Thanks Thanks:  0
Likes Likes:  0
Needs Pictures Needs Pictures:  0
Picture(s) thanks Picture(s) thanks:  0
Results 1 to 8 of 8
  1. #1
    Join Date
    Nov 2010
    Location
    South Africa, Cape Town
    Age
    60
    Posts
    26

    Default Handwheel Driven Leadscrew

    I have a Quantum 210 x 400 mm Metric Lathe with a 2.0 mm leadscrew. This lathe is very similar than the Warco 180 lathe.

    I recently visited the Warco 180 lathe web page and asked the owner a question or two. One of the questions was about backlash in the Handwheel that moves the saddle left and right. I found the answers on the page of the gadget builder as his lathe is similar as well.

    Andy pointed out that I will have better results if I put a handwheel on the leadscrew. I have studied the mod on this page and I wholeheartedly agree that it will be a very good mod / improvement.

    My leadscrew ends exactly flush with the end of the lathe bed and my leadscrew is of right hand thread. If I add the handwheel onto the leadscrew directly, it will have to be turned anti clockwise to move the saddle left, and not clockwise as all the other handwheels. I am thinking of adding a small gear onto the leadscrew onto a small axle that I will epoxy into the leadscrew. Onto that gear will run anothe gear that will turn the laedscrew in the opposite direction if I turn the handwheel clockwise, causing the saddle to move left (towards the spindle). This way will cause the handweel's centre to be not on the leadscrew's centre but about 20 mm towards the rear. I can mount it in a movable part that can slide away to disengage when I do screwcutting or anything where I don'st want this handwheel to turn.

    Is there perhaps somewhere a mod of similar design? The mod that I have seen on mike's mod page is where the owner has extended his bed a few inches and added a longer leadscrew. The new handwheel have space left on this extended bed to be mounted and can move to disengage. I do not have this space, however I may be able to fix a type of an angle plate to do this mod, mut it will extended more to the right as the first mentioned idea and will still be working the othe way around.

    I will appreciate any suggestions or references to other existing mods.
    Regards

    Johan

  2. #2
    Join Date
    Aug 2007
    Location
    Melbourne
    Age
    68
    Posts
    1,410

    Default

    A leadscrew handwheel is indispensable for milling in the lathe. It used to be an optional accessory on most 3in1 lathes, such as most lathes of 11" und smaller made by the Austrian EMCO. This option was often automatically included when purchasing the milling attachement. Such handwheel is fitted with a graduated collar. Essentially, it controls the x-axis when using a rear-bed mounted milling column, and it controls the z-axis when using a cross slide mounted vertical slide.

    But Nowdays 3in1 lathes have become rare. Vertical slides are very limited in the size of workpieces you can machine, think about the size of a cigarette pack as the outer limits (if you think this is small, do not forget the milling cutter diameter has to overlap your workpiece on all sides). Finally small mills like the Sieg minimills have become so cheap it just does not make much sense anymore to mill in the lathe. About the only argument left is space saving, and that is only valid if your workshop is in a spare bedroom. There is a third type of "3in1 lathe" though where milling in the lathe still makes a lot of sense, and thet is a toolpost mounted milling head (also known as a 4th axis, or a driven tool). Think of slotting a long shaft, or making a spline.

    Other cases: in very small lathes, like watchmakers size lathes, there often is no rack drive for the saddle nor half nuts, the handwheel on the leadscrew is all there is to move the saddle. Some low cost hobbylathes of the past like the Myford ML10 was also made in this way.

    I have listed above most reasons to justify a leadscrew handwheel, covering some 98% of its practical uses. The remaining 2% are the rare cases when it would make sense to use it when turning to a precise depth. But other techniques like using a carriage depth stop achieve the same. Reading your post, I have the feeling you are not after milling in the lathe. You are mostly upset about the backlash in the carriage handwheel. I am afraid you simply have to learn living with this backlash. All lathes have backlash in the rack driven saddle, even very expensive "toolroom" lathes. After a while of using your lathe and learning the techniques, it is unlikely you will still miss a leadscrew handwheel. But if you still want to go ahead, I have one good tip left: omit a handle on this handwheel, or make it very small: otherwise there is the constant danger the handle catches on a rag or similar when you least expect it. Chris

  3. #3
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default

    Jors,
    this came up a while ago on the Forum, and as I recall, the general consensus was that a leadscrew hand-wheel was of limited benefit.

    I can foresee a problem when using it to adjust DoC when milling. I like to use the powered cross-feed when milling on my lathe. If I were to use the leadscrew hand-wheel to adjust the DoC I would have to move the power-feed lever from the cross-feed position to the lontgitudinal feed position. I would then have to move it back to the cross-feed position. If I were to forget the last step and the clutch star-wheel was engaged it would be a disaster when I switched the machine on. Then again, maybe you never intend milling on your lathe, so this point is irrelevant.

    If you are intent on fitting a hand-wheel, I don't think the fact that it rotates anti-clockwise to advance would be a major problem. I'm sure you would quickly learn which direction to turn the wheel.

    I agree with Chris- use a depth stop or a dial indicator mounted on the bed for accurate setting of the X axis. You can very accurately position the saddle this way using the saddle hand-wheel, despite the large amount of backlash.

    Regards,
    Chris

  4. #4
    Join Date
    Jun 2012
    Location
    SA
    Posts
    1,649

    Default

    Quote Originally Posted by jack620 View Post
    Jors,
    this came up a while ago on the Forum, and as I recall, the general consensus was that a leadscrew hand-wheel was of limited benefit.



    I agree with Chris- use a depth stop or a dial indicator mounted on the bed for accurate setting of the X axis. You can very accurately position the saddle this way using the saddle hand-wheel, despite the large amount of backlash.

    Regards,
    Chris
    I mill on the lathe regularly and regardless of how you set the DOC you must use a dial or digital indicator of some sort to set it accurately.

    You can use the carriage handwheel quite easily provided you allow for backlash, or you can use the ram on the tailstock to push against the centre/back of the mill slide.

    For jobs like plunging this is by far the best method as it provides support right on the centre milling line.

    I looked at a handwheel on the leadscrew years ago but saw no advantage.

    Rob

  5. #5
    Join Date
    Nov 2007
    Location
    melbourne australia
    Posts
    3,228

    Default Handwheel Driven Leadscrew

    Thanks for the tailstock tip Rob.
    Chris

  6. #6
    Join Date
    Jun 2012
    Location
    SA
    Posts
    1,649

    Default

    Quote Originally Posted by jack620 View Post
    Thanks for the tailstock tip Rob.
    It's a good trick to use when milling on the lathe.

    There will always be some canting of the work, as it is supported by the carriage ways, which are quite a distance from the centre line.

    Try drilling a deep hole through your work using the handwheel. Press hard and see how much deviation from 90 deg you get. There will be a lot if you apply a lot of pressure.

    Now try it using the tailstock ram. There will be no deviation - and you can apply as much pressure as you like as all the forces are at the lathe centre line.

    I usually put a drill chuck in the tailstock with a short bolt in it - the head presses against the back of the mills slide.

    You can't use this method when feeding in with the cross slide, but for drilling and plunging it is the only way to do it accurately.

    It also heavily reduces chatter when plunging as the work can't oscillate away from the cutter.

    Cheers

    Rob

  7. #7
    Join Date
    Aug 2007
    Location
    Melbourne
    Age
    68
    Posts
    1,410

    Default

    For about 20 years, milling in the lathe was all I had. Of the three available methods, the one using a vertical slide is in my experience the most limiting.

    If you are using a cross slide mounted vertical slide, you must use a leadscrew handwheel and the half nuts engaged. This setup is self hemming, the cutter can not draw the workpiece including the apron into itself. If you are simply using the big apron rack/pinion, the cutter may catch and because of the big backlash the pinion/rack has, there is nothing you can do to stop it. Same if you use the tailstock to push. It may be ok for small cuts, but watch out if milling brass or copper. Also with half nuts engaged there is very little backlash.

    Another problem when using a vertical slide is that the cross slide dovetails are on purpose offset at an angle to the lathe spindle centerline (check any inspection record to verify this fact). This is to ensure that when facing a slightly concave surface is produced. When milling this same offset makes sure that if you mill a cube or rectangle, it won't have exactly right angles. This may matter if what you do needs to be accurate. It is also the reason, why when using a flycutter with a vertical slide, it always cuts on one side only.

    Chris

  8. #8
    Join Date
    Jun 2012
    Location
    SA
    Posts
    1,649

    Default

    Yes, totally agree with all that Chris.

    The tailstock helps a lot, but you need to keep your left hand on the carriage handwheel to reduce the chance of catching and the work being pulled into the cutter.

    Plunging is always a bit risky on a lathe mill. Always use a carriage stop.

    Rob

Similar Threads

  1. Removing cast handwheel from steel shaft
    By billrule in forum METALWORK GENERAL
    Replies: 14
    Last Post: 10th Oct 2009, 08:24 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •