This post is for those interested in how the PTP came into being.
A history lesson:

Posted originally in 2006.

reinderspeter said:
I have just posted at Audiogon about my plans to have a custom made topplate lasercut from 5mm steel. What I want is a 50x50cm plate with room for two arms and the option to use a 12" one. I have (am still working on) a simplified speed adjustment system and I have tried to get as much decoupling between motor and bearing as possible. Because the big cost will be in programming the lasercutter it would be interesting to see if more people would like to have one. I could then have a small series made. A plate like I propose will weigh around 8kg so shippingcost might also be an issue. I have not made inquiries about cost yet so I don't know what the price might be, but through my work I have a few contacts that will at least give me a reasonable quote.

-General view:



-View with components attached to the plate:




reinderspeter said:
I intend to use the original way to mount the motor, but the way the mounting screws are fixed to the lenco topplate prevents recycling. I will have new ones turned that can be screwed onto the new topplate which will have M4 holes. Peter

reinderspeter said:
I am also attempting to keep motor vibrations away from the topplate as much as possible. This is why I have drawn a slot around the motor mounts. In this way the mounts are on an "island" that is attached to the rest of the topplate by three very small (just 1mm wide) bridges only. In the same manner the bearing position is decoupled from the part of the topplate that is not directly coupled to the plinth. I am interested in your ideas though, maybe we can combine things.

reinderspeter said:
makes sense However it occurred to me that what you describe is already there in the form of springs. I am also slightly worried about adding another damping system which will automatically be a resonant system and having two resonant systems in series is usually not a good idea. if you really want to get rid of these motor vibrations you should mount the motor to something else than the topplate, for instance to a second part of the plinth that is decoupled from the rest of the tt. I have thought about this option but decided it probably isn't worth the trouble. I think Jean did something similar in one of his first attempts. It is still possible to do with the proposed plate, though.

Grant (gjwAudio) said:
Hi Peter May I first say what an extremely clever concept for isolating the motor - the "mounting island". Am I correct in assuming that the underside of this island would NOT come in contact with the mass of the plinth ? Do you have a drawing that shows the contact area & cut-outs for the top layer of the plinth ? For some time I've been thinking about how to improve upon the standard Lenco top plate - and remove some of the challenges it forces us to deal with. You are much further down that road than I gone... Obviously you have been working at this a while - Wonderful Work - and thank you for sharing with all the enthusiasts ! I'm very curious to see the solution to the speed adjustmet question. Thanks... I'll be watching the developments closely. Grant BTW, what application are you using for your drawings ?

reinderspeter said:

picture of the bottom:



Richard said:
Let's check on one thing first: has anyone heard the sound of the motor mixed into the audio?

reinderspeter said:

This is an interesting question. My reasoning is that first you want as little motor vibration entering the plinth as possible (which is why Lenco uses the spring mount). My plate design just tries to enhance this. Of course some vibration will enter the plate and then you have the heavy plinth to sink it.

reinderspeter said:
the cutout is universal. you need to put an armboard with a specific cutout on top of it. The plate will 5mm thick.

Ropie said:
A couple of things: 1. Is the 'motor island' really an island at all? Looking at your drawing with three connecting points it would still seem to be fairly rigidly connected to the rest of the plate

Colin said:
Hi Peter, The replacement top plate is an admirable project, well done and good luck. I would prefer to make it smaller and mount arms to the plinth, but that's me. As regards the motor island - if you enlarge it slightly to make good contact with the underlying plinth then you can disconnect it from the top plate completely. The whole rear left corner could be separately bolted to the plinth, indeed that part of the plinth could then be a separate island. Lots of possibilities here, and interesting to see which ones if any can be retrofitted to the stock chassis. Good fun! Regards

reinderspeter said:

I think this is a very interesting idea. I am going to sit in a quiet corner and think about it for a while


reinderspeter said:
If you make different mounting posts that instead of going up to the plate go down to (or even through) the plinth you can use the standard spring arrangement. Indeed this could be the easiest and best solution. The only reason I have not done it this way yet is that Jean has in one of his earlier builds and reported no advantages. :?: Jean if you read this could you perhaps elaborate a little on what you did and what results were back then? Peter


rturja said:
For what it's worth I think that the "original" mod of coupling the motor into heavy mass plinth is still the way to go, but there might be ways of mounting the motor or designing the top plate diminishing the exixting vibrations even more. If the motor was in its separate plint, the heavy mass for damping the motor would still be needed, making the arrangement much more complicated - For myself I think trying to find simpler solution to the vibrations could be more beneficial.

Mario_b said:
Hi Peter, So glad you’ve started this technical wildfire! We’re truly “back in the saddle, again”. So just to take advantage of this formulative time in your top plate design (which, by the way, you’ve unselfishly offered to lay bare for us all to ponder), I’ve got to ask whether you envision any special treatment for the main platter bearing as it plays into this design either via the top plate or plinth?

reinderspeter said:
Hi all, Following the developments in this thread I have made a new version of the toplate where the motor is mounted on an island that is completely detached from the rest of the plate as opposed to the previous version where the island was actually more of a peninsula. This island can be screwed to the plinth or to something that is even more decoupled. Secondly I have drawn two alternative plates that are smaller in size that might be a more universally acceptable. the main difference is that one (or both) arm(s) are no longer on the plate. Whether this is good or bad I don't know.  Comments welcome! Peter

the new revisited pictures of the project:
-Version 1.



-Version 2.



-Top plate with totaly detached "motor board".




Grant (gjwAudio) said:
Hmmmm... Is that a clever scheme I see for changing the speed ? Peter... What are the nifty green bits all about ? Grant

reinderspeter said:
Hi Grant, Whether these bits are clever or not remains to be seen, but yes it is my speedchanging system. The idea is that by rotating the big green strip in the middle you can change speed. Both 33 and 45 are possible. To set the exact speed for the first time will be a bit of a hassle. you have to take the platter off each time to fine tune the speed (take off platter-loosen screw-move the strip-fasten screw-put platter back-check speed) You redo this until correct speed is achieved . The smaller green bits are there to make sure you have to go through this process only once. When you have found the right position you screw down one of the smaller strips against the big strip to act as a stop for that position. Once the stops are in place you can change speed much more quickly. You will still have to take off the platter to do it and use a screwdriver, but unless you change speed often it's easily done. The big advantage of the scheme is that you lose all the mechanics that are under the standard Lenco pan and take away a lot of contact area between plate and plinth, especially so near the bearing

reinderspeter said:
One mountingpoint of the current motor island will be outside the platter and therefore be visible. I have designed a different version of the motor island in which I have attempted to keep the island inside the platter as much as possible. Whether it is as good functionally I am not sure, I am slightly worried it won't be as stiff as the first version.



Colin said:
Peter, You need to think like Microsoft and make a problem into new exciting feature! If you let the motor island extend right to the edge of the plate like a large irregular pie slice then it will be obvious to the viewer that this is indeed the new improved isolated-island-motor-version (IIMV). Many tt makers would charge a considerable sum for such an upgrade. The acronym IIMV would be touted around the forums as the badge of the discerning listener. Much Kudos!! Regards


reinderspeter said:

True, the angle of the idler arm does change, but I have designed it in such a way that both correct 33 and 45 position are on the ideal line, so as long as your idlerarm isn't bent you will be in perfect position for both speeds. And even if you need a slightly different position the deviation is quite small.

This is not the case, the idlerarm is NOT parallel with the motor shaft but instead with the line of contact on the conical shaft the idler makes when changing speed. :roll:

reinderspeter said:
It has been quiet lately as I have been busy with other things (like work) for a bit, but I have now what I consider the final design. See below. I have changed the plate's thickness to 4mm because of platter clearance and because I can then make all parts the same thickness and cut them from the same sheet. If you have any questions or brilliant thoughts left please let me know.






reinderspeter said:
The main reason for these cutouts is flexibility. I made them in such a way that all 9"arms can be used. If I knew the exact arms I wanted to use I could of course make a much smaller optimized cut, but I like to be able to change them around. In my experience the things I think are secure are the first to change :x In order to at least get the coupling as tight as possible I decided it best to mount the armboards on top of the topplate instead of on the plinth next to the topplate. Peter


reinderspeter said:

The hole is not for SME either, it just has a similar shape but is much bigger than that. The size and shape were dictated by the different mounting distances various 9"arms have. The idea is that you cover the hole with an armboard that can be any shape or material you like. The arm will then be mounted to the armboard that has an appropriate armhole made into it. The armboard is then screwed to the topplate and plinth through the six holes surrounding the big opening.

True and if you want something else you can of course drill a hole in another location, but

Drilling holes in 4mm steel with the diameters needed (let alone SME-like shapes) is not for everyone and certainly not for me. But my main concern is the lack of flexibility. Once you made your hole and you have glued the plate to the plinth, there is no way you are ever going to make another one. The solution I use is no different than many "Big plinth builders" have used mounting their arms on an armboard that in turn is screwed to the plinth. Peter

reinderspeter said:
Ok, I have changed the speedadjustment design following the above discussion. The advantages are that you can use the standard Lenco shaft and the motion is now completely linear so no change in idler/motorspindle angle anymore. It also makes it simpler to fit the parts inside the 450x450mm area in the "no armholes version" so it can be cut without the need of extra material. The new piece is simply bolted from above.



bottom view



Top view

The final result:





Then in 2007 came the PTP2:

reinderspeter said:
Ok, here we go… As most of you know I developed an alternative (4mm thick steel) topplate for the heavy platter Lenco around a year ago. 

With it I tried to achieve three things:
1. Better DE-coupling of the motor from the bearing and arm by giving the motor its own "island".
2. Create as much coupling area between plate and plinth as possible
3. Get the best coupling between the bearing and the arm.
 
 The project resulted in a small production run of 17 plates, which were sent all over the world. Soon after people started to ask if there would be more plates available. And yes, even though I don’t need any myself I am willing to do another run. But since there’s no fun in doing the same thing twice I have tried to improve upon the first model. The result is what you see here:



 1. Extra holes under the armboards so you can screw the plate to the plinth independently.
 2. Two holes so you can use the transport screws if you want to (travelling to Annecy taught me this )
 3. I will explain these later.
 4. An extra opening to allow the motor a little more cooling
 5. A changed design for the speed setting stops ( like the ones I did on the PTPL)
 6. Overall size has gone from 450x450mm to 440x440mm (more on this later).
 7. An extra hole to make it easier to attach an earth wire to the plate.
 
 Idler decoupling. The first generation PTP has the idlerwheel in contact with the motor and platter all the time. I have found no problems doing it like that but it would be nice if some sort of disengagement system was possible. This is what the holes nr.3 are for. It is a really simple way to do it:

 

 Just turn the lever underneath the plinth and the eccentric wheel pushes the idler arm away.

 

It is a kind of combination of my own 16rpm disengagement trick and Francois' Überlenco solution. The plate just provides a hole. The actual mechanism is something you will have to make yourself. You can leave it out if you don't want to use it of course. Detail of the new speed setting stops (the blue bits):

 

Size. PTP1 was designed as a two armed machine and therefore rather large. Several people asked me if a smaller version would be possible. This time I am considering three sizes:
Large (440x440mm):



Medium (320x440mm):



Small (320x340mm):


 
I am not sure yet whether or not I will make all three, this will depend on your reactions. Motor mounts. I think these were the most difficult part of the project to get right. I will try to have these made as well and sell them together with the plates as a kind of kit. I had a set made for my PTPL and they were VERY expensive. I expect a larger series will bring the price down a great deal! Threaded holes Quite a few of the holes in the PTP need threading (M3, M4 and M5). I am considering to have this done too as not everyone has the means to. Cost. I don't know yet but it won't be as cheap as the first series. The original project came about as a way to keep the cost down of the plate I wanted for myself, by spreading the machining costs over a larger amount of plates. This second run is different: I don't need any! It does cost me a lot of time though. That said I haven't asked for quotes yet as everything will depend on the number of plates needed. That's it for now.  Peter



And in 2008 the PTP3 arrived:

reinderspeter said:
It is that time of year again…. All PTP2’s of last year’s batch are sold now but I keep getting requests from all over the world. I think I can say the PTP2 has been a great success and that I will need to make some more. I have been thinking about possible improvements. Most comments and questions I had where about the fit of the motor mounts, where to put the power switch and most of all the possibility to change speed without taking the platter off. Another obvious observation is that the Small version is by far the most popular. This leads to the
PTP3:







I will do a Small version only I have adapted the speed change mechanism so that it can be used with the platter in place. It is a combination of the PTP2’s system and MarioB’s (thank you!) construction. I have added a hole in the left front corner where a switch can be fitted. I will probably include a suitable switch in the kit. I will make sure the motor mounts will be easier to use. Since not everybody may want the new speed mechanism I will also produce a bunch of Small PTP2’s. I have added the Switch hole to make it the

PTP2b:



I have asked for some quotes but haven’t had an answer yet. I do know the price of steel has risen a great deal Comments are welcome!

reinderspeter said:
Is anybody interested in a PTP3 from Stainless steel?

mumford said:

Yes.

Today the new batch of stainless steel plates came in. As an experiment I ordered part of the plates in a brushed finish. I think they came out looking really good, no more finishing needed. The quality is very difficult to capture but here are a few pictures to give an impression.

its not SHINY enough yet ! I am still polishing my old ones !  >

Which large gap do you mean ???
If you mean the opening between island and plate near the bearing it is to give the motor a bit more airflow for cooling. In the first series this gap wasn't there and I found the motor would run quite hot. after the change I haven't had that problem so I assume it works.

For me, the brushed finish is the way to go.  Looks absolutely superb, Peter.

Dear Peter:
Very nice work your PTP 3, congrats !
Sorry if I ask stupid questions, I am new to this, but how do you change speed from 33 to 45 RPM and
than fine adjust the correct speed ? Is it with the small shaft sliding on the right ? Is it working like the
original device on the left of the plate ( 4 speeds locked and unscrew for fine adjust) ?
Jean.

OK, I understand, so everytime the platter needs fine speed adjustment we need to unscrew the hex screws
UNDER the platter, not so easy with a very heavy plinth, or use a mirror and a special squared hex screwdriver?
It is not easier to do this from the UPPER part of the plate, like original Lenco ?

OK Peter, i was confused with this "set and forget" subject, because I am new to Lenco and with the TD 124 I constantly have to fine adjust the speed. I am looking forward to set up the new PTP. Thank you.