Re: [CAD_CAM_EDM_DRO] Cool Worm Gear

Ian,

I get how the tap can hog out a gear, but what size taps are suitable
for this? You must run the lathe slow? I can calculate the proper gear
blank size (well, for normal gears). I want to try this!

Alan

Ian Wright wrote:

>
> Hi Smoke,
>
> With the tap method its quite simple - make some sort of fitting to go in
> place of the tool holder which will allow you to put the blank on a vertical
> axle, freely rotating and at centre height (in my case with the Harrison
> lathe that involves removing the tool holder and putting a stack of packing
> washers on the bolt which normally holds the toolholder down. Now with the
> blank free to rotate in a horizontal plane, put the tap you want to use in
> the chuck or collet, set it going and wind the blank into it (in the 'Y'
> crossfeed direction). Let the tap
> cut its own teeth and, as it does so it will rotate the blank automatically.
> Just keep feeding the blank into the tap a bit at a time until the teeth are
> cut to full depth (whatever you want that to be). I normally cut them to
> almost the full depth of the tap teeth then just tidy the top edge up with a
> bit of emery paper and cut a chamfer on each side to make it look pretty.
> That's it at its simplest. As another correspondent said, it can be useful
> to have first gashed the blank with the right number of teeth but it isn't
> really necessary if you have the size of the blank about right. This method
> can be quite useful if you want to make a worm and wheel with an unusual
> ratio - one that I needed was 127:1 - not a particularly easy number to
> divide.
>
> Ian
> --
> Ian W. Wright
> Sheffield UK
> www.iw63.freeserve.co.uk
> ----- Original Message -----
> From: "Smoke" <Smoke@...>
> To: <CAD_CAM_EDM_DRO@egroups.com>
> Sent: 03 November 2000 00:06
> Subject: Re: [CAD_CAM_EDM_DRO] Cool Worm Gear
>
> > I wish some one would draw up both of these methods of generating these
> worms. No one seems to be explaining it very well.
> >
> > Smoke
> >
> >
> >
> > I have seen a method for cutting worm gears that looked real interesting.
> > The gear is held on the lathe carriage in a manner that you can index it
> for
> > each tooth. The gear is heldhorizontal so it's centerline is inline with
> the
> > center of the spindle. A boring bar is paced between centers with a tool
> > ground to the worm profile. The gear is fed across this tool using a
> > threading operation that is the pitch of the worm, using the cross slide
> to
> > set the cutting depth. This generates the correct tooth profile. I hope
> this
> > explination is good enough to understand, if not I'll have to try and draw
> > it up.
> >
> >
> > -- Greg Nuspel
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
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