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  1. #41
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    Quote Originally Posted by TNB View Post
    Yes, but that kind of arrangement is much more difficult to make. Plus in Bruce's situation, the centering of the attachment would be provided by the OD of the spindle nose. So no need (nor possibility) for the short taper.
    Not clear that I can get the centering from the OD of the spindle nose -- the ring has to be high enough to allow the 4 retainer screws to enter, with some meat below those as well. That might lift the adaptor flange so high that it is entirely above the spindle nose. I need to draw it.

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    Quote Originally Posted by TNB View Post
    ...

    What I would do is get a cheapo Deckel MK4 centering vice that I could butcher without hesitation. ...
    Tien I would assume that the idea is to be able to mount all 89 mm indexing head accessories, chucks, punch milling attachement (first or second generation if one is lucky enough to have one....:P)

    A bolt on adapter as per Ross's initial suggestion (with a groove or divots to accept the accessory set screws) but enhances with anti-rotation keys and a short centering taper would not be elegant, short, and relatively fast to install, but, also, a really challenging project!

    Looking forward to seeing what you'll end up with Bruce!
    BR,
    Thanos

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  4. #43
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    Quote Originally Posted by thanvg View Post
    Tien I would assume that the idea is to be able to mount all 89 mm indexing head accessories, chucks, punch milling attachement (first or second generation if one is lucky enough to have one....:P)
    And what's the problem ?

    Re-thinking about it again after all, I'm glad we did not launch production yet, because I wonder if there would really be any kind of benefit in taking the "regular" T-slot top plate of the table to mount all those accessories after all...

    One could just make an adapter that would register in the center bore of the table, and mimic the Deckel dividing head spindle nose at the other end !
    Or simply bolt any generic cross-slide on the table, and make its own dual-axis punch milling attachment...

    Maybe we're talking about a problem that did not need to be adressed in the first place (save for the height loss under the spindle) !

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    Thanos is right -- I have a centering vise and three and four jaw chucks on the correct mount flanges. I'd like to use all of them without any butchering.

    Quote Originally Posted by TNB View Post
    I wonder if there would really be any kind of benefit in taking the "regular" T-slot top plate of the table to mount all those accessories after all.
    Good point. Instead of making an adaptor which goes on top of the spindle, I could make one which bolts to the table, with a centering spigot. This has some advantages (simplicity) and some disadvantages (mainly less Z clearance).

    Time to stop discussing this and to make a drawing or three

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    Glad you guys finally cough up with a point i made back in post 32.....about mounting adapters to the "universal" table. And yes i have made some...have a setup that uses a tapered mandrel
    on a mounting flange that carries expanding mandrels as an ID collet.....Mounted 3 jaw chuck (as previously mentioned) and of course directly clamping my lathe chucks directly to the table top.(one
    of the nice things about "D" style chucks...the cam lock pins are easily removed giving a flat back that you can set the chuck on....Also have a key action 5-c collet fixture that fits the lathe that a use on the table top....

    Cheers Ross

  7. #46
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    Quote Originally Posted by AlfaGTA View Post
    Glad you guys finally cough up with a point i made back in post 32.....about mounting adapters to the "universal" table. And yes i have made some...have a setup that uses a tapered mandrel
    Ok, ok....
    You don't have to be sarcastic just because you're jealous you can't take the top plate off your 2038 !

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  9. #47
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    OK, here's a simple solution:





    This plate is 10mm high at the thin part, 18mm high over the keys. It would support the accessories 1mm above the "base level" (where the rotary table normally sits). With this design, the accessory flange overlaps the spindle flange by 9mm, so radial position control comes directly from the spindle itself. The plate controls upwards motion and rotational about the spindle axis. Radial force is controlled directly by the spindle flange. Downwards force is transmitted through the plate and controlled by the spindle flange.

    Note that only two of the four accessory flange locking screws are used; the other two locking screws are replaced with brass-tipped screws that bear on the spindle flange but are not seated in holes. These add some radial stiffness but provide no axial or torque control.

    The challenge was to make this thin enough that the accessory flange overlaps the spindle flange enough for to control the radial position.

    This would be held on with four DIN 6912 M12 short SHCS and two standard M6 SHCS. I think it would be quite rigid, but have not tried to estimate the stiffness. It helps that most of the cutting forces would be radial or downwards.

    Other variants of this idea are also possible, using the SK40 taper and/or the S20x2 drawbar for hold-down.

    Another nice thing about this design: I can make it in a morning or afternoon, then try it out.

    Edit: on reflection I think I'm going to drop the M6 screws, because they reduce the cross section too much around the two clamping screws. Better to have some more meat there and rely on the M12 for holding down the plate.



    So I'm going to go with this instead:



    Final Edit: this idea won't work. I just had a closer look at the accessory interface on the Deckel dividing head. The accessories have to register on a 45-degree slanted feature at the BOTTOM of the accessory flange. I have the registration at the top of the accessory flange. So I'll need a different design, unfortunately.
    Last edited by ballen; 02-28-2021 at 08:14 AM.

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    The table came with this handwheel, but without any indexing plates.



    Fortunately it uses the same 4 degrees/revolution 90 turns per rotation standard as Deckel. So I made an adaptor so I can use my Deckel indexing plates. I also picked up a spare rotation handle from Ebay (got lucky, was 20 Euro) and modified it. Here are the parts, the ones with the red arrows are the only ones I had to make. Top row is the parts for the handle it came with, bottom row is the parts for the Deckel indexing plate.

    For the dividing disk handle I needed to shorten the plunger nose tube, rear part of the plunger, and spring by 5mm. I also had to provide 3mm of relief along the slot to enable it to be installed. That's visible in the final photo of this post, below.



    I also needed to modify the flange on the Hermle by threading the center hole M32x1, and adding a 4mm anti-rotation pin for the Deckel dividing plates. In the previous photo you can see how I trepanned a circular slot in the back of the stock aluminium dial, so that the 4mm pin won't interfere with using the stock handle.



    It installs the same as standard Deckel:

    (1) Put plate on pin, screw in the part I made (knurled here)



    (previous photo was taken before I blued the knurled bit)







    (2) Slide on the clock arms, which are retained with a spring clip.



    (3) Final step, put on dividing handle, add the short keyed spacer ,and secure with the stock retaining screw.

    A nice aspect of this approach: it is completely reversible. After removing the 4mm pin (punches out from behind) one could still use standard Hermle dividing plates and fittings. So if some of those show up at my doorstep one day, I could use them instead of the Deckel hardware.
    Last edited by ballen; 02-28-2021 at 10:23 AM.

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  13. #49
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    OK, here's the revised design, 33mm high, larger OD 100mm, smaller OD 89mm, ID 89mm.





    The 45 degree taper is the fiducial or reference surface for the accessory mount. {EDIT: THIS IS NOT CORRECT! SEE POST 52 BELOW.]

    Hard part of making this is to get the OD and ID exactly concentric and coaxial. If I had a high-speed grinding head for my Deckel, I could do it "in place" mounted on the Hermle spindle.
    Last edited by ballen; 03-01-2021 at 01:47 AM.

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    I can not see your part yet, but the easiest / best solution for keeping ID/OD concentricity in you case will be to pre-drill/tap a 90mm OD piece of round stock, chuck it up, face the end, the,finish the OD so as to be able to light press your adapter onto it,...
    Mount your adapter, and secure it with the bolts, finish its OD, done.

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    Hi Tien,

    Yes, I can turn a stub on the lathe, then mount the adaptor to it and turn the outside. That will probably get it concentric within 5-10 microns. But I'd like to figure out an approach that will get it better than that. I'm thinking I will turn it overside by 50 microns on the OD and undersize by 10 or 15 on the ID, then mount it on a magnetic chuck in the cylindrical grinder and grind OD and ID in a single setup. But I'll also need to figure out a way to grind the 45-degree section in the same setup.

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    Think you are mistaken. The 45* taper is in effect a dirt shield. Its shrunk on to the spindle of the dividing head.
    It goes on from the rear to a shoulder. Can't apply any force to that angle or you will displace it against the body of the dividing head.....
    It is just like the front outside ring on the milling spindles, the ones that Frantz replaces with bronze to prevent damage..

    My belief is that the tools are held tight against the face of the dividing head spindle to get then to run flat. Concentricity is via the OD/ID fit up of the
    straight section of the spindle....
    I have made adapters for my chucks and the like and i machine mine with a bit of clearance between the ID of the adapter and the OD of the spindle. Makes fitting up easier and
    allows using the mounting screws to dial in the run out of the chuck....
    The jacking screws in the adapter need to be slightly forward of the position of the countersinks in the spindle that way when tightened they apply jacking force to pull the adapter tight to the face of the spindle...
    Never had any issues with rigidity....
    Cheers Ross

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    Dear Ross,

    Quote Originally Posted by AlfaGTA View Post
    Think you are mistaken. The 45* taper is in effect a dirt shield. Its shrunk on to the spindle of the dividing head.
    It goes on from the rear to a shoulder. Can't apply any force to that angle or you will displace it against the body of the dividing head.....
    You are right, look at the cross sectional diagram:



    and in real life:



    Thanks very much Ross! You just saved me from spending a lot of time making a very precise piece of scrap. Also means I need to stone the inside upper surfaces of my dividing-head accessories. Some of those (purchased used) have dings on those surfaces.

    I have made adapters for my chucks and the like and i machine mine with a bit of clearance between the ID of the adapter and the OD of the spindle. Makes fitting up easier and allows using the mounting screws to dial in the run out of the chuck....
    How much clearance do you typically leave? In my design I am centering on the Hermle spindle itself, and that's a pretty snug fit on the accessories I have tried, it's a hassle to get them on and off without cocking and jamming.

    Given what you've explained, does the design in Post #47 above look OK to you? It's easy to make, but only provides definitive locking on 2 of the four screws. Or do you think I should go with the taller version (but seating on the top and not on a 45-degree feature)?

    The jacking screws in the adapter need to be slightly forward of the position of the countersinks in the spindle that way when tightened they apply jacking force to pull the adapter tight to the face of the spindle.
    Yes, that's clear. What is less obvious to me is how to machine the holes in my adaptor. The Deckel holes are about 10mm deep, and taper from about 9 mm to around 6mm. Do you know if there's a standard tool for that? Or do I need to grind one myself? [Edit: there are some inexpensive HSS tapered cutting tools to make holes in sheet metal, one standard size is 3-14mm, the angle looks about right, so I can grind the tip off so it does 6-14mm.]

    Cheers,
    Bruce
    Last edited by ballen; 03-01-2021 at 05:50 AM.

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    Quote Originally Posted by ballen View Post


    How much clearance do you typically leave? In my design I am centering on the Hermle spindle itself, and that's a pretty snug fit on the accessories I have tried, it's a hassle to get them on and off without cocking and jamming.

    Given what you've explained, does the design in Post #47 above look OK to you? It's easy to make.
    I don't know if clearance value is very important. It must be enough to make operation easy.

    But if you want your adapter to be relatively easy to mount and to take off, the required clearance will be more than one can accept for a centering workholding device (be it a centering vice or lathe chucks) anyway.
    In your case, I'd say something like H7g6.

    So in the end,what will hold and (more or less) center the adapter concentric to the spindle will be the radial screws.

    Your design in post #47 doesn't provide any kind of centering on the spindle. There's no overlaping of the adapter on the spindle nose.
    Of course you could indicate it each time you'll mount it but I think it will soon be boring !
    If you want to keep your adapter low, a solution could be to use a mounting tool that would look like a piston ring compressor : put your adapter on the spindle nose, slide the mounting tool (overlaping both the adapter and spindle OD) and tighten it, tighten the bolts of the adapter, take the mounting tool off...
    Just a thought.


    As for the tool, why bother ? A simplistic single lip tool ground with proper angle will do the trick easily !

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    Hi Tien,

    Quote Originally Posted by TNB View Post
    Your design on post #47 doesn't provide any kind of centering on the spindle. There's no overlapping of the adapter on the spindle nose.
    That's not correct. The design in post #47 has a total height of 18mm, the top ring is 10mm thick, and the key adds an additional 8mm. The Deckel adaptor flanges have an inside height of 18-19mm. So the bottom 8-9mm of the Deckel adaptor flange will overlap the Hermle spindle. That's crucial to the design!

    Changing topics... one of the things that I like about the Hermle design is that the table top is light enough that I can pick it up with my hands -- I don't need to use the chain lift. So it's fast to remove. It's also easy to replace, thanks to this nice design feature:



    The T-slot bolt bars each have a bearing ball with spring, and there is a positive detent hole in the T-slot track, visible in the photo, which engages that. This holds the T-slot bolt bars in their default 180-degrees opposed locations. So the T-slot bolts stay in position when installing the table, which makes it go a lot faster.

    Cheers,
    Bruce
    Last edited by ballen; 03-01-2021 at 05:58 AM.

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    Quote Originally Posted by ballen View Post

    That's not correct. The design in post #47 has a total height of 18mm, the top ring is 10mm thick, and the key adds an additional 8mm. The Deckel adaptor flanges have an inside height of 18-19mm. So the bottom 8-9mm of the Deckel adaptor flange will overlap the Hermle spindle. That's crucial to the design!
    My mistake ! I had overlooked that point..

    Nevertheless, keep in mind the key will provide some centering effect of the adapter on the spindle nose in one axis at best (perpendicularly to the key).
    And once the accessories mounted, you don't have access to the bolts anymore, so you can't rely on the overlapping of the Deckel flange for centering your adapter because the latter must be secured first.
    Last edited by TNB; 03-01-2021 at 06:00 AM.

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    Quote Originally Posted by TNB View Post
    Keep in mind the key will provide some centering effect of the adapter on the spindle nose in one axis at best (perpendicularly to the key). And once the accessories mounted, you don't have access to the bolts anymore, so you can't rely on the overlapping of the Deckel flange for centering your adapter because the latter must be secured first.
    In this design, the adaptor plate is intentionally slightly undersized, because the accessory flanges are already a snug fit over the Hermle spindle. That snug fit is what keeps the parts coaxial.

    The two locking screw prevent rotation and upwards motion. Since the face of the accessory flange seats on the top of the adaptor plate, the accessory flange should not be able to tilt in any direction, either along the axis between the two locking screws or along the axis between the two "unused" locking screws. I put that word in quotes because I would still employ those "unused" two screws (with copper or brass pads) to tweak centering and provide additional tension/rigidity.

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    Re clearance....Think i gave mine about .003"-.004" clearance total...
    And as "T" points out needs indicating to get the run out down to an acceptable level....
    But, remember that the adapter carries a 3 jaw chuck, which never holds true regardless, so the dial up is almost always required if the
    job needs any accuracy no matter how well the adapter fits up to the spindle.
    Also, there is the 40 taper on the dividing head (or Hermle table) that accepts the direct mounted Deckel collets which provides quick "acceptable" accuracy holding for small work.

    Cheers Ross

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    For my FP4NCs, machined a 1.5" steel tooling plate to accept the bolt patterns on all my flat back lathe chucks (4-6" 3, 4 and 6 jaws) plus a Jacobs Rubberflex chuck. There's a boss that can bolt onto the plate to exploit the set-tru function of the chucks if desired, left around .010 per side clearance. Does require indicating but it's pretty quick and easy. Having the thru hole available comes in handy for a lot of my work- you lose that with a 40 taper toolholder inserted.

    Think you could get quite good accuracy/repeatability, as Ross suggested, mounting 40 taper collets direct into the table, a CAT40/NMTB40/BT40 ER32 or ER40 collet chuck would cover odd sizes- obviously limited to small-ish work under 1". One tip for this would be to use a torque wrench on the toolholder drawbar and always tighten to the same value.
    Last edited by Colt45; 03-02-2021 at 10:37 AM.

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  28. #60
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    Quote Originally Posted by Colt45 View Post
    Think you could get quite good accuracy/repeatability, as Ross suggested, mounting 40 taper collets direct into the table, a CAT ER32 or ER40 collet chuck would cover odd sizes- obviously limited to small-ish work under 1".
    I've got a good collection of collets and collet holders that I can use for the taper mount:
    - all standard inch and metric sizes of the direct SK40 collets
    - all the standard metric and inch sizes of the "U2" style collets (plus SK40 holder). These cover 1 to 18mm in 0.5mm increments.
    - Sk40 S20x2 ER25 holder
    All of these were originally intended for toolholding.

    - Burnerd Griptru 3-jaw chuck mounted on an SK40 S20x2 backplate (part of the spiral milling attachment)

    The adaptor I am making is to let me use the Deckel 2-, 3- and 4-jaw chucks, and 250mm faceplate. I don't get as much shop time as I would like, so not having to mess around with workholding is important to me.

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