How best to eliminate LP warps

@mijostyn A spindle within a Bearing Housing and rotating being guided by Bush Parts with excessive wear on the inner walls will allow for the Spindle to take on a eccentric 'off axis ' rotation.

As said it would be good to know if the device was able to detect this being present.    

Two mechanical comments on warp removal.

1. Sometimes you just want the record flat for recording purposes. I have used small pieces of transparent tape with mostly good results. I tape over about half the lead-in-groove width and adhere the remaining tape to the vertical edge of my platter. This usually moves the warp a few inches away so that more tape is required. If more than three pieces of tape are required it’s usually not worth the effort as the warps will just continue to appear. Extreme care must be used in placing in the stylus into the first track to avoid catching the tape. I use the arm lifting mechanism to lower the cartridge.

2. Rather than using a soft foam washer under the record to reduce warps I use four small pads near the spindle under my rubber record mat. Their height is roughly 1/8 of an inch tall. I use a custom made screw on clamp that looks like a VPI but has a longer and lowered thread height. This is to accommodate an acrylic disc under my rubber mat. ( but, that is a different topic) Being careful to watch the amount of warp as it is tightened. Warps are usually reduced or can actually increase with excessive clamping pressure. Each record has its own requirement. The hold down pressure will vary a little with each album. I used to use a rigid spacer under the record over the spindle, but think pads under the mat are better.

I’ve experimented with record clamping for over two years to come to the conclusion in item number two. Item one is still a valid option but, item two is repeatable and less risky, (though maybe not as visually correct). Sometimes a mounted and clamped record will not be as flat as you think, but have a slight curve which can affect azimuth and antiskate. In my experience these undesirable variables are manageable and better than excessive warps. FYI, I have not tried a ring clamp for comparison. 

Pindac, You seem to have more than average problems with wobbly spindles caused by excessive wear in the bearing shaft, or your friends do.  I can't recall ever having observed it.

@terry9 , you have to be kidding me! Both Kuzma and SME use reflex clamps. Check out their manuals.

@pindac ,what are these jet engines? The bearing wears at the thrust plate and ball. There is virtually no stress on the bushing. They never wear unless you put sand in them. 

@mijostyn

Not kidding at all. I wouldn’t do this for just anybody, but I took a highly warped record and laid it flat on the platter. Dished up about 0.195". Put the ’washer’ in place, put the record down in the same position, put the 2kg weight in place, and measured less than 0.028" by feeler gauge. A 0.028" soft feeler gauge was the smallest soft gauge that I had, so the actual corrected dish may have been quite a bit less than that.

That’s reduction of a severe dish by a factor of 7 or more. And that’s with a first generation ’proof-of-concept’ washer. My next one will be a precisely made CNC piece, specified to a strict mathematical formula.

The washer and its shape make all the difference.