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Old 13th February 2019, 08:16 PM   #2741
niffy is offline niffy  England
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Join Date: Nov 2013
Location: Dartmoor
AAAAAAAaaaaagggggggghhhhhhHHHHHHHHHHH.

Major disaster.

I've just discovered that I've suffered a massive computer catastrophe. Virtually all my turntable design files, calculations, drawings and experiments from 2013 onwards have mysteriously disappeared. Only files created or modified in the last year or so remain after then. To make matters worse my backup file has suffered the same loss. I've probably lost a hundred files including all the subchassis and plinth designs and calculations. Loosing all those experiment and test results is a major bummer. On the bright side, at least I finished building the deck long before I lost the files.

Sad sad Niffy.
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Old 13th February 2019, 09:42 PM   #2742
hottattoo is offline hottattoo  United States
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Join Date: Sep 2006
Niffy,

That is a major loss for you and your DIY friends. You spent a tremendous amount of time and effort making a record of all your accomplishments. Any possibility of removing the hard drive and sending it to an expert ? Don't be surprised if you see a Chinese turntable / tonearm looking like yours on ebay !!!! Hope you will be able to retrieve the data somehow. Best of luck.
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Old 13th February 2019, 10:30 PM   #2743
niffy is offline niffy  England
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Join Date: Nov 2013
Location: Dartmoor
I think I've worked out what happened by going back through the photo album on my phone and looking at the dates of each stage of construction. My old computer died in 2016. When I got a new computer I loaded all my files from my backup. Unfortunately I used an old backup device instead of the correct and up to date version. The missing files never made it onto my current computer. The correct backup storage device was used to store some music files for use at my wedding reception. In the tidy up after the reception this device was lost. I finished building the deck in late 2015. I did all the investigation and upgrading of the arm bearings in 2016 and I think I have these files as they were done on the new computer. I've lost everything from sometime in 2013 until 2016. This is the fine tuning and final designs of the subchassis, suspension and plinth. I was looking for calculations for belt length and tension and couldn't find the correct files which alerted me to the loss.

On a brighter note all my tonearm files seem to be intact.
Also I finished making the new idler wheels yesterday and they look like they have come out perfectly. I just have to fit them to the deck and run them in then I can start experimenting with belt tension and a nifty little idea I've had for running multiple belts that should hopefully improve the runout of the main bearing when playing unbalanced records. The new idlers are more accurately centered than the current ones and initially tests would indicate that they are lower friction and lower noise (not that the current ones were bad in any of these respects). The current idlers run in Teflon bushes, the new ones use the same pin bearings that I developed for the tonearm. Fingers crossed.

Niffy
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Old 14th February 2019, 01:16 AM   #2744
hottattoo is offline hottattoo  United States
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Join Date: Sep 2006
Hi, Niffy,

That is good news that you figured out how the data was lost. Even though you have a back up for your data perhaps you should also put it on a memory stick. I was worried that some hacker stole your data. Hope you retrieve all your data.

Are the idler pin bearings the same size as your tonearm or are more beefy because of the added stresses involved ?
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Old 14th February 2019, 01:53 AM   #2745
super10018 is offline super10018  United States
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Join Date: May 2010
Niffy,

That is terrible. I use an iMac and back up all my documents on iCloud automatically. So, even if I have problem with my iMac, all documents are always safe.

Last edited by super10018; 14th February 2019 at 01:56 AM.
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Old 14th February 2019, 05:27 AM   #2746
niffy is offline niffy  England
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Join Date: Nov 2013
Location: Dartmoor
Hi all,

I was using double physical backups and probably got lazy with my backup routine. I'll check my wife's external hard drive as I might have stuck a copy on there at some point. I think the cloud might be a better solution for a double backup plan.

The bearings for the idlers are very similar to those for the arm. The original arm bearings were made erring on the side of caution, I could have used smaller radius but went for the sizes I did as they were the same as the jewelled bearings I was planning on eventually using. I have kept the radius of the pin the same but have decreased the radius of the vee slightly, this will increase the maximum load of the bearing. One of the problems with my current idler bearings is that the belt tension has to be kept low as the Teflon bushes are not robust enough. Hopefully the new bearings will allow higher tension. I'll run the new bearings at my current belt tension for a couple of weeks to check for wear then start experimenting.

Niffy
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Old 14th February 2019, 07:14 PM   #2747
niffy is offline niffy  England
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Join Date: Nov 2013
Location: Dartmoor
Although the new idler bearings are basically the same as the arm bearings the requirements for the two roles are quite different. The arm bearings need to have very low friction and operate in a stop/start manner. Their angular velocity will be very low, about 0.5rad/s maximum on a badly eccentric record. In contrast the idler bearings will be operated at a constant (hopefully constant) angular velocity of 27.7rad/s. Still relatively low but much higher than the arm bearings. Although keeping friction low is advantageous it doesn't have to be at the very low level that the arm requires. Both applications do require that the bearings be very quiet though the types of noise that is most important is different for each. With the idler bearings the main type of noise will be "rumble" though for bearings of this size the frequency will be quite high so it's more of a "rush". For the Tonearm the most problematic type of noise is chatter, the pin type bearing is excellent in not suffering this type of noise. Mechanical grounding is very important for the tonearm but much less so for the idlers. Both bearings will be operated at low loads, the idler bearings will have around 3-4times the load of the arm. The aim is to make the bearings just large enough to have long-term reliability but no bigger. Making them larger will increase both friction and noise. The idler bearings will probably be run with petroleum jelly lubrication in order to minimise noise. The arm bearings are run dry in order to minimise friction. I think that the pin bearings will work as well in the idlers as they do in the arm. I'm hoping to be able to fit the new idlers tomorrow, fingers crossed.

Niffy
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Old 14th February 2019, 08:56 PM   #2748
hottattoo is offline hottattoo  United States
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Join Date: Sep 2006
Niffy,

I hope the pin bearing works for your idler, but if it don't, I would be willing to give you up to 2 inches of my 1" diameter Vespel rod. I am sure you would put it to good use !!!
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Old 15th February 2019, 03:49 PM   #2749
walterwalter is offline walterwalter  Ukraine
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Join Date: Mar 2011
Niffy, I do have a question, as to bearing noises. For motor, platter bearing, as well as idler drive, I can clearly hear the noise, both directly with stethoscope and through the speakers. As to tonearm bearing, I'm unable to hear any kind of chatter, as well, as other noises (other than those, coming from the motor and drive)... What is your opinion of how chatter influence on sound happens, and how to detect it?
Picture shoves, how I tried to detect the arm bearing noise. Cartridge, placed directly on the arm with stylus in contact with the arm body near the horizontal bearings. Cables go into the phonostage.
Sorry, the arm is not linear.
Walter
Attached Images
File Type: jpg P1010701.JPG (73.3 KB, 138 views)
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Old 15th February 2019, 05:02 PM   #2750
niffy is offline niffy  England
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Join Date: Nov 2013
Location: Dartmoor
Hi Joe,

Thanks for the fabulous offer. As I don't have any specific need for vespel at the moment I won't take you up on it, but thank you anyway. If my current idler experiment fails I might look at making some bushes from a higher tech material than Teflon. 1" diameter would be a bit extreme. The bushes in the current bearings are made from 1/16" Teflon rod.

Niffy
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