[sugpro] Re: Toolpost spindle

  • From: Steve Peterson <steve_peterson@xxxxxxxxxxxxx>
  • To: sugpro@xxxxxxxxxxxxx
  • Date: Tue, 10 Mar 2015 07:31:12 -0700

Hi VL,
Thanks for the compliments--projects like that will tend to keep you from getting any work done on rockets, however.
I know you're all set up with your divider, but perhaps others will find my setup useful. Like you, I didn't want to deal with milling, I didn't want to modify the lathe, and I wanted something that was easy to set up and remove.
Here's a view of the "frame" that holds the index pin. The frame is simple and just clamps onto the headstock of the lathe. Since there's never much force put on it, it maintains it's position very well: 

https://www.flickr.com/photos/91343876@N07/9263452856
Here's the end view. The gear has been coated with layout dye and is fastened to the expanding mandrel which I fabricated myself. Sorry I don't have a picture of that part right at hand. Tightening the nut holds the gear on and expands the mandrel--the gears came with a slot for a key, so I slotted the mandrel (on the lathe) and made a small key. The index pin is just a piece of rod that I ground down to match the angle of the gear teeth. It fits quite snugly so there's no slop. It rides in rectangular channels that I cut (with a table saw) in the two haves of the clamp. The black handwheel tightens the clamp. The secret to a setup like this is eliminating all sources of play in the various parts once they're tightened down. 

https://www.flickr.com/photos/91343876@N07/9263452776

--Steve

On 03/10/2015 04:07 AM, Vertical Limits wrote:


Hi Steve,
Impressive work & great engineering, that’s some precise injector drilling. I played with the idea of using a gear as a divider – many threads on the internet doing the same. But any design I came up with, suitable for my lathe, required a bit of milling one way or the other with fiddly bits etc. The expandable mandrel type I made can be machined on a lathe only. The SOBA Chinese dividing table <https://www.hbm-machines.com/producten/gereedschap-en-toebehoren/verdeelapparaten/hbm-75-mm-verdeeltafel-met-opspanset>, read out accuracy 0,1-0,2 degrees, was only EUR 50,- and works perfectly for the job. My next upgrade will likely be a more heavy duty 43mm mill <https://www.damencnc.com/en/tools/kress/kress-milling-motor/87>(currently it’s a 20mm mount) however that one can’t go as close to the head stock as the 20mm one. 

VL
On Tue, Mar 10, 2015 at 12:13 AM, Steve Peterson <steve_peterson@xxxxxxxxxxxxx <mailto:steve_peterson@xxxxxxxxxxxxx>> wrote: 

    As I promised in a msg yesterday, here are some photos of my
    toolpost-mounted spindle that I built about a year ago. The motor
    is an RC motor, about 750 watts--more than enough power for
    drilling holes, and powerful enough for usable milling in both
    steel and aluminum.

    First photo is an overview of it, mounted for radial drilling. It
    fits on top of the compound, so I don't have to remove the
    compound to use it. There are some positioning screws that allow
    for fine alignment, but once they're set, I can remove and replace
    the spindle without any further adjustments assuming the compound
    hasn't been changed (or if it has, has been realigned properly):

    https://www.flickr.com/photos/91343876@N07/14129355203

    Here it is "flopped" into position for axial drilling. Again,
    positioning screws (seen at the top right edge in previous photo)
    are now engaged to position it accurately for axial drilling.

    https://www.flickr.com/photos/91343876@N07/14106038341

    Radial drilling, shot from directly above. The workpiece has been
    spotted with an endmill to make a flat spot, then spot drilled
    with a spotting (not center) drill, then my #81 drill is used to
    drill the injector holes.

    https://www.flickr.com/photos/91343876@N07/14106209232

    Closeup view:

    https://www.flickr.com/photos/91343876@N07/14129359533

    As I mentioned in the previous post, I use one of the gears
    intended for threading as a divider. It is accurate enough that I
    can drill a bulkhead, then drill a casing and have them match up
    (no need for match drilling). In the photos here, I went "around
    once" with the endmill, then went around again with the spotting
    drill, and around a third time with the #81 bit--by the time I got
    to the drill bit things were still well enough aligned that no
    adjustments were needed.

    Everything you see in these photos was milled on the lathe--I
    don't own a mill.

    --Steve

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