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  1. #1

    I've got a homemade CNC machine, 3 axis, mostly made of MDF. I'm new to CNC machines.

    I want to drill lots and lots of 10mm holes in wood. The holes will go right through the wood and are 45mm deep.

    What kind of tool would you use for that?

    Right now I've fixed a bosch hand-drill in the machine and I'm drilling the holes with a 10mm brad point drill bit. To get a good finish on the surfaces I'm drill from both sides and meeting in the middle. If I try drilling all the way through it just blows out badly on the bottom surface.

    I'm not getting that great a finish anyway (the drill is pulling fibres up) and it is taking an age! The maximum feed speed I'm using is 50mm/min and my program to drill 120 holes is taking over 90 minutes.

    I imagine I want to fit the router head and put some kind of end mill in there but I don't know what.

    Any help very gratefully received!

  2. #2
    Hi Alan welcome to the forum!

    Is the blowout on the bottom because your not using a spoil board under the stock? It sounds like it. If you do the above that should stop the blowout and allow you to get the depth you want so in this case a through cut/hole.

    Is the feed speed of 50mm/min the plunge speed or the speed your moving to the next hole? It sounds like the hand drill is spinning the bit to fast.

    Fitting the router would be the better option I would think, you could then (hopfully) setup the correct rpm for that size bit, if your doing drilling like that then a nice sharp slot drill would serve you well, however what you should probably be doing is something called peck drilling, this is where you drill down into the hole 1 or 2mm a time, rasing back out of the hole after each plunge/cut, this helps to clear the chips, keep the cutter cool and do the drilling in a nice controlled way.

    You could go with a smaller end mill say something like half, so a 5-6mm diameter, you would then machine out the holes to the 10mm size you need. A standard end mill would work but a drill bit would be better as end mills are designed for cutting sideways rather than drilling.

    Last edited by Lee Roberts; 09-01-2014 at 07:57 PM.

  3. #3
    Thanks for the welcome!

    I have tried with a spoiler board of plywood but that didn't help. Or rather it did help a bit but didn't stop the problem.

    I'm using a Colt 10mm brad point drill bit - a normal HSS wood drill bit for a hand drill. The wood is pine.

    You think the hand drill is spinning too fast? I can slow it down. The top speed of the drill is probably something like 2000rpm.

    The 50mm/min is the plunge speed. The traverses between holes are much faster.

    Would peck drilling, with all the up and down movements, ultimately be faster?

    When you say "drill bit" do you mean the kind of bit you'd put in a hand drill / drill press or do you mean some kind of special end mill for drilling you'd use in a router head? I'm presuming you can't put a normal drill bit in a router head because it would spin too fast. The router head I have is a cheap hand router with limited speed control. Can you recommend a router head?


  4. #4
    You want a router dowel drill like this Wealden Tool Company Limited Dowel

    Unfortunatly the size you want is showing out of stock here but will give you idea of what to look for.

    You may need to peck but just do 2 -3 pecks to clear the hole.

  5. #5
    Dowel drill 10mm diameter x 35mm
    This is a bit pricey if you are in a rush to get the job done, i am fortunate and have a lathe so make a split collet to fit my router and adjust the speed to suite, i use a standard drill, grind it flat bottom then just relieve the centre so you are cutting on two points(works a treat)

  6. #6
    oops! sorry about that the one shown isn't long enough, ground drill will be fine

  7. #7
    Gave Wealden a ring and they are expecting restock 28th Feb

  8. #8
    Hi Mike,

    Thanks for calling Wealden!

    I assumed the flutes on a normal drill are too steep to run fast in a router but you're saying it will work if I flatten the bottom and recess the middle? What speed would I run the bit at? And can you recommend a reasonably cheap router head?

    Many thanks!

  9. #9
    Thanks for the advice JAZZCNC!

    When you don't know the word for something it's really hard to search for it. It looks like "dowel drill" are the magic words!

  10. #10
    Hi Alan
    Can you give us some idea of what you are trying to make/what size/what quantity and the accuracy required on your hole location ? even if you could fit a router to your machine it wouldn't last very long working 9 hours a day so perhaps there's another option.

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