A unipivot made from scrap

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Paul Barker
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Re: A unipivot made from scrap

Post by Paul Barker » Sun May 07, 2017 8:28 am

I think youve just done it well enough. Surely unipivots are as easy to mal-design as anything, and bodge in the implementation, if not easier.

In the same space of time Ive achieved wrecking a 103 trying to implement a Mayware and I'm not happy with the tracking so not playing records right now.
I can do it right or I can do it now, but I can't do it right now.

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Dr Bunsen Honeydew
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Re: A unipivot made from scrap

Post by Dr Bunsen Honeydew » Sun May 07, 2017 9:23 am

Cressy - It is the Rega arm being crap thing. Die casting / extruding through a tool that wears is not a good idea, many problems as well like foaming. His original arm he imported from Japan the R200 is musically far better than most of the RB series arms.

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cressy
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Re: A unipivot made from scrap

Post by cressy » Sun May 07, 2017 11:13 am

Did you get the 103 I sent up yet Paul?

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Re: A unipivot made from scrap

Post by cressy » Sun May 07, 2017 4:39 pm

2 down, got a fingerlift on it, I cut a strip out of a platter brake for a lenco. It had holes in it already where it bolts on that were the right spacing.

Also got the pin sorted ish. Turns out the hardened steel was resistant to my hacksaws, didnt put a dent in it. Couldnt be arsed to get the grinder out just for this bit though. But, I did manage to get the brass bit off the top using the bench vice, mole grips and brute force..

It actually made quite a noticable difference. When trying to saw the end off i could see it vibrating so it will have been adding some sort of vibration in use, and it settles down much quicker than it did earlier. Its still abit long, but i can live with it

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Re: A unipivot made from scrap

Post by cressy » Sun May 07, 2017 4:54 pm

Might drill out the brass bit off the pin and use it as a bias weight. Waste not want not :D

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Paul Barker
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Re: A unipivot made from scrap

Post by Paul Barker » Sun May 07, 2017 6:23 pm

cressy wrote:
Sun May 07, 2017 11:13 am
Did you get the 103 I sent up yet Paul?
oddly not, but a post office card came Friday, I was working lal day yesterday around Yorkshire until 10.30, so d0nt know what that is. Have many things in post as usual.
I can do it right or I can do it now, but I can't do it right now.

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Paul Barker
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Re: A unipivot made from scrap

Post by Paul Barker » Mon May 08, 2017 10:40 am

The parcel was something else. When did you send it?
I can do it right or I can do it now, but I can't do it right now.

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Re: A unipivot made from scrap

Post by cressy » Mon May 08, 2017 11:54 am

I'll check the reciept, there will be a tracking number for it

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Paul Barker
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Re: A unipivot made from scrap

Post by Paul Barker » Mon May 08, 2017 12:13 pm

Ta
I can do it right or I can do it now, but I can't do it right now.

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cressy
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Re: A unipivot made from scrap

Post by cressy » Mon May 08, 2017 2:44 pm

Inbetween other stuff ive cut off the top of the bearing pin so there is just enough stuck up to get hold of so thats another job done on it, and added some 60k cs silicon fluid to the bearing cup for damping.

Its calmed it right down although a less than flat record still sets it off rocking.....

I've made a heavier weight for the outrigger so it can be gotten closer in to the pivot point, but it's still easily set off so im still not entirely happy with it.

Hmmmm

It seems happer with a higher tracking weight than the 1.35g I was tracking the shure at so ive dropped the brush and bumped the weight up to 1.7g. Thats helping stability but masking the issue so more thought is needed.

Might look at using a ring magnet in the base and a single little magnet in the housing at 90 degrees to the wand.....

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Re: A unipivot made from scrap

Post by cressy » Mon May 08, 2017 7:06 pm

No need to bugger about with magnets, the thumb nuts I ordered arrived, put 2 of them on to make up 11g, adjusted them up and hey presto, no more rocking. The mass is closer into the pivot so there isnt as much momentum to stabilize, so the balance is not so easily upset now.

And Ive discovered that the new wand doesnt clout the record weight in the runout groove now either.

There is one other issue to deal with which is a clearance issue. The wiring plug is in the way of the counterweight stub. And the counterweight if its too far forward. Rotating the base so the arm is pointing inward alleviates its hitting of the stub as the arm isnt traversing as much distance so doesnt clout it.

Ive stuck the audio technica at-f7 in it and had to add a 2g ortofon shim to the headshell so that the counterweight could go further back. Doesnt clout the plug now but it isnt ideal

It wont do, i'll have to sort something else out.

Other than that relatively minor issue id say it was a success, or it will he once ive dealt with it.

With the audio technica in it, its much better than i ever expected it to be

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Re: A unipivot made from scrap

Post by cressy » Mon May 08, 2017 7:39 pm

Pretty much done

Image

You can see the 2 thumb nuts, the profile is much slimmer for the pair and is 2g heavier than the bodged weight, so it adjusts in nice and close to the housing.

Much betterer

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cressy
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Re: A unipivot made from scrap

Post by cressy » Tue May 09, 2017 9:06 am

Found the 103, apparently its in a sorting office local to me :shock:

Just called them and apparently the address label was torn so illegible. Good job I put a sender address on the box........

Shall go fetch it

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Re: A unipivot made from scrap

Post by Paul Barker » Tue May 09, 2017 11:47 am

:shock:
I can do it right or I can do it now, but I can't do it right now.

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cressy
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Re: A unipivot made from scrap

Post by cressy » Thu May 11, 2017 7:04 pm

Been and fetched it, the bloody box was torn at the top..... Good job it was inside a bag.

I'll resend it.

Having had the cx arm 'finished' for almost a week, im really rather happy with it. Clearance issues notwithstanding, its a keeper. Its settled down and is appreciably better than the modded rega in most ways, and at least as good as in others.

Wether better than a modded rega is some sort of accolade is debateable, but suffice to say, I dont want to take it off to do the bits of finishing work I was going to do :D

Listening to it trying to pick it apart, poke holes in it or find something to complain about has quickly given way to just enjoying what is being played.

That'll do

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