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  1. #11
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 1 Week Ago Has been a member for 9-10 years. Has a total post count of 1,600. Received thanks 110 times, giving thanks to others 69 times.
    Quote Originally Posted by EddyCurrent View Post
    Thanks.

  2. #12
    Are these clearance holes for 4 and 5mm bolts?
    If so you can just drill them 4 and 5 mm because the bolts are slightly under size.
    I often drill 0.5mm larger just to get me some assembly allowance but that is just a convenience

    I think one of your worries is whether the Chinese spindle will drill holes in this size due to limited torque. Well because the drills are small you can spin them quickly so there are no issues there and I regularly mill 3 mm holes using a twist drill to 15mm depth.
    You need to watch the flutes blocking after about 10mm so need to do small pecks and wipe the bit with an oiled brush each time it comes out of the hole between pecks. If it welds in the hole it will snap off and ruin your day.

    Are these shoulder bolts? If so you can ream them after drilling to register on the shoulder.
    Last edited by routercnc; 25-07-2017 at 08:05 PM.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  3. #13
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 1 Week Ago Has been a member for 9-10 years. Has a total post count of 1,600. Received thanks 110 times, giving thanks to others 69 times.
    Quote Originally Posted by routercnc View Post
    Are these clearance holes for 4 and 5mm bolts?
    If so you can just drill them 4 and 5 mm because the bolts are slightly under size.
    I often drill 0.5mm larger just to get me some assembly allowance but that is just a convenience

    I think one of your worries is whether the Chinese spindle will drill holes in this size due to limited torque. Well because the drills are small you can spin them quickly so there are no issues there and I regularly mill 3 mm holes using a twist drill to 15mm depth.
    You need to watch the flutes blocking after about 10mm so need to do small pecks and wipe the bit with an oiled brush each time it comes out of the hole between pecks. If it welds in the hole it will snap off and ruin your day.

    Are these shoulder bolts? If so you can ream them after drilling to register on the shoulder.
    Ye, just clearance for bolts and agreed, 4mm should work too. Ill do very slight pecks and take my time with the drilling.

  4. #14
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 1 Week Ago Has been a member for 9-10 years. Has a total post count of 1,600. Received thanks 110 times, giving thanks to others 69 times.
    Many thanks to Lee Roberts for providing some drills that will be suitable for these holes :-)

  5. I have 4mm endmill length 22mm.

  6. #16
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 1 Week Ago Has been a member for 9-10 years. Has a total post count of 1,600. Received thanks 110 times, giving thanks to others 69 times.
    Quote Originally Posted by cncmachineokk View Post
    I have 4mm endmill length 22mm.
    Where did you get these from?

  7. #17
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 1 Week Ago Has been a member for 9-10 years. Has a total post count of 1,600. Received thanks 110 times, giving thanks to others 69 times.
    So I tried to drill this today, 0.25mm pecks, 24K RPM, 75mm/min plunge. Went OK initially however about a third of the way and the drill snapped. I didnt want to go faster however it was just rubbing most of the time, was the feedrate too low? It had a mix of air and WD40 on it all the time.

    Argh.

  8. #18
    what material are you drilling?

  9. #19
    Chaz's Avatar
    Lives in Ickenham, West London, United Kingdom. Last Activity: 1 Week Ago Has been a member for 9-10 years. Has a total post count of 1,600. Received thanks 110 times, giving thanks to others 69 times.
    Quote Originally Posted by johngoodrich View Post
    what material are you drilling?
    Alu.

  10. #20
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 2 Days Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,908. Received thanks 360 times, giving thanks to others 8 times.
    For deep hole drilling, you really need good lubrication, and good chip clearance.

    I've got an aluminium part that I drill on the lathe using a 6.8mm drill and 30mm deep (about 4.5 dia x depth). If the flood coolant fails (even just getting knocked away from hitting the drill), the drill will be welded to the part and snapped within a couple parts.
    Polished drills greatly reduce chip welding (I use Phantom 11.160's, which are a polished cobalt stub drill).

    For good chip clearance, you really need to ensure you're getting a good chip by using a reasonable DOC, which you may struggle to do with your spindle.

    Having just ran the figures based on the drills I use, the optimum speed in soft aluminium is around 4400RPM, with a DOC of 0.135 per revolution, which should result in a required spindle torque of 0.7NM for a sharp drill.
    Even with a solid carbide drill, the max speed is 12500rpm, but with a slightly higher DOC (and subsequently higher torque requirement - I've only got my spreadsheet setup for 11.160 drills)

    The key thing is DOC and torque. Your spindle should be pretty much constant torque regardless of speed, so if it can't manage the require torque at a few thousand RPM, then it's not likely to manage at a higher speed. You could set the VFD to give a torque boost at lower RPM (increase the max current), but you do risk overheating the windings, however for peck drilling the load will be intermittent.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

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