perhaps a drawing or 2 of what you have in mind might make it a little clearer
Bill
----- Original Message -----
From: Tim Krause
To: legacy-ornamental-mills@googlegroups.com
Sent: Sunday, July 29, 2012 5:04 PM
Subject: Re: Creating spirals on the rotary table
I'm going to answer my own question because I think I'm wrong and right. The
part about the spindle turning eight times and the travel being .375" per
rotation of the rotary table is correct. The .046" is irrelevant. I started
to look at this problem a different way. The leadscrew needs to turn 1.5 times
while the spindle is turning 8 times. This would make the rotary table rotate
once and the carriage would advance 3/8" (1.5 turns time .25" lead equals
.375"). That's my goal.
So, I just need a ratio of 5.333:1 to make this work. How did I figure that
one out? I started by dividing the 8 spindle rotations by the required 1.5
rotations of the leadscrew. Next, I made a spread sheet that found some
integer numbers I could work with for the gears. By multiplying whole numbers
by the travel of the carriage per single spindle rotation ( .375/8 = .1875) I
found the first whole number that worked was 16 (16 *.1875 = 3). That gave me
a 16:3 ratio that I could then break down into gear ratio combinations. That's
the easy part to me. The combo can be done with a 4:1 ratio on the leadscrew
and a 4:3 on the spindle. My initial gear thought is 36 tooth on the spindle,
a 48/22 on an idler and a 88 on the leadscrew and whatever is need to space
things out correctly. The 88/22 comes from the idea I can use my main drive
gear on the leadscrew. Then I only need to cut 3 smaller gears.
How many people am I losing here? Honestly I'm lost, but I'm still moving
forward. I'm sharing this because I really suck and math and I'm sure there is
a faster way to figure this stuff out. What I will end up doing is cutting
some gears using my ratios above and then I will see what happens. I do think
I'm on the right path. Does anyone agree?
-Tim
----- Original Message -----
From: Tim Krause
To: Legacy-Ornamental-Mills@googlegroups.com
Sent: Thursday, July 26, 2012 10:48 PM
Subject: Creating spirals on the rotary table
Hello All,
I had a crazy idea that a continues single start spiral can be made on the
rotary table. The goal is to get the pitch right on the x-axis. I started
looking into the geometry required with a 1/2" cove bit. It looks like a
spacing of .375" would do the job. In other words, the x-axis would move 3/8"
with each rotation of the rotary table. I think this would create a spiral
pattern but I'm not sure. Maybe the pitch needs to decrease as it get closer
to the center?
Then I started to consider the problem a little further. It's not quite
that easy. You see, the problem is my pitch is right, but I did not take into
consideration the spindle turns 8 times to make the rotary table turn once.
So, I really need to take that .375" pitch and divide it by 8. The new pitch
number that I need is actually .046". That way the x axis travels the .375"
per rotation of the rotary table ( 8 x .046 = .375 ).
Now, I can think of two ways to get the pitch so that's not my concern.
The real concern is if I've come up with the right pitch in the first place and
if a fixed width would even work.
Any thoughts would be appreciated.
-Tim
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