Lathe troll advice wanted

Topics regarding professional record cutting.

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audiocarver
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Lathe troll advice wanted

Post: # 30155Unread post audiocarver
Sun May 18, 2014 5:51 pm

Hello,

I've been thinking about this for a while and can't get around which way to go with this....so, here goes.

I've got a Presto 8GV that has been sitting here awhile that was modified with dual feed screws on the top overhead mechanism. There is a selector solenoid mounted behind the cutter head carriage that can automatically change direction of cutter head. I thought that would be nice for spiral cutting. When they did the mod, they removed the original drive parts for variable pitch and ran a heavy belt from turntable platter drive shaft to overhead mechanism driveshaft for added torque to run both feed screws. The original parts are now long gone. Given the rarity of this lathe, I thought about if I could find another 8GV, making drawings of parts from the example lathe and having my local machinist make the parts by hand basically restoring the lathe back to what it was when new.

What I'm leaning towards is to leave the lathe mods as is for the most part and remove the belt drive and install a DC motor to the overhead drive shaft mechanism and make an electronic variable pitch system using some kind of PWM control that I could integrate to my Neumann SP-75 console. Have the solenoid there for a "spiral" button function. But, with electronic control, I could do the same by reversing DC motor direction.

So, I guess, should I go for originality here, or more modern type conveniences and base it around a Neumann system?

Either way, this is the wickedest Presto lathe ever! :)

Regards,
Andy

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dubcutter89
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Re: Lathe troll advice wanted

Post: # 30162Unread post dubcutter89
Mon May 19, 2014 7:35 am

We wanna see pics :D

Basically, I think retrofitting it is the way to go...and then maybe update with modern stuff
One Outside-In feed screw and a dc motor and you will have a nice record cutter...

If the solenoid (choosing between feed screws?) selects the direction, how can you use it for lead in/out?? (normally you change speed, not direction)

ASFAIK the 8d (gv - does yours have vacuum platter?) has a mechanism on the feedscrew to change direction outsid-in/inside-out...still ther?

maybe theres no answer for you...if so keep on asking!


Lukas

PS: there were some modded prestos (for changing LPI) but I think nowadays someone would use a second motor for pitch...
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Wanted: ANYTHING ORTOFON related to cutting...thx

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audiocarver
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Re: Lathe troll advice wanted

Post: # 30167Unread post audiocarver
Mon May 19, 2014 11:15 pm

Hi Lukas,

Yes, normally to change speed is correct, but this lathe changes direction. It was modded back in the 1960s for the studio in Boston that bought it new, from my understanding, they cut for Muzak, but I'm not really sure about that.

Here are some pics of the top. I have the base cabinet in my garage still in storage. The 8D top parts all interchange with the 8GV, the only parts that are different are the variable pitch drive controls. Alan Graves had a 8GV but sold it and I never knew who bought it. I would really like to contact them first before I start anything with this.

I have the reverse engineering capabilities here, I just need another example to get some dimensions and pics of the parts I would need.
http://s1152.photobucket.com/user/magwheels1/media/001_zps640d1358.jpg.html
Image
Image
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audiocarver
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Re: Lathe troll advice wanted

Post: # 30168Unread post audiocarver
Mon May 19, 2014 11:18 pm

Here are the pics as attachments:
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audiocarver
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Re: Lathe troll advice wanted

Post: # 30169Unread post audiocarver
Mon May 19, 2014 11:22 pm

Another couple of pics:
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dubcutter89
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Re: Lathe troll advice wanted

Post: # 30174Unread post dubcutter89
Tue May 20, 2014 9:16 am

That machine looks great!!!

Never seen a vacuum presto - looks like it's gonna play in pro league!
To me it looks like the whole overhead except for the sliding-bar, head-mount-plate are custom...and probably no worse than the original
clean it, fix it, get a cutterhead on it and cut records!
to really retrofit it would be a huge undertaking and you still would not have an original old one nor a better one..(just my opinion)
but if you still insist then I can send you some pics of one I once restored...

Lukas
Wanted: ANYTHING ORTOFON related to cutting...thx

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audiocarver
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Re: Lathe troll advice wanted

Post: # 30178Unread post audiocarver
Tue May 20, 2014 3:20 pm

Hi Lukas,

Yes, please do send the pics! Yeah, the overhead pieces would need to be changed. The 8D used the same as the 8GV.

The only thing I need that is custom to the 8GV is the quill block and all assorted pieces to copy to make the original variable pitch system work again. I have a part blow up diagram, see attached:

Other than that, the cabinet is in good shape too!

I'll keep this overhead mechanism here.

Thanks,
Andy
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dubcutter89
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Re: Lathe troll advice wanted

Post: # 30186Unread post dubcutter89
Wed May 21, 2014 4:16 am

Ah, that strange manual mechanical pitch thing...
some time ago another forum member did work on one of those, but I can't remember the name...
still I think it's easier to use a small dc motor (or something else)

Do you have some parts or want to completely clone it?

Lukas

there's a video of it
Wanted: ANYTHING ORTOFON related to cutting...thx

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audiocarver
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Re: Lathe troll advice wanted

Post: # 30190Unread post audiocarver
Wed May 21, 2014 11:09 am

Wow! That video is wicked crazy! I'm not sure how that clockwork arrangement actually works, but it somehow does!

I think the quill block approach like what they had in the part diagram is much easier to clone than what was done in that video! Looking at my lathe, it seems more like what they did. Trouble is getting dimensions of the original parts to clone from.

The lathe in the video might very well be an early prototype for sure between the 8DG and 8GV before they came up with the quill block design!

The only part in that diagram I have is the LPI indicator plate. Everything else would have to be cloned.

Andy

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