Turntable clamp

[ucl82]

Hi all,
For ages I had wanted a turntable clamp. These are essentially heavy cylinders that sit over the centre of a record and mount on the turntable spindle. They are useful for slightly warped records that may not play well, they flatten out the record whilst it is being spun. As a vinyl lover this was a fantastic invention but also a rather pricey one... The cheapest clamps cost about £20 and go up to several hundred pounds.
I ideally wanted a weight of about 500g, so I cut down a length of manganese bronze which after turning would come out to around 500g. It was cut on the school's mechanical hacksaw to save some time (this was a one evening job).
I then had to decide which lathe to use, the school has a choice of many but when making another project I had soon discovered not all were in a good state. There is a lovely Myford Super 7 which someone else had set up for their needs so I couldn't use that, a small Axminster job whose chuck would not tighten correctly (teeth were very worn), a Colchester lathe who was no longer connected to the mains, and in another workshop a choice of another two Colchester lathes. One of these had a vicious chuck who would throw one jaw out at you, the other had a tailstock which would no longer correctly operate. I swapped the tailstock onto the lathe with a good chuck and I was able to begin!
The bronze was faced off to start with, and then turned down before using the tailstock to drill in several mm for the centre spindle of the turntable to lock into the turntable clamp. It was then parted off and was tidied up on the buffing machine.
A lovely simple little project, it works very well and saved a lot of cash! Will have to do one in timber next....

[AlanBeckett]

Very swish, although I've never felt the need, yet. I suppose steel is out 'cause of magnetic effects.
Where did you get the bronze from? or shouldn't I ask
A piece that big wouldn't come cheap.
Your tales of the Colchester lathes are pretty depressing as they're often advertised a 'ex school' which implies splendid condition.
Alan

[ucl82]

Thanks Alan Steel may work ok but as you say the magnetism may have an affect on static etc and near a magnetic cartridge too.
The bronze came from school but due to it's expense is rarely used in projects (I used some for my main A2 design project, more on that later).
These lathes are kept by the school but are very rarely used, I've only known two other people to use them in the last two years. They used to teach engineering courses at the school but now the council have built a special centre for this with brand new top spec equipment so the school's own stuff is rarely used and as such isn't maintained Same for the wonderful milling machine which in five years at the school I have never seen anybody use.
'Ex school' to me tends to mean vandalised and badly maintained but perhaps that depends on which schools you have been too I have seen many ex school lathes for sale and it seems as though they are usually reconditioned or if not can be done so once bought. Eventually when Suffolk scrap the three tier education system and they build a new larger school they will of course get new equipment, so myself and my friend will be standing by armed with wallets and a van! We've already bought several surplus bits of kit including a Gryphon bench grinder, similar ones new cost in excess of £1000. There is a BBC Computer controlled lathe which has been bodged to become hand operated via the control panel but they want a fair bit of money for it

[tiv48]

nice ,like me you have a lenco deck,but a warning dont try this on a suspended sub chassis type ie thorns td150,lin sondek.a clamp is the only thing to use on these.there is also bearing wear to consider no problem on lenco,garard 401/301,thorns td124. by the way what is the arm you have fitted looks rega? mine is fitted with a lin basik,to save any metal work.
rob t

[fido]

Does it not overload the motor, turning all that extra weight? You could have something that clamps to the spindle and applies spring pressure to the record.

[AlanBeckett]

Not unless the extra weight increases the bearing friction. Once it's rolling it doesn't matter. It may be an advantage to give it a bit of a shove to start it. That much weight near the centre won't even make much difference to the inertia simply because it is close to the centre.
Alan

[tiv48]

the wieght of a gl75 is vast more than 3kg so the extra wont effect it
rob t

[ucl82]

Hi all,
The weight hasn't made any difference in the deck's performance or speed and seems to be doing well. Thanks for the advice r.e. not using it on suspended decks, to be honest I don't think I will ever part with the Lenco as it's such a good turntable. My next plans for it are to make a slate plinth and maybe do another tonearm upgrade but that won't be for several years yet as it will be rather expensive to do to say the least.

Rob, the tonearm is a Mission 774LC which has had a custom brass headshell and brass counterweight fitted. It sounds good, a little bit lighter on bass than the standard Lenco arm but a lot lighter tracking. It's got a Grado Prestige Gold cartridge which performs very well in this setup (some have criticised Grado carts for hum etc, I haven't noticed any but that could be because I don't play test records I play music ). I have done some modifications to the Mission's arm rest etc as I had some problems with the arm dropping out of it's rest and onto the platter breaking the stylus (about £100!). I was able to incorporate the Lenco arm rest and lever mechanism after a bit of experimenting with a junior hacksaw.

As Rob says the Lenco platter weighs nearly 4kgs so this extra weight won't hurt! The clamp isn't in use all the time either.

Josh.

[tiv48]

josh how did you overcome the problem with effective lenght as for the mission its 228mm, the original thorns arm was 210mm.the reason i used the linn was its 211mm only one out
rob t

[ucl82]

Hi Rob,
I haven't got the Lenco tonearm anymore but according to the VinylEngine database it's effective length was 227.9. It lists the Lenco L75 as being 211mm but mine is a GL75 (although I didn't think there was any difference between the L and GL's tonearms). I remember it was very close to the length of the original tonearm.

Josh.

Edit:
They also have the Linn Basik as being 229mm... all the more confusing
http://www.vinylengine.com/tonearm_database.php?make=Linn&sort=4&ascdesc=ASC&search=search&mdl=&eflo=&efhi=&mdlo=&mdhi=&ohlo=&ohhi=&amlo=&amhi=&cw=&mp=