Variable speed motor for lpi?

[Ciuens]

Look, 25kg of mass.

Ciuens

[rsimms3]

Hi There Rsimms3,
Yes, I wouldn't dream of calling into question the Expert and Erudite Analysis Of Closed Loop Systems described in depth both here, and elswhere on the Forum by Markrob, and I concur, that would be the way to go if you are looking for the Nth degree of Precision and Control. I can neither measure, or even reasonably estimate, what Variance/Drag there may be on the Loading of the Leadscrew at any given Radius on a Disc or Amplitude of Audio Delivered to the Cutterhead. Whatever measure is used whether it be Amps, Milliamps,Watts, Milliwatts, Foot-Pounds, Ounce-Inches, Newton-Metres, Millinewton-Millimeter or a Star Trek Type Graviometricspondulycations. Then of course one would have to examine, how much this Variance in the Load Changes, translated into Variance within the Cut Groove. Nor am I suggesting there aren't plentiful drawbacks on using this system. If your'e looking to find faults with this Set-up then you surely will. I'm not advocating it's use or suggesting that this is the only way to go, but I'm merely sharing the results with Sameal (The one who Originally asked the Question) and Michaela, and anyone else interested enough to read the post, of my own Efforts and Observations into the Examination of this Issue. The drawbacks are quite numerous, and I'm completely aware of most of them. I would ask you what happens with Platter Driven Overheads, Presto's, Rek O Kuts and the like? Notwithstanding the "Inertial Flywheel" of the Platter, I'm sure if if you wanted to "Split Hairs" you maybe could find faults if you examined in detail, Variance in the LPI, caused by Load Changes when using a machine such as this too. Given that the Gear Reduction of these Little Gearmotor Models vary Between 200 and 300:1, I think any concerns about Hypothetical Load Changes on a Leadscrew and the Resultant Effects whilst probably measurable, is also "Nit-Picking" in the Extreme, or to Para-phrase my late-lamented Granny "Utter and Total Bollocks" No, I'm fully aware this is not a High-Tech approach I grant you, if I wanted one of those, I'd visit Flokason in Switzerland and buy a Great System from Florian Kaufmann. This approach to driving a Leadscrew though, might just be OK to those of us who are Budget Conscious, and not looking to own a Neumann, nor trying to make a Livelihood, from what to many of us, is simply a stimulating Hobby or Pastime
Soulbear

I was simply asking some clarifying questions regarding other information I had read and been told related to open loop design for DC motors. For those that want Nth Degree quantum mechanics style control, then what you are proposing wouldn't work for them as you have so elegantly stated.

As for your example in the variances in a mechanically coupled system, yes there would be variances based on tolerances, especially in use of rubber idler wheels on speed. I would argue less possibility of inconsistent variance as the motor is designed to self regulate it's speed so the adjustments made using a stroboscope for consistent speed would be translated into accurate groove width when translated to the feedscrew. With a coupled overhead system you have the advantage of the coupling - if the platter isn't turning, neither is the feedscrew so the head doesn't advance so you know for certain you will have overcut/recut at any LPI. Uncouple the feedscrew from the platter and then you have to rely on the accuracy of the motor for the feedscrew and speed adjustment system.

I have a system I am slowly refurbing and these are the issues I am looking into. The sled carrying the overhead weighs about 35 pounds so whatever I develop has to have sufficient torque to drive this sled and remain accurate. I don't have Scrooge McDuck piles of money laying around so I have to rely on the knowledge and experience of others to guide development. Even those who would feel threatened by someone asking some clarifying questions.

[rsimms3]

Oh, and to contribute to the conversation related to cheap options; I've done some preliminary research into use of salvaged treadmill systems since they appear to use a closed loop system of speed control on a DC motor.

[Soulbear]

Hi There Rsimms3,
You never mentioned you were driving a 35Lbs Sledge, but even so, propperly maintained and lubricated I'm sure there are many other types of Drives and Drive Motors to choose from, better suited to the much Greater Frictional Resistance you'll undoubtedly encounter, and which you will probably find much more suited to your application. However I might just point out, as it appears to be the case that your'e struggling with the concept, a 35Lbs Sledge is not quite the same as a Leadscrew Driven Overhead. This would be moving a Leadscrew Driven Small Carriage with a Cutterhead attached, and at a real push might weigh in at perhaps 10Lbs Max, and also in many cases, is carried on very, very, Low Rolling Resistance Linear Bearings. A subtle but important difference, I think you'll find. As you will I'm sure find out, when you get more deeply into your Restoration Project. As for your assertion in your sniping/bitching comment about feeling threatened, I think you must have been reading something elsewhere, and other than my response to your enquiries, which I tried to answer in a most courteous and civillised manner. In any event, I'm now well into my 7th decade and on many occassions I've heard "Ducks Fart" before now. I can tell you most assuredly and in complete honesty, I wasn't in the least intimidated, either then, nor now, and if you want pick an argument, I laughingly implore you, to go and find someone else, someone who perhaps might just conceivably care about your infantile garbage.
Best Regards Soulbear

[mischmerz]

Look, 25kg of mass.

Ciuens

Impressive

[sameal]

Well the setup for the 8dg the platter used to have a pulley system over to the feedscrew assembly. Of course parts are missing, so i have a completely independent of the platter feedscrew as described earlier in the thread.

Ive never messed with arduino. Is it a huge learning curve?

[Gus]

Stepper motor with 4.6 Kg/cm torque drives the feedscrew of my Fairchild overhead take a look.

Also take a look at Norman's Field page he modified his MSS Lathe with stepper motor too BUT controlled by a very famous 555 timer IC
http://www.normanfield.com/homemade78rpmrecords.htm

[socialroots]

Taiwan is full of electric bikes, scooters , I dont have enuff expertise on this topic, but those electric motors on the bikes can carry me and someone on the back uphill at the lowest speed or maximum speed, so im guessing this kind of electric motor doesnt loose torque when less voltage is used to go slower speeds. I would love for some of the experts in this forum to share knowledge about these motors because over here there so many in the scrap yard because most people will just buy another new bike instead of replaceing the rechargible battery, which is almost the price of a new bike, so plenty cheap motors with no batteries, would it be suitable for driving a record lathe?
Patrick

[Soulbear]

Hi Patrick,
These Types of Motor are something I've wondered about myself. I purchased one of these, to Test as a Potential Lathe or Overhead Leadscrew Drive Unit :-

24 Volt Lathe Drive.jpg

24 Volt Lathe Drive3.jpg

Now whereas the much less Powerful Little Gearmotor mentioned earlier in this Thread benefits by from a nearly 300:1 Speed Reduction (296.2:1) which makes it quite stable Speed-Wise, on even moderate Load Changes. This Motor, although quite "Chunky" and 17x more Powerful than the Gearmotor, Driving Directly, and not through a Gear Box, is adversly affected to a Large extent by even modest Load Changes, (I'm talking of simply Pinching the Shaft twixt Finger and Thumb!!) This Motor is usually fitted to a Childs Scooter, which you say are quite plentiful in Taiwan, and though these are quite Powerful (Being rated at 120Watts) I think it would definitely benefit from, and need to be driven, via a "Closed Loop" system, which would be more suitable to closely regulate its Speed. Whether this "Closed Loop Feedback" is acheived via a Tacho, Hall Sensors, or some other means, I don't think this Particular Model of Motor, would readily lend itself to being modified to be used in this way. Other Trolls though, may have had a modicum of success with other Motor Types, and may be better able to make recommendations and Guide You.
Best Regards
Soulbear

[EpicenterBryan]

Hey guys,
I just started looking over this thread. It's quite interesting. It sent me off to think about some things and as the internet does so well, sent me in some odd directions - some old technology and some new. Some things I ran across may apply (or not), but I'll save the best for last.

First, here are some terms that apply to some interesting things I ran across:
Continuously Variable Transmission (CVT)
Infinitely Variable Transmission (IVT).

Here is a quick example of a CVT application. I'll skip explanation. You will get it from the video link.
https://www.youtube.com/watch?v=eFShKSFnrGw

Here is another interesting design. This is an IVT application. It can slow down to an idle condition, but still can't reverse directly.
https://www.youtube.com/watch?v=cd2-vsTzd9E


So here is the crème de la crème of an Infinitely Variable Transmission (IVT) like system. It's called the D-Drive. It can reverse as well in IVT mode. It's truly mind blowing. Imagine a mini version of this for an overhead. Think about this... and scratch you head a few times like I did.

Bryan

[sameal]

I think that d-drive would fit in the presto cabinet as-is!

I definitely cant build something like that.

[EpicenterBryan]

I definitely cant build something like that.

Yes, I know. But that was intended to get people thinking.
I'll share something this weekend that might be doable.

Bryan

[ROLANDJAYS]

super genius !

[sameal]

Hi Sameal,
I'm currently having a Play Around with This Type of Motor/Gearbox Combination.

Lathe Feedscrew Drive Motor 24V 27RPM A.jpg

Lathe Leadscrew Motor1.jpg

Lathe Feedscrew Motor2.jpg

I actually bought this from a U.K. based company, but have since found them sold much cheaper and for far less cost on the Bay. The Ebay Seller is either Sellerbible or Assisi Electrics. They come in various Voltage and Speed Combinations from around 2RPM up to 500RPM. I'm currently checking out the 27RPM 24Volt Motor/Gearbox Combination, and seeing what it will Slow Down to without Juddering when Powered from a PWM Speed Controller. I got it to around 4RPM at 6Volts ish. Depending on what Pitch Leadscrew I finally settle on, I may go to the 50RPM Output Model, as I said it's Experimentation and Playtime at the Moment. It's not noisy, and with the Mounting Rubbers theres Very Little Vibration, and Driving the Leadscrew with a Belt Drive, should Further Reduce any Potential Vibration Transfer Problems. If you go on the Bay and Type in DC Gearmotor, I'm pretty sure you'll end up with Someone who sells these, as there are quite a number of Sellers of these items.
Hope This Helps.
Soulbear

Is that gear on the motor also an ebay item? I found a few similar.

Would a belt drive setup be better then say, a direct drive/geared?

[Soulbear]

Hi Sameal,
By "Gear" I assume you are meaning the "Toothed Pulley" on the Gearbox Output Shaft. I bought mine through a Power Transmissions and Bearings Supplier here in the U.K. You have to be careful what you order. Mine are T5 5mm Specification, the XL Timing Belts are almost the same Pitch (5.08mm if memory serves me well) and will fit, however the Metric Tooth Profile is of a "Square Form", whereas the XL Tooth Profile is "Rounded" and this can Lead to the Belt "Riding Out" of the Teeth on the Pulley when it's under a load, so you shouldn't mix up T5 and XL Timing Belts and Pulleys. I think connecting the Leadscrew via Drive-belt would also help to minimise any Transmission of Vibrations from the Gearmotor. I also must point out what I believe to be erroneous in my earlier Post. After checking 2 Other Gearmotors over the past few days, I suspect the 1st Gearmotor I tested was a 50RPM Model, I believe I was mis-sold this 1st Gearmotor, insofar as the other 2 Gearmotors I've since Tested, both Maxed Out at 35 RPM, which is much much closer to the 27RPM figure given in the Specification Table which I also Posted. I wouldn't mind too much except the "Rogue RPM" Gearmotor was sourced from a U.K. Based Supplier, and not the Far East, and cost considerably more that the Ebay sourced Gearmotors HUMPH!!. The Specification Table also lists Max Efficiency Torque and Stall Torque and is given as 1.62Nm and 4.95Nm which Compute to 16.5Kg-cm and 50.4Kg-cm, you could check these values yourself at http://www.numberfactory.com/nf%20torque.htm others may dis-agree but in my view they seem plenty strong enough to power a Leadscrew without any serious Speed Fluctuation Issues, I'll be able to confirm once my Lathe build is finished. Sorry about the Duff Max RPM information in my earlier post, the weight-lifting exercise though was Handled by this "Higher RPM" Gearmotor, which may be better suited for higher speed, Lead-in and Run-out Grooves, than the 27RPM Gearmotor.
Best Regards
Soulbear

[sameal]

If that motors ends up working i think i could construct something with off the shelf parts on evilbay.

[petermontg]

Chiming in as I also is searching for a speed motor.

Has anyone considered a maxon motor for this scenario.

Any thoughts??

Best
Peter

[Soulbear]

Hi Peter,
Yes, the Maxxon Motor is Used on the Pitch Control from Flo :- http://www.flokason.ch/fs_pitch13.html

If costs weren't too much of a factor in my purchasing decisions (£4000/€5000 is frankly beyond Me) I would have one of these systems from Flo in double-quick time. Others have made more basic Pitch systems for a considerably smaller sum, using Arduinos and such-like, but whether they've shared, or are willing to share their designs, remains a moot point.
Regards Soulbear

[petermontg]

Some helpful hints with a controller would be great.

Paint by numbers is not really our thing.

Stop, start, mark and runout would be perfect.
They way I have it in my head is with arduino boards.
but its a bit messy.
A simplified version would be great.

I shall keep searching.

[sameal]

I think i might just purchase this motor and some off the shelf gears and play around. I dont see too many options available too me otherwise.

Any suggestions on gear sizes?