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Thread: Get me over the hump

  1. #81
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    Jan 2004
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    Here is a less expensive one of similar size, with regular belt change speeds.... same power everywhere, no excuses. Still more or less a change gear machine. but .....

    https://www.grizzly.com/products/Gri...Gearbox/G9972Z

    Here is one a little smaller, but with both a useful QC box, AND belt change speeds for no excuses power. This one has 9 feeds or threads for each set of change gears, making it a good bit nicer to use. Less than half the price of the PM

    https://www.grizzly.com/products/Gri...ch-Lathe/G4000

    manual

    https://cdn0.grizzly.com/manuals/g4000_m.pdf
    Last edited by J Tiers; 01-11-2019 at 03:17 PM.
    1601

    Keep eye on ball.
    Hashim Khan

  2. #82
    Join Date
    Jan 2005
    Location
    Buffalo NY
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    When I was 16 years old, one of my first projects when I bought my 1940's
    Atlas 10" lathe, was to make an exhaust manifold flange adapter to delete
    the heat riser on the engine of my '75 F-100 truck. It involved cutting a
    6" piece of 1/2" plate, making a 2-1/4" hole, and cutting a 45į angle for
    the exhaust doughnut. Kind of a larger size workpiece for my first lathe
    job ever. I remember it worked out well. I even trepanned out the center,
    which now I understand can give even experienced machinists a fit over.
    I think I made king pin bushings for that truck on it and a few other
    automotive things.
    Later it was go-kart parts. Lots of small doo dads and pulleys and sprockets.
    When I got to missing with mini bikes and rear sprockets and drum brakes,
    I found myself wanting a larger lathe, something like 12" to fit the size of the
    parts I was playing with.
    When I got a job at a company that had some real lathes, (16" and 18" size)
    I was amazed how rigidity came into play. I could take more than .025" at a
    time, like my Atlas was limited to. I could peel off .25" at a time on the big
    Mori Seiki lathe if I wanted to. It made fiddle farting around with my Atlas
    lathe seem really unproductive.
    With all this in my mind, I believe a 12x36 lathe is a good size for automotive
    and hot rod work. It does not limit you to ornamental knobs and simple
    bushings. This size should have SOME rigidity as not to be frustratingly slow
    when taking cuts. You can get a gearhead lathe in this size as well.
    Anything smaller and I think you will be disappointed.

    -Doozer

  3. #83
    Join Date
    Apr 2017
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    Kelowna BC
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    1,859

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    Lathes are a bit like motorcycles..
    You can get onto a 125, and get used go it fast., but on the open road you may find it lacking.,

  4. #84
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    Jan 2003
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    Chilliwack, B.C.
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    The G9972 looks like it would be a great starter lathe, and it could easily be someones 'workhorse' lathe for years to come. Without spending a lot more money you probably wouldn't get bigger than a 1 inch spindle bore- and that alone would be an upgrade for my hobby uses. I like the belt drive to spindle for it's quiet and smoothness, but I never liked having the back gear driven all the time. On my lathe ( 8x18 ) I removed that whole assembly. The reduction in noise was worth it to me.

    I have the three position pulley on the spindle, but I virtually never use the two smaller ones- it's always in the highest reduction setting (greatest torque but slowest speed) but because I've changed the motor to a treadmill one with 5000 rpm maximum speed I can still get over 1000 rpm at the spindle. With the supplied variable speed motor on the Griz, you probably won't have any issue with torque. If you do, or if you can't get a slow enough spindle speed without the motor bogging out, then you can always make a larger pulley that would fit over the existing pulley, and use a longer belt. It's not a major mod, and doesn't require removing the existing pulley- in other words it's a practical mod you can do yourself if you actually do find you need the extra torque, or an even slower speed than you already have.

    I don't recall from reading the specs on that 9972 if it has reverse threading capability, but again that's something that a lathe like that will allow you to add fairly simply by adding an idler gear to the gear train. I did it on mine (which looks to have almost the identical gear train) and its first use was to make a new lead screw for the cross slide. On my lathe the lead screw was so poorly made that this became my first upgrade project. First the reverse idler, then the new lead screw.

    Back to the spindle pulley- for my lathe I made the larger pulley to fit onto the existing one, and it's about a foot in diameter. That corresponds to a bit more than double the reduction ratio, more than double the torque, and more than halves the slowest speed available. I went one step further, which was to add a second motor- a geared down dc motor from a wheelchair. Using this I can get down to 3 rpm. At this speed I'm not doing any direct machining on a part, but I use it to rotate motor armatures while I saturate the windings with epoxy. It's just about right to prevent dripping and uneven distribution of the epoxy. It's useful if you were using a tool post grinder on a large diameter part. I've used this mod more than I thought I would. The large pulley couldn't be made on my lathe, so I set up on the table saw to cut the groove for the belt. It was easy to set the angle to suit the belt, and reversing the pulley blank let me cut both sides of the groove identically. My new pulley was made from sheet pvc, but could be made from aluminum sheet almost as easily.

    My whole point in suggesting all this is that with a lathe like the G9972 you do have the option of doing these mods if you wanted to. That could mean that this lathe is all you'll ever need.

    You have to consider weight obviously- you do have to be able to get the machine to and onto it's stand, and again it's obvious that a space restriction will set the maximum size of machine you can have. It's been said many times that you can make a small part on a large machine, but you can't make a large part on a small machine- very true, and a good reason to not go for the smaller machines if you can manage a larger one. Do pay attention to the power requirements though- you may not have the ability to supply 220 if the machine needs that, let alone 3 phase.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  5. #85
    Join Date
    Oct 2013
    Location
    USA MD 21030
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    The G4000 is essentially the same as my HF 9x20. Note that it is mounted on a piece of 2x12 lumber and a flimsy angle iron machine stand, on a wobbly plywood floor:


    After clean-up:


    I needed to chase some 3/4"-8 LH square threads to fix my "new" 6" independent chuck, so I had to make a tumbler to reverse the direction of the saddle. That was a fairly easy project:


    Chasing the threads was a bit more involved, and I ended up making a hand spindle crank. Turned out OK:


    Here is a video (perhaps too long) showing the details of the lathe chuck mounting and repair. It may give you an idea of what this lathe can do. I did this project before I took the machine tools classes at the local community college, so some of the techniques may be amateurish, but I got the job done!

    Last edited by PStechPaul; 01-11-2019 at 07:11 PM.

  6. #86
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    Jan 2004
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    Missouri
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    Hmphhh

    I can take a 0.187" DOC with the Logan... I know that folks do that with Atlas also. I can't do it at an 8" diameter, but that's as much limited by the belt slip as anything else. In back gear I can do considerably better than 0.025" on larger work, and an Atlas should be able to also.

    It's not like either of them is a roll turning machine, max swing is generally faceplate work, I d0 not recall what the swing over crosslide is for the Logan, likely a little over 6".
    1601

    Keep eye on ball.
    Hashim Khan

  7. #87
    Join Date
    Nov 2008
    Location
    SF East Bay.
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    6,187

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    Quote Originally Posted by J Tiers View Post
    Hmphhh

    I can take a 0.187" DOC with the Logan... I know that folks do that with Atlas also. I can't do it at an 8" diameter, but that's as much limited by the belt slip as anything else. In back gear I can do considerably better than 0.025" on larger work, and an Atlas should be able to also.

    It's not like either of them is a roll turning machine, max swing is generally faceplate work, I d0 not recall what the swing over crosslide is for the Logan, likely a little over 6".
    HMPHHH. My 7x12 can do much better than that. .250 in a single pass.

    But of course these numbers are meaningless unless you include the feed rate and material too. Makes more sense when I say that I routinely remove 1/10 inch from the diameter (.050 DOC) at .020 IPR on bars of 6061T6. This is using 5/16 inch carbide insert lathe tools. Put in real world terms, that's 5 passes to reduce a 2 inch bar to 1.5 inches. Each pass is a couple seconds per inch.

    So many machines have been suggested that one has to wonder what these people have in mind. There are many factors that make a lathe suitable to a purpose. Horse power is one aspect. So is the spindle bore. And the reach of the tailstock quill. And the number of threads a QCGB can choose. And the weight/size/electrical needs. And power feeds for BOTH horiz and crossfeed. And so much more.

    But the OP has said that he wants to do occasional machining of parts for his hobby. That might go faster with a bigger lathe or one with more capabilities or features, but most of us are not in a hurry. Remember, auto restorers spend days prepping a car for painting and spend hours honing cylinders and such. Speed of the work is not usually an issue when doing it for a hobby. In general, if you make it big enough to handle the parts that you will work on, there are work arounds for the lack of most features.

    So get one with a swing large enough for the biggest disk that you will need to work on.
    Get one with enough room over the cross slide for the largest shaft you will use.
    Get one with enough length for the longest shaft that you will need to turn / thread.

    Don't worry about power. Virtually all bench sized lathes have enough power, and you can usually just take a shallower cut. Don't worry about quick change gear boxes, since change gears do the same thing in a matter of minutes. Don't worry about power feeds, since anything with a leadscrew can do a horizontal feed.

    Alas, like most of us, the OP will never know what he will be working on until he gets there.

    Dan
    There is a profound difference between spare parts and extra parts.

  8. #88
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    Jan 2005
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    Buffalo NY
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    Jerry- How do you walk with that thing
    swinging so long and hanging so low?

    -D

  9. #89
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    Missouri
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    Dan, if you are taking a 1/4" cut, your math is off... it would be a half inch off the diameter. pretty good for a mini-lathe. I stick with up to 3/8 off the diameter. And that is normally with smaller work, because there is a power consideration.

    Quote Originally Posted by Doozer View Post
    Jerry- How do you walk with that thing
    swinging so long and hanging so low?

    -D
    Quote Originally Posted by Doozer View Post
    .....
    When I got a job at a company that had some real lathes, (16" and 18" size)
    I was amazed how rigidity came into play. I could take more than .025" at a
    time, like my Atlas was limited to. .....


    -Doozer
    Oh, I don't carry the lathe around with me, I leave the lathe at home.

    Point was just that your old Atlas would have done the same thing..... but the machine has to have the power applied properly. And the tool ground properly. It's not the amount of power, I have a 1/3 HP motor on the machine.

    You see the same thing with old SB advertisements... there is a big bar between centers, and the chip is coming off it iin a long spiral.... and that is using a lantern toolpost in the ads. Obviously they used back gear (I do not in the case of the chips I mentioned, that was at around 200 rpm), and they must have a good deal of side rake.

    In the ads, they seem to be taking a DOC of nearly a half inch, or an inch off the diameter. I have never tried that, I think I'd get chatter if I went up to a half inch off the diameter.

    And doing that may actually not be the most effective way to remove material. It may be faster overall to do more passes at 0.050 or 0.075 DOC, because the feed rate has to be smaller for the big DOC. But there are cases where the large DOC is the best way to do the job, even if it is slower.

    It ain't what's swinging, it's more about thinking with the right head........
    Last edited by J Tiers; 01-12-2019 at 01:17 AM.
    1601

    Keep eye on ball.
    Hashim Khan

  10. #90
    Join Date
    Jan 2005
    Location
    Buffalo NY
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    Probably did not help that my Atlas had loose babbit
    bearings. Even when shims were removed, the spindle
    was not aimed right, and it tended to cut a taper.
    If I were to attempt re-babbiting it, I could never
    think how I would get the spindle alignment back
    parallel with the bed properly. Timken bearing models
    I am sure are much better.

    -D

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