Feedscrews

[jason udallParticipant @jasonudall57142]

Mmmm…thinks…. lever mech….simple “feedscrew” drives say 100 to 1 lever…op has 1/100 noise from feedscrew .
Mech damping added to taste?. ..

[jason udallParticipant @jasonudall57142]

Further. ..how much noise is seen in turned / milled / finishes?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John McNamara on 26/07/2013 07:44:48:

Hello Roger

Gee The last time I recommended this book it cost less… 70 bucks now, secondhand… New is off the planet! 1.5k it is becoming hard to get.

Precision Machine Design By Alexander J Slocum

**LINK**

Anyway it is the book you need. you local university library will have it or your local libraray?

It will answer all your questions.

Regards
John

In the absence of Slocum's book … this may be a useful alternative.

MichaelG.

[VersabossParticipant @versaboss]

Easiest way out: buy one of these:

Vinylrecorder

Greetings, Hansrudolf

[John McNamaraParticipant @johnmcnamara74883]

Good paper Michael

It looks like you like browsing through "Google Scholar" too.. Or prowling around "pergatory" at MIT.

Hi All

with regards to the recording machine. I think it is an ideal candidate for a mineral casting also known as polymer concrete base and slide. (Polymer concrete has several times better vibration damping than cast iron) **LINK**

There should be two castings.

1. The main base supporting a turntable and drive motor, and a slide with drive screw and motor.
2. a moving slide attached to the base with attachment points for the cutting head.
Both these components should be heavy castings to damp out vibration.

Being smallish these parts could be easily made in a home workshop.

Note the cutter head dissipates quite a lot of power maybe 200 watts via two voice coils. if you study the Scully machine it is no lightweight I do not know the actual weight but found a site that gave the dimensions 22 x 48 x 29 inches tall **LINK** a cast iron machine of that size would be quite heavy. No doubt the designers took vibration very seriously.

regards
John.

[Sub MandrelParticipant @submandrel]

I would use a good quality screw in a bronze nut, and if there was any 'noise' from the combination polish them together with very fine abrasive paste. Any backlash will be unidirectional and easily overcome with a spring.

Neil

[Roger YarwoodParticipant @rogeryarwood66088]

Thankyou all for your input, i will check out the suggested reading material.

As for the "Vinylrecorder" …..Thats a good machine but has it's limitations, which make it unsuitable for all purposes. I want to go a bit further!

I am fully aware that the machine needs to be big and heavy, although i believe the required result can be achieved in a lighter machine using modern techniques.

The pro machines in use today where developed not long after WWII. The latest pro machines made by Neumann went out of production in the '80s and took 40 years of development, so the technology is very dated now.

I'm going to be researching until at least the end of the year so if anyone thinks of anything usefull i'm all ears!

Another question: How practical is it to get custom parts casted in metal?

Thanks again

Rog.

[John McNamaraParticipant @johnmcnamara74883]

Hello Roger

It easy enough to get metal castings made, and as long as you make good patterns properly scaled for shrinkage and following the various other rules for good casting practise it will go well. (Best you read up on it).

One concern is large castings like the frame of the record lathe require Machinery large enough to machine them.

That is why I suggested you use Epoxy castings instead. There is almost no shrinkage and the paterns are simple to make. You cast in steel mounting points for the various other parts attached. These can be mad on a smaller lathe or mill.

I had a play with a concept design for your new lathe. The turntable is 350mm in diameter. I would make the base and the "C" frame carriage from a mineral casting.

Cad images are in my Album

Regards John

Edited By John McNamara on 28/07/2013 09:49:23

[Roger YarwoodParticipant @rogeryarwood66088]

Great drawings John! What CAD software do you use? May i ask how long it took to do these? You are obviously familiar with the software.

I will definitely be reading up on the things mentioned by all, thanks again for all the input, i have plenty to be getting on with, and much to read!

Thank you all again.

R.

[Roger YarwoodParticipant @rogeryarwood66088]

So is this what you mean regarding epoxy castings?

**LINK**

[John McNamaraParticipant @johnmcnamara74883]

Hi roger

Maybe two hours total time, I did not time myself. The actual drawing would be less than half of the total time spent. The rest would be thinking and analysis. Prior to starting I did browse around the net for Ideas. The design I drew is smaller than the commercial machines I found. Tucking the "C" frame under the turntable does save space, and it will be just as stiff.

I Use Autocad 2014. having just installed the latest upgrade pack. I use it for construction as well as mechanical design, so have to keep it updated.
There are other 3D programs available (free) maybe Google Sketchup would be a good choice. You can import sketchup files into Autocad. **LINK** or sketchup to autocad **LINK**,
Being able to export to a mainstream CAD package is a good idea if you want any machining or laser cutting from your designs done, just about all CAD packages can read Autocad DXF files.

Yes I am fairly familiar with CAD particularly with the 3D side of Autocad. There are other better and just as expensive 3D CAD programs that are better for mechanical design. however they don't work so well for building design. Anyway I know Acad and it works for me.

There have been many discussions on this site re 3D CAD **LINK** I hope this thread does not get clogged up with CAD discussion, may I suggest using one of the other threads I found.

Regards
John

Edited By John McNamara on 30/07/2013 09:30:48

[John McNamaraParticipant @johnmcnamara74883]

Hi Roger

Yes however no re your link which shows a cast Iron frame being filled with epoxy concrete to increase the stiffness and add damping.

The method I am proposing is to use the mineral casting material alone. It is the frame or part.

Here is a link to a rather long thread I started describing the manufacture of a tool grinder that uses mineral castings for the base and a moving slide. **LINK** Page down a bit to see it. Designed with Autocad too…..

I use this grinder every day to grind carbide and High Speed steel lathe tools, It is solid as a rock… (Excuse pun!) it has minimal vibration. With a diamond wheel I get an almost mirror finish.

Note the method of manufacture and the steel insert attachment points for the steel parts. You should be able to transpose the concepts employed in the grinder into your record lathe.

You may like to browse the following link. **LINK** Hermle is a German machine tool builder. Nearly all their machines use a frame made from Mineral Castings. They they work in Microns

Regards
John

[Sub MandrelParticipant @submandrel]

A bit more solid than Mr Edison's wax cylinders…

When I was a lad they had a booth on Barry Island where you could record yourself and out popped a playable record. There were romours of small bands trying to fit in several voices and a guitar into the booth!

Neil

[Roger YarwoodParticipant @rogeryarwood66088]

My research has uncovered a recording lathe that uses a type of hydraulic positioning system for the carriage that was measured to be superior.

Can anyone give any insight or links to useful info on hydraulic positioning or feed systems?

[John McNamaraParticipant @johnmcnamara74883]

Hello Roger

In the middle of the 20th century pre solid state microprocessor controlled electronics Hydraulics were used to drive some machine tools, There are still a number in use, hydraulic copying attachments for lathes for instance. Some Swiss "SIP"Jig borers and Cincinnati production mills also come to mind.

If you go the hydraulic path electro/hydraulic servo control valves to control the speed are available. The total hydraulic system cost could get quite high maybe equal the cost of a new small car, certainly a good secondhand one.

A modern dc servo drive should work well (Better), as used on diamond turning lathes that can machine steel to a mirror finish, or high end CNC mills.

Regards John

[frank brownParticipant @frankbrown22225]

You say that modern stepping motor modulate you groove, I would guess because they literally switch from pole to pole, Have you tried a multiphase AC servo motor , they should be less notchy. The other thing is, if you can detect the position of the head and compare it to where you would like it to be, you could use a CD laser piezeo electric positioning unit to retard. or advance it to where it should be. Or even if the spurious modulation is fairly consistent, pre-correct the heads position with it.

Bring back the hum bucking coil

Frank

[Author]

Posts