I've used a Poor Man's lathe. To dress the contact surface, I put an idler wheel in a Dremel (or larger drill, if needed) chuck and spun it against a flat lapping stone.
It's not as elegant as a lathe, but it works if you carefully apply pressure.
Dual 1219 Wow&Flutter?
- Thread starter Fishead
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I've used a Poor Man's lathe. To dress the contact surface, I put an idler wheel in a Dremel (or larger drill, if needed) chuck and spun it against a flat lapping stone.
It's not as elegant as a lathe, but it works if you carefully apply pressure.
I use an emery board, much flatter than my finger.
The issue with accuracy in “roundness” is the radial play in the quill bearing of whatever tool you’re using.
Dremels are useful tools, but “accurate” is not a term I would to apply to it. The quill bearing is sloppy as heck on every one I’ve ever used. Good for what they are intended for, but “accurate”? Meh.
The lathe is down in the 0.001-0.0005 range of bearing play. But I freely admit its not a machine most people have access too. Even my old Atlas (Its a 1954 model) is not something most will spend their hard earned cash on. Their “usage per dollar” ratio just wouldn’t make sense.
Even a good drill press will still have 5-10 thou runout.
Still, both dremel or drill press will do better job of it than holding it in hand drill. More so if you use a couple simple techniques to improve your chances. Namely, remove the “human powered” clamping/feeding part of the process.
All of it can be improved by using something with a feed screw to put your abrasive media into the work. For example, if you chuck it up in something like my drill press and use its x/y table to just “graze” the idler rubber while accounting for backlash and using little to no pressure, I think you could make a reasonably good go of it:
Even if you held the abrasive media down against the bare drill press table and just slid it in until you saw it graze the rubber would/might suffice in the contest of what we’re talking about. It would also ensure the idler and abrasive are held at right angles to each other. Right angle cutting is another important factor.
It’s the “hand held/feed” part thats the issue with keeping any kind of accuracy to a tolerance on any machine.
Of course, it all depends on what you define as accurate. Some might define it as “good enuff” is good enough. In many cases, it is.
I define it in thousands of an inch. A professional machinist might define it as in the 0.0001’s. A machinist who is used to making air bearings might even be more critical.
Of course, no amount of “truing” up an idlers running surface is going to matter if the rubber is older and has some harder and softer spots. Rubber (real rubber, not synthetic) is not a homogenous material. It “ages” at different rates inside of itself. Just the nature of the beast.
Now, the practical question: How much matters for a rubber idler? Eh. Who knows…just gotta try and find out what is and isn’t “good enuff”.
Audiovault had a video up at one point showing the runout on their idlers. Might still be there, dunno. Was chucked up in a collet device. About as accurate as you would need for this type of thing. Not even a thousandth on the gauge. Although, in all fairness, the gauge resolution (IIRC) was to 0.001….still, nothing to sneeze at for something like an idler wheel.
For me, that was “good enuff” and why I bought one.
Haven’t been disappointed.
Dremels are useful tools, but “accurate” is not a term I would to apply to it. The quill bearing is sloppy as heck on every one I’ve ever used. Good for what they are intended for, but “accurate”? Meh.
The lathe is down in the 0.001-0.0005 range of bearing play. But I freely admit its not a machine most people have access too. Even my old Atlas (Its a 1954 model) is not something most will spend their hard earned cash on. Their “usage per dollar” ratio just wouldn’t make sense.
Even a good drill press will still have 5-10 thou runout.
Still, both dremel or drill press will do better job of it than holding it in hand drill. More so if you use a couple simple techniques to improve your chances. Namely, remove the “human powered” clamping/feeding part of the process.
All of it can be improved by using something with a feed screw to put your abrasive media into the work. For example, if you chuck it up in something like my drill press and use its x/y table to just “graze” the idler rubber while accounting for backlash and using little to no pressure, I think you could make a reasonably good go of it:
Even if you held the abrasive media down against the bare drill press table and just slid it in until you saw it graze the rubber would/might suffice in the contest of what we’re talking about. It would also ensure the idler and abrasive are held at right angles to each other. Right angle cutting is another important factor.
It’s the “hand held/feed” part thats the issue with keeping any kind of accuracy to a tolerance on any machine.
Of course, it all depends on what you define as accurate. Some might define it as “good enuff” is good enough. In many cases, it is.
I define it in thousands of an inch. A professional machinist might define it as in the 0.0001’s. A machinist who is used to making air bearings might even be more critical.
Of course, no amount of “truing” up an idlers running surface is going to matter if the rubber is older and has some harder and softer spots. Rubber (real rubber, not synthetic) is not a homogenous material. It “ages” at different rates inside of itself. Just the nature of the beast.
Now, the practical question: How much matters for a rubber idler? Eh. Who knows…just gotta try and find out what is and isn’t “good enuff”.
Audiovault had a video up at one point showing the runout on their idlers. Might still be there, dunno. Was chucked up in a collet device. About as accurate as you would need for this type of thing. Not even a thousandth on the gauge. Although, in all fairness, the gauge resolution (IIRC) was to 0.001….still, nothing to sneeze at for something like an idler wheel.
For me, that was “good enuff” and why I bought one.
Haven’t been disappointed.
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I had been thinking about making a setup with the tools I have to provide even and steady pressure on the wheel against the abrasive paper. I should be able to come up with something between the drill, a bench vise, some clamps......hmmmm.....the wheels are turnin', pun intended. MIght take me a few days because I have other irons in the fire that need attention.
If you want, I might be able to offer some advice on tweaking it when you get it set up. Snap a pic of your setup and ask if you would like.
Cheers
Cheers.
It can be done. Slow and easy are the words. Or find a friend that has a nice drill press.
Really, at that point, it's cheaper to buy a new idler wheel than find a good used drill press. No?
Wrap duct tape around the idler shaft and place it into the chuck. Emery cloth on a wooden block. Then, lightly and evenly touch the wheel as it spins.
HAHAHA that's a little crude but hey, if it works!?!? I doubt he's getting a very true circumference, and I think a drill press with a block of sorts with the sandpaper adhesed to it and introduced to the side of the wheel might produce much better results. I'm cookin' up a plan, but my neighbor just had knee surgery so it may be a little while before I can get into his garage to use the drill press. I also wondered how he was able to get those nuts back on the screw so easily after filing down the threads??? That is a good idea for the type of idler he has, but mine has a very small opening in the top so it would require a much smaller screw, which might affect stability. I think I'll try to chuck it as it is because it fit in my drill chuck so ought to fit in the drill press.....stay tuned!
I have to say, perhaps this might help with the W&F issue, but how will it possibly increase the speed to normal levels? I dunno, maybe an even rougher surface than what I was able to achieve in my very slight dressing of it? Will that have that much of an effect on speed? I'm just thinking something with the motor and so far, haven't heard back on that issue with regard to testing the field coils, did I do it right? In other words, are they both working as they should and providing sufficient power because that's my gut feeling, like there just isn't enough horsepower since the platter takes so long to get up to speed while @loudnoises gets there within 1 rotation!!! That's what I'd like to see, and that's when I will think I've made real progress. The lack of power in the motor might also affect W&F, don't you think? And, especially since I have to adjust my pulley so far up that the wheel touches those ridges on it that are between the 3 steps.....just seems something is not as it should be, especially because the service manual from Dual says to put the idler in the middle of the steps. If I do that, I'm over a rotation per minute off and can't adjust to on speed even by turning the pitch control to max. There's gotta be an answer to this......
I have to say, perhaps this might help with the W&F issue, but how will it possibly increase the speed to normal levels? I dunno, maybe an even rougher surface than what I was able to achieve in my very slight dressing of it? Will that have that much of an effect on speed? I'm just thinking something with the motor and so far, haven't heard back on that issue with regard to testing the field coils, did I do it right? In other words, are they both working as they should and providing sufficient power because that's my gut feeling, like there just isn't enough horsepower since the platter takes so long to get up to speed while @loudnoises gets there within 1 rotation!!! That's what I'd like to see, and that's when I will think I've made real progress. The lack of power in the motor might also affect W&F, don't you think? And, especially since I have to adjust my pulley so far up that the wheel touches those ridges on it that are between the 3 steps.....just seems something is not as it should be, especially because the service manual from Dual says to put the idler in the middle of the steps. If I do that, I'm over a rotation per minute off and can't adjust to on speed even by turning the pitch control to max. There's gotta be an answer to this......
After following this thread, I became aware of the new platter spindle bearing for the Dual 1219 turntable! This wasn't available a few years ago when I purchased the excellent idler wheel. While my current bearing seems just fine, I have no doubt that the new bearing is exceptional! I just placed my order!
I'm thinking of two things.
1.) A friction issue (or lack of) between the rubber idler and the steel rim.
2.) An elasticity issue with the rubber idler's glazed and hardened contact surface.
Breaking the hard glaze by sanding it and treating it with a rubber renewal agent may give your idler a couple more years of service. I've used MG Chemicals 408C Rubber Renue on hardened car parts, which may work for your idler.
I'm fairly certain this isn't necessarily true for elastic materials. Pulley and rim will/might penetrate/deform the idler tyre to different degrees creating two different active radii thus introducing a new gear ratio...quasi "splitting" the idler into two, whereby they have same rpms and the bigger radius/diameter drives the rim and the smaller is driven by the motor pulley.
I guess the idler tyre is done, if the speed can't be reached. I feel it is about the same/simmilar behaviour than a rubber belt altering gear ratio with thickness (with different sized pulleys, that is).
Sure, a foam roller probably would not work. But that's not what's at hand. We can always find an exception to the rule.
I think you'll find that the minute variations in contact and deflection in an idler are well outside anything you can measure, and orders of magnitude below audiblity.
That's exactly what I have been thinking all along.....not saying that the idler isn't in need of replacement, no matter how nice it looks and feels, but I've always had this sense that there just isn't enough horsepower there and that leads me back to the motor itself! So, either the motor is giving up the ghost, or did I perhaps not get it back together properly and the spindle is ever so slightly binding? I don't think that is the case because I've done it 3 times now with the same result, and each time taken great care to reassemble so spindle is moving very freely and also listening with a stethoscope for the lowest possible noise as I tightened the two bolts holding the halves together. This motor was designed for either 220v or 110v......our power here in the USA, at least in my house, hovers at about 118v. Could that be making a difference???? I would think that more power would give the motor more horsepower, not less, but then I really don't know.....
If it were me, I’d be looking at the motor again.
I know I’ve assembled thing incorrectly many times before the light bulb came on.
These are pretty simple construction as that goes, but you just never know.
If its a similar construction to the big “can motor” on my 1229Q, i just tightened down the teo case screws and was done with it.
I know I’ve assembled thing incorrectly many times before the light bulb came on.
These are pretty simple construction as that goes, but you just never know.
If its a similar construction to the big “can motor” on my 1229Q, i just tightened down the teo case screws and was done with it.
You might need a new motor. No spares in the old toolbox?
Heck, you might as well try breaking the hard glaze on the rubber surface and treating it with Renue. What have you to lose?
Heck, you might as well try breaking the hard glaze on the rubber surface and treating it with Renue. What have you to lose?
Penn42
Well-Known Member
FWIW I've only got the AudioVault Idler on my 1219 and I like it very much, but all my others Dual's are running OG idlers I dressed with a hand drill and fine sandpaper held with my fingers. My 1009 just read .03 W&F, which admittedly is probably a fluke on the low side, but I would expect an average across multiple reading to hover around .06, which I know I can't hear. For whatever reason both my 10xx series Dual's read better than my 1219, which I stated earlier hovers in the .08 range.
I would also guestimate that 0.03 is a bit of a brain fart on the app’s part. I know once in a blue moon the iphone app I use will have some kind of aneurism and toss out a number I know to be too low/high. I just disregard those and another run returns a more representative value.
These apps are like a gps to me. If the thing says turn left and I’m looking at a cliff or forest, well…..lol!
My 1229Q hovers around 0.004-0.006 wf. Considering (iirc) the factory spec is 0.006 and when I stated it was up around 0.014-0.016, thats about as best as can be expected (from this particular table).
Nothing to complain about for around a 45-50 year old idler drive table. I certainly can’t hear it at that level, so no need to chase it anymore. I just check it every couple months to catch any increases which may indicate a worn part, adjustment, lack of lube, etc.
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