Cutting gears with your laser

[Mark Winlund]

Hi... As a machinist, I often come across the requirement for gears. In a machine shop, the process can be expensive and time consuming. I have made a number of gears out of wood and acrylic for various projects that, while not the most durable gears in the world, are useful for display clocks, toys, and decorations. I have made a few awards with them, all with working gears.

The secret is to find a program that will generate reasonably accurate gear profiles (hopefully free) and easily transferrable to Corel.

The program to use is Allycad, and it has a free download. This program is fully functional, except that the output file is limited to 150K in size. Since very few gear drawings would ever exceed this size, this is not a problem. The web site is:

http://www.allycad.com/

The only other limitation is that the gear flanks are not true involute curves; they are circular segments. This usually will make no difference when used for light duty applications. A photo is included to show some veneer gears for decorative purposes. A closeup is included to show the curves. The "wiggles" are a problem I have been having with Y axis vibration in my laser cutter.:(

The spokes are variations created in corel.

Mark

[Mitchell Andrus]

I've made (well, my son and I) some very acceptable gears in Corel X3. I have yet to reproduce the process 'cause I haven't need to, but below you'll see a link to an old thread with an attached file that may get you started. Grab a node with the 'shape' tool and give it a wiggle.

http://www.sawmillcreek.org/showthread.php?t=41709

Mitch

[Dennis Perry]

Hi Mark, is it possible the wiggles are because of the image density setting in the advanced driver settings? This will happen if it is set to low, try using a setting of 6. If you already are then you have a problem.

Dennis

[John Esberg]

Hi... As a machinist, I often come across the requirement for gears. In a machine shop, the process can be expensive and time consuming. I have made a number of gears out of wood and acrylic for various projects that, while not the most durable gears in the world, are useful for display clocks, toys, and decorations. I have made a few awards with them, all with working gears.

The secret is to find a program that will generate reasonably accurate gear profiles (hopefully free) and easily transferrable to Corel.

The program to use is Allycad, and it has a free download. This program is fully functional, except that the output file is limited to 150K in size. Since very few gear drawings would ever exceed this size, this is not a problem. The web site is:

http://www.allycad.com/

The only other limitation is that the gear flanks are not true involute curves; they are circular segments. This usually will make no difference when used for light duty applications. A photo is included to show some veneer gears for decorative purposes. A closeup is included to show the curves. The "wiggles" are a problem I have been having with Y axis vibration in my laser cutter.:(

The spokes are variations created in corel.

Mark

Mark,

Can you explain the what you mean by an involute curve? And how this compares to a normal curve?

V/R,

DAK

[Ed Newbold]

Mark,

Can you explain the what you mean by an involute curve? And how this compares to a normal curve?

V/R,

DAKHi DAK,
Here's a great free intro to gears and involute curves:

www.cadquest.com/books/pdf/gears.pdf

Cheers,

[Mark Winlund]

Hi....

DAK.... an involute curve is a curve that changes its radius along its length. It can be generated by wrapping a string around a disk, and tying a pencil to the end of the string. Unwrap and draw!

A "normal" curve is a circular curve. It requires only 3 points to define it. (It is also the simplest type of curve.)

There are lots of curves available; for instance bezier curves as are available in Corel. Many older programs could not do bezier curves, such complex curves were a string of circular curves (Casmate was an example of this), or even straight line segments. The early corel distortions converted everything to straight line segments.

The purpose of involute curves in gear making (spur gears) is to avoid sliding contact (and therefore wear) on gear teeth. It is also intended to prevent axial vibration due to teeth engaging and disengaging.

Most modern gears are made with a machine tool that generates the involute curve as an inherent property of the cutting process. One of the machines that does this is called a hobber. I have one of these machines that I found on ebay.

Gear cutting is a fascinating subject, and can get very mathmatical in a hurry... far beyond my abilities!

Dennis... on the vibration in my Universal machine:

I think there is a problem in the machine.. it sounds like a garbage disposal working on a spoon at any speed setting above 5% (cutting vectors). I have tried the settings you suggested to no avail. The vibration is only in the Y axis.

Mark

[Rick Hutcheson]

Gears can be made in Corel. I designed 6 wood gear clocks and 8 of the Wacky Gears all in Corel.
You have to draw a tooth then use the transformation tool to duplicate around a circle. Then weld the teeth to the circle.
Try cutting this one for fun, let me know how it works for you.http://www.scrollsaws.com/images/ForSalePics/SqGear.jpg

[Mike Hood]

Thanks for that one Rick... I just found your website last night. What a small world (and a TON of scroll saws you have there).

Beautiful work you do there. Are you exclusively scroll-sawing? Or do you laser now as well?

[Rick Hutcheson]

I do mostly scroll work and now lathe work too. But I do have a CNC router that I play with a lot too.
The laser is the next toy I want to buy.

[Todd Schwartz]

Rick,

I am about 5 miles from you in Urbandale. We purchased our laser for the primary reason to cut gears. Personal clocks, one off designs. Still working on the first one. If you want to see the laser in action, drop me a note, would love to trade tours of shops.

Been to your website a while back - impressive work and collection.

Todd

[Carol VanArnam]

Rick- you said you have 6 wood clocks designed. Did you laser the gears? I am a wood worker and want to make an all wood clock with gears and everything. I'm been looking for a pattern I can make on my laser....

[Rick Hutcheson]

All of my clocks and gear projects were cut on the scrollsaw. The clock plans are not available in any format other than printed in a book.
The wacky gears I normally sell as PDF files.
I have over 2100 victorian patterns that I do sell in cdr files.

[Dave Jones]

Carol, take a look at the plans on this site for wooden clocks:

http://www.pathcom.com/~u1068740/index.html

[Ed Newbold]

Carol, take a look at the plans on this site for wooden clocks:

http://www.pathcom.com/~u1068740/index.html (http://www.pathcom.com/%7Eu1068740/index.html)Hmmm... I get a 404 Not FOund error with this link.

Cheers,

[Dave Jones]

Hmmmm... Worked OK a few minutes ago. Be right back.

[Dave Jones]

Not sure what's going on. The site worked fine a little while ago, but seems to be missing right now. If it's not back in a few hours I'll send an email to the guy who's web site it is. His name is Gary Mahony and you can see a couple of his clocks here:

http://www.woodcentral.com/shots/shot384.shtml

Here's a pic of one of his wooden clocks.

http://www.redtengu.com/images/raw/woodclock.jpg

[Mike Hood]

I was just on that site last night... seems to be gone now?

I hope we didn't kill it.. :)

Anyone else know of someplace to find some free dxf plans? I really would like to play around with the mechanics of some laser cut gears in a wooden clock.

[Carol VanArnam]

I'm with Mike- I really would love to laser cut a clock with gears... anyone know where I can find gears to try out or.... I'd love to find a wooden clock set of plans I can cut on my laser.... that would be way cool!!!!

[Dave Jones]

I sent him an email last night. The site seems to be back up today. He has lots of different clock plans, and a simple gear test drawing.

They're really designed for scrollsaws, but many should be adaptable to lasers. At least most of the parts. Some parts of some clocks may still need extra work beyond the laser, or may need to be split into several layers of thinner woods that are glued together.

Here is the link again.

http://www.pathcom.com/~u1068740/

[Lee DeRaud]

I sent him an email last night. The site seems to be back up today. He has lots of different clock plans, and a simple gear test drawing.

They're really designed for scrollsaws, but many should be adaptable to lasers. At least most of the parts. Some parts of some clocks may still need extra work beyond the laser, or may need to be split into several layers of thinner woods that are glued together.

Here is the link again.

http://www.pathcom.com/~u1068740/
Hmm...that's not the one I thought it was...
(some time later)
D'oh. Took me awhile to find this...for some reason it wasn't with the rest of my woodworking stuff:
http://www.woodenclocks.co.uk/

His parts were all originally cut by "hand", but the files are PDF and import into Corel fairly well. There's also a page somewhere in there where he talks about some experiments with using a laser to cut the gears.