Stefano,
By the way, I do not know how to balance the flywheel other than to completely machine it on a lathe to the best precision possible. If the geometry is perfect the balance should be perfect. Not really, but I think it will be as good as possible without better method to balance.
Jamie
By the way, I do not know how to balance the flywheel other than to completely machine it on a lathe to the best precision possible. If the geometry is perfect the balance should be perfect. Not really, but I think it will be as good as possible without better method to balance.
Jamie
Wonderful!
I am selecting the final motor, I will be able to post it here very shortly, that way you can have full mechanical specs, which will give you shaft and everything.
I will also tell you what my target for the motor speed is, I am doing calculations right now, only based on efficiency for the motor and for my provisional driving system; the pulley and flywheel will have to be worked around it.
Considering we want the flywheel to clear out the pod by a minimum amount in order to allow people to get the flywheel in contact with their platter (check the picture it is represented by the dimension d), we will need to establish what that dimension is (perhaps 10cm would be enough, I will check my VPI later to get an idea).
This will impose a minimum diameter for the flywheel and enclosure.
Once I will be done with calculations, I will have to talk with the application engineer at Maxon Motor to determine the best speed for the specific motor and application I have chosen.
Can you start with a preliminary sketch of the mechanical design? Even hand sketched to begin with, that way we can make sure we are all set on the same page and we can have a community discussion on it.
Regarding the housing, I see, you have a very valid point and I have a possible solution to it. What if we have like we said machine Aluminum billet and at the bottom we attach with flush screws an heavy steel plate perhaps with an intermediate absorbing material (Teflon?!) so that it is perfectly damped and heavy at the same time? That way the mass of the pod will be high enough to maintain the inertia of the flywheel under control.
Now, what the minimum mass needs to be based on the momentum of the wheel and factored in with the counteracting force exert by the platter, I don’t know, this goes beyond my skill but I am assuming that as long as we can make it heavy enough, this shouldn’t be a problem.
Thank you very much for making your expertise available to everybody!
Attachments
well I would assume the same, I don't think that VPI or other manufacturer do any other specific things. Considering the low speed the thing is spinning at I don't think nothing fancy other than perfect machining to tightest tolerance is needed. Maybe we should pay attention to the quality of the material we use for the flywheel.
What do you think?
good idea. Check my idea though and let me know. People can have machined a simple steel plate by local shop very easily and we can still ship the pod that will be low mass and people can attach the steel plate.
Let me know your thoughts.
DD
The areas you mention with direct drive, clogging, servo hunting, etc. are bolted rigid so to speak, right on the platter and need a filter from these so elegantly solved with belt drive. DD needs a filter of some kind to separate itself, and that hasn't happened and I,m not buying
Stefanoo
If the only thing that ever existed was rim drive and all of a sudden belt drive came on the scene reporting a new and better concept based on what I mentioned would it sound logical enough that audiophiles would lay down long green for it?
And then they placed a strain gauge on the plinth and low and behold, the BD was quiet in comparison.
If I knew the rim drive was at least as quiet up to this point, I would be building one right now as I have a lathe and like certain aspects of this.
Until we put an accelerometer on the plinth and measure what's going on I wouldn't let the emotional side of the audiophile kingdom rule my decisions
Anyway, go for it. Usually when one builds something, it's for personal satisfaction and becomes emotional fulfilling in the end
It looks like you will get there sooner or later and wish you the best!
Regards
David
The areas you mention with direct drive, clogging, servo hunting, etc. are bolted rigid so to speak, right on the platter and need a filter from these so elegantly solved with belt drive. DD needs a filter of some kind to separate itself, and that hasn't happened and I,m not buying
Stefanoo
If the only thing that ever existed was rim drive and all of a sudden belt drive came on the scene reporting a new and better concept based on what I mentioned would it sound logical enough that audiophiles would lay down long green for it?
And then they placed a strain gauge on the plinth and low and behold, the BD was quiet in comparison.
If I knew the rim drive was at least as quiet up to this point, I would be building one right now as I have a lathe and like certain aspects of this.
Until we put an accelerometer on the plinth and measure what's going on I wouldn't let the emotional side of the audiophile kingdom rule my decisions
Anyway, go for it. Usually when one builds something, it's for personal satisfaction and becomes emotional fulfilling in the end
It looks like you will get there sooner or later and wish you the best!
Regards
David
Stefano,
I think making drawings of things without knowing the rpm's, diameters, etc. is really not a good use of time. The design comes out of these basic engineering criteria.
I'm not very excited about a steel plate. It's not that easy for people to get their own. If the plate is attached with intermediate material then it's mass does not dampen the enclosure. We end up with two mass with a spring between them. This would keep the steel plate from seeing resonance from the enclosure, and the enclosure from seeing resonance from the steel plate. I don't think the steel plate cares about the resonance and I don't think the steel plate will add resonance.
We'll want the entire enclosure to act as one large mass. We may want to isolate the motor from the flywheel and we may want to isolate the enclosure from the supporting surface, but there is no advantage to adding sprung mass in the enclosure.
Let's first see how the parts shape up and how we decide the working dimensions. The mass and shape of the enclosure is just then following all of the constraints provided.
Jamie
I think making drawings of things without knowing the rpm's, diameters, etc. is really not a good use of time. The design comes out of these basic engineering criteria.
I'm not very excited about a steel plate. It's not that easy for people to get their own. If the plate is attached with intermediate material then it's mass does not dampen the enclosure. We end up with two mass with a spring between them. This would keep the steel plate from seeing resonance from the enclosure, and the enclosure from seeing resonance from the steel plate. I don't think the steel plate cares about the resonance and I don't think the steel plate will add resonance.
We'll want the entire enclosure to act as one large mass. We may want to isolate the motor from the flywheel and we may want to isolate the enclosure from the supporting surface, but there is no advantage to adding sprung mass in the enclosure.
Let's first see how the parts shape up and how we decide the working dimensions. The mass and shape of the enclosure is just then following all of the constraints provided.
Jamie
David,
Why would you put a strain gauge on the plinth? I was thinking the noise of the drive must be measured at the platter or maybe it must be measured through the cartridge? The only two solutions I've really found were to use a stethoscope to listen to the plinth and to use some FFT software to look at the signal.
Simon, sq225917, posted some images of FFT analysis of a TT showing where there was some bearing noise. I thought this was a clever way to look at noise.
I am concerned about bearing noise in all it's uses, whether rim, or belt and looking for a way to measure.
Jamie
Why would you put a strain gauge on the plinth? I was thinking the noise of the drive must be measured at the platter or maybe it must be measured through the cartridge? The only two solutions I've really found were to use a stethoscope to listen to the plinth and to use some FFT software to look at the signal.
Simon, sq225917, posted some images of FFT analysis of a TT showing where there was some bearing noise. I thought this was a clever way to look at noise.
I am concerned about bearing noise in all it's uses, whether rim, or belt and looking for a way to measure.
Jamie
Then ok, let's not use the steel plate, I like also the idea of filling with sand compartments on the block of aluminum, but keep in mind that sand on that little quantity won't add up much mass unfortunately and that is why I was thinking about steel plate.
Perhaps, I would say to not use an intermediate material, you have a good point, but steel plate still seems to be the material with highest density that will allow the pod to increase in weight yet keeping dimension controlled. If you have a different solution to get to the same result, I have no problem and no real saying on the mechanical design either way
I think that having a steel plate cut and drill few holes is available to anybody, but we can see how to shape it up, like you said, once we have dimension shaped out.
So calendar for the day:
1) select motor for the system
1a) get diameter of motor and shaft and lenght of shaft
2) Determine target speed at 33 1/3 RPM
3) Determine "d" dimension from my sketch
I can get you these information by today, would that be enough for you to calculate the diameter of the pulley, wheel needed and draft an approximate dimension for the enclosure and start a mechanical drawing?
If you let me know what else you need I can try to get these info to you as quick as possible.
In the background Pyramid and I are working on the block diagram for the motor control and we have very good ideas on the boiling pot, Pyramid is great we are really fortunate to have him on our team!
The way I am going to measure is by using the residual noise test on the test disc, connect it to my super low noise phono and connect the output to my spectrum analyzer to see what is the residual noise and compare it to the belt system. This will give us a base line of how quiet the RIM drive system will be compared to the Belt. The noise of the bearing depends upon the TT used and every TT is different and we have no control over that; our goal should be to make the bearing for the flywheel as quiet as possible.
The acellerometer is probably not needed because the acellerometer could have a bandwidth that the cartridge doesn't or viceversa and ultimately the needle is what's playing and what we hear out of the speakers!
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Jamie,
Here is the motor I selected (specification wise it is incredibly good and price wise still affordable and very likely better than 99.9% of the motor used on any commercial TT regardless its price):
DCX 22 L Ø22 mm, Precious Metal Brushes, sleeve bearings
http://www.maxonmotor.com/maxon/view/product/motor/dcmotor/DCX/DCX22/DCX22L01EBSL703
It has some mechanical option for the flange configurable. You might want to take a look at the configuration option and let me know how you want me to order it.
On the specification you will find all the mechanical information.
At to this point on the list, points 1) and 1a) have been solved.
Here is the motor I selected (specification wise it is incredibly good and price wise still affordable and very likely better than 99.9% of the motor used on any commercial TT regardless its price):
DCX 22 L Ø22 mm, Precious Metal Brushes, sleeve bearings
http://www.maxonmotor.com/maxon/view/product/motor/dcmotor/DCX/DCX22/DCX22L01EBSL703
It has some mechanical option for the flange configurable. You might want to take a look at the configuration option and let me know how you want me to order it.
On the specification you will find all the mechanical information.
At to this point on the list, points 1) and 1a) have been solved.
Sefanoo:
For a motor pod you can go to sales@speedymetals.com where they sell heavy wall aluminum tubing by the inch at a reasonable price. I dealt with them many times and they offer quick and reliable service.
For a motor pod you can go to sales@speedymetals.com where they sell heavy wall aluminum tubing by the inch at a reasonable price. I dealt with them many times and they offer quick and reliable service.
Thanks for the link, you are the second one here who thinks we have a round pad, so I am going to comment on this.
As you can see from all our drawings, our enclosure is not going to be cylindrical bur rather rectangular and completely custom made to accommodate our design.
Anyhow, Jamie is going to take care of all the mechanical enclosure, pulley, flywheel aspects. He is got the machines the skill and everything needed to get the job done precisely and efficiently.
We will rely on him and on Ted for manufacturing parts.
We said the Box will be machined from aluminum Billet and we will define how we are going to achieve the necessary weight and yet maintaining a reasonable size and easy for shipment to other users as we move forward with this project.
This is going to be a gourmet product!!!
As you can see from all our drawings, our enclosure is not going to be cylindrical bur rather rectangular and completely custom made to accommodate our design.
Anyhow, Jamie is going to take care of all the mechanical enclosure, pulley, flywheel aspects. He is got the machines the skill and everything needed to get the job done precisely and efficiently.
We will rely on him and on Ted for manufacturing parts.
We said the Box will be machined from aluminum Billet and we will define how we are going to achieve the necessary weight and yet maintaining a reasonable size and easy for shipment to other users as we move forward with this project.
This is going to be a gourmet product!!!
Well if people who are interested in this project would actually take some little time and look at what we are actually doing, everything would go much smoother and probably we would be getting more inputs.
If nobody reads what we do, then it gets hard to keep repeating things and the post gets unnecessary long!
Yes it will be a custom shape! The good news is that we will provide the entire kit to who is interested.
Obviously, who has the capabilities of doing it on their own ,they are free to do so.
The kit will have a price that we will have to establish once the thing is done, which is also based on what the demand will be; nevertheless, it will certainly be affordable to the great majority (not everybody unfortunately as the complexity and quality of the project has still a basic cost).
This is intended to be the ultimate that DIY can do without spending one lung and 200-300 hours of full time development! It won't probably be as good as the $5K motor upgrade from TW but it will certainly not be that crazy expensive.
Hope I made it as much clear as possible to everybody. If there is any question please don't hesitate to ask.
Jamie,
would you be also willing to create the final enclosure for control system?
Something simple, solid that looks kind of nice?
This way we can really provide the entire kit: motor, pulleys, flywheel, o-ring, Motor pod and enclosure for the controller, with assembled and programmed and tested boards.
what do you think?
would you be also willing to create the final enclosure for control system?
Something simple, solid that looks kind of nice?
This way we can really provide the entire kit: motor, pulleys, flywheel, o-ring, Motor pod and enclosure for the controller, with assembled and programmed and tested boards.
what do you think?
Have you ever look closely at a direct drive turntable? Nothing is "bolted" and in fact nothing is in contact other than the bearing shaft sitting in a bearing well, a male inside a female, which ALL turntables have. The better way to explain is that the platter is magnetically driven. There's a magnet underneath the platter and there's some coils below the magnet (typical coreless motor arrangement) and they are electronically driven to generate a magnetic field to make the platter spin at 33rpm! Remember, the motor/platter spins at 33rpm, that's half hertz and where is the vibration?! The misconception is that you're thinking of a belt drive motor that spins from 300rpm all the way up to 1800rpm. 1800rpm is 30Hz so of course that's audible and you can even feel the vibration by just touch the motor. It's a noisy beast so of course it needs "filtering". Let's stay with belt drive and imagine you have a motor spins at 33rpm and the rotor or pulley is 12" diameter and then use this motor to drive a passive platter one to one ratio. Do you really think you need "filtering"? There wouldn't be any noise to filter with. I have a rather technical friend who never dealt with DD tables and it never dawned on him that a DD motor runs at 33rpm because he was always thinking of a noisy fast motor underneath the platter until I told him the motor runs at 33rpm which is a slow speed ALL platters of ANY drive system has to spin at. "Duh!" was his response. Yes, I agree that running a motor at such slow speed has the disadvantage of cogging and servo over adjustment but that can be reduced or eliminated with quality motor and electronics. The compliance of the magnetic field is the filter, soft and hard just like a belt. But the belt in a BD system has its own problem such as elasticity, aging, inconsistent thickness, etc... and if you eliminate the elasticity, say, by using thread or non-stretching material then there is no compliance and no filter -- back in the soup again. The one big advantage of the belt-drive is the motor's high speed so cogging is not a problem but it creates enormous vibration. It's really all about the execution. I am not a devotee of DD, regardless of my username. I happen to like all three drive systems and they all can create good sound. I just can't help to comment on blanket statement on DD system.
There are more and better implementations in DD development in recent years such as Brinkmann Bardo, VPI Classic Direct, etc... and it's making people paying more attention to the technology. If people are put off by days of Technics tables, all I can say is to keep an open mind.
Once again, you can complain about all the problems with DD but noise is not one of them.
I find it interesting that Brinkman in the Bardo DD chose a 22lb. platter that takes 12 seconds to reach proper speed. Most belt drives are faster than that!
I have a JVC ql10 DD that uses a coreless dc motor with a cast alumiuim platter maybe 6 pounds and comes up quickly and sounds terrible and bright no matter the arm combo
I pull it out from time to time and back it goes.
The Brinkman does appear to be one of the better DD,s. A very nice TT looking at the design and I,m certain it sounds nice.
Cogging and slow speed requires big pulse torques that higher speeds and inertia blend together in other drive systems
It appears the Bardo,s DD design is clearly trying to be a belt drive without a belt, no?
Looks like an identity crisis, and well done at that!
It,s all good fun
I have a JVC ql10 DD that uses a coreless dc motor with a cast alumiuim platter maybe 6 pounds and comes up quickly and sounds terrible and bright no matter the arm combo
I pull it out from time to time and back it goes.
The Brinkman does appear to be one of the better DD,s. A very nice TT looking at the design and I,m certain it sounds nice.
Cogging and slow speed requires big pulse torques that higher speeds and inertia blend together in other drive systems
It appears the Bardo,s DD design is clearly trying to be a belt drive without a belt, no?
Looks like an identity crisis, and well done at that!
It,s all good fun
What is that? A turntable???? 6lbs platter, is not high mass to damp resonances to begin with. Sounds also depends on how the motor is controlled, how much feedback to control speed. I am assuming a 6lbs platter needs more feedback than the heavy platter from Binkman.
Not to mention the bearing and associated noise. Plinth?
You can't compare an old JVC or take is as reference to decide that DD or RIMs don't sound as good as belt drive, I am just saying!
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