Presto 8dg vari-pitch schematics.

[sameal]

Kind of a long shot, but if anyone has ANY presto 8dg schematics id be really interested to see them.

[sameal]

Is there a folder someplace here with drawings?

If not there should be. And services that would make the parts......

[sameal]

Im willing to pay for drawings that i could hand to a machine shop and get this fabricated.

[EmAtChapterV]

I'm not sure how much this would help, but here's an exploded view. The knob moves the cylinder with the worm gear left and right to move the idler on the far left inwards and outwards on the rotating disc coupled to the turntable shaft.

[sameal]

Thanks! I ended up getting the 8gv schems from alan graves, and talked with a cnc shop about making one possibly, but i think a variable dc motor would acheive better, more accurate results.

So now i need to look at what motor and how it can be implemented.

[audiocarver]

Hi Sameal,

Here's how it's going with my 8GV. The bottom plate w/pointer and quill block are finished, as in the picture. The sleeve that goes into the quill block is at the shop right now getting fitted for the bearings which the drive shaft will go through. I still have to have the pulleys and flange plates made for the turntable and feed screw drive shafts.

I thought the 8DG had a pulley tree underneath the lathe to change pitch by moving a belt to different steps on the pulley tree? I would have thought your lathe at least had that?

004.JPG

[sameal]

Unfortunately the pulley tree nor the pitch mechanism came with mine, so im left to construct something in its place.

A variable motor seems the best option if i have to engineer a whole new part.

[audiocarver]

I didn't realize you were in the same boat I'm in with this lathe, as far as pitch system being missing.

Here's a drawing that I guess came from Alan Graves for the tree pulley, I presume you spoke with him about it? At least you can get up and cutting for now with this.

I opted to go back to the mechanical vari pitch system to have the turntable platter ganged to the feed screw. Besides that, I didn't think adding a pitch control computer would make this a better lathe anyways.

Maybe you can get accurate results with high resolution motors/encoders and sensors and controllers, but they get pricey as well.

I would be willing to sell you the drawings I made these parts. I'm still debugging them as I go along though, which is going to be awhile as I still have to figure out how to change the overhead mechanism back from what was modified.

Alan_Graves_Presto_8D_pulley-tree.jpg

[sameal]

I did get the pulley tree drawing, but when i brought it to a cnc machinest, he felt the top two segments had an error in the measurement. Thats what got me thinking about a variable motor.

Either option is going to be pricey i feel at this point, starting from scratch.

I may still be interested in those drawings however, after the kinks are worked out.

Im having trouble sourcing a 16" tonearm too. Well, one that doesnt cost as much as my car.

Otherwise aside from a vac pump, the big bits are purchased. Now i just have to recap, get missing screws, do a lube job and check platter functions and such.