4.3 mm holes, 20 mm deep

[EddyCurrent]

Number Drill set; http://www.ebay.co.uk/itm/RDGTOOLS-6...EAAOSwx~JWFOOB

[Chaz]

Number Drill set; http://www.ebay.co.uk/itm/RDGTOOLS-6...EAAOSwx~JWFOOB

Thanks.

[routercnc]

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.

[Chaz]

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.

[Chaz]

Many thanks to Lee Roberts for providing some drills that will be suitable for these holes :-)