The Secret Society of Lathe Trolls

Thanks for explaining the input protection. I wasn't familiar with the THAT1200 series, and you motivated me to pull up the data sheet. That's a fairly impressive part, especially for the cost.

It sounds like you're making good progress. I look forward to your future notes.

Cheers -- KtG

I haven't tuned into the Trolls in a while, so I know I'm late to the game here, but I thought I'd mention that D21 seems to be backwards in the clip detector. I'm puzzled by the protection diode arrangements on the Input Stage sheet (D1-3, D6-10). As drawn, they limit the voltages at the +/- inputs...

Grooveguy, We love failures! How else will one find out what's possible? I'm going to say that both Soulbear and Epicenterbryan are correct. Tandem fans need either (1) a large-ish plenum space between stages, or (2) a flow-straightening element between stages, or (3) counter-rotating blades. All th...

Soulbear, is that 3 psi figure for static vacuum (sealed jar), or is it with the chip suction flowing? If it's the static vacuum, then I'm wondering how much it drops with chip suction, which would lower the available platter clamping force. Thanks.

Regards -- KtG

That pipe looks like it has a U.S. standard 1/2" IPS (pipe) thread, but as Bahndahn pointed out, you'll need to check this. If it does, then you might be able to use a socket like this Leviton 10051, plus a 1/2" close pipe nipple: Leviton_10051.jpg I can't tell from the photos how the shade is attac...

Opcode66, do you plan to saw a slot across those aluminum forms, maybe on the side opposite the wire-start hole? It seems to me that such a massive shorted turn is going to waste a lot of your coil drive power as heat, whether the coil is moving or not. Regards -- KtG P.S. It's eddy current, not edd...

Thanks to the buyers (in three countries!). I've made a donation to Steve E. for this site from the proceeds.

Thanks also to uvoscillator and jesusfwrl for posting photos of your mounting systems.

Regards -- KtG

Hi jesusfwrl, You're right, the LM317T is rated 1.5 A. My most recent usage was the LM317M, so I had 500 mA on my mind. On the issue of power dissipation, I'll accept that the LM317T can probably dissipate 20 W (although the Fairchild data sheet says only "internally limited"). My point was that the...

Soulbear, I grew up building stuff with relays, so I love "clatter and bang!" ICs and MOSFETs are just too darn quiet. But I'm also passionate about reverse-engineering things because of what I might learn that I can incorporate into my regular work as an EE. When I see something unusual in a schema...

Hi Soulbear, Are you sure that's drawn correctly? I don't see a reason for the diode being connected to the right end of the 220 ohm resistor, and as drawn, the available output current is rather limited. In fact, the higher the voltage setting, the less output current is available. It makes more se...

Folks,

I always appreciate the ingenuity of the folks on this board in creating solutions like this!

Aside from that, this thread has finally convinced me to part with some Airpot dampers I acquired about 30 years ago. Here's the Classified Ad post.

Regards -- KtG

Hi folks, For those of you wishing to add damping to your cutterhead suspension, one of these just might be the answer: Photo-1.jpg Photo-2.jpg This is an Airpot dashpot, carrying the custom part no. 64264-3. It appears to be the same as a type 2K160A, with a .627" bore, a 1" stroke and adjustable t...

By the way, the gentleman at the center of the top photo is almost certainly Howard Holzer (of HAECO). I withhold 100% certainty because I didn't know him until 1969-1974, and he's a bit younger in that photo than I remember him. I don't know what association Howard had with Gold Star, but (1) it wo...

Clearly, this is the solution you've been waiting for:

A working turntable made out of Legos

Adding the Lego feedscrew and cutterhead suspension is an exercise left for the reader...

-- KtG

It takes very little power to energize a mechanical telephone ringer, only about 1 watt. However, the impedance is very high, so it takes a lot of voltage. You may have seen the term Ringer Equivalence Number or REN printed on wireline telephones. 1 REN is equal to the impedance of a "traditional" m...

He's also a stickler for detail, into vinyl ...

And he's not going to be bothered by seeing the disc spinning at half speed?

Just sayin'... KtG

I haven't been in the audio business in 35 years, but I peek in here almost every day. I love the enthusiasm and creativity the members show for this "mature" technology. Keep on cuttin'!

Cheers,
KtG

That is an AWESOME book!

I'm something of a junkie when it comes to engineering history, and the more details the better. I know I'll be spending many a happy hour studying it.

Thank you! -- KtG

Item # 290694440792

Scully lathe modified with VP-1000 control, SC-2 cutterhead, $25K obo.

Just FYI! -- KtG

Surgical hose is very flexible, but not very resistant to crushing from vacuum. It's been a long time since I saw a Neumann setup, but I seem to remember that it used a gum rubber hose. Go to McMaster-Carr's web site and search on 5543K46 as a starting point, and you'll see a whole pageful of sizes ...