Gear Hobbing Attachment Pix

I just sent some pix of my spur gear hobbing attachment to the Dropbox. Hob 1.JPG, Hob 2.JPG, Hob 3.JPG, and Hob.txt. My first attempt at using the
Dropbox, so hope it works. Jim.
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Your submissions to the dropbox worked well, thanks for sharing this project.
Very nice project, and clear pictures showing project details. Others might take notice of how unneccessary it is to send huge images (or use giant images for other web postings).
WB metalworking projects http://www.kwagmire.com/metal_proj.html ...........

Hob
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Hey Jim,
Very nice. Neat work.
A question.... I see worm gears, but how do you get automatic "X" direction motion passes for the plain spur gears, or do you do multi passes at small steps?
Take care.
Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXX
wrote:

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The "X" feed is manual. The aux. table has dovetailed ways, a gib, and is fed at the lead angle by a 1/2-10 acme rod with a hand wheel on its end. The main mill 'X" table is locked. Feed can be continuous or at the end of each rev. of the blank. I find both work, but one can argue that feeding at the end of each rev. is best. The blank is fed 'underneath' the hob. Jim.
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JimL wrote:

Oh! Then it works!
Nick
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Brian- I should of added that with 16 DP in aluminum I make one pass. With steel , two passes. Jim.
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JimL wrote:

I'm quite puzzled with your setup and doubt it works. You have rotated the (sub-)table according to the hob's pitch. OK. But if you feed your workpiece, you have to feed along its axis and *not* along your table (X). There is an error exactly of the hob's pitch. If you try it with a verrry wide gear, you'll see clearly. You get a spiral.
Nick
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Nick Mueller wrote:

I should have written "helix"
Nick
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Please see my answer to Brian Lawson's post. Jim
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Looked like he has the indexer on a dovetail slide mounted on the rotary table, with a seperate feed handwheel, so that the feed should be exactly as you say, along the gear axis and not the main table axis. Is there something else there I am not seeing? --Glenn Lyford
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Nick, If you look closer, you will see that he Does feed along the axis of the hob, not the "X" axis of the mill.
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Nick Mueller wrote:

It looks to me like the aux table has it's own feed.
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Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space
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Worked fine. http://www.metalworking.com/dropbox/Hob.txt
http://www.metalworking.com/dropbox/Hob_1.JPG
http://www.metalworking.com/dropbox/Hob_2.JPG
http://www.metalworking.com/dropbox/Hob_3.JPG
I thought I'd post a direct link for the internet challenged.
Wes
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wrote:

Thanks, Wes-I should have done that. Jim.
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    [ ... ]

    [ ... ]

    Also -- note that the spaces in the filenames got converted to underscores -- because spaces in filenames are a serious problem on command-line driven systems, while everyone with a semi-modern system can handle the underscores.
    Nice photos, BTW.
    Enjoy,         DoN.
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Perhaps you just removed them for pictures (the usual excuse, along with "I'm perfect and that will never be a problem for me...eeeEEEYOUCH!") but I'd want some guards for the gear trains. Being imperfect, and comparatively fragile .vs. steel, I'd rather put an hour or two into making guards than spend it in the emergency room.
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Cats, coffee, chocolate...vices to live by

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wrote:

===========Very nice job -- thanks for sharing.
What is your approximate setup time? How do you set/check the helix angle?
Unka' George ===============When we are planning for posterity, we ought to remember that virtue is not hereditary. Thomas Paine (1737-1809), Anglo-American political theorist, writer. Common Sense, ch. 4 (1776).
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Greetings. The desired lead angle is given on the hob, 1.7 degrees in my case. I put a straight arbor between centers on the aux. table, place a dial indicator on the rear column of the mill. and run the main mill table back and forth , adjusting the table angular position for a difference in DI reading of 0.104" in 3.5 inches of mill table travel. Mill table travel is measured by the micrometer dials on its end. The arctan of 0.104/3.5 is about 1.7 degrees- close enough. For a given hob, one could make a simple gage referenced off the base of the main mill table and the aux. table. I guess that starting from scratch, to mount a gear (with the same number of teeth as the gear to be cut) on the output of the gear train on the rear of the mill, set the angle, mount a prepared blank on the arbor, mount the arbor, connect the telescoping drive shaft, takes about 20 minutes or less. No longer than it takes to set a dividing head, an index plate, tailstock, and align same when using single involute cutters. HTH, Jim.
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