Re: ATM Worm Gears

["AstroIdiot" <tgooch@arkwest.com>]

Hi
Our club made an equatorial gear in much the same way.
But we used a spiral flute tap because the lead in is much
better. The biggest problem with the setup is the disk deflects
and the tap just chews up the edge of the disk. The best way
to do it on the cheap is to make a jig that will hold the edge
between two bearings. Also you must put pressure on the tap
and just let it cut. It can be made with a hand drill but you must
make sure the drill is perfectly steady and the disk cannot deflect.

Tommy
----- Original Message -----
From: "Charvell" <charvell@sofnet.com>
To: <atm@shore.net>
Sent: Sunday, August 19, 2001 7:59 AM
Subject: ATM Worm Gears


>
> This one's been bothering me for a while now. If I'm going to construct a
> worm gear from a ie: 1/4" X 15" circle of alluminum, I put my disc in a
jig
> with a hole in the dead center with a nail to hold it firmly but still
allow
> it to turn. Now I set up my hand drill in another jig at right angles to
the
> disc, with a tap in the chuck. I can now press the trigger on the drill
and
> if everything goes just right I'll be able to put teath into the disc (I
> hope). After every pass I'll just move the tap closer to the disc allowing
a
> deeper cut every pass. I don't have a lathe and am limited in equipment.
>
> I want to do this in "alluminum" utilizing a "stainless steel" ie: 1/2"
> threaded rod.
>
> Questions:
>
> 1) Will the tap track the way I think it's supposed to without ruining the
> tap and/or disc?
>
> 2) what happens when you get all the way around the disc and the threads
> start to overlap? What if they don't come out in exactly the same place?
Is
> this a chance event or is there a formula I need to use?
>
> Is there a better way to do this?
>
> Thanks
>
> Herb Watson
> Lamar. Mo.
>
>