Drilling holes

zoidberg

zoidberg

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.... in mast

I need to drill some 30mm holes in a 3mm mastwall. The tool needs to be handheld, for the mast cannot be taken to a bench-mounted pillar drill. What's to choose between a 30mm step drillbit, and a 30mm cone drillbit? Oh, and optimum lubricant...?
 
zoidberg said:
.... in mast

I need to drill some 30mm holes in a 3mm mastwall. The tool needs to be handheld, for the mast cannot be taken to a bench-mounted pillar drill. What's to choose between a 30mm step drillbit, and a 30mm cone drillbit? Oh, and optimum lubricant...?
Click to expand...

Cutting fluid is 90~95% water, the main job is cooling, not lubrication.

+1 for hole saw.
 
Swarf ? Probably worth having a suction cleaner hose near the bit to minimise the amount of sharp swarf falling into the body of the mast and becoming embedded in halyards.
 
If you are doing it with the mast still up, do not do what I did & drill through the halyard whilst at the top of the mast whilst sitting in a bosuns chair with no spare halyard ( nothing up there to use)
New dynema halyards are expensive

Halyard 2.jpg
 
I imagine the wall is curved, so a hole saw is the way as suggested above.
Lubricant is a bit more tricky depending how difficult / important cleaning up is going to be: WD40 prevents clogging of the saw by the soft material but will run everywhere then attract dirt if not removed, bearing grease would stay put and hold a lot of the swarf so you can remove it (cutting compound melts and runs), plain water will probably prevent clogging and not leave any residue inside the mast. Using nothing will most likely be fine if the hole saw is new anyway. You can pick the teeth out part way through the job if necessary.
If the hole diameter is critical it is wise to do a test run on something else and measure first, also make sure that when the hole saw is cutting, the pilot drill is far enough through the job that it is running on plain shank not flutes, as they can cut sideways and allow the saw to wander.
Hole saw swarf is fairly compact and gritty so I would expect it to not cling to the ropes but a Hoover operator would be useful nonetheless.
I hope that wasn't all too boring
 
You can lead some old haliards or cheap polypropylene line through the mast whilst you do the drilling this will prevent the swarf getting into your proper haliards or you ruining them by drilling through. Hang on tight to the drill with both hands as it may snatch and twist your wrist when the main cutter engages. When picking your spot to drill consider lining up vertically below any other holes if you can as these places are less likely to have internal flanges in the extruded section
 
I've had very good results with Bosch colbolt holesaws not that you'll need them for aluminium but possibly future projects. The worse thing will be the aluminium clogging up the teeth, slow and steady and stopping now and then to check.
 
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