Drilling spindle attachment accessory

Can you guys at Carbide 3D come up with an accessory for the Shapeoko 4 machine compact router that would be an attachment for drilling? It could be attached via mounting to the spindle carriage with a modified spindle mount to hold both the compact router and the drilling attachment. It would be belt driven by the compact router using a pulley that would by inserted into the compact router collet and “geared” down to the larger pulley of the drilling attachment. You could set the compact router speed to the lowest setting (10000 rpm) and the drilling attachment speed would be ratioed down by the larger pulley to about 2000 rpm. The collet on the drilling attachment could be compatible with either a standard 3/8" drill chuck. The drilling attachment would be strictly used for drilling toolpaths only. I think it would be very useful for doing drilling toolpaths for precise hole placement and the various hole sizes one would need to make using standard drill bits. What do you think? Joseph


The issue with drilling has a few parts. If you use drill bits they are meant to run much slower than a trim router can run. The only solution for that is to upgrade to a real spindle. The second problem is sourcing cnc drill bits. They are plentiful but expensive. The cnc drill mills/bits are made for the higher speeds of a cnc.

Unfortunately there is no cheap or easy solution to drilling with a cnc.

There are quite a few cribbage board makers on the forum. They recommend some particular bits for drill the hundreds of holes required for a cribbage board. I found this on youtube and this guy sells bits specifically for cribbage boards.

This guy has a youtube web presence but please be advised he is selling himself and products. So with any web stuff buyer beware.

He also sells an 1/8" bit.

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He was not talking about using just a trim router, He was speculating on developing an attachment for a trim router that would gear down the cutting speed so you could use conventional drill bits.


I saw that but there are already solutions for the drilling problem that do not involve attachments. :grinning:


It would be great if it works but there are a few issues to surmount,

  1. If one were to fit a nomad like belt drive and attach that to the router, with pulleys well enough balanced for router RPM (chip ingress might well prevent this) and a belt rated for that linear speed and small pulley radius we still have the problem that the router bearings may well not survive the constant large radial loads required for this

  2. Drilling is not particularly precise unless you use specific spot drills to start (see reply from gdon above) and if you use a larger drill to open out the hole you will get a hole which is somewhere between a circle and triangle and vaguely near the nominal diameter. If you need a round, accurate hole, boring toolpaths or reaming are likely better bets

  3. When drilling you need to maintain a ‘feed per tooth’ just like milling, but this force is vertical and as drill bits get larger increases non linearly, this very rapidly gets to the point of visibly bending the X rail as you head up through 5-6mm in things like Aluminium and serious vibrations ensure. You can get away with a lot more in softer woods



What’s wrong with just boring out the hole with a plain old end mill?

Depending on the material it can be slower and wears out more expensive tools. Drills are very good at making holes.

  1. gears? (instead of belt)
  2. Even drilling with spot-drilling is not meant for super high tolerance. I’ve been peck drilling & hole-milling with an end mill for the aluminum parts I’m doing.
  3. I can see wearing out your Z axis if doing this a lot

I gotta believe a drill press is going to be a lot cheaper than a drill attachment.
Spot drill on the cnc for location, then move to the drill press.


Hello, thank you for all the chatter on my suggested drilling attachment accessory. Come on Carbide! I am not talking about making cribbage boards with hundreds of drilled holes all the same size. My suggestion is for a Carbide 3D accessory that if a proof of concept prototype is made and then made producible, could be offered for purchase on the Carbide 3D accessory shopping site. There are already other accessories available there that are not necessarily in high demand, but a drilling attachment for the compact router might be very desirable as a lower cost solution than using expensive CNC drill bits and a special spindle. I am looking at this for purposes of making drilled holes using standard drills or brad point drills. Standard drill or brad point drills will make very precise diameter holes. Endmills are not good at making precise diameter holes with the drilling toolpath because there is going to be some amount of runout on the compact router collet. Since endmills will cut on the side of the cutter, this runout will make your drilled holes using an endmill slightly oversized. A drill bit having no cutting ability on the side of the bit will not have this problem like an endmill. As far as the comment on the expense of CNC drill bits that can handle high rpms, I am wanting to avoid this expense for every size bit that I would need. If I can use a standard brad point drill bit with such a drilling attachment that is belt driven by the compact router, then I also would not have to purchase an expensive special spindle for drilling with CNC drill bits either. Such an attachment would probably need a condition that states that it is for using on wood only up to say 3/8" diameter holes with a feed rate recommendation. All the other Carbide comments suggesting reasons why this idea of a drilling attachment accessory wouldn’t work is all speculation because this doesn’t appear to have been made to try out. Until Carbide actually makes a proof of concept prototype, you are not going to know whether this is achievable until a prototype is made and tested.

Thank you
Joseph DeLaPaz

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