kilowattski said:
I should clarify that aluminum by itself (without damping) will ring. I'm not sure what you're referring to.
I met Peter in California a few years ago when he was basically touring with his turntable. He showed up at a local audio club and I spoke with him and also listened to his turntable.
kilowattski said:
I will find the webpage of the person who did an extensive inspection of his Teres bearing. Anyway, the Teres website states that the bearing is machined from stainless steel and I do not believe the shaft is hardened.
kilowattski said:
I don't understand your comment regarding "any size". I briefly outlined my opinion since you did ask for any or all opinions and you basically don't agree or are confused, so be it.
Machining wheels on a vertical mill is something quite different than turning the O.D. of a platter where the surface is super sensitive to "roundness and concentricity, at least that is my belief.
kilowattski said:
It's simple, believe me. As I said, I machine acrylic and many other performance plastics on a consistent basis, Delrin, ABS, Polyimide, etc. It's a large part of my business.
Have your machinist friend show you.
On some points we will agree to disagree. I had always planned on turning the outside of the turntable but only after the machining is done. I don't understand why you put down a proven design like the Redpoint. I don't want to build anything that will require a suspension so I have ruled out a lightweight mass design. I have done alot of research on this. The proof is in the sound. If you lived close to Long Island I would invite you over for a couple beers and a listen.
As I said my first attempt at this was maching a block of acrylic on my home milling machine using a rotary table, maybe it was not the right way to do things but at the time thats all I had at my disposal. I will take your word on this as you are a machinist and I am only a amatuer.
I already have the Teres bearing so I will use it. If it fails I will look to maybe get a Sheu Bearing. I do stand corrected though. It is stainless not hardened. You are absolutely right.
I think this is the article you are looking for:
http://www.theanalogdept.com/bearing_wear.htm
I have not read this in a while. After rereading the article I will use a Tungsten Carbide Ball. I do agree that the Teres Bearing requires regular maintenence to be effective.
Agree or disagree I do appreciate your input.
As I said my first attempt at this was maching a block of acrylic on my home milling machine using a rotary table, maybe it was not the right way to do things but at the time thats all I had at my disposal. I will take your word on this as you are a machinist and I am only a amatuer.
I already have the Teres bearing so I will use it. If it fails I will look to maybe get a Sheu Bearing. I do stand corrected though. It is stainless not hardened. You are absolutely right.
I think this is the article you are looking for:
http://www.theanalogdept.com/bearing_wear.htm
I have not read this in a while. After rereading the article I will use a Tungsten Carbide Ball. I do agree that the Teres Bearing requires regular maintenence to be effective.
Agree or disagree I do appreciate your input.
Too bad they didn't use 17-4PH since it is relatively easy to work with and can be easily heat treated. We even machine it in some of the hardened states.
I look forward to making my turntable shortly on the MacTurn (9 axis of joy) at work. It will be nice to be able to machine all the lead shot pockets, ID and OD in one setup. I am designing the process so that the OD and top are finish machined with the spindle in place and dialed in on a manual lathe. CNC is nice but it has it's place.
I look forward to making my turntable shortly on the MacTurn (9 axis of joy) at work. It will be nice to be able to machine all the lead shot pockets, ID and OD in one setup. I am designing the process so that the OD and top are finish machined with the spindle in place and dialed in on a manual lathe. CNC is nice but it has it's place.
kilowattski said:
I have no recollection of putting Redpoint down, perhaps my points were poorly stated, sorry for that, however I definitely am not putting Redpoint down.
I think my 30+ years experience in machining in areas such as tool & die making as well as model making have exposed me to a variety of machining techniques. I have owned and operated my own machine shop for the past 14 years and take the profession seriously. There are a number of hobbyists who like to knock out metalworking projects and sometimes I chime in with a few words of advice, keep in mind I do this for a living so I am somewhat critical about things such as concentricity, surface finish, and perpendicularity when it comes to building bearings and platters, etc.
I think it's great you have a few machine tools to build some parts for your turntable project. I hope it turns out the way you want it to.
I have no doubt in my mind that you are an excellent machinist. I am but an amatuer. When it comes to machining metal I take whatever you say seriously. I won't be doing any machining on this project though. My neighbor has graciously volunteered his time to help me out. I wouldn't have the foggiest idea how to run the Haas. I will only write the G-Code (with his help) to run the pieces. My first foray with G-code was with the Top-Plates for the Maxon Motor Group Buy.
As I mentioned the plinth and platter will be finished on a lathe. My neighbor suggested that for the same reasons you did.
As for the bearing, I understand your point. Being the bearing is Stainless as you suggested and not Case Hardened like I thought, I will have to keep an eye on it. This is my first attempt at a turntable, it doubt it will be my last. In the future I would like to try other bearings.
I would like to balance the platter some how when it is done. I could add shot in some spots and take away in others. Do you have any suggestions on balancing the platter.
As I mentioned the plinth and platter will be finished on a lathe. My neighbor suggested that for the same reasons you did.
As for the bearing, I understand your point. Being the bearing is Stainless as you suggested and not Case Hardened like I thought, I will have to keep an eye on it. This is my first attempt at a turntable, it doubt it will be my last. In the future I would like to try other bearings.
I would like to balance the platter some how when it is done. I could add shot in some spots and take away in others. Do you have any suggestions on balancing the platter.
Balancing is relatively easy:
Machine out the holes equally around the platter. Drill each one to the same depth. Then fill one with the lead shot - leaving enough room for the teflon etc to go on top. Then take out the lead shot and weigh it. Add the same amount +/- 1g for each of the other holes.
If you then want to be super precise and balance it further, I would imagine you would need some kind of jig to hold the platter but yet allow it to turn very freely. Give it a spin then let it settle. A small amount can be removed by drilling say a 6mm rebate at the heavy side.
In reality though, if the block is machined true on a lathe, and you add the same amount +/- 1g I think it would be good enough.
Remember - Teres does this but using wood which does vary somewhat in density (although cocobolo doesn't vary that much). A couple of grams here or there isn't going to make that much difference.
Fran
Machine out the holes equally around the platter. Drill each one to the same depth. Then fill one with the lead shot - leaving enough room for the teflon etc to go on top. Then take out the lead shot and weigh it. Add the same amount +/- 1g for each of the other holes.
If you then want to be super precise and balance it further, I would imagine you would need some kind of jig to hold the platter but yet allow it to turn very freely. Give it a spin then let it settle. A small amount can be removed by drilling say a 6mm rebate at the heavy side.
In reality though, if the block is machined true on a lathe, and you add the same amount +/- 1g I think it would be good enough.
Remember - Teres does this but using wood which does vary somewhat in density (although cocobolo doesn't vary that much). A couple of grams here or there isn't going to make that much difference.
Fran
platter balance.
Hi,
1) A method which we have used to good effect is to make a plug for the centre hole in the platter and accurately drill that plug with a small dia. drill. then suspend the platter on about 3' of chord (which attaches at the dead centre!) In your case you could hang the platter upside down and simply add/subtract lead until the platter hangs horizontal in all planes.
2) for a record interface mat we have tried everything possible and found that - in our opinion - the purest fine grain graphite is without doubt the best material. In fact we have built TTs using this material for the entire platter ( excluding a brass drive rim.) The deeper the carbon the better. I am talking pure graphite - not a graphite based composite.
Good luck,
Brian
Hi,
1) A method which we have used to good effect is to make a plug for the centre hole in the platter and accurately drill that plug with a small dia. drill. then suspend the platter on about 3' of chord (which attaches at the dead centre!) In your case you could hang the platter upside down and simply add/subtract lead until the platter hangs horizontal in all planes.
2) for a record interface mat we have tried everything possible and found that - in our opinion - the purest fine grain graphite is without doubt the best material. In fact we have built TTs using this material for the entire platter ( excluding a brass drive rim.) The deeper the carbon the better. I am talking pure graphite - not a graphite based composite.
Good luck,
Brian
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