drive gear or pulley, and when the pulley turns in its normal direction, the spring tightens around the screw and drives it…. Most of the Rek-O-Kut lathes I've had work this way.” Another thread describes this as a “clockspring overrunning clutch.” ROK’s advertising describes this as a “dual clutch spiraling control: A fool-proof device which eliminates the danger of spoiling a record while the crank-handle is in motion.” My sense is that this is a very simple spiral clutch design involving a very small number of parts between the crank shaft and the crank handle, likely only on the the right/outside of the lathe brass endpiece.
The two-gear design on the inside of the lathe, which connects the crank’s shaft to the leadscrew, seems easy enough to replicate. I’m curious though about your photo’s off-center screw embedded between the gear and the crank’s shaft. This simply affixes the gear to the shaft, right? (Normally that would be done by a screw in a collar extension on a gear.) Or is there another hidden purpose behind the other side (inside) of the gear?
This B5S/M5S clutch appears to be what is located in the middle collar-section on the shaft in the attached photo from Basplin. The handle end has an outside black metal clip and a washer connecting the handle to the clutch via a slightly larger tubing that slides over the crank’s shaft.
Beyond the clear exterior shots I now have, what I have really hoped for are shots (or a diagram/sketch) of the assembly and individual parts of this middle-section “dual clutch” (I can’t figure our what ROK means by “dual”). Of course that would require a lathetroll hobbyist-rebuilder to dissemble the mechanism from the clip end of the crank, and I fully understand that this is not something every lathe owner is comfortable with. But surely some lathetroll hobbyist has done this in the cleaning/repairs process.
Can anyone help?
Sincerely, John
Basplin: I just saw your above/online thread mention of Eposlab's own B5 crank modification. I will try to reach out and see if Eposlab can help here.
For others:
My eBay ROK lot included the B-5 lathe, the core mechanics of a G-1 transcription turntable, a (likely useless) Brush RC-20 crystal cutting head, and a transcription tonearm. At present, I only have an early 1930s RCA MI-4840/MI-4841 cutter head to use from my other lathe rebuild. (I’ll keep trying to acquire a better, more period-appropriate cutter head for the B-5, but I also intend to experiment with DIY head designs – I’ve long hand-built guitar pickups, and these mono cutter designs are just as simple.)
ON THE CRANK MECHANISM:
Based on various lathetroll/internet evidence, there appear to be several 1-3+ generations in the development of the B-5S and M-5S crank/clutch designs. For example, some are embedded in the right-side brass endpiece, and others have the two-gears raised above the surface of the inside of the endpiece. The latter will be the easiest to replicate cleanly.
With the B5/B5S and M5/M5S lathes, all photo evidence I have seen suggests that they are identical on the spindle/post left side of the lathe, hence my query about the crank side.
Among the very few lathetroll discussions of the B5/M5 ROK cranks are the following from grooveguy (https://www.lathetrolls.com/viewtopic.php?f=22&t=6729&p=44355&hilit=rek+o+kut+spiral+crank#p44355): “Very often the one-way 'clutch' that drives the leadscrew uses a coil of spring wire wrapped around an unthreaded part of the screw. One end of this spring is connected to a drive gear or pulley, and when the pulley turns in its normal direction, the spring tightens around the screw and drives it…. Most of the Rek-O-Kut lathes I've had work this way.” Another thread describes this as a “clockspring overrunning clutch.” ROK’s advertising describes this as a “dual clutch spiraling control: A fool-proof device which eliminates the danger of spoiling a record while the crank-handle is in motion.” My sense is that this is a very simple spiral clutch design involving a very small number of parts between the crank shaft and the crank handle, likely only on the the right/outside of the lathe brass endpiece.
The two-gear design on the inside of the lathe, which connects the crank’s shaft to the leadscrew, seems easy enough to replicate. I’m curious though about your photo’s off-center screw embedded between the gear and the crank’s shaft. This simply affixes the gear to the shaft, right? (Normally that would be done by a screw in a collar extension on a gear.) Or is there another hidden purpose behind the other side (inside) of the gear?
This B5S/M5S clutch appears to be what is located in the middle collar-section on the shaft in the attached photo from Basplin. The handle end has an outside black metal clip and a washer connecting the handle to the clutch via a slightly larger tubing that slides over the crank’s shaft.
Beyond the clear exterior shots I now have, what I have really hoped for are shots (or a diagram/sketch) of the assembly and individual parts of this middle-section “dual clutch” (I can’t figure our what ROK means by “dual”). Of course that would require a lathetroll hobbyist-rebuilder to dissemble the mechanism from the clip end of the crank, and I fully understand that this is not something every lathe owner is comfortable with. But surely some lathetroll hobbyist has done this in the cleaning/repairs process.
Can anyone help?
Sincerely, John
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Re: Machining a spiral crank for an ROK B-5 lathe
Being owner of a similar Master Pro cutting lathe , mine also with a standard B-5 overhead , i had to fing a way how to make spiral in / grooves easier and smoother! For long time i was trying to figure out how to install a hand crank and i ended up to 3 options:
A) hand crank with gears , similar to original. This option is the most professional-heavy modification and more expensive as you need great experience & precise tools for making the parts ready and install them properly! Good is that you can customize move ratio. Bad (imo) is that the crank moves counter clockwise.
B) direct hand crank. Much more easier solution with little modification. Just replace the feedscrew holder with a crank assembly! I made this crank assembly with just using a "radio program knob! Good for direct is 1:1 move ratio!
C) belt drive crank. The most easier mod as not much accuracy is needed. Easy to install , easy go remove! More options of move ratio! Hand crank can also be replaced with step motor!
Soon i will try to make & add some drawings but as for now you check the pics & videos:
A) hand crank with gears , similar to original. This option is the most professional-heavy modification and more expensive as you need great experience & precise tools for making the parts ready and install them properly! Good is that you can customize move ratio. Bad (imo) is that the crank moves counter clockwise.
B) direct hand crank. Much more easier solution with little modification. Just replace the feedscrew holder with a crank assembly! I made this crank assembly with just using a "radio program knob! Good for direct is 1:1 move ratio!
C) belt drive crank. The most easier mod as not much accuracy is needed. Easy to install , easy go remove! More options of move ratio! Hand crank can also be replaced with step motor!
Soon i will try to make & add some drawings but as for now you check the pics & videos:
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Epos Laboratory Phono Cartridge Retip & Lathe Cuts
http:\\www.eposlab.gr
info@eposlab.gr
IG EposLab (https://www.instagram.com/eposlab/?hl=en)
http:\\www.eposlab.gr
info@eposlab.gr
IG EposLab (https://www.instagram.com/eposlab/?hl=en)
Re: Machining a spiral crank for an ROK B-5 lathe
Thats a better picture...
You do not have the required permissions to view the files attached to this post.
Epos Laboratory Phono Cartridge Retip & Lathe Cuts
http:\\www.eposlab.gr
info@eposlab.gr
IG EposLab (https://www.instagram.com/eposlab/?hl=en)
http:\\www.eposlab.gr
info@eposlab.gr
IG EposLab (https://www.instagram.com/eposlab/?hl=en)
Re: Machining a spiral crank for an ROK B-5 lathe
Excellent! Looking forward to more details when you have the time. John
Re: Machining a spiral crank for an ROK B-5 lathe
Here are some photos of the crank pieces from my M5. It's a clever design. The metal sleeve has a set screw that tightens to the flat spot on the gear rod. Inside of the metal sleeve is a metal coil with a hook on the end that catches on the slot on the crank itself.
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Re: Machining a spiral crank for an ROK B-5 lathe
Many thanks basplin! This is precisely what I was hoping to see. I'm now considering trying to develop some marriage of the design of the original spring clutch and the direct belt-drive crank eposlab has developed. If/when I get to this, I'll be sure to add to this thread for the benefit of other ROK owners!