Free 186 More Best Homemade Tools eBook:  
Get 2,000+ tool plans, full site access, and more.

User Tag List

Page 1 of 2 1 2 LastLast
Results 1 to 10 of 11

Thread: Mini Metal Lathe Digital Tachometer

  1. #1
    Supporting Member Paul Jones's Avatar
    Join Date
    May 2014
    Location
    Del Mar, California
    Posts
    1,231
    Thanks
    5,810
    Thanked 1,440 Times in 655 Posts

    Paul Jones's Tools

    Mini Metal Lathe Digital Tachometer

    I was inspired by the “Lathe & Mill Tachometer” post by Catfish (see the 4-2-2014 post by Randy Richard) and decided to install the same type of product on my 7" swing mini lathe I bought new in 1993. Randy advised searching for “Hall Effect Tachometer” parts on eBay. I found many offered in the range of $13 to $20 and I purchased one with a blue LED display. The eBay purchase included the LED display with bezel and its attached circuit board that snaps into a rectangular cutout, the cabled Hall Effect sensor NPN with nuts and lock washers, and a small rare-earth magnet. The simple wiring diagrams are posted with the products photos on eBay. I used eBay “Buy It Now” and the parts arrived within two days.

    I mounted the digital display into a rectangular hole I cut into the cowling covering for the change gears at the rear of the lathe. The cowling space had sufficient room for this thin electronic part and did not require mounting a separate enclosure. I cut the opening using a Dremel tool with a reinforced abrasive wheel. However, the enclosure near the top of the cowling has very little room inside for the cabled sensor. This restriction required installing the sensor from the outside at the back of the cowling covering. This mounting works well and allows less than a 2 mm gap from sensor end to the spinning magnet mounted near the rear of the spindle (sensor specs require a 1 to 10 mm gap). The north end of magnet must be facing the sensor for it to work correctly. You have a 50:50 chance doing this correctly so I delayed epoxying the magnet in place until this could be tested. I decided to use 5-minute type epoxy to make sure the magnet stayed in place when the spindle spins at over 3000 RPM.

    The sensor and power supply wires were secured to the inside walls of the cowling with silicone caulk and this keeps the wires safely away from any spinning gears. Also, inside the cover there are several strengthening ribs that I drilled through for passageways to secure the wires very close to the side walls. The tachometer electronics requires 9V – 15V DC and I measured the current at less than 40 mA. I purchased a small 120 VAC to 9 VDC power supply listed on eBay. The power supply was mounted inside the lathe speed control box (see photo) and connected after the power switch into the 120 V AC screw terminal connector. Later I may consider adding a separate on/off switch for the display. Finally, I used an optical tachometer verified the digital tachometer output was correct.
    Attached Thumbnails Attached Thumbnails Mini Metal Lathe Digital Tachometer-mini-lathe-tachometer-installion.jpg   Mini Metal Lathe Digital Tachometer-mini-lathe-tachometer-120vac-9vdc-power-supply.jpg  

    186 More Best Homemade Tools eBook
    Last edited by Paul Jones; Mar 21, 2016 at 08:49 AM.

  2. The Following 3 Users Say Thank You to Paul Jones For This Useful Post:

    Inchbeag (Oct 31, 2014), jjr2001 (Sep 1, 2016), kbalch (Oct 30, 2014)

  3. #2
    Supporting Member Catfish's Avatar
    Join Date
    Oct 2013
    Location
    Mariposa, California
    Posts
    268
    Thanks
    55
    Thanked 414 Times in 156 Posts

    Catfish's Tools
    Paul,
    Very nice clean install. I like having a tach on the lathe.
    Randy

    2000 Tool Plans

  4. #3
    Supporting Member Paul Jones's Avatar
    Join Date
    May 2014
    Location
    Del Mar, California
    Posts
    1,231
    Thanks
    5,810
    Thanked 1,440 Times in 655 Posts

    Paul Jones's Tools
    Randy,

    Thank you and thanks again for the tip on where to purchase the components. Today, I used eBay to purchase another HE sensor and tachometer display for my drill press. I plan to install it soon and will post it.

    Also the tachometer versions I bought use one surface mount IC and a few surface mount resistors and capacitors. I choose this version vs. ones with more discrete components because I thought maybe the surface mount technology may draw less current. Originally wanted to tap in directly to the correct voltage somewhere on the lathe electronics to my motor speed regulator but would put a 0.1 quick-blow inline fuse in the connection to protect it. I decided against this only because I didn't want to chance destroying a $150 controller board for the less than $20 tachometer so I used a separate power supply. Just an FYI the tachometer with surface mount components draws current ranging from 25 mA at zero RPM and up to 36 mA at 3000+ RPM.

    Paul

  5. #4
    Supporting Member Catfish's Avatar
    Join Date
    Oct 2013
    Location
    Mariposa, California
    Posts
    268
    Thanks
    55
    Thanked 414 Times in 156 Posts

    Catfish's Tools
    We are off to Hawaii for 10 days soon, when I get back I will order one up for the Lance. I am surprised how well these units work.
    Randy

  6. #5
    kbalch's Avatar
    Join Date
    Jun 2012
    Location
    Clermont, FL
    Posts
    5,034
    Thanks
    2,275
    Thanked 531 Times in 383 Posts
    Thanks Paul! I've added your Mini Lathe Digital Tachometer to our Electrical and Measuring and Marking categories, as well as to your builder page: Paul Jones' Homemade Tools. Your receipt:


  7. #6
    Supporting Member Hotz's Avatar
    Join Date
    Feb 2013
    Location
    South of Brazil.
    Posts
    360
    Thanks
    157
    Thanked 75 Times in 51 Posts

    Hotz's Tools
    Paul congratulated for excellent finish assembly. Very interesting this accessory.
    You gave me an idea for the future perhaps to the reader phase or ABS sensors (automotive) be able to pass a satisfactory signal.
    Projects and ideas for the future, thanks for sharing.

    Paul.
    Sorry my mistakes in english.
    to share your tip >>> http://www.homemadetools.net/forum/tool-tips-tricks/ <<<

  8. #7
    Content Editor
    Supporting Member
    DIYer's Avatar
    Join Date
    Aug 2013
    Posts
    3,056
    Thanks
    772
    Thanked 1,850 Times in 1,652 Posts
    Neat work! I love tidy jobs.

  9. #8
    Supporting Member Christophe Mineau's Avatar
    Join Date
    Jul 2014
    Location
    France, Brittany !
    Posts
    913
    Thanks
    825
    Thanked 1,687 Times in 481 Posts

    Christophe Mineau's Tools
    Hi,
    Maybe for a much slower application, I wonder if one could'nt use a bike computer, it's the same principle, isn't it ?
    Cheers !
    Christophe
    ________________________________________________________________
    Visit my Website : http://www.labellenote.fr/
    Facebook : La Belle Note
    All my personal works, unless explicitly specified, are released under
    Creative Commons BY-NC-SA license.

  10. #9

    Join Date
    Oct 2014
    Posts
    1
    Thanks
    1
    Thanked 0 Times in 0 Posts
    Christophe, yes Bike computers do work but this one is illuminated so easier to read. Bike Computer LCDs are not good when looked at an angle.
    Nice application Paul, just bought one on eBay

  11. #10
    Supporting Member Paul Jones's Avatar
    Join Date
    May 2014
    Location
    Del Mar, California
    Posts
    1,231
    Thanks
    5,810
    Thanked 1,440 Times in 655 Posts

    Paul Jones's Tools
    Thank you DIYer. I made one more improvement by attaching with silicone caulk, a thin Plexiglas cover at the back of the display to protect the open circuit board from metal particles. Also, all the soldered connections are covered with heat shrink tubing to prevent electrical shorts. Installing the tachometer display and wiring took about an hour (before waiting for the silicone to harden) and was one of the easiest tool projects I have completed this year. Paul

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Tags for this Thread

Bookmarks

Posting Permissions

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