How to Cut Gears with CNC


Results 1 to 12 of 12

Thread: How to Cut Gears with CNC

  1. #1
    Member kolias's Avatar
    Join Date
    May 2009
    Location
    Canada
    Posts
    1326
    Downloads
    0
    Uploads
    0

    Default How to Cut Gears with CNC

    The attached shows a 7” OD gear I want to cut with my CNC out of 1/2" Plywood and I have 8 more similar gears to cut of various size. I will use a 1/16” 1 flute endmill at 12K RPM, 40 IPM

    Never did this before and in my CAM program I select “Chains” and the whole gear is selected, I ask to make each pass 1/16” deep and I do a simulate the cut and the simulation completes. Is this the right way to cut a gear?

    Next question is how to hold the plywood on my table. I normally use 1” long finish nails or double sided tape to hold to plywood into the top of my table but this gear has so many openings inside so I don’t know where to put the nails or tape. Any suggestions?

    Thanks

    Similar Threads:
    Attached Thumbnails Attached Thumbnails How to Cut Gears with CNC-gear-wheel-image-jpg  
    Nicolas


  2. #2
    Community Moderator difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    729
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    I would use a 1/4" compression bit to do the bulk of the cutting, followed by a 1/8" bit for the places the 1/4" bit can't get to. Is there a reason to use the 1/16" bit? I've cut plenty of gears with 1/4" and 1/8" and they have worked great.

    For the gears I cut I just used a screw in the center (hole cut with CNC to ensure being in the center).
    How to Cut Gears with CNC-small-gear-cnc-jpg
    How to Cut Gears with CNC-larger-gear-cnc-jpg

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  3. #3
    Member kolias's Avatar
    Join Date
    May 2009
    Location
    Canada
    Posts
    1326
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    Wow what beautiful gears you got there David, thanks for your time

    Never heard of a compression bit but I will search and see what I can get

    Thought the 1/16” will do a better job in between the gears teeth but I will give it a try with 1/8” on pc of scrap.

    Wouldn’t a single screw at the center allow for the ply to turn during the cut?

    Nicolas


  4. #4
    Community Moderator difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    729
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    Quote Originally Posted by kolias View Post
    Wouldn’t a single screw at the center allow for the ply to turn during the cut?
    Thanks! I have cut about 500 Longworth chucks out of 1/2" BB and about 400 of those had a single screw in the center and a couple of them spun. It just made more sense for the last hundred or so to add another screw through one of the finger holes to ensure it didn't spin. But on the gears I've never had one spin; seems like I've cut about 20 gears.

    Given the way I cut the gears, to clear out the inside first, it would be easy to add a hold-down screw with a washer or small clamp to the interior of the gear to ensure it doesn't spin if that makes you feel more secure.

    When I designed the gears in Fusion 360 I made certain the 1/8" bit was smaller than the smallest radius at the bottom of the teeth and it cut perfectly.



    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  5. #5
    Member kolias's Avatar
    Join Date
    May 2009
    Location
    Canada
    Posts
    1326
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    Thanks for the info David, cutting the inside of the gear first sound a good approach and I will do so.

    Nicolas


  6. #6
    Member
    Join Date
    Jun 2012
    Location
    usa
    Posts
    182
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    CA glue and painters tape works much better than double sided tape. Cut the center hole (or other opening) in the gear first and add a safety screw if you don't feel confident with the CA glue.

    Use the largest endmill which can do the smallest radius on the teeth. The hardest part of a job like this is controlling the tearout in the plywood



  7. #7
    Member kolias's Avatar
    Join Date
    May 2009
    Location
    Canada
    Posts
    1326
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    Quote Originally Posted by difalkner View Post
    Thanks! I have cut about 500 Longworth chucks out of 1/2" BB and about 400 of those had a single screw in the center and a couple of them spun. It just made more sense for the last hundred or so to add another screw through one of the finger holes to ensure it didn't spin. But on the gears I've never had one spin; seems like I've cut about 20 gears.

    Given the way I cut the gears, to clear out the inside first, it would be easy to add a hold-down screw with a washer or small clamp to the interior of the gear to ensure it doesn't spin if that makes you feel more secure.

    When I designed the gears in Fusion 360 I made certain the 1/8" bit was smaller than the smallest radius at the bottom of the teeth and it cut perfectly.
    A wonderful video David, and BTW what is “Longworth Chuck” and where/how it is used?

    Notice you are going 150 some IPM !!! wow that’s pretty fast. I never went more than 50 IPM and despite my cnc is built with 3/8” thick flat bars/plate I don’t have the experience to run it so fast.

    Thanks for your time

    Nicolas


  8. #8
    Member kolias's Avatar
    Join Date
    May 2009
    Location
    Canada
    Posts
    1326
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    Quote Originally Posted by elfrench View Post
    CA glue and painters tape works much better than double sided tape. Cut the center hole (or other opening) in the gear first and add a safety screw if you don't feel confident with the CA glue.

    Use the largest endmill which can do the smallest radius on the teeth. The hardest part of a job like this is controlling the tearout in the plywood
    It’s true that the tearout in the plywood is a PITA but after a cut I use some wood putty/filler and a lot of sanding afterwards and it looks pretty good but time consuming. I noticed David’s video below and I see no tearout but I assume he is using compression endmill and good quality plywood.

    What’s “CA glue”? If it is carpenters glue how do you take it apart after the cut?

    Nicolas


  9. #9
    Community Moderator difalkner's Avatar
    Join Date
    Nov 2014
    Location
    United States
    Posts
    729
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    Quote Originally Posted by kolias View Post
    A wonderful video David, and BTW what is “Longworth Chuck” and where/how it is used?

    Notice you are going 150 some IPM !!! wow that’s pretty fast. I never went more than 50 IPM and despite my cnc is built with 3/8” thick flat bars/plate I don’t have the experience to run it so fast.

    Thanks for your time
    Thanks for watching! I was actually cutting at 175ipm and have cut those at 250ipm but the job is over so quickly that I feel like 175ipm is sufficient.

    A Longworth chuck is used to turn or clean the bottom of bowls after you've completed turning the inside/outside of the bowl. It's named after the inventor, Mike Longworth of Australia. Here's a brief video showing how they work -
    Quote Originally Posted by kolias View Post
    It’s true that the tearout in the plywood is a PITA but after a cut I use some wood putty/filler and a lot of sanding afterwards and it looks pretty good but time consuming. I noticed David’s video below and I see no tearout but I assume he is using compression endmill and good quality plywood.

    What’s “CA glue”? If it is carpenters glue how do you take it apart after the cut?
    Yes, good quality plywood; I use 1/2" (12mm) Baltic Birch with a compression bit and cut the slots, finger holes, and perimeter in one pass. They come out very clean, indeed.

    CA is cyanoacrylate or super glue.

    David
    Romans 3:23
    CurlyWoodShop - www.etsy.com/shop/CurlyWoodShop
    David Falkner - www.youtube.com/user/difalkner
    difalkner - www.instagram.com/difalkner


  10. #10
    Member
    Join Date
    Jun 2012
    Location
    usa
    Posts
    182
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    Quote Originally Posted by kolias View Post
    It’s true that the tearout in the plywood is a PITA but after a cut I use some wood putty/filler and a lot of sanding afterwards and it looks pretty good but time consuming. I noticed David’s video below and I see no tearout but I assume he is using compression endmill and good quality plywood.

    What’s “CA glue”? If it is carpenters glue how do you take it apart after the cut?
    Put one layer of tape on the spoilboard and one on the stock. Super glue between the layers. It comes apart easily, but holds the parts well.



  11. #11
    Member kolias's Avatar
    Join Date
    May 2009
    Location
    Canada
    Posts
    1326
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    Quote Originally Posted by elfrench View Post
    Put one layer of tape on the spoilboard and one on the stock. Super glue between the layers. It comes apart easily, but holds the parts well.
    Thanks, sound very good and easy

    Nicolas


  12. #12
    Member kolias's Avatar
    Join Date
    May 2009
    Location
    Canada
    Posts
    1326
    Downloads
    0
    Uploads
    0

    Default Re: How to Cut Gears with CNC

    I bought this set of 5 compression endmills (shipping included) which hopefully will do a better job when I start cutting the gears I want into 1/2" plywood.

    Since I’m not an experienced cnc user I’m asking how do you set the –Z axis limit switch with such a short endmill. The way I see it I will have probably about 1/2' between the bottom of my chuck to the top of my plywood which is not very much.

    When I start a cut I use the Mach3 Auto Tool Zero utility which sets my endmill to 1” above the plywood. When the cut starts the endmill will eventually go in steps to -1/2” to finish my cut.

    Instead of using the -Z limit switch is there perhaps a line I can insert into the g-code to prevent the endmill going below -1/2” ?
    If yes, where do I insert this line?

    Thanks

    Attached Thumbnails Attached Thumbnails How to Cut Gears with CNC-5-pcs-end-mills-jpg  
    Nicolas


Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

How to Cut Gears with CNC

How to Cut Gears with CNC