The Secret Society of Lathe Trolls

Hi, That seems backwards from what is normally done. If you take a file with a 20Khz bandwidth and play that file back at 78 the 2.3X speed change will shift the top frequencies to 46Khz. The cutter head can only cut to 10-15 Khz before rolling off, so your bandwidth will be limited to 4 -6Khz once ...

Hi, Really nice work! I'm interested in checking out these exciters. They seem to be quite a bit more efficient than the Dayton drivers I've been using. Good power handling as well. If these are not ferrofluid damped, you might want to consider adding some. That will increase the max power rating an...

Hi Again, I decided to see if the AI could derive the formula to create the desired front angle. In my case, since the front face is cylindrical, it calculated a projection. In the case of a square shank, I think the numbers will hold. This update Its seems to be correct, but I will do some testing....

Hi Everyone, I also have a Vevor machine, but I am for now, just fabricating embossing styli using 1/16" drill blanks of HSS, tungsten, or Carbide. I was running into the same issue of trying to get my head around the geometry. I ended up using Gemini AI to derive a formula and and simple calculator...

Hi David, My bad, you are correct PETG with a diamond for cutting. Since the stylus has ~90 degree included angle groove width is 2X depth. That assumes no tip radius. So you would just need to go a bit deeper. But as long as the playback stylus tracks, you are fine. Something around 5 mils should w...

Hi David, Interesting project. I don't think you need to be too concerned with the cutting stylus geometry. A modern microgroove stylus should be able to cut a standard size wide groove that will play properly with a 3mil playback tip. You just need to cut a bit deeper than normal. The playback styl...

Hi, Going with a big driver is generally a bad idea. You need to look at a few parameters. The BL factor which is the force in Newtons per Amp of drive current is very important. Large drivers will generally have a high BL which is a good thing. However, that typically comes at the cost of large mov...

Hi, I'm in the process of finishing up the design and debug of an eddy current sensor system to allow bench testing of cutter head response without the need to do the cut -> capture -> analyze workflow. It's not an end all as it does not take into account the changes to the head response when intera...

Hi,

I think he is talking about cutting, not embossing. You should have no trouble embossing polycarb.

Mark

Hi, I don't see why not. As long as you can install the stylus reversed. You would also want to tilt the head back from 90 degrees about 3-4 degrees or so for best results. Finally, you'll want the down force to be around 40-60g. In fact, you can probably get by with using old styli that have be dul...

Hi, Glad you found this helpful. Many times, on these older units with field coil speakers, the field winding was used as a choke in the power supply as part of the B+ filter. So you would need to leave the speaker hooked up even if you replace with a modern type or modify the B+ supply to deal with...

Hi, Unless you are really interested in keeping things original, I would drive the head with a modern solid state amp. Something in the 10-50 watt range should get you started. If you want to test the head on the bench, try inserting a 1/16" drill as a stand in for the stylus. If you have the means,...

Hi, You are asking for a complete course on disk recording here. 1. For turntable speed, there are a few smart phone apps that use the on-board sensors to measure platter rpm and even variation. They are reasonably accurate to start with. 2. Disc recording and playback EQ is standardized to a set of...

Hi,

Just need to increase your resolution by a factor of about 1000 and your are there. Cutting a disc requires resolution in the nm range down near and below the wavelength of light.

Mark

Hi, You should be able to connect it to a solid state power amp and feed some audio to it. Add a 1/4A fast blow fuse in series to start to protect the head. Hit it with a 1Khz 2V RMS level and see if you can hear it moving. If you take a plastic cup and couple the stylus to the bottom, it will act l...

Hi, If you are looking to keep the vintage aspect of the lathe, then of course, go for it. You can usually get by with an RCA tube manual from the era and some knowledge of electronics if you can't find a schematic. I think you will find its almost identical in design to a standard audio tube amp li...

Hi, I have not tried to cut using any type of blank. The stock blanks are quite expensive, so I quickly dropped them from any consideration. Spere supplies (e.g. styli and blanks) seem expensive and not so readily available. I don't see why you couldn't use a diamond stylus and do some cutting, but ...

Hi, Older mono moving iron heads are quite a different beast as compared with open loop moving coil stereo designs such that its much easier to flatten the response. In a moving iron head the drive coil is stationary, many more turns of wire can be employed resulting in the ability to produce higher...

Hi, I think you have it right. You don't want the stylus to dig into the material. That would cause tool chatter not unlike you would find on a metal lathe. Vertical or a slight tilt back is what is needed. If you are embossing, you generally tile back a bit further to make sure you do not transitio...

Hi,

Enjoying watching your progress.

You should check these guys out:

https://www.theearnesttube.com/

I have a couple of their releases (Tim Easton and also the Analog Rebellion discs) and they really capture a great sound and vibe. The music really shines through.

Mark