DIY lathe! Need help/suggestions!

[Woodbury]

Ok. I am new to the world of record cutting, I have never owned one and do not even know how one works exactly..here is my project though, its a completely home made record cutter. I used a track to create a moving table top which is driven by a worm gear, powered by a 6V DC motor run through a few small-to-big gears that I took from bikes and what not. A record player is put on the table top, and it is very very very slowly moved via the motor (I also put a rheostat on the DC current so the speed is variable). I then made a cutting mechanism by attaching a bent sewing needle to a small speaker. The speaker is attached to a board fixed over the moving record player, which can be raised or lowered via nuts....so here is the deal, I have been trying it out cutting onto transparencies and plastic plates and it DOES WORK!! but, it does not work well. The sound is distorted, has lots of noise and is quiet. Also, the playing needle has a hard time staying in the grooves. The problem is defiantly in the speaker/needle system. Does anyone have any ideas of a better DIY way to do this, using the machine that I have made? How does a REAL one work anyhow? should I use a different type of needle? which way are the vibrations supposed to be cut, up and down, or side to side? please give me suggestions on what to try next, and check out the photos below.

http://c3.ac-images.myspacecdn.com/images02/67/l_b91769c6aac24ca59ef4ed32d3f63daa.jpg

http://c1.ac-images.myspacecdn.com/images02/88/l_1e5bf72128734cedbd2c69fbbf59272c.jpg

http://c2.ac-images.myspacecdn.com/images02/92/l_327d88effc1c436cab1139b71b765a71.jpg

[Aussie0zborn]

Well for someone who doesn't know much about this stuff you have done well. The sliding turntable is an interesting variation on the theme - the carriage driven by the worm screw is the usal way of doing things but this is an interesting idea.

To cut a good record you need a proper cutting head. The head simply needs to glide across the face of the disc and your sliding turntable allows this.

You are nearly there - good work! Just get your self an inexpensive mono cutterhead and you will be more than 50% of the way there.

[Woodbury]

thanks! any ideas of where to purchace a proper cutting head?

[oliver8bit]

I think the grooves need to be side to side, though frankly it surprises the hell out of me that it works up to down. I had the same problem (quiet sound, lots of noise, too much bass) when doing this "How to Make a Record Lathe!" video one youtube, which is by Mason who posts here:
http://www.youtube.com/watch?v=eTO9XKrlDnA

This is what he said in a response to my question:

"this happens because it records in an up and down motion. it cant digg verry deep for the bass tones, and only has a certain range because of gravity on the needle playing the music. when the needle falls into a dip in the groove, it will always be faster than when it comes over a hill in the groove.
to fix this, we need to find a way to engrave left and right, instead of up and down. almost all real records work with left and right movemet in the groove. this gives ALOT more range and there is no gravity factor. im not sure if that would fix the loudness problem, but it will fix the bass tones "

The solution is either something like this:
http://www.youtube.com/watch?v=xfHWbQxZBro

Or, as someone points out on the first video page, a diagonal.

Looks amazing, tho Woody! Hell yes!!

[VRCM]

Well diamond disc was up and down right? I was actually thinking about an up and down cutter or a edison diamond disc electric pick head.

[markrob]

Hi,

Nice job on you DIY lathe. It was interesting to see a totally different take on the problem. Here is a link to my DIY lathe:

http://home.comcast.net/~markrob1066/site/

Here is my two cents on some of your questions.

You may be recording louder than you think. If you are playing back your cuts using a standard stereo pickup, the vertical component will be lower in output unless you combine the L+R channels out of phase. To do this connect the two - terminals together and take the output from the two + terminals of the pickup. If the sound is recorded side to side the L+R are added to recover the information. If recorded vertically, then you must subtract L from R.

The skipping might be due to over modulation or your depth of cut is too shallow. It looks to me like you are cutting on the soft turntable mat. Perhaps try a harder surface so you can get more force to bear on the material. Also, try reducing the amout of bass in the signal fed to your cutter speaker. This will reduce the excursion of the speaker and may prevent over modulation.

I suspect the high noise floor is due to the geometry of your cutting needle. The playback stylus needs to ride on the walls of the groove. If the groove geometry you create is such that the playback stylus tracks on the bottom of the groove, you will have extra noise. Also, the faces of the cutting sylus need to be formed so that it cuts the material smoothly. I can send you a copy of a drawing that shows the proper geometry. Finally, the material you are cutting into will have a large effect on the noise.

Hope this is of some help to you. Feel free to ask away. Keep experimenting!

Mark

[Aussie0zborn]

Nice lathe Mark!!

[emorritt]

Hmmm... what you have is basically an old style lathe like those used for mechanical recording! Those machines were designed so the turntable traveled under the recording head. The horns used for 'channeling' the sound were attached directly to the cutting head assembly, which would have made it nearly impossible for it to move across the surface of a recording disk. I think the Sooy brothers that worked for Eldridge Johnson/Victor called this type of lathe a "barn door roller machine". It wasn't until electric recording that the overall design of recording lathes changed so that the cutter traveled over the surface of the disk and not the other way round.

[markrob]

Nice lathe Mark!!

Thanks! Its still a work in progress. I've since aquired a 6N and have been working with that. I intend to improve my DIY stereo head design and outfit it to the Presto. Right now I'm working on adding feedback to my mono Presto 1C head. I'm starting to get some good results. I have a mono ceramic cartidge coupled directly to the aramture. The ceramic seems attractive to some other approaches I've tried because it does not suffer form stray coupling from the magnetic field generated by the coils. It has a much higher output that any feedback winding and will be easy process. I'll post some details once I'm a bit further along.

Mark

[oliver8bit]

How does it sound with that drill blank? What made you decide to use it, if you don't mind me asking...

[markrob]

How does it sound with that drill blank? What made you decide to use it, if you don't mind me asking...

It works well on lacquer blanks, even better with some heat applied. When you get the surfaces right (e.g. mirror finish), I think it works almost as well as a commercial stylus. I don't have the skills to lap the burnishing facets on all of the edges, so there is probably some performance hit there. However, some of the papers I've researched indicate that these facets are not required when using heat. In fact, it shows that facets too large kill the high frequency response.

I selected drill blank material because its made of high speed steel, which is hardened. It must be ground into shape. Back in the day, steel was used for home cutting applications because its cheap and easy to work with. I went with 1/16" because that is the size of the shank for Presto and similar cutter heads. The downside of HHS is the cutting life, perhaps 1 or two sides. But since I've have my DIY grinding and lapping setup, its no big deal to re-sharpen and/or make new stylii.

I've also been working with carbide steel drill blanks and saphire rod. I would have thought that the carbide would work better (since it much harder) than the HHS, but so far, that does not seem to be the case.

I've started to get good at making aluminum shanks to hold small .032" saphire rod (much like you would see from Transco). I found a source for these at a cost of about $5 ea. I mount the rod in the shank and then grind and lap on the same setup. The problem I find working with saphire is that it is very brittle and chips easily. I've made a few that have worked well.

Hope this makes some sense.

Mark

[motorino]

incredible!!

very good work Mark!

[Cutterwoller]

You will get to much bass and reduced top if you are not cutting with reverse RIAA curve.

Lewis

[markrob]

You will get to much bass and reduced top if you are not cutting with reverse RIAA curve.

Lewis

Hi Lewis,

You have to do quite a bit more than that. Since the head has very little damping, and is a spring/mass system, you have to compensate for the peak in the response. Also, since this type of design is cosntant amplitude below resonance (about 1Khz in my case) and rolls off -12db/oct above resonance, you have to apply the inverse RIAA keeping this in mind. I ended up recording white noise uncorrected to a blank and creating an record EQ curve based on playback of the test signal using a standard pickup with the RIAA curve in place. One of the reasons that the modern heads need so much power and cooling is due to the fact that they have a similar characteristic. There is a ton of high frequency boost applied to get the head to do what is needed.

Mark

[joegarrison]

where did you get that gearbox

i need one