Deep drilling

[Trevor Drabble 1Participant @trevordrabble1]

When I worked at Ital in Sheffield we were part of the Clarkson group ) we made small diameter but long crankshaft drills ( minimum length 10x diameter ) that were purpose made for such tasks . In order  to minimise wander , they had thicker webs , worm type flutes and modified points to reduce size and angle of chisel points . The most common problem we encountered were the drills not being driven fast enough and also the application of excessive feed , resulting in the drill wandering and sometimes even breaking within the work .

Assuming only standard HSS drills and limited facilities are available to OP , suggest using highest speed possible , the use of diligent thinning of the point to reduce chisel width and angle ( from 130° to around 115°) , copious use of paraffin to prevent the chips from binding to the lands ( since drilling aluminium) and also light , repeated pecking technique . Cumulative use of the above should minimise wander .

Hope the OP finds the above of constructive use .

[Speedy Builder5Participant @speedybuilder5]

Pleased to say that the deep drilling following advice on here – Spot drill, jobber and extended drill gave perfect results.  Approx 3″ deep by 4mm diameter in Al Alloy using WD40 as lubricant, flush of debris.

Thanks to all

Bob

[bernard towersParticipant @bernardtowers37738]

Most times with jobs like this its the attention to detail that sees you through not just wade in and hope for the best, glad it went well.

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