Your design will of course work ... probably very well.
Too bad you have to "split" your platter into two halves to get the shaft & nut in place.
Although your bronze (or brass or wood :>) ) bearing is out of the center of mass of your platter, the distance from the center of the bearing is probably not great enough to make much difference ... and your design is much easier to make.
The only thing I might add is to try to make your hole in the bottom of the "plinth" where the ball sits as flat as possible and install a "wear plate" or teflon disc as described above ... This point is where most of the rotating friction occures and if the hole is flat in the bottom, then the teflon disc (or delrin or even wood) will not distort and increase the friction. ...
(I used Apple Works Drawing program for my drawings ... You?)
Too bad you have to "split" your platter into two halves to get the shaft & nut in place.
Although your bronze (or brass or wood :>) ) bearing is out of the center of mass of your platter, the distance from the center of the bearing is probably not great enough to make much difference ... and your design is much easier to make.
The only thing I might add is to try to make your hole in the bottom of the "plinth" where the ball sits as flat as possible and install a "wear plate" or teflon disc as described above ... This point is where most of the rotating friction occures and if the hole is flat in the bottom, then the teflon disc (or delrin or even wood) will not distort and increase the friction. ...
(I used Apple Works Drawing program for my drawings ... You?)
HBarske said:
Could you explain that a little? Do you mean that I should make the hole in the plater a tight friction fit, so the shaft stays in by itself?
And both Holger and FastEddy remarked on the platter "split". Thing is, I was thinking of making the platter of Baltic birch plywood, somewhere between 1 1/2" - 3" (37 - 75 mm), which would require gluing up the laminations anyway.
The advantage of doing it that way is that I can cut the first disk (3/4", 18mm) with a circle cutter attachment on the router, then use a flush-trim bit to make subsequent laminations match exactly. Well, exactly within woodworking tolerances, anyway.
If the issue is the void in the platter, this could probably be filled with epoxy - and, if that were done, I guess I wouldn't need the nut 🙂
Aengus
[edit] Just realized I missed a question. I'm from the dark side - I used Microsoft Visio 😱
Could you explain that a little? Do you mean that I should make the hole in the plater a tight friction fit, so the shaft stays in by itself?
And both Holger and FastEddy remarked on the platter "split". Thing is, I was thinking of making the platter of Baltic birch plywood, somewhere between 1 1/2" - 3" (37 - 75 mm), which would require gluing up the laminations anyway.
The advantage of doing it that way is that I can cut the first disk (3/4", 18mm) with a circle cutter attachment on the router, then use a flush-trim bit to make subsequent laminations match exactly. Well, exactly within woodworking tolerances, anyway.
If the issue is the void in the platter, this could probably be filled with epoxy - and, if that were done, I guess I wouldn't need the nut 🙂
Aengus
[edit] Just realized I missed a question. I'm from the dark side - I used Microsoft Visio 😱
Missed another point as well.
FastEddy said:
My thought on this was that the shaft would rotate on the ball bearing (single point of contact) while the bearing sitself tayed still owing to friction in the hole. If this is incorrect, I suppose another possibility is the one suggested by a poster (can't remember who it was, sorry) in another bearing thread: put three bearings small enough to fit flat at the bottom of the hole, with a fourth bearing sitting in the gap on top of them. Should minimize friction significantly and would be self-centring to a large extent.
Aengus
FastEddy said:
My thought on this was that the shaft would rotate on the ball bearing (single point of contact) while the bearing sitself tayed still owing to friction in the hole. If this is incorrect, I suppose another possibility is the one suggested by a poster (can't remember who it was, sorry) in another bearing thread: put three bearings small enough to fit flat at the bottom of the hole, with a fourth bearing sitting in the gap on top of them. Should minimize friction significantly and would be self-centring to a large extent.
Aengus
Absolutely. If the fit isn't that tight, your platter will tend to tip.Aengus said:
And: The shaft should rotate in the bearing, not in the platter.
" ... Thing is, I was thinking of making the platter of Baltic birch plywood, somewhere between 1 1/2" - 3" (37 - 75 mm), which would require gluing up the laminations anyway ..."
Cool!!! ... A wooden platter !!!
All suggestions above still apply (including Holger's about a nut ... or not).
First: If you intend to remove the platter from time to time, then, as Holger suggests, that nut (and shaft) may get mis-aligned or it's pilot hole may get "woobely". If the nut & washer are left out, then lifting the platter from the shaft would be the same as lifting the platter and shaft out together ... the advantage being that when the platter is reinstalled on the "nut less" shaft, the chances of pilot hole distortion may be less. This may not be intuitive, but its is true to some extent.
Second: The act of tightening the nut and lock washer will intruduce some distortion or mis-alignment during first time assembly ... no nut and no washer = no tightening distortion = no torqing mis-alignment ... and there should be nothing wrong with having a "floating" shaft ... (I believe this is what Holger is driving at) ... And you could put another hard steel ball inside the hole of your platter at the top of the shaft as well.
Cool!!! ... A wooden platter !!!
All suggestions above still apply (including Holger's about a nut ... or not).
First: If you intend to remove the platter from time to time, then, as Holger suggests, that nut (and shaft) may get mis-aligned or it's pilot hole may get "woobely". If the nut & washer are left out, then lifting the platter from the shaft would be the same as lifting the platter and shaft out together ... the advantage being that when the platter is reinstalled on the "nut less" shaft, the chances of pilot hole distortion may be less. This may not be intuitive, but its is true to some extent.
Second: The act of tightening the nut and lock washer will intruduce some distortion or mis-alignment during first time assembly ... no nut and no washer = no tightening distortion = no torqing mis-alignment ... and there should be nothing wrong with having a "floating" shaft ... (I believe this is what Holger is driving at) ... And you could put another hard steel ball inside the hole of your platter at the top of the shaft as well.
Hi Eddy,
what you are suggesting ist to build something like a "secondary bearing". I would not recommend that. The shaft should have a tight fit in the platter and it should stay there forever once it is mounted. Only on the bearing itself you can control tolearnces, everything happening inside the platter is more or less coincidence.
what you are suggesting ist to build something like a "secondary bearing". I would not recommend that. The shaft should have a tight fit in the platter and it should stay there forever once it is mounted. Only on the bearing itself you can control tolearnces, everything happening inside the platter is more or less coincidence.
HBarske: " ... The shaft should have a tight fit in the platter and it should stay there forever once it is mounted. ..."
A "press fit" ?? Yes, I suppose you are correct here, that shaft should not be allowed to wooble (woobel ?). (Maybe roughening up the top end of the shaft, using some kind of adhesive and a press fit would be better than a nut & lock washer.)
Was I right about your reasoning about "to nut or not to nut" = causing distortion and mis-alignment during assembly ??
A "press fit" ?? Yes, I suppose you are correct here, that shaft should not be allowed to wooble (woobel ?). (Maybe roughening up the top end of the shaft, using some kind of adhesive and a press fit would be better than a nut & lock washer.)
Was I right about your reasoning about "to nut or not to nut" = causing distortion and mis-alignment during assembly ??
FastEddy said:
If I understand this, the ideal is to have the bearing within the platter. An inverted bearing is one in which the shaft is fixed to the plinth and the bearing is fixed to the platter; the drawback being that it is hard to lubricate (oil runs out).
So what we need is an extension of the plinth - the bearing portion, as it were - into the platter. Putting a batch of thes ideas together gives this drawing.
If I understand this, the ideal is to have the bearing within the platter. An inverted bearing is one in which the shaft is fixed to the plinth and the bearing is fixed to the platter; the drawback being that it is hard to lubricate (oil runs out).
So what we need is an extension of the plinth - the bearing portion, as it were - into the platter. Putting a batch of thes ideas together gives this drawing.
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Holger, you posted while I was editing. Thanks for the response - I think the drawing follows your recommendations.
Aengus
Aengus
" ... So what we need is an extension of the plinth - the bearing portion, as it were - into the platter. Putting a batch of thes ideas together gives this drawing. ..."
Yes, but without the nested balls. That would make three or more points of contact for the shaft and the top of the nest ball. One ball just a little smaller than the shaft diameter, resting on something very hard, like teflon or delrin (or a even very hard wood).
Yes, but without the nested balls. That would make three or more points of contact for the shaft and the top of the nest ball. One ball just a little smaller than the shaft diameter, resting on something very hard, like teflon or delrin (or a even very hard wood).
FastEddy (who is living up to his name in this thread) said:
What my intuition says is that the rotation point will be where the shaft contacts the top ball - that this will have the least friction. The only function of the other three balls is to center the bearing that's doing the work. This is a field in which my intuition is definitely not highly tuned, though, so if your experience says this is wrong, I'll listen.
I suppose a way of getting a hardened surface in the plinth - also intended to be Birch plywood - without having to use a thrust washer would be to soak epoxy into the wood. If I made a flat-bottomed hole (or as flat-bottomed as a Forstner bit allows), I could then build up a thin layer of epoxy at the bottom and hope that capillary action would draw it up the sides a bit, leaving a very slightly concave bottom to aid in centering the ball.
Aengus
What my intuition says is that the rotation point will be where the shaft contacts the top ball - that this will have the least friction. The only function of the other three balls is to center the bearing that's doing the work. This is a field in which my intuition is definitely not highly tuned, though, so if your experience says this is wrong, I'll listen.
I suppose a way of getting a hardened surface in the plinth - also intended to be Birch plywood - without having to use a thrust washer would be to soak epoxy into the wood. If I made a flat-bottomed hole (or as flat-bottomed as a Forstner bit allows), I could then build up a thin layer of epoxy at the bottom and hope that capillary action would draw it up the sides a bit, leaving a very slightly concave bottom to aid in centering the ball.
Aengus
Holy this thread ran away on me ;>..> After reading all this I'm sure I can come up with a design 😛
That three ball nest bearing does look like it could cause issues. Way too much opportunity for rumble to occur. So I too would have to agree with fasteddy on this one.
Not ofr lubrication in the bearing I've seen some desings with channels spialling up the shaft inside the bearing, to bring oil up to the bushing, I'm not sure if this would be neccesary myself but I'ts something I've considered
Also where would I get something like glass filled teflon for the thrust plate?
That three ball nest bearing does look like it could cause issues. Way too much opportunity for rumble to occur. So I too would have to agree with fasteddy on this one.
Not ofr lubrication in the bearing I've seen some desings with channels spialling up the shaft inside the bearing, to bring oil up to the bushing, I'm not sure if this would be neccesary myself but I'ts something I've considered
Also where would I get something like glass filled teflon for the thrust plate?
Hi Tal,
Well, it's not glass filled Teflon, but this stuff has proven to be very rugged and friction free in my bearing.
-Casey
Well, it's not glass filled Teflon, but this stuff has proven to be very rugged and friction free in my bearing.
-Casey
" ... NYLON 6/6 is ... excellent combination of wearing resistant qualities ..."
Go for it. The idea is to use something that is a) flat, b) wear resistant, c) low friction, d) hard, e) if possible, self lubricating or reacts well to light machine oil.
Go for it. The idea is to use something that is a) flat, b) wear resistant, c) low friction, d) hard, e) if possible, self lubricating or reacts well to light machine oil.
Interesting design variation: Shaft, bearing and ball will be this: http://3dotaudio.com/images/UNI_0085x.jpg
(Interesting story about this intake valve. It is from a Lee Chapman Cosworth Engine rebuild, a "spare" part of no value = http://www.leechapmanracing.com/Services.htm ... My neighbor has a junk box full of 'em, so he let me have a set. Keeping the valve intact, no cutting, makes the top of the platter to the deck about 6" total height overall. Note that the bearing is up inside the platter, close to the center of mass.)
(Interesting story about this intake valve. It is from a Lee Chapman Cosworth Engine rebuild, a "spare" part of no value = http://www.leechapmanracing.com/Services.htm ... My neighbor has a junk box full of 'em, so he let me have a set. Keeping the valve intact, no cutting, makes the top of the platter to the deck about 6" total height overall. Note that the bearing is up inside the platter, close to the center of mass.)
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Used this previously for guide rollers, good all round engineering plastic where moisture absorption isn't an issue. Could be used for bearing as well as thrust plate. Tends to wrap around cutting tools in lathe, sort of like a cassette tape that's been pulled out of it's case.
Jeff
hey that nylon stuff looks awesome. Thanks!
that site also has a lot of supplies I could use as well too bad i didn't see it before, I could have gotten the acrylic I'm using a lot cheaper from there.
I think i may start over again now whit all this new information and this website available. hehe either way i'll post an autocad design soon.
that site also has a lot of supplies I could use as well too bad i didn't see it before, I could have gotten the acrylic I'm using a lot cheaper from there.
I think i may start over again now whit all this new information and this website available. hehe either way i'll post an autocad design soon.
Tal & vinylkid58: I just took a better look at their ( smallparts.com ) raw materials pages and discovered these: http://www.smallparts.com/products/descriptions/bao.cfm ... " ... comparable to Synthetic Ruby and Sapphire Balls. ... a standard component for endo-prosthesis joints. ..."
These balls would probably be more than hard enough for a turntable thrust bearing, unless its weight is measured in tons ... 😀
("Should you require a ceramic ball with unusually high fracture toughness and flexural strength, coupled with a near-to-steel low modulus of elasticity, zirconium oxide balls are available." ...) ( ... "also a mild detergent" as the punch line goes ... :>)
...
Q&A: Suppose one were to get 10 sheets of this: http://www.smallparts.com/products/descriptions/las.cfm ... 3/8" X 12" X 24" and make a laminated turntable of 20 layers, slightly less than 12" overall diameter ... Wondering what kind of adhesive to use? Any electrostatic problems? Costs would be < US$600 with shipping for material plus machine costs ... would this work out? ... problems ??
Target configuration as previous:
These balls would probably be more than hard enough for a turntable thrust bearing, unless its weight is measured in tons ... 😀
("Should you require a ceramic ball with unusually high fracture toughness and flexural strength, coupled with a near-to-steel low modulus of elasticity, zirconium oxide balls are available." ...) ( ... "also a mild detergent" as the punch line goes ... :>)
...
Q&A: Suppose one were to get 10 sheets of this: http://www.smallparts.com/products/descriptions/las.cfm ... 3/8" X 12" X 24" and make a laminated turntable of 20 layers, slightly less than 12" overall diameter ... Wondering what kind of adhesive to use? Any electrostatic problems? Costs would be < US$600 with shipping for material plus machine costs ... would this work out? ... problems ??
Target configuration as previous:
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