How best to eliminate LP warps

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.

At no time have I made it seem like it is going to be a common discovery to encounter a TT, that has a Platter Spindle housed with Interface materials that are showing excessive signs of wear and the most likely cause being, the interface parts are doing, 'as said on the tin' and having a service life associated with being sacrificial and expected to yield in their soundness by design.

The fact is that it does occur, an interest in the subject can easily show cases where discoveries have been made.  I have hands on experience of these unwanted conditions having occurred and through discussions with others face to face and through using a forum as communication channel, knowledge becomes available of unwanted conditions that have been discovered within a TT's Platter Spindle Bearing Housing.

I have no beef with anybody who does not care for the subject, but as there are many who visit forums, and somehow end up with a desire to buy into a Vintage TT, it is no harm in informing them of a condition that they might inherit as part of their purchase. It is for these reasons only that I keep the subject live.

I have been instrumental without making any profit, in helping some Vintage TT owners acquire a necessary part to overcome a condition that has been wanted to be remediated. The conditions have not been fantastical as seems to be suggested by a few members on here recently, but quite real and enough of a concern for the TT owners to seek guidance to correct the condition.  

A Individual who is buying TT that has been a model available in the used market for a very long time and especially the Vintage Period, can be supplied a TT that has a condition in a Bearing Housing that might need a rethink and corrective measures used to make an improvement. It is best to identify with this being a Possibility prior to going down the rabbit hole, not all users of TT's are settled with the idea of carrying out surgery on them, the very idea, might make them feel quite queasy. 

I know a individual who has a well respected Japanese Vintage TT, one that quite a few would aspire to own. This individual has been quite proud of their TT and had made it known on a few occasions, how they would be happy to have it used in a Line Up at a Bake Off.

This same individual when stumbling on a discussion about Bearing Condition on another forum, was to become a vehement adversary to the notion their TT could be in need of a overhaul of the Bearing.

At a later date a Off Board Key Strobe was used and a discovery was made that encouraged the individual to suspect something was amiss. The investigation lead to the Bearing Assembly, and the result of the investigation was such that the Bushes were showing signs of excess wear and the Interference fit Ball was with a  scribed surface.

This individual was aware of the work was having done on a identical model TT, and inquired if they could queue Jump, as they were not wanting to use their TT, in the condition it would be in if reassembled using the Vintage OEM Parts.

I agreed to let the other TT have the work carried out in advance of my own one.

The Engineer tied up and the work run on longer than planned, the TT owner waiting for their bearing parts to be produced, bought in another identical model TT, to use as a stop gap. The having the possession of two TT's got their thoughts going and two identical Plinths were produced from the materials of choice.

The Identical Plinths and Same Model TT's was now in a position where both versions could be A/B compared using the same Tonearm and Sub Plinth Structure.

The outcome of the A/B testing was quite a revelation, the Original Parts TT, did not survive the whole of the selected tracks to be used during the comparisons.

The TT with the Bearing Parts using a modern approach and modern materials was the much preferred, they claimed it was like two different TT's.

The Vehement Adversary to the notion, was now making appraisals for the changes that were not present prior to the first experience of the new design bearing assembly.

There are now in place other additional methods that have been adopted for use by this individual, they are convinced that looking after the bearing assembly and housing are key to creating a valuable improvement. There is now a method produced to rigidly fasten the Bearing Housing. The curiosity has not stopped there, there is also one of the TT's with a Lignum Vitae Bush and Thrust Pad produced, that is yet to be A/B demonstrated between the two modified TT's.         

A Worn Thrust Pad is the most likely to be expected, many that are inspected for wear will usually show some form of indentation.

It is quite common to see a Thrust Pad that is interfaced with an interference fit ball in the base of the spindle, to have shown an ellipse shape as the wear seen formed at the indentation on the Thrust Pad. This condition serves as an indicator, and suggests the Spindle Rotates of Axis.

Another condition reported on, is a flattening of a Steel Ball and another much more unwanted condition, being a scribing on the surface of the Steel Ball, I have been shown these conditions first hand and have seen it presented as an item needing to be corrected on other forums. It has also been a subject shown by a respected service engineer, who is referred to on this forum regularly. This is not a fantastical idea, it is real and it occurs.

The Bushes are probably the hardest item to think of as showing a Wear, but again they do. When the condition is present, an eccentric rotation is most likely to occur, the longer the period of rotations, the longer the exposure to operating conditions that can increase the wear, resulting in increased Bush Wear and an increased eccentric rotation. I have had my fingers on Spindles that have been able to produce a Tapping Noise when gentle finger pressure is applied. I know of others who have been able to produce a Tapping noise as well, using similar lightly applied finger pressure. It is not a fantastical idea, it occurs. 

I like to think that when a individual has a TT in use with an unknown usage history, they are fully confident about the condition of the TT's Bearing Assembly and that is is functioning to a standard that is mechanically sound.

The idea of a very expensive Stylus interfacing with an LP Groove that is most likely eccentric in rotation due the pressing of the LP, and then this being amplified further by the Off Axis rotation of the Spindle, is a condition I wish to avoid.

I have taken a few steps to overcome across many years, and have had Bearings Overhauled by a Specialist Service, or alternatively Supplied as a New Design to be used on a Vintage TT. 

As always 'each to their own'.

If there are individuals not wanting to concern themselves with the the possibility for mechanical issue being present, that may be a concern, within the assembly of the Bearing Housing, that is fine. At no time have I made it seem the enjoyment of music is not to be had on any condition of a Bearing Assemblies Parts.

Alternatively there might be an individual who is aware of something that is a concern to them, then stumbling on these types of post's might be enough to motivate them to learn more, there can be no harm in that happening.    

Then there are the types that like to think the Bearing Assembly is able to be  brought up to a very high specification and has exchange materials in use that are modern and fit for the purpose of the role they are selected for, I'm sure those types really enjoy stumbling on Post's that cover the subject of carrying out such work.