Gear Template Generator users?

[myxpykalix]

I bought the Gear Template Generator pgm from Mathias Wandel and i'd like to ask a few questions of any experienced users...

I want to make a jewelry box for a young girl with a brain tumor.

I want to have a small 3d carving on the lid that is not glued to the lid but is connected to a shaft that goes thru the lid that acts like the "doorknob" that you would have to turn say a quarter turn in order to unlatch the lid.

I plan on cutting the gears from .25" corian plastic.

My dilema is a few things, i don't know how to use the program to make the pinion gear, and how to program it in order to give the gears a .5" travel or throw(?) and how many gears i would program to do that.
The inside dimensions of the box are 10"wide by 8" high. The gears and the pinions don't necessarily have to be real small, i'm just not familiar enough with gearing to know how to figure this out.

I asked that question of Mathias and here is the response i got:

To do rack and pinion, set one of the gear types to "rack".
UNDERSTOOD
As for how much throw, the throw of the rack for a quarter turn will be one
quarter of the circumference at the pitch diameter. If that is, for
example, three times as much as you want, you could gear it down 3:1 before
going to rack and pinion.

NOT UNDERSTOOD:confused:
So if you just think of a typical doorknob and latch i just want about .5" of travel and you would have to turn the carving on the lid say a quarter turn to open the box.:confused:

[myxpykalix]

still looking for advice:confused:

[Ajcoholic]

If you are wanting a rack and pinion, that would move the rack 1/2" in a quarter revolution, you need the pitch diameter of the pinion gear to be about 2". Since the diameter of the gear is set by picking the # of teeth, and the size of the teeth (forget the term used but it is the parameter that changes how coarse or fine the teeth are) - play around with it until the diameter shows about 2".

If you want a smaller gear, you will just have to turn it through more than 90degrees to get the 1/2" linear movement.

AJC

[Ajcoholic]

still looking for advice:confused:

So am I... pretty much daily! ;)

AJC

[myxpykalix]

I did not understand any part of your explaination :confused:

not because you didn't explain it probably correctly, i just didn't "get it":eek:

After dinner i will open the pgm and go word by word to see if while looking at the settings i can make sense of it. Do you own this pgm?

[Brian Harnett]

I have the program but instead of trying to explain what to do it may be easier for you to just cut some scrap and get a hands on idea.

Sounds like a cool project.

[Ajcoholic]

OK lets try again..

I am assuming you want a rack and pinion - and you want to have 1/2" of linear movement, with a quarter turn of the gear (90 degrees).

Independent of the # of teeth on the pinion, or the size of the teeth, you need to have a pinion gear that is approx 2" (measured at the pitch diameter, which is roughly in the middle of the teeth - not at the tip not at the bottom of the groove).

When you draw up the gear & rack, you will have to play around with the # of teeth, and the size of the teeth to get a decently sized tooth profile (not too big, and not too fine) and adjust until the pitch diameter is about 2".

If 2" is too big of a diameter, then yoiu can certainly go with a smaller diameter, but you will have to turn the pinion gear through more of a revolution, in order to get the 1/2" of linear travel on the rack.

AJC

[myxpykalix]

Andrew,

I had to laugh out loud when i read your instructions above because to me it was a repeat of what you said in a previous post....

What struck me funny was that it was like you were repeating the same thing only saying LOUDER hoping i would understand it:D
(a classic comedy routine from SNL...."Our top story tonite....")
I just don't understand but i do appreciate your help for sure..

Brian might be right about cutting scrap only that is a big waste of time and frustrating when you have no base from which to start. There could be hundreds of teeth/diameter combintions.

I wonder if there are "formulas" or mathematical equations that could give you the info you need,
For example Pitch (length of travel of pinion) divided or multiplied by diameter (of gear) somehow dictates the width and height of teeth required to move a specific distance....??:confused:

[Bob Eustace]

Jack the answer is to scrap the box idea and give her a nice gear operated vyce. Simply copy the beautiful one Brian made.

[Ajcoholic]

Jack
You are not getting this point... It doesn't matter what the size of the teeth are or how many teeth are on the gear. What only matters is the diameter - you want the rack to move a specific distance in 90 degrees of rotation. That means the curcumferance of the full circle has to be 4X that since there are 4 90's in a full circle.

Try it with a smooth wheel on a straight board. Now add whatever teeth you want it works the same. The teeth size are not relevant to the outcome

[myxpykalix]

ok, it is starting to make sense...once i "get it" a light bulb will go on in my head and i'll say "NOW i understand what Andrew was trying to teach me"!

till then this is me.....:confused:

[Ajcoholic]

Ok I saw one error I wrote. The circumference of the pinion has to be 2 inches and not the diameter. Does that help? I am sorry about that, it makes a huge difference ( and also your gear will be smaller )

[bryan5358]

Since the formula Circumference = Dia./pi wouldn't Dia.= Circumference/pi be correct?
If so the the dia. of the gear would be 0.6366". Might be a little tough to cut the teeth because of the size of the bit involved. Jack you may have to use multi-gears with different sizes to get the increase in gear dia.
Sounds like a lot of figuring and layouts Jack.

[ssflyer]

Actually, I think C = pi * D, so D = C/pi

[Brian Harnett]

Jack maybe this will make sense If you make a rack gear with 12 teeth and make a pinion gear with six it would take two revolutions of the pinion to run the length of the rack.

If the pinion was 12 teeth it would be one revolution for the rack to travel its length.