Presto 8dg refurb. (Lathe porn)

[Stevie342000]

Dont worry. I got kids gloves on handling this machine, with the scarcity of parts and all.

Im thinking a full teardown is in order.

I agree with that, do not forget to replace bearings, there should be YouTube clips on taking bearings out and on stripping motors down too, or just a simple search should get the results you are after.

[rsimms3]

If you do need to replace your bearings, I just had a good experience from BC Precision out of TN. Good prices, fast shipping, and included tracking information. Shipped same day I ordered.

http://www.bcprecision.com/

[sameal]

Well i did finally get into the motor. Theres not much to do in there.

The bearings are sealed in either endcap.
The armature is sealed with a coating.

But i put it back together and it has a hard time spinning again. I was able to break it free with some wd-40, but i feel like the bearings arent the best.

[grooveguy]

What brand of motor is it, and what type of bearings are in the end bells? If they're ball bearings, you can find replacements anywhere. If sintered bronze, that's more difficult but should not be a problem to clean, using the right solvent.

[sameal]

Its a bodine brand motor. Nyc-34

I was mistaken. There is a ball bearing, but its only one at the opposite end, under a cap.

I got the 33 back together, and its working, though slightly noisey.

Trying for the 78, but presto made it a serious pain to remove.

The 45 relay actually does pull the puck to the rim, but the puck does not spin the platter. Probably needs a re-rubber.

[grooveguy]

You're lucky, Bodine is a great company and, in my own experience some years ago, will bend over backward to help with 'legacy' products. I'm sure they would provide you a drawing of that complete assembly, which you really need to completely disassemble to do the job right.

[sameal]

I may contact them and see what i can dig up. Maybe they can tell me maintenence specifics. That would be uber helpful at this point.

Its running outside the assembly, with low heat buildup. I just feel like it could be quieter. Its not over powering by any means, but louder then i think it should be.

The 45rpm motor has its own mains plug on mine. Is that a mod? And for what? Why not tap the same way the 78 & 33 does off the barrier strip under the tabletop by the switches?

[grooveguy]

Well, it may be running, but I'd definitely break it down and clean it. Any idea of the condition of the grease in the worm gear assembly? That worm drive has a reduction ratio of 54:1. Ever wonder where 33-1/3 r.p.m. came from? Divide the motor speed, 1800 r.p.m., by 54.

'Fraid I can't help you with the 45 r.p.m. business, the lathe we had at school didn't have that. In fact, it was the 8D, not the 8DG, the lesser rim-drive turntable for both 78 and 33.3 speeds. If I'd spirited that lathe away when no on was looking, back in the 1960s, I would have turned the 78 spindle down to drive the table at 45. You're lucky to have a 3-speed table. Oh, by the way, divide 1800 r.p.m. by 23 to get the real speed of "78" r.p.m. records. It's 78.260869 r.p.m, actually. All that math is linked to the US AC-mains frequency and gear ratios that have to be whole numbers. When lathes were used for broadcast program delay, they had to have split-second timing, so rim (puck) drive just wouldn't do. Gears all the way.

[rsimms3]

Well i did finally get into the motor. Theres not much to do in there.

The bearings are sealed in either endcap.
The armature is sealed with a coating.

But i put it back together and it has a hard time spinning again. I was able to break it free with some wd-40, but i feel like the bearings arent the best.

Does this motor or any of the motors have a slotted screw with a hex nut on it? Most of the Bodine motors I've seen used with lathes have a large slotted screw in the bottom that is the cup for the ball bearing. It's used to adjust the pressure against the top sleeve which has a fiber washer. There are oil tubes that are used to oil the sleeves on both ends that hold the center shaft.

When you had the one motor apart, did you check the bearing to see if it was smooth?

[sameal]

Thats the crazy thing, there's nothing to clean! The armature has a coating on it, the other coil is clean as a whistle and the fan blades barely had any dust.

I think it just needed some oil. More then the required 4 drops, as it hasnt seen any drops in forever.

I just took the whole assembly apart. Inside the gear housing is clean.

The only drawback is the puck drive 45. I really wish it was gear driven. But, beggars cant be choosers as finding a lathe at all is pretty rare, especially in your place of residence.

Thats some crazy math!

[sameal]

Well i did finally get into the motor. Theres not much to do in there.

The bearings are sealed in either endcap.
The armature is sealed with a coating.

But i put it back together and it has a hard time spinning again. I was able to break it free with some wd-40, but i feel like the bearings arent the best.

Does this motor or any of the motors have a slotted screw with a hex nut on it? Most of the Bodine motors I've seen used with lathes have a large slotted screw in the bottom that is the cup for the ball bearing. It's used to adjust the pressure against the top sleeve which has a fiber washer. There are oil tubes that are used to oil the sleeves on both ends that hold the center shaft.

When you had the one motor apart, did you check the bearing to see if it was smooth?

The motor you describe is the motor im dealing with. The bearing feels good. I might get new ones, just to be safe.

How much play should the armature have after adjusting the bearing cup?

[sameal]

Two things of note for other owners:

The fourth screw for the 78rpm motor is placed right above the vibration plate, making it impossible to get an allen key in it. Replace it with a hex bolt.

SAE20 oil like the manual suggests is pretty thick, and where the drain/fill plugs are located make it a messy job.


Might also want to drill the table top mounting holes in the cabinet a smidge bigger. Taking the table top on and off is a b×tch but makes working on the motor much easier.

[audiocarver]

I'm surprised the 8DG was that much different than the 8GV then, as far as the table drive. Mine uses the Ashland motors instead of the Bodine motors though.

Here are some pics:

Presto8GV.JPG

Presto8GV5.JPG

Presto8GV4.JPG

Let the good work continue!!

[sameal]

Wow! That is a very fine lathe!

The 45rpm motor is an ashland, the other two are bodines, and the mounting bracket is different.

[audiocarver]

That's weird! I'm surprised they would have used both brands on the same lathe?

Bodine should be able to rebuild yours though. Or there might be a Bodine dealer near you? As someone else mentioned, they have good legacy support. I called Ashland, and they were at least willing to help, but their documentation for anything older than like 30 to 40 years gets sparse.

Here's a pic of the top of mine with platter cleaned up and scope and stylus heater power supply now working again. The variable pitch parts I had made are installed, at least the cover fits! Ha..Ha!

Presto8GV6.JPG

[sameal]

I cant help but still think this 8dg is a prototype.

The platter on your 8gv although aluminum, is constructed in a very similar manner to my platter.

The heat stylus section was never installed on mine as far as i can tell. But the westrex head installed had a heated stylus, kinda homebrew looking.

[sameal]

The 8d model has the same assembly as mine minus the 45 rpm section. Bodines and all.

[grooveguy]

According to Oliver Read's The Recording and Reproduction of Sound, the 8DG is gear-drive and the 8D is idler (puck) drive. I may have it wrong, but the one we had at school was definitely a rim-drive turntable, looks like the one pictured in this thread except that it sat on a tabletop. Regardless, I'd give my left arm for one of those! Oh, here's the relevant page from Read's book:

Snap11.jpg

[audiocarver]

The 8D, 8DG and 8GV are all part of the same family of lathes though and share the same parts between them. I've only hear of people mounting a Westrex 2B head on a Presto before, yours is the first I've actually seen that way.

If you think your lathe was a prototype, mine was weird as well with a half speed reducer on the 33 motor to give 16 2/3 and the overhead had dual feed screws. The platter is deceiving, though. The top plate is aluminum, the bottom is nickel plated cast iron and weighs 55 to 60 lbs! The holes are for vacuum hold down and there is a rubber hose that runs out the back of the lathe cabinet.

012.JPG

015.JPG

[grooveguy]

Wow! That Bad Boy doesn't look 'stock'; someone has modified that one bigtime, or somebody at the factory did a 'special' for who-knows what. I guess you could cut outside-in and then reverse direction and cut inside-out... kinda like streetcar tracks that cross over one another. Twice the playing time, but with some pops and ticks. Seriously, I wonder what that utility was for. The original Presto could cut either direction, I think there was a manual clutch to change screw rotation. Really beautiful machinery.