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Old 18th November 2012, 08:07 PM   #161
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Default More on bath temperature

I also had a problem with heat, but it involved warping, not melting. The short story is that serious permanent warping to the point of making an LP unplayable even with a peripheral ring can occur at temperatures below 120 degrees. The key difference with BB's and others' positive results appears to be slow, even rotation vs. 1/4-turn rotations. So this is a warning to people trying manual rotation while waiting to get their rotisserie operational, but might be of interest as a note of caution to others as well.
(Lengthy) details follow.

I purchased a chef's thermometer to monitor temperature, and had planned to not exceed 120 degrees F. However, I didn't realize how fast the temp would go up after reaching that target, and started an 8-minute cleaning cycle when the bath reached 120 without turning off the heat. Like Rick, I also used 1/4-turn rotations with 2-minutes at rest in between. Unfortunately, the first time I tried heat, I also tried 3 records at the same time and wrecked 3 records in one go. I didn't notice a problem until I removed the lps from the bath and saw visible warping. When I checked the temp, it had risen above 150 during the 8-minute cycle. I hoped that the warping would go away as the records cooled, but no. The warping was mostly in the outer bands of the record. The outer bands are unplayable, even with a ring clamp, with the inner bands still playable.

I tried again with a single lp at 110 degrees. This time, I shut off the heater before I immersed the lp when the bath reached the target temp. I used the same schedule of four 1/4-turn rotations. The temp stayed pretty constant during the process. Surprisingly, the single lp also warped at this lower temperature. Somewhat less severe warping than the previous run, but still enough to trash the record.

Then followed a period of self-flagellation, followed by a longer period trying to figure out why this happened (at a temperature below what others report as safe). The obvious difference was the slow continuous rotation by motor and the large-increments of manual rotation I used, but why does this matter?

I came up with the following explanation. The warping appears to be the result of buckling in the heated portion of the outer bands which go into compression as their natural tendency to expand is restricted by the cooler parts above the waterline. With slow continuous rotation, the extent of the heated part is roughly constant at less than half the circumference, leaving more than half the outer circumference at cooler temps to provide support against buckling. With a sudden 1/4-turn rotation, there is a time when the heated region extends well over half the circumference. If this unsupported length for 90 degree rotations is roughly double the corresponding length for continuous rotation, it would drop the critical buckling stress by something like a factor of 4. Another contributing factor might be that the peak rates of heating/cooling at any point on the record is much higher than would be obtained with slow constant-speed rotation.

Whether my explanation is correct or not, I tried a couple of single-lp runs this weekend at the same 110-degree bath temperature. I still rotated manually, but tried to approximate slow continuous rotation as best I could. The rate worked out to be roughly 2 complete rotations over 8 minutes (1/4 rpm). This time I obtained no permanent buckling. I did see some milder temporary deformation into a bowl shape after rinsing with distilled water on one side on my VPI 16.5, but this deformation disappeared after rinsing the second side. Apparently, the record was not completely cooled when I began the rinse.

So my conclusions on bath temp are:

Temperatures in the range of 110 - 120 degrees are not necessarily safe against permanent warping. At these temperatures, the particular motion of the lp through the bath can make the difference between a great result and a ruined record.

It might be wise to work at an even lower temperature to be extra conservative for particularly valuable lps.

If there is no reliable means to maintain a desired constant temperature, turn off the heat before inserting the lps. The temperature will not change much in 10 minutes (probably due to the thermal mass of over a gallon of water plus the heat added by US excitation).
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Old 18th November 2012, 09:36 PM   #162
bbftx is offline bbftx  United States
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Default Thermometers

Quote:
Originally Posted by Ishmail View Post
I purchased a chef's thermometer to monitor temperature, and had planned to not exceed 120 degrees F.
Ish, Sorry to hear about your troubles. Chef's thermometers aren't a good tool for this process. Most aren't accurate below oven temps of 250F or so. We're measuring temperatures around 100F, plus or minus. Most coffee/espresso/milk thermometers are designed for the range we're working in and will give more accurate readings.

Room temps in Texas often get to 110F, particularly in the days before A/C was so widespread. Records don't warp at temperatures below 120F. That's not very hot for vinyl. I've not had a single record warp, and I've now cleaned hundreds in my heated URC. If you're having this many problems, I suspect your thermometer is reporting lower temps than you're actually reaching.

And yes, don't spray cold water on a hot record -- yet another reason to avoid the rinse procedure....
B B
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Old 18th November 2012, 09:39 PM   #163
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Sorry to hear about the vinyl damage. Thankfully, I have not had any warping. My cheap Chinese 40KHz machine has a thermostat that has proved to be pretty accurate. I usually keep it set at 40 degrees Celsius (approx 110 F) and that combined with a 6RPH rotation speed has ensured damage free cleaning (knock on wood).
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Old 19th November 2012, 12:15 AM   #164
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Default Preliminary results with Alconox

I have preliminary results with Alconox (powder) to report. All of these tests were in the range 100 to 120 F with 8 mins of manual rotation during US cleaning. I used generic distilled water to mix the bath.

The manufacturer recommends 3 tablespoons per gallon, and there is minor foaming at this concentration. I've settled on using much less --- about 1/4 tsp. of Alconox powder for about 5 quarts of liquid. I add the powder directly to the US cleaner's tank, and the degassing process quickly dissolves it. There is no foaming at this concentration. I follow the cleaning with a vacuum and rinse with ultra purified water on a VPI 16.5. One lp was in pretty good shape as far as damage goes, and sounded spectacular after the US cleaning. Another lp had a fair number of surface scratches. Still, the detail that came through was pretty impressive despite the scratches and noticeably better than I generally get from a 3-step vacuum procedure using AI products.

Keeping in mind that I haven't done very many tests yet, my preliminary impressions echo rickmcinnis' enthusiastic comments.

I might try adding some IPA, and at some point it would be interesting to compare to other formulations.

I still plan to test a rinse in my automated process --- both to remove all traces of the surfactant (even at the reduced concentration) and to remove any fine particles that might still be in suspension in the bath (it's not clear that filtering during the cleaning process completely addresses this issue, but I'm sure it helps and I do plan to add a filter). My design should allow me to move the rotisserie assembly with LPs still mounted from the US cleaner to a separate food pan filled with ultra distilled water (probably Aquafina) for rinsing (in lieu of the rinse I now do on the VPI machine).

The only things I'm still lacking for final assembly are a few plastic parts to form a deck and arm. A local plastics supplier promised to produce these in "a few days" that was three weeks ago. Unfortunately for me, a big job from a large local manufacturer bumped my smaller project. I hope he delivers soon.
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Old 19th November 2012, 02:23 AM   #165
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Quote:
Ish, Sorry to hear about your troubles. Chef's thermometers aren't a good tool for this process. Most aren't accurate below oven temps of 250F or so. We're measuring temperatures around 100F, plus or minus. Most coffee/espresso/milk thermometers are designed for the range we're working in and will give more accurate readings.

Room temps in Texas often get to 110F, particularly in the days before A/C was so widespread. Records don't warp at temperatures below 120F. That's not very hot for vinyl. I've not had a single record warp, and I've now cleaned hundreds in my heated URC. If you're having this many problems, I suspect your thermometer is reporting lower temps than you're actually reaching.

And yes, don't spray cold water on a hot record -- yet another reason to avoid the rinse procedure....
B B
Hi BB. Thanks for your sympathy; I'm feeling better now. Only now I have to join the thread for diy flattening presses for warped lps.

I am in fact using a thermometer intended for liquids (soups, coffee, etc.). It tops out at 220 F, 110 F is the middle of its range. I think it's reasonably accurate. I know it reads correctly at room temperature, for example.

I agree that 120 F is not a problem if the whole record is close to that ambient temperature and there are no sustained external forces to generate a warp. However, an lp bending under an external load at 120 degrees in Texas will develop a permanent warp at a lower stress than a similar lp in Minnesota in November, and the warp in Texas will grow faster.

Temperature differences and gradients matter here, although absolute temperature comes into play, too. Partial immersion in a 120 degree bath sets up a maximum temperature difference of about 50 degrees --- a substantial difference --- between the immersed parts and the exposed part of the disk at ~70 F. Higher absolute temperature also lowers the stress level that causes slipping and rearrangement of vinyl's polymer chains at the molecular level. This molecular rearrangement is what causes permanent warping.

The warp in the heated outer part of the disk might be a result of buckling under the compressive stresses that develop where free expansion from heating is resisted by the cooler parts of the disk. The critical stress for buckling drops as heating lowers the vinyl's tangent modulus. In addition, rotating the disk 90 degrees all at once results in elevated temperatures in a greater fraction of the disk and a smaller fraction in cooler states. Doubling the unsupported circumference of the heated part would further reduce the critical buckling stress by a factor of roughly 4 (by very rough analogy to column buckling theory).

This is what I think is going on, I could be wrong. But one thing is for certain: the buckling happened before the rinse, so the rinse did not cause the warping.

The good news is that I've cleaned about half a dozen disks this weekend with slow manual rotation in baths ranging from 100 - 120 F, including a rinse every time, and have had no worping problems. But I agree, one should think long and hard and test carefully before throwing cold rinse water on a hot LP you care about. That being said, it does not appear that rinsing itself necessarily causes warping.

If someone is curious and motivated, they could try to replicate my results (with an lp they don't care about) by manually rotating through a 1/4 turn every 2 minutes for 8 minutes total in a bath at, say, 120 degrees. Skip the rinse. Let me know if you get a permanent warp.

If your US cleaner is up and working well at your desired temperature range, all this should have little practical significance for you under normal operation. If you are using continuous rotation at a reasonably slow speed, I see no reason for concern. This is more an issue for those, like me, who are waiting for parts to come in and decide to give their cleaner a try with manual rotation. It seems that a subtle change in the procedure can have big consequences.

I also think this phenomenon poses an interesting puzzle in mechanics, but that's just me.
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Old 19th November 2012, 02:44 AM   #166
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Quote:
Originally Posted by Vinyladdict View Post
Sorry to hear about the vinyl damage. Thankfully, I have not had any warping. My cheap Chinese 40KHz machine has a thermostat that has proved to be pretty accurate. I usually keep it set at 40 degrees Celsius (approx 110 F) and that combined with a 6RPH rotation speed has ensured damage free cleaning (knock on wood).
Agreed. My GemOro might have 60KHz transducers, but I have to say its controls are not very good. Only on-off for temperature, and the mechanical timer for powering the transducers is not calibrated in any meaningful way. Even worse, I can't find a way to shut the US off when my external timer says time's up --- it seems I can't force the mechanical timer ahead. I can pull the power cord, but the mechanical timer still keeps on clicking. Certainly the recent Chinese products and other brands are sporting more useful controls than my somewhat dated machine. But I knew this going into the purchase.

So my typical procedure is:

1. Monitor temperature with external thermometer until desired temperature is reached.

2. CRITICAL: Manually shut off the heater when target temperature is attained

3. Set an external timer (e.g, my phone) for the desired time and set the GemOro's mechanical timer for a little more than the time needed.

4. Remove the disks when the external timer signals; then just let the timer run out and (finally) shut down the GemOro.

This is all pretty clunky, but the worst of it is the risk of damage if I forget step 2.



My tests this weekend, not to mention your results and all the previous reports, suggest you should be fine at your current settings.
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Old 19th November 2012, 03:59 AM   #167
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Default An alternative to cork spacers

Here's an alternative to the cork spacers used to space the lps on the spindle. I don't claim they're any better, just an alternative. In my case, I had dual uses for the foam rubber (see below), and the black color matches the finish on my cleaner.

I purchased a "kneeling pad" made out of closed-cell* nitrile foam rubber with a nominal 1" thickness (more like 1-1/8" by my measurement). Then I used a hole saw mounted in a hand power drill to cut out circular disks to make the spacers.

One mat** yields 9 spacers (see photo). It's quick work, but it takes a little practice to cut cleanly and keep the drill vertical to get a nice right cylinder. It would be very easy if you have a suitable drill press handy (I don't).

I used a 4-1/8" hole saw (foreground of 1st image). It's fine, but I would use 4-1/4" if I were to do this again. Be sure to thoroughly clean the disks of all loose particles before first use. The hole saw mandril uses a 1/4" guide bit, so you create the hole for the spindle, auto-centered, at the same time you cut each disk.

I'm using the same end-cap solution described elsewhere on this thread. These, combined with 3 spacers allows up to 4 lps on a spindle, which is about the max for my tank size. It's also slightly above, but perhaps close enough, to the max recommended surface area for my transducer configuration. I can always cut back to 3 lps with two spacers if necessary. So, if all your cuts are good (mine were not), you get 3 sets of 3 spacers from each mat.

I will use two foam rubber strips, cut from the rounded ends of the mat and then shaped with a Dremel rotary tool, as the means of attachment between the deck of my rotisserie and the top of the GemOro cleaner. So, I'm getting good use out of my mat. More on this later.

* Closed cell foam is important because it won't absorb water.
** See, for example, the Kneesaver Kneeling Pad listed under Home Mats at matsmatsmats.com. $14.99. This pad has a nominal 1" thickness, but it's more like 1-1/8" by my measurement. This provides generous spacing to promote good penetration of the US wave field between lps. I ended up buying 2 mats; the second one is for the product's intended use.
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Old 19th November 2012, 03:15 PM   #168
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Default Record warping and other maladies

Sorry to hear of your damaged LPs, Ishmail. Though we are grateful for your experimentation.

I think the warping issue might be completely unpredictable. I have had one record warp, though the peripheral clamp did allow the record to be played. I was thinking in my case it might have been due to my standing the record on edge for drying. Though this only happened with one - that one could be one too many!

There are probably a million different PVC mixtures and some will have different melt points. I hope Ishmail is correct that the rotisserie will eliminate this from happening.

I had thought that maybe I should lay the record down flat after taking it out of the machine? I am using diapers for drying and do not think I am losing anything from this. I had shied away from laying them horizontally due to dust settling on top of them. One could simply cover with another diaper which is what I will try next.

Regarding your use of the rinse and the VPI I cannot stop myself from asking you if you have tried it without doing this. I think bbftx is on to something with his disregard for brushes. Not to say I could be missing something, too. BUT, my experience so far has told me that I have never heard as much information from my records as I am now with NO BRUSHES. Excuse my zealotry.

I received a very informative note from the DISK DOCTOR fellow. I had asked him about using his concentrate with this set-up. I had been using this with the MERRILL spigot system so the path of least resistance dictated giving this a try.

He says he has a few customers who have the AUDIODESK and are using both of his cleaning products - one is a concentrate the other not as concentrated.

He offered to sell a solution with this form of cleaning in mind. I have asked for a quote on cost.

He did say he does not recommend the use of the photographic chemicals. As long as he has been at this his opinion is very valuable.

Still waiting for my parts to get the rotisserie motorized.

I have the motor installed in the housing and when I look at that little motor shaft and I think of the weight of shaft and the records I am concerned that that little 1/8" shaft of the motor - can it really hold all of that weight? Obviously it can since bbftx would have told us - but one wonders what will happen first - it snapping off or bending?

I keep thinking of a way to support the shaft and still allow putting records onto the thing - the only place one could do this would be near the motor housing. And that could be really tricky.

So, bbftx, is your motor shaft holding up well to this duty?

My curiosity is killing me!

Thanks to all for this great thread.
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Old 19th November 2012, 04:49 PM   #169
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Not really qualified yet as my USC is still in the post so I have not yet done any experimenting, But I was thinking that warping may be avoided if the record is set spinning in unheated water and then bought up to temperature thus heating the the disc evenly. Not sure how long this takes but if it,s less than 7 or 8 minutes that should be fine
Anyone tried this?
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Old 19th November 2012, 05:23 PM   #170
bbftx is offline bbftx  United States
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Default Shaft Load Limits

Quote:
Originally Posted by rickmcinnis View Post
He offered to sell a solution with this form of cleaning in mind. I have asked for a quote on cost.

He did say he does not recommend the use of the photographic chemicals. As long as he has been at this his opinion is very valuable.
Hi Rick, Interesting comments from Disc Doctor. Thanks for checking with him. Please do remember he is trying to sell you something, so take what he says with a grain of salt. The formulations aren't that complicated and can be created at home at much lower cost. The same surfactants in PhotoFlo are recommended by dozens of people mixing their own LP cleaning solutions. And I'll bet whatever DD is using for a surfactant is probably in the same family.
I think audiophiles tend to go overboard at times worrying about "residue". At the dilution levels we're talking about in these formulations, there really shouldn't be any concerns.

Quote:
Originally Posted by rickmcinnis View Post
I have the motor installed in the housing and when I look at that little motor shaft and I think of the weight of shaft and the records I am concerned that that little 1/8" shaft of the motor - can it really hold all of that weight? Obviously it can since bbftx would have told us - but one wonders what will happen first - it snapping off or bending?

I keep thinking of a way to support the shaft and still allow putting records onto the thing - the only place one could do this would be near the motor housing. And that could be really tricky.

So, bbftx, is your motor shaft holding up well to this duty?
My shaft is holding up fine. I will say that I am probably not far from the bending limit on the shaft. (The Synchron shaft will definitely bend before it will break in a brittle fashion.)

I'm limiting loading as follows: The weight of my spindle, set screw, cork spacers, and 3 LPs is 1.55 lbs (=24.8 ounces = 700 grams). A 4th LP would be too much (yet another reason to limit the number of LPs cleaned in a cycle).

Also note that I am supporting the other end of the spindle during the cleaning cycle. Furthermore, some care is needed during loading and unloading so you're not pushing down and applying even more bending torque on the motor shaft.

And, in actuality, the edge of my LPs rest slightly on the base of my rotating arm during loading and unloading, taking some of the load off of the shaft.

Your idea of adding some kind of support near the motor housing is workable. I think it is possible to support the spindle (not the motor shaft per se). I'll play around with that thought.

As I think more about this, I also think one will definitely run into sagging problems if a shaft coupling is used, rather than machining the record spindle to fit directly over the motor shaft.
B B
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