Re: [CAD_CAM_EDM_DRO] Cool Worm Gear

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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