Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Diy Rcm
Diy Rcm
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st July 2018, 01:58 PM   #1
DiyGazza is offline DiyGazza  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Kent, England
Default Diy Rcm

Well, I haven’t been on the forum for a while now as I’ve been quite busy with a few small projects
Including this RCM based on the Keith Monks – Loricraft – Heath Robinson Design.

Pictures at the bottom of page.

I posted a thread some time ago regarding the cleaning of vinyl as I could never get the results I wanted with a Spinclean system on some albums I thought had been ruined by a stuff called “Permostat” that I applied to some of my albums in the early 80’s, While it did a good job of brightening everything up and removing the gunk from the grooves, I always had problems with surface noise after cleaning and no matter what I tried with regards to rinsing and the type of cloth’s used to dry the record including drip drying things never improved much.

While looking for the best method of cleaning, countless YouTube Videos, and hours of reading through forums, I kept getting drawn back to the Monks and Loricraft machines, but both were out of my price range, or at least more than the wife was willing to let me spend , so if I wanted one or something that worked on the same principle I would have to build one, and on a budget of a couple of hundred s.

So, for starters there’s the case (box) made of 11mm ply and the top plinth made from 18mm ply with a 3mm black acrylic top.

Unable to find a suitable bearing and drive system that didn’t cost more than the entire project, I found a company called (Motionco) that supply small bearings, gears, Shafts etc., and as luck would have it a 300mm Turntable Platter.

Finding a suitable motor also turned out to be tricky, but I found one on eBay that is 230v and reversible and runs at 60rpm for around 19.00, the downside is that it starts to run hot quite quickly.
The motor drives the platter via a toothed belt and two 48 teeth gears (one on the motor and one on the platter spindle) The Platter drive shaft is 8mm diameter and has a bearing at the top and one at the bottom, The bottom bearing (and here comes Heath Robinson) allows for some adjustment of the shaft to allow it to run true to the plinth top.

The motor shaft also caused a bit of a headache as it’s 7mm in diameter, after a bit of head scratching, I found that some 8mm brass tube with a wall thickness of 0.5mm was a nice fit on the motor shaft, but a tight fit in the gear, I had to press it in with a vice, and not forgetting to drill a hole in it first to allow the grub screw to pass through to catch the flat on the motor shaft.

I’m going to rewind just a little here, some of you may be wondering why I didn’t simply just drive the platter directly from the motor .. and the answer to that is because the motor shaft is not running completely true, and that small amount of wobble equals quite a large amount of runout at the platter edges, I did try and compensate for it by using some packing washers to try and even things out, but that didn’t work out too well. With it setup as it stands at the moment using the bottom bearing for adjustment I have about 0.75 - 1mm of runout.

The Vacuum Arm is made from 10mm Brass Tube and approximately 12” long, with the pivot point at about 9”.
I filed a half round section on one end to accept the “T” piece, Filing it carefully so the two pieces butted together neatly also made it much easier to solder.
The Vacuum tube on the top is 3mm Brass Tube, as is the Thread Feed Tube on the bottom, and simply bent by hand (actually not quite so simple, It’s pretty tough stuff)… until I had the right shape bends and then cut and de-burred the ends for the correct lengths.

I used High Temp Caption Tape to hold things together for soldering, and also to stop any access solder running around the tube.
I was quite surprised how well the tape held up after being subjected to a blowtorch, any burnt pieces were easily removed with some fine steel wool.

The two pivot pillars, made from 20mm Brass Rod I had machined at a local machine shop, they put a radius on the tops, and drilled and tapped a M5 hole in the bottom, a hole was drilled in the side and tapped to accept a M3 Allen Bolt, the hole was recessed on the opposite side to allow the head of the bolt to be screwed in out of sight, A 10mm collar with a 3mm hole drilled either side forms the pivot point, the arm slides into the collar and is secured by a grub screw, which also allows some adjustment of the vertical axis.

The base is 2mm thick Brass Plate, cut and filed to the necessary shape to accept the pillars, Drive Shaft, and thread reel.

The drive shaft for the arm sits between the two pivot pillars, and is made from a 100mm length of 20mm Brass Rod (a bit overkill) but its weight and downward force helps offset the weight of the arm (before I had made the counterweight) and helps to keep it in a more or less balanced position through the Plinth and top and bottom guides, stopping it from pulling one way or the other if that makes sense.. ?

On the very bottom of the shaft is a 20mm Plain steel washer held in place with double sided sticky foam tape, which forms one part of the magnetic clutch.

The arm shaft drive is driven by a 1.6 rpm 12v motor, further reduced to a ratio of 10:1 using a toothed belt driving the two gears, the Gears, Belts, Shafts, Bearing Blocks and other construction parts were again sourced from (Motionco).

On the Larger of the two gears are two 20mm diameter Neodymium Magnets, One is glued to the top of the gear and the other simply sits in top of the glued magnet, the Brass Drive from the arm with the steel washer on the bottom then passes through a 20mm I/D Brass Sleeve and sits on top of the magnets, the sleeve prevents the arm slipping off centre of the magnets (something I did have some intermittent problems with) I also had random spots where the arm would slip on the magnets making the speed inconsistent, so I cut a circle of 2mm thick rubber and fitted it in between the steel washer and the magnets, and this seems to have cured the problem.

The Suction Nozzle: Is made from a piece of 10mm Round Teflon available from Ebay.

I started by cutting a length 10 – 15mm longer than I actually needed, I then drilled a 1.4mm hole through the centre (there a videos on You Tube showing how to drill a almost perfectly centred hole in a piece of round material using a pillar drill) I then opened up part of the hole to 1.5mm at the end where the silicone tube would attach, but not deep enough to affect the 1.4mm hole at the suction point.

I then used the pillar drill, and a medium file to turn down the part where the silicone hose would attach, Slow and easy … A medium file makes short work of this, I didn’t bother smoothing this part off once I had the correct diameter, as I figured it would allow the tube to grip better. Next to turn down the material so it would fit inside the Brass “T” piece of the arm, The inside diameter of the tube is around 8mm, so again, a small medium file was used to turn the material down just enough so that it was a snug fit inside the tube.

With those two parts done I could now cut the rod to the correct length and start to shape the Nozzle. This was again done using a file to get the basic shape, and then using decreasing grades of emery Paper to finally shape and smooth the nozzle tip, It was then washed in isopropyl and blown though with an air hose, The finished length is approximately 35mm.

The Vacuum Pump: As mentioned, I needed to do things on a pretty tight budget, and looking at the KNF Diaphragm pumps and the like, proved to be a bit too expensive. What I did have to hand is a rotary vane pump used for things like Automotive A/C systems, and with a whopping 2.5 cfm airflow,
But being an oil type pump, the oil is easily contaminated with water vapour and could be easily damaged.
looking at an online conversion chart this appears to be around 70 L/min, a bit over the top? Probably…. But boy does it suck !!

When I threaded the machine for the first time, it pulled the thread through the feed tube no problem, I left about 6” of thread laying on the plinth ready to get it through the nozzle, connected the pipe, and turned around to switch the pump on, when I turned back I couldn’t find the thread, and then I realised that the vacuum had picked up the thread from the plinth, sucked it through the nozzle and threaded itself ! …Bonus…. The thread by the way is the original Talbot #30 Nylon Thread.

I do know that the pump will pull just over a negative 800mbar through the 1.4mm orifice and about 850mbar while pulling fluid off of the surface of the record.

The other plus side to this is the fact the arm has a VTF of Zero, Once ready to vacuum, the nozzle once placed on the record label will stay in contact under its own suction, and when it reaches the end of the outer edge simply floats off, so no risk of the brass tubing dropping down and possibly damaging or knocking the edge of the record.

While it’s great to have that amount of suction, the downside is the pump is big, heavy and gets very hot in a short space of time, plus the oil / water contamination problem. I also think it is quite possible to have too much suction, i.e. the suction is so great it will partially dry surrounding grooves and so when it comes to the point where the nozzle passes over these grooves there isn’t a solid liquid for it to pull out, so possibly leaving some debris / residue left behind (Just a thought).

I have been looking at the cheap Chinese 5L/min oil less diaphragm pumps available on Ebay at around 11.00 delivered, I already have one and have another on order, I believe it is also possible to get them in 8/10/20 and 40 L/min sizes.

I did a bit of an endurance test on the one I have, one test at maximum vacuum at which it pulls about a negative 650mbar for about an hour, and again just pulling free air through a small inline filter. In both cases the pump housing and motor remained very cool, considering it was 35C in my shed, pulling a continuous vacuum the pump housing was slightly warmer than when pulling free air.
Going back to pulling a vacuum again there was no degradation in vacuum pressure or motor / gear noise, so first impressions look quite promising for these cheap little pumps, albeit if they are a little noisy, but this seems to come mainly from the outlet / exhaust port, and by placing a small piece of foam around the port the noise is reduced quite dramatically, with no impact on suction. The downside is that one pump on its own will pull 0mbar through the nozzle and around 25mbar with the nozzle and thread placed on a dry surface.

I have seen two of these pumps used in series on some DIY machines, but my train of thought would be to use two in parallel, better still .. Two 10 litre pumps in parallel, this mode of operation could possibly give me the chance to run them at a lower voltage thus decreasing the noise, I think the motors are the same size just the pump heads are slightly larger.

So, how well does it work with the current setup?

The first attempts were performed on a few records that had just minor crackles in between tracks and quiet passages of music using l’art du son, the results were a little hit and miss, one area would be nice and quiet but background crackles seemed to have moved elsewhere on the record, after getting the same results on a few records, I realised that because the platter is only rotating at 60rpm, and the arm taking just over a minute to traverse the surface of the record, certain areas were getting missed.

Measuring the distance from the label to the outer edge of the record gave me a figure of 110mm, so to effectively cover the entire surface I reduced the speed of the arm to two minutes, this made a world of difference and while there was still the odd tick here and there it was a great improvement to the results I had been getting.

The records that I thought had been trashed by the ”permostat” I put on them back in the late 70’s early 80’s, (and I’m finding more and more of them as I work my way through my collection)The l’art du son just doesn’t cut it, and won’t remove it, so I mixed up a 1:4 bottle of Isopropyl / Distilled Water with a couple of drops of Ilford Ilfotol, and ran that, but this time with the platter running CCW, I followed this up with a rinse of plain Distilled water again with a few drops Ilfotol and running the platter CCW, and finally the LDS and again ran the platter in a CCW direction.

The difference this made was incredible, nearly every single tick has been eliminated, the run in track is silent, the Bass smooth but still punchy, snare drums have “snap” that almost makes you blink, and cymbals are clear smooth and sweet, it’s like the difference between night and day, and a far cry from the woolly, distorted, stylus gunking noise I had previously.

I’m not sure if running the platter in a CCW direction has made an improvement, but as I’m still dialling the machine in, I’ll try a few already cleaned records to see if there is any improvement to be made.

Last but not least, In an attempt to help keep any static down, there is a long weak spring that is connected to ground, and this is just in contact against the arm spindle, I thought that any static may travel through the wet thread and get discharged to earth, I don't know if this really works, but the records are or appear to be totally static free after cleaning.

So issues I need to address;

I need to find a Platter motor that has plenty of “Grunt” but will stay cool for a long period of cleaning, preferably reversible and a slow speed, it doesn’t really matter if it’s AC or DC.

Get the platter speed up to 78 – 80rpm so that the suction arm can speeded up.

Play around with some of these cheap Chinese vacuum pumps to see it I can still get the same results as the monster pump I’m running at the moment, I know I should be aiming to achieve 15 – 16 L/min.

I think that’s about it …. Phew.
Attached Images
File Type: jpg P1010506 copy.jpg (778.9 KB, 377 views)
File Type: jpg P1010509.jpg (690.1 KB, 364 views)
File Type: jpg P1010510.jpg (617.2 KB, 364 views)
File Type: jpg P1010513 copy.jpg (535.3 KB, 358 views)

Last edited by DiyGazza; 1st July 2018 at 02:53 PM.
  Reply With Quote
Old 1st July 2018, 05:54 PM   #2
Pyramid is offline Pyramid  United States
diyAudio Member
 
Pyramid's Avatar
 
Join Date: May 2006
Location: Behind the Cheddar Curtain
Nice Job!

Last edited by Pyramid; 1st July 2018 at 05:59 PM.
  Reply With Quote
Old 1st July 2018, 06:47 PM   #3
DIYNick is offline DIYNick  United Kingdom
diyAudio Member
 
Join Date: Aug 2010
Location: Merseyside
Wow! Liking your work!
__________________
DIYNick
(also known as nitrous in some places)
  Reply With Quote
Old 1st July 2018, 08:34 PM   #4
DiyGazza is offline DiyGazza  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Kent, England
Thanks Guys.
  Reply With Quote
Old 2nd July 2018, 04:09 AM   #5
rewind67 is offline rewind67
diyAudio Member
 
Join Date: Nov 2009
Default Pumps in parallel

Very nice work, diygazza! Re: the cheap pumps you are experimenting with; I used two, running in parallel, in my own thread-buffer RCM. It works well and met the pressure/airflow spec Id found in researching the commercial machines. They are quite noisy though. Ill give the foam-over-intake a tryI assume you used a very porous foam, like an a/c filter?

Ive also had the runout issue, due to directly coupling the platter to the motor shaft. The belt drive seems like a good solution, which I will also have to try.
  Reply With Quote
Old 2nd July 2018, 07:57 PM   #6
DiyGazza is offline DiyGazza  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Kent, England
Quote:
Originally Posted by rewind67 View Post
Very nice work, diygazza! Re: the cheap pumps you are experimenting with; I used two, running in parallel, in my own thread-buffer RCM. It works well and met the pressure/airflow spec I’d found in researching the commercial machines. They are quite noisy though. I’ll give the foam-over-intake a try—I assume you used a very porous foam, like an a/c filter?

I’ve also had the runout issue, due to directly coupling the platter to the motor shaft. The belt drive seems like a good solution, which I will also have to try.
Thanks, It was very enjoyable to build, I like a bit of a challenge, always have to think that little bit ahead.

What sort of pressure do you get with two of these pumps working in parallel? I would have imagined somewhere around 200mbar just pulling free air through the nozzle. I actually ordered 2 12L/min pumps last night, but they won't get here until the end of July / beginning of August, at least that's the estimated delivery time.

Putting a small piece of foam over the outlet port just takes the edge off the noise, it doesn't work miracles, but it helps. I used a small piece of sound dampening foam I happened to have to hand, it's about an inch thick, so I cut a small square and cut a slot in it to slip over the outlet port and cable tied it in place, as I mentioned it didn't appear to affect the vacuum at all.

Getting the platter to run true was a bit if a headache, and looks like we both had the same issues, I'm not overly pleased with the appearance of the big lumps of wood sticking up from the bottom, but I couldn't mount anything from the top downwards because of other parts in the way.

Regard's,
Gary.
  Reply With Quote
Old 3rd July 2018, 05:12 AM   #7
Nanook is offline Nanook  Canada
diyAudio Member
 
Nanook's Avatar
 
Join Date: Feb 2004
Location: Chinook Country.Alberta
Default diyGazza nice RCM machine.

Hi DiyGazza;

It looks very good, and is reminiscent of the Keith Monks machine. AFAIK, the Keith Monks turns at about 17 RPM. The slower speed provides deeper cleaning. There has been some discussion on the proper thread to use. What thread have you been using?

I've been thinking about using a small portable vacuum (an old "Shark" handheld). If their is too much vacuum, then a means to bleed off some vacuum could be arranged. To keep the noise down it would have to be housed in box with sound dampening /absorber used.

The absolute quickest way to make a RCM is a direct drive turntable, an existing small vacuum, some tubing, thread, and appropriate flexible tubing. If the DD frequency is halved and doubled then that would be good too. So 17, 23 RPM, 33, 45, 66, 90 RPM.

I have an old Yamaha PD751 DD tt that I could use.
__________________
stew -"A sane man in an insane world appears insane."
  Reply With Quote
Old 3rd July 2018, 08:26 PM   #8
DiyGazza is offline DiyGazza  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Kent, England
Quote:
Originally Posted by Nanook View Post
Hi DiyGazza;

It looks very good, and is reminiscent of the Keith Monks machine. AFAIK, the Keith Monks turns at about 17 RPM. The slower speed provides deeper cleaning. There has been some discussion on the proper thread to use. What thread have you been using?

I've been thinking about using a small portable vacuum (an old "Shark" handheld). If their is too much vacuum, then a means to bleed off some vacuum could be arranged. To keep the noise down it would have to be housed in box with sound dampening /absorber used.

The absolute quickest way to make a RCM is a direct drive turntable, an existing small vacuum, some tubing, thread, and appropriate flexible tubing. If the DD frequency is halved and doubled then that would be good too. So 17, 23 RPM, 33, 45, 66, 90 RPM.

I have an old Yamaha PD751 DD tt that I could use.
Hi, I did consider using an old turntable, but it seemed a shame to ruin a perfectly good piece of equipment, plus the cost of buying a DD turntable would cost probably as much to buy as I spent on the entire project, you then have issues with the existing arm mechanics and finding a way to drive the arm / suction wand.

I was going for the "Loricraft" look which I believe spins at 80rpm

The thread I'm using is the original Talbot #30.

I did look for a more appropriate "Thread" section, but couldn't find one.

Regard's,
Gary.
  Reply With Quote
Old 3rd July 2018, 08:46 PM   #9
rewind67 is offline rewind67
diyAudio Member
 
Join Date: Nov 2009
Quote:
Originally Posted by DiyGazza View Post
What sort of pressure do you get with two of these pumps working in parallel? I would have imagined somewhere around 200mbar just pulling free air through the nozzle.
I just tested the free air flow again and got 237 mbar; so your guess is about right. YMMV as I think there is a fair bit of tolerance in these little vacs.

During the cleaning cycle, with the nozzle resting on the thread, I get 19 in/Hg or about 643 mbar. Very close to the 20 mentioned as the Keith Monks operating level.

A spec sheet I dug up for these pumps ("Airpon D2028") gives a free airflow range of 12-15LPM (roughly .5 cfm). Running the pumps in parallel, in theory, should double that. I think the reality is that both flow and "pull" benefit, but flow isn't doubled. Still, experimentation showed I needed a higher flow rate than a single pump could provide, so I went with parallel.

Somewhere I did see there was a range of these pumps with different specs. It would be interesting to try different ones.
  Reply With Quote
Old 3rd July 2018, 09:00 PM   #10
rewind67 is offline rewind67
diyAudio Member
 
Join Date: Nov 2009
Quote:
Originally Posted by DiyGazza View Post
I was going for the "Loricraft" look which I believe spins at 80rpm

The thread I'm using is the original Talbot #30.

I did look for a more appropriate "Thread" section, but couldn't find one.
Hi guys. I also went with what I understood to be the Monks/Loricraft speed of 80 rpm (my DC motor is actually 81rpm). The arm speed is quite slow; my RCM takes ~1min 30sec to traverse an LP. I believe the combination of fast-platter/slow-arm positions the nozzle so that it gets a fair bit of time over each section of the groove.

I'm using a nylon thread that is sold for wrapping fishing poles; but it's practically the same diameter spec of the original Talbot thread.
  Reply With Quote

Reply


Diy RcmHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 03:30 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki