Ejumacate Me on Pulleys, Please?! - Page 2
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  1. #21
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    Now...

    If I had an old pulley, why would I be needing another? Yes, there is a pulley but it is the wrong OD, and only a single. I can probably take groove dimensions off of it though... if you think Mr. Pete is not reliable in that regard. The thing to keep in mind about those videos is, A) making them is harder than it seems, and knowing what to include or not is pretty difficult, given time constraints, etc. It takes practice, and a SURPRISING amount of time. B) He's not likely to please the "engineer types" very much. He is what I would call a "farmer machinist." I don't consider him meticulous enough to be a toolroom, Hardinge, tenths-of-thous kind of guy. Maybe he was at one time in his shop life, but he now makes stuff that works with a mid-western sensibility of getting the job done as good as it needs to be. I would not accuse him of over thinking a lot of his work. I personally don't care for the way he tosses tools around on the benches and tables, but that is just me. Despite any shortcomings, he does provide a lot of tremendously useful information for people just starting out, and if nothing else, his videos possess a certain humor, for what that's worth.

  2. #22
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    I assume there is a certain Humor, Bubba machine shop! But machining is precise. Just a few days ago there was someone asking how to set the micrometer stop for internal threading like tubalcain did on his video. Seems tubalcain forgot to mention the lathe he was using was equipped with a half-nut opening device. Do that on another lathe and you will have a serious crash!
    So the Pulley you mentioned is the size on the machine. So calculate what spindle speeds you want and that will give you the motor pulley diameters you will need. You might have a speed chart on the lathe so use those speeds. That would be your start point.

    Frank

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    Quote Originally Posted by RedlineMan View Post
    [.....] The motor shaft in question is 5/8 keyed and the double pulley ODs are approximately 2.31" & 4.28" in diameter. [....]
    Perhaps I should have said that these are the original and correct pulley sizes. The motor has only a single on it now; an adjustable width job about 4" OD.

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    Ok then those size are your finished OD for the two pulleys, I assume they match with 2 other pulleys so they will give you the Center distance between the 2 Vees. 4.28 is quite large so IF I were doing it I would groove the face of the large diameter large enough to fit my chuck jaws leaving enough for the Vee and 5/8" shaft hub similar to most cone pulleys. That way you can chuck it and not need an arbor. Flip it around and mount it on the chuck, gripping with the outside of the jaws on the larger ID and drill a center hole, put your center in it for added support. Machine the Vee to match the mating pulley. Remove the center and drill about 1/2" thru, bore the hole to make it concentric with the machined Vees. If you can't bore to size, leave about .010 and ream the hole. Now you can broach the key. If you don't think that possible drill and tap 2 holes 1/4" X 20 thru in line and on center with the 5/8" reamed hole one in the center of each Vee. Turn it about 90 degrees and do it again. In one set of holes insert Extra-Long Extended Point set screws (long Dog Point) (McMaster Carr online catalog) and use that as your Key and screw them into the key-way on the motor shaft. Put 2 regular set screws in the other 2 holes to help lock the pulley on the shaft. Be sure when planning what your doing that if you decide to use the Dog point screws in the key-way to make the inner hub big enough for the set screw threads.
    Simple!

    Frank

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    Just a couple of random comments.
    First, remember that the belt should ride on the sides of the V and not on the bottom of the groove.
    If you don't have it already, I'd suggest you getting a copy of the Machinery's Handbook from at least the 80s or the 90s (my most recent one is the 24th edition--1992--and is extremely useful).
    Videos: Personally I have very limited time for that and I tend to agree with some of the above comments about Tubalcain. I instead enjoy watching Keith Fenner ("The Wright Machine Work" https://www.youtube.com/user/KEF791). I find there is the right balance between "improvisation” and following a blueprint, plus there is an exciting mix between old techniques and leading-edge technologies.

    Paolo

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    Default "It seems to me that there "should" be some sort of a modular system..."

    G&G Mfg.
    WELDAPULLEYS

    You could set up a Followed ebay search on "logan lathe motor pulley" or whatever the pulley needs to be:

    I found this:

    http://www.ebay.com/itm/LOGAN-LATHE-...item27d372d1e7

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    Not understanding why there is so much drama on this question. I had a 14" Logan for while- the variable speed transmission was pretty cool but its still plain old v-belts and that was using a 5hp motor. Any smaller Logan just needs a simple A section belt, some bearings and pulleys from Surplus Center and just get on with it. Select sizes so the ratios get you sort-of close for the max spindle speed (say +/- 20% kind of thing).

    The system is modular. Choose the sizes of pulleys, with the sizes of bores, modify to suit. The belts are standardized, as are all the fasteners.

    Plenty of solutions for diy keyways above also; plenty of sources of shafting w/ keyways already in. How much more modular is necessary?

    Greg

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    Done;



    Good reminder on Surplus Center. Didn't think of them. Not overly keen that they are from Chiner, but that's the way things are these days. Nicely enough made, at least. Pulleys are not the exact size "required," but pretty close. Two of them + a belt + shipping; all in for $30. With the addition of a new set screw hole**, it should work just fine. Worst case, I might have to mill down the shoulder on the outer pulley a tad, but a straight edge says it clears as of now.

    ** How much patience does it take to make a set screw hole? Quite a lot, in this case. How much FEEL? Quite a lot. Cue that twangy guitar from the Cialis commercial. "This is the age of knowing how to get things done" the man says. Indeed. How many taps and screws have you busted, learning how to feel The Edge? Chart says #7 drill for a 1/4-20 tap thread. Tap says "You really gonna twist me this hard?" (Cue the guitar again) Guy who knows how to get things done says, "Nah... I'm taking you out farther, son." Step by step by step all the way to a #1 'till the tap stops jawing and starts working. Counter bore the top of the hole a 1/64th over even, because the tap is too short. No snapped tap, no tears, no worries, done. That was a lot for a simple hole. Play that guitar. Where's that babe, and those bath tubs?

    Thanks to those that offered real help.

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    Is that because you are using a cheap ass tap or because the china pulleys are a mix of old cars and our old machine tools with a few files thrown in for good measure?

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    I've used a bunch of surplus center pulleys of various diameters, all A size belts though. I've bored some and bored/broached keyways in others. None have machined badly. There is no exact when you're talking about v-belt stuff though, just "closer" and "farther" in relation to some ratio. If your goal is an exact ratio (with a reasonably tight tolerance for "exact") then you should be talking chain, gears or maybe cog pulleys.

    Tapping small stuff like this is easier if you jig the pulley in your mill or drill press, tap drill & spot face or counterbore if needed, then put the tap into the chuck and start it in by hand by turning the chuck manually and putting mild pressure on the feed, so the machine guides it. Once its started then put on the tap handle and do your thing. Those small taps are easy to break, particularly when starting freehand.

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    Quote Originally Posted by moonlight machine View Post
    Is that because you are using a cheap ass tap or because the china pulleys are a mix of old cars and our old machine tools with a few files thrown in for good measure?
    Well...

    Not unless you consider original old murican Greenfield (GTD) cheap ass. Can't really speak to the alloying of the pulleys...

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    You solved your problem, but I might mention that AFAIK you can get the correct pulley from Logan. Ain't cheap, but not as stupid a price relative to what you'd think as from other companies.

    If you do switch speed ranges with the "V-flat" pulley deal, the right motor pulley is good, because you won't have to adjust the tension

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    Yes;

    - Starting/finishing taps by machine has the benefit of radial accuracy, and perhaps speed. What it lacks, especially in this case, is any sense of feel. You can watch a tap twist, and get nervous if you know what you are doing, but I much prefer also having the feel of that twist. That feel for the amount of torque applied, the sense of whether I can properly run it in using just finger pressure, hand muscles activated, or the danger zone of getting the whole arm involved with such a small size. Frankly, I was surprised that it drilled so easily and tapped so hard. I'm glad that guy was playin that GUITtar and that I'm at the age of knowing how to get things done. At least some things...

    - I was probably trying to put too fine a point on the sheave size thing. Still, one shoots for the best one can get. And, sometimes good enough, is. Good point on the belt tension on different/incorrect size sheaves. I think just the weight of the motor hanging on the belts will be enough for my use. We shall see. It's fairly easy to tension properly, if I ever do have need to change ranges.

    - No, I have not seen the correct early pulley size for sale used anywhere. The one mentioned by someone here that was on that famous auction site (I had seen in previously) was not the correct one.

    - Yes, Logan offers the right part, and I'm guessing that $135 isn't bad if you compare it to your time to make one. Part of me wants to support them in their efforts, but the other part doesn't have that much bread to expend.

    I'm glad to be moving on to more interesting bits.

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    For the lathe particularly, the idea of weighted belt tension just does not work out for regular weights. Once a long time ago I did try it. A previous owner of one of the lathes here also seems to have tried a variety of it, using springs. I did away with it quick in both cases.

    The problem is that with a v-belt, when the torque requirement goes up, the pulley wants to "climb the belt". That slows the spindle a bit for a short time, and when the higher torque is over with, the motor falls back. If you have any sort of uneven cut, for instance when facing an irregular part, or turning a slightly eccentric part, the motor will be bouncing up and down like crazy, and there will be obnoxious speed variations as well.

    That bouncing will shake everything, and mess up your cuts. Life will suck in the shop until you get that straightened out with a solid motor mount using a fixed distance.

    The original pulley sizes are set up so that the distance in either speed is the same, and the belt can be slipped off the one size and put over the other without fiddling.

    Of course, one might spend the bucks on a VFD and bag the first stage speed changing altogether. That probably makes more sense, and allows a nice solid motor mount with no bouncing or hassles, not to mention the speed control. You'll still want some belt control and back gears with that machine, so don't count on the VFD for everything unless you use a very much larger than required motor.... which will better tolerate lots of amperage and poor cooling at low speed.

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    Thanks JST;

    Very good info. Not really surprised that weight tensioning is a flop, literally. I've spent plenty of time watching my ancient power hack slogging away with a weight-on-lever tensioner. These sheaves are not the exact size called for, may or may not match the primary shaft pulley, and so may not allow slip changes. The original tensioning adjuster is in place so it's an easy go either way.

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    Quote Originally Posted by thermite View Post
    Beer, wine or just OCD, you are over-thinking it.



    When, ever, on a hobby / student grade, lightweight, vermicelli-bed lathe did you have the 'perfect' SFM anyway? And who said it was?

    Bill
    I really think that if you're going to compare lathe beds to pasta that since a Logan has flat ways the comparison should be to fettuccine not vermicelli

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    Quote Originally Posted by Thermite
    When, ever, on a hobby / student grade, lightweight, vermicelli-bed lathe did you have the 'perfect' SFM anyway? And who said it was?
    Quote Originally Posted by Dociron View Post
    I really think that if you're going to compare lathe beds to pasta that since a Logan has flat ways the comparison should be to fettuccine not vermicelli
    Yes;

    Humerous. Not everyone's idea of a worthy machine, or one for anyone to get excited about. Regardless of anyone's opinion of a Logan, they are indeed capable of doing plenty of good work. If I were a machine snob, I might be disgusted with myself even. However, the machine is far more capable than I, so it is easy for me to keep myself well grounded, and to enjoy slumming in the lower echelons. Other than the intrinsic value that a top flight machine offers, which I most definitely can appreciate, the practical difference is moot. Hopefully we will make a good team, the old Logan and I.

  18. #38
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    Quote Originally Posted by Dociron View Post
    I really think that if you're going to compare lathe beds to pasta that since a Logan has flat ways the comparison should be to fettuccine not vermicelli
    Sorry to bust up the pasta, but a Logan has regular V and flat, just like a (small version of) a Monarch....

    You must be thinking of that unmentionable brand starting with "A".

    Logan made lots of hand turret lathes, and Brown and Sharpe made tooling for them, just as if they were Acme's. The regular Logans were made up to 14", with hardened ways, L series spindle noses, etc.

    All the parts are actual cast iron etc...... none of that hobbyist pot metal.

    Don't be confused.

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    Quote Originally Posted by JST View Post
    Don't be confused.
    I wasn't

    And even flaked, no less, for the intrinsic enjoyment of we hobbyists.
    Attached Thumbnails Attached Thumbnails loganvways.jpg  

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    Quote Originally Posted by RedlineMan View Post
    And even flaked, no less, for the intrinsic enjoyment of we hobbyists.
    As John Knox, who worked as engineer for Sheldon for many years, says: "There are more flaked beds now than when they left the factory."
    Apparently, flaking beds is the favorite pastime of used lathes salesmen. ;-)

    Anyhow, going back to the pasta issue: somebody else uses to define lathes as pieces of stiff robber, some stiffer than others. Essentially the bed, carriage, compound, toolpost, tool, spindle, etc. of any lathe will deflect under stress. Some deflect more, some less. Sometimes the deflection is even visible at the naked eye, sometimes you notice it indirectly, like with chatter.
    Therefore, bringing back the discussion to pastas, I'd say that a Monarch is much more “al dente” than a South Bend or a Logan and that other lathes (mostly not mentionable here) are definitely “scotta”.

    Paolo

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