544,220 active members*
3,078 visitors online*
Register for free
Login
IndustryArena Forum > MetalWorking > General MetalWork Discussion > hole drilling with a high-speed (low-torque) 3-axis CNC router?
Results 1 to 6 of 6
  1. #1
    Member
    Join Date
    Dec 2019
    Posts
    48

    Question hole drilling with a high-speed (low-torque) 3-axis CNC router?

    I need to drill 7/16" diameter x 2" deep holes in 6061-T6 aluminum. Making 50+ parts, 9 holes each. Problem is my cnc router doesn't have low-rpm torque. How do people with high-speed spindles mill or drill deep holes?

    From what I understand, and recently tested, just pushing up the RPMs into a range my spindle can support isn't a good answer. At least using standard high-speed-steel twist trill bits was pretty ugly, resulting in pilling/etc even when I got it to work by shallow pecking. I understand my chipload was way too small at that high-rpm/low-feed setup but watching it bog, my guess is horsepower requirements at higher feeds won't work.

    Is the answer to use a carbide (full or carbide tip) twist drill bit, just use high speed (peak torque is above 15K RPM) and see what feed it can sustain?

    Is pre-drilling a pilot hole part of the solution? I hate to do more (manual) tool changes but if that's the best solution, ok.

    Or should I use a smaller end-mill, spiral cut the hole & try to evacuate the chips the best I can? Would high pressure compressed air (mist) or medium pressure flood remove chips from this deep pocket better?

    Right now I'm thinking a combination of using carbide-tip twist drills, pre-drilling a 1/4" pilot hole + shallow pecking might have the best combination of job time/tool cost/etc and might be the best way to go.

    Or am I missing something? I'm pretty new to the cnc-machining game so if some folks with actual experience could tell me what works best I'd really appreciate it.

    Thanks

  2. #2
    Registered
    Join Date
    Jan 2008
    Posts
    1267

    Re: hole drilling with a high-speed (low-torque) 3-axis CNC router?

    Don't drill with a router spindle, they are not built for the axial loading and the RPM are too high (ok sometimes for quite small holes)

    Spiral pocket with a small end mill

    Compressed air will evacuate chips better

    Even in wood I will either spiral pocket holes, or just spot drill then follow up with manual drilling (unless very small hole where RPM are appropriate and axial load is low).
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  3. #3
    Registered
    Join Date
    Jan 2018
    Posts
    709

    Re: hole drilling with a high-speed (low-torque) 3-axis CNC router?

    Quote Originally Posted by dwg123 View Post
    I need to drill 7/16" diameter x 2" deep holes in 6061-T6 aluminum. Making 50+ parts, 9 holes each. Problem is my cnc router doesn't have low-rpm torque. How do people with high-speed spindles mill or drill deep holes?

    Or should I use a smaller end-mill, spiral cut the hole & try to evacuate the chips the best I can? Would high pressure compressed air (mist) or medium pressure flood remove chips from this deep pocket better?

    Right now I'm thinking a combination of using carbide-tip twist drills, pre-drilling a 1/4" pilot hole + shallow pecking might have the best combination of job time/tool cost/etc and might be the best way to go.

    Or am I missing something? I'm pretty new to the cnc-machining game so if some folks with actual experience could tell me what works best I'd really appreciate it.

    Thanks
    If I want anything above 7mm or 9/16" drilling I use a smaller size end mill and spiral / helix it in.
    It's way faster.
    I spiral all the way down leaving stock of about 0.1mm on. Then I do a finish pass at final depth to smooth it out and remove the 0.1mm. This is at 1" deep holes though. Takes me about 1 minute for this (mill). Something like 2500rpm, 2.5deg spiral, and whatever feedrate calculates about right.
    For 2" I'd spiral all the way down and then do a finish at 1" and 2".
    I do use flood cooland but mist or air should work if directed ok.

    For 7/16" (11.13mm) I'd prob use an 8mm 3 flute bit. (I always use the cheap chinese throwaways for spiral drilling).
    At 2" deep I'd use my long bit. These can vibrate a little if going too fast.

    But that's just how I'd do it.

  4. #4
    Member
    Join Date
    Dec 2019
    Posts
    48

    Re: hole drilling with a high-speed (low-torque) 3-axis CNC router?

    Thanks for sharing your knowledge guys. I think you're right that the best way forward is to spiral mill the holes & work on deep pocket chip removal.

  5. #5
    Registered
    Join Date
    Mar 2017
    Posts
    823

    Re: hole drilling with a high-speed (low-torque) 3-axis CNC router?

    Where does the info on cnc router spindles not being able to handle axial loads (and whatnot) come from?

    I'm far from being an expert but it sounds wrong...

    Even a cheap Home Depot router spindle is considerably more robust than any hand drills and at least comparable to a cheap Ryobi drill press (for loads in any direction).

    The basic design of the spindles is mostly the same except that drills usually have fewer bearings (which is why you can't use a drill press spindle to mill).

    The ER collet system is also way more robust than your average drill chuck (even the key kind).

    The bigger problem I can see is the spindle speed. I.e. Most router spindles are too fast and have too little torque to use regular drill bits (or HSS end mills). But, there are specialist tools specifically made for drilling with high speed spindles.

    I can't see anything in my drill press spindle (that isn't also in a router) that would help with axial loads. What am I missing?

    I mean, obviously a high speed spindle isn't the right tool for the job if drilling steel is the main purpose. But what harm would there be in some occasional slow (feed) drilling of aluminum and wood on a CNC router?

  6. #6
    Member
    Join Date
    Jan 2005
    Posts
    12411

    Re: hole drilling with a high-speed (low-torque) 3-axis CNC router?

    Quote Originally Posted by Goemon View Post
    Where does the info on cnc router spindles not being able to handle axial loads (and whatnot) come from?

    I'm far from being an expert but it sounds wrong...

    Even a cheap Home Depot router spindle is considerably more robust than any hand drills and at least comparable to a cheap Ryobi drill press (for loads in any direction).

    The basic design of the spindles is mostly the same except that drills usually have fewer bearings (which is why you can't use a drill press spindle to mill).

    The ER collet system is also way more robust than your average drill chuck (even the key kind).

    The bigger problem I can see is the spindle speed. I.e. Most router spindles are too fast and have too little torque to use regular drill bits (or HSS end mills). But, there are specialist tools specifically made for drilling with high speed spindles.

    I can't see anything in my drill press spindle (that isn't also in a router) that would help with axial loads. What am I missing?

    I mean, obviously a high speed spindle isn't the right tool for the job if drilling steel is the main purpose. But what harm would there be in some occasional slow (feed) drilling of aluminum and wood on a CNC router?
    Correct there is no problem with drill with any spindle, depending on speed and size of drill, and the Hp available, this is a thrust loading, Milling is a different story though
    Mactec54

Similar Threads

  1. high speed and low speed dual spindle CNC mill
    By GusBiz in forum Mechanical Calculations/Engineering Design
    Replies: 0
    Last Post: 02-13-2021, 08:54 AM
  2. Replies: 1
    Last Post: 01-16-2020, 11:41 PM
  3. Low speed high torque VF motor?
    By Azalin in forum Spindles / VFD
    Replies: 1
    Last Post: 10-18-2016, 04:12 AM
  4. High Efficiency and Low Cost 4 axis cnc router machine
    By Dekcelcnc in forum News Announcements
    Replies: 0
    Last Post: 02-24-2016, 09:14 AM
  5. High-Speed 3 (4?) axis cnc router
    By rherman in forum DIY CNC Router Table Machines
    Replies: 29
    Last Post: 10-21-2005, 04:31 AM

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
  •