new HW-19 Mkiii owner questions

Re: new HW-19 Mkiii owner questions

Postby twentyhertz » Tue Dec 26, 2017 3:31 pm

oooh materials science nerd fight! I'm going to love this forum :D

I appreciate the comments and will research further- But just to clarify, BRF- are you saying that you think (or you know, not trying to say you haven't checked) that the bearing on an HW-19 operates at 100C? As in 212 Fahrenheit? What would cause such a temperature- friction? It would seem like a good bearing, with a load like a platter spinning at 33rpm would...not get that hot. But I'm not a scientist. I wish I still had my infrared thermometer from my mechanic days.

In any case, this discussion is fascinating- Since the load of the platter is so light (compared to so say a motor) that maybe a different (non automotive motor) oil would be best? something like this?
https://eliteoiltech.com/product/nano-o ... phEALw_wcB

Anyway, I love working on this table. The combination of engineering, materials and craftsmanship is just outstanding. Bill if we could determine a way to have a consistent starting speed I'd challenge you to a spin-off. After I put this together the other day I spun it gently by hand and took a video to show my audio nerd friend and got bored after a minute of recording with no perceptible slowing of the platter :P
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Re: new HW-19 Mkiii owner questions

Postby Brf » Tue Dec 26, 2017 5:12 pm

twentyhertz wrote: I appreciate the comments and will research further- But just to clarify, BRF- are you saying that you think (or you know, not trying to say you haven't checked) that the bearing on an HW-19 operates at 100C? As in 212 Fahrenheit? What would cause such a temperature- friction? It would seem like a good bearing, with a load like a platter spinning at 33rpm would...not get that hot. But I'm not a scientist. I wish I still had my infrared thermometer from my mechanic days.


No, I am not saying that a turntable bearing operates at 100C/212F. As I wrote previously.......

Brf wrote:It should also be noted that the Viscosity Index rating between two temperatures is not linear and acts more like a logarithmic function. What that means is that at colder temperatures, the viscosity decreases more rapidly than at warm temps. Turntable bearings operate at around 25-30C which is closer to the oil’s base index rating at 100C, therefore, the viscosity difference between 25C and 100C is not that great


twentyhertz wrote:
In any case, this discussion is fascinating- Since the load of the platter is so light (compared to so say a motor) that maybe a different (non automotive motor) oil would be best? something like this?
https://eliteoiltech.com/product/nano-o ... phEALw_wcB


This light of oil will cause premature wear due to lack of lubrication. Don't forget that we are talking about thousands' of pounds per square inch of pressure.
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Re: new HW-19 Mkiii owner questions

Postby Johnny » Tue Dec 26, 2017 6:36 pm

Brf wrote:This light of oil will cause premature wear due to lack of lubrication. Don't forget that we are talking about thousands' of pounds per square inch of pressure.


Really, thousands of pounds???
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Re: new HW-19 Mkiii owner questions

Postby Pevo » Tue Dec 26, 2017 7:16 pm

Johnny, I did a quick calculation for which I made some assumptions. I had a picture of my worn ball bearing and roughly calculated the area of the wear. Not sure if the wear area is truly the contact area, but it’s close. I also made an assumption it was flat, which it isn’t, it’s convex. I’m too lazy to find the formula for the area of a partial sphere and the curvature is so small the error can’t be more than 10-20%. This gave me a contact area of 0.0044 square inches. With a 20 pound platter that equates to a contact pressure of 4545 pounds per square inch (PSI). Perhaps Brf has done the calculations without the assumptions I made so he might be able to give a more definitive answer, but the point is contact pressure is quite high.
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Re: new HW-19 Mkiii owner questions

Postby Brf » Tue Dec 26, 2017 7:23 pm

Johnny wrote:
Brf wrote:This light of oil will cause premature wear due to lack of lubrication. Don't forget that we are talking about thousands' of pounds per square inch of pressure.


Really, thousands of pounds???


Yes, to be more specific, around 25,000 pounds per square inch of force for a Classic/Prime 20lb platter.

P = F/A
20 / 0.0008 inch^2
25,000 lbs per square inch

The above assumes a new unworn bearing.
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Re: new HW-19 Mkiii owner questions

Postby Johnny » Tue Dec 26, 2017 9:12 pm

Brf wrote:
Johnny wrote:
Brf wrote:This light of oil will cause premature wear due to lack of lubrication. Don't forget that we are talking about thousands' of pounds per square inch of pressure.


Really, thousands of pounds???


Yes, to be more specific, around 25,000 pounds per square inch of force for a Classic/Prime 20lb platter.

P = F/A
20 / 0.0008 inch^2
25,000 lbs per square inch

The above assumes a new unworn bearing.


Thanks Pevo and Brf. Now I understand why bearings can wear so quickly if not properly lubricated.
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Re: new HW-19 Mkiii owner questions

Postby madrac » Wed Dec 27, 2017 9:23 am

Brf wrote:
You must have misread my post.

I never said that 0w50 and SAE 50 were formulated the same, I said that at 100C both 0w50 and SAE 50 will have the same viscosity, as will 5w50, 10w50. Although the viscosity index rating of each oil grade will be significantly different between the various grades i.e. cold temperature viscosity

Again, I never said that viscosity classification was dependent of base oil type, I said that 0w50 “synthetic” oil has a “base” oil of 50 (because it can be synthetically manufactured that way) and that “mineral” oil has a base oil of 0 in which viscosity index improvers (polymers) are added.

Other than the above semantics, I believe that we are on the same page.


Hi Brf,

Yes, I think we are on the same page and just semantics.

I know you never said that a 0W50 and 50 were formulated the same, nor that the vis class was dependent on base oil type. :-)

I think the semantics relate to the bolded above. I'm reading this as equating the base oil viscosity to the SAE number (eg 50, or 0 / 0W), which isn't true. Also, need to be careful in that all "synthetics" are not necessarily made with PAO (sometimes with esters). "Synthetic" oils can also be made from Group III base oil (which is a highly processed mineral oil, but considered a synthetic in the industry (except for 1 or 2 countries where synthetic oil must be made with PAO).

If the 0W50 were made with PAO, then technically yes could have a 'base' oil viscosity similar to an SAE 50 oil (around 20 cSt) assuming all the 0W-50 viscometrics are met. If made from Group III (or GP III+, w/ or w/o some PAO if needed, along with VM's), the base oil viscosity would be around 4 cSt KV100, not 0. The 0W is related to CCS (cold cranking) at -35C, MRV (pumping) at -40C, and kv100c of 3.8 cSt min.
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Re: new HW-19 Mkiii owner questions

Postby Brf » Wed Dec 27, 2017 8:09 pm

madrac wrote:
I think the semantics relate to the bolded above. I'm reading this as equating the base oil viscosity to the SAE number (eg 50, or 0 / 0W), which isn't true.

A synthetic 0w50 and a synthetic base 50 both have the same viscosity at 100C but the 0w50 will have a much higher viscosity index rating.

madrac wrote: Also, need to be careful in that all "synthetics" are not necessarily made with PAO (sometimes with esters). "Synthetic" oils can also be made from Group III base oil (which is a highly processed mineral oil, but considered a synthetic in the industry (except for 1 or 2 countries where synthetic oil must be made with PAO).

This is another common misconception. Group I, II, and III are all derived from crude oil which in effect means these are mineral based oil. Group IV and V are are true synthetic lubricants, made through a process called synthesizing. Those are the true technical classifications.

As a result of a legal battle between two large oil companies, an argument was put forward and won that if a mineral base oil is effectively similar to a synthetic oil in performance, it can be legally "marketed" as a synthetic. Synthetic was deemed too broad of a definition to be enforceable.

madrac wrote:If the 0W50 were made with PAO, then technically yes could have a 'base' oil viscosity similar to an SAE 50 oil (around 20 cSt) assuming all the 0W-50 viscometrics are met.

This has been my position from the very start

In any event, we have gone beyond the scope of the initial question and I have enjoyed my exchange with madrac who obviously knows his oils.
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Re: new HW-19 Mkiii owner questions

Postby madrac » Thu Dec 28, 2017 2:35 pm

And I with you, Brf....
I've been in the oil industry for 30 years.... a few more until retirement!
Happy New Year.
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Re: new HW-19 Mkiii owner questions

Postby Johnny » Thu Dec 28, 2017 3:53 pm

madrac wrote:And I with you, Brf....
I've been in the oil industry for 30 years.... a few more until retirement!
Happy New Year.


+1 Brf and madrac...well done
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