Need help to drill at an angle

[garage nut]

Need to fit some rod holders to the boat today.
fortunately for todays hole...45mm I have a 43mm hole saw. I am sure once it is done it will be closer to 45 than 43.

2 problems..1 there is a 12mm hole in the centre where I need a 4.8mm hole. Solution use yesterdays method and create a new hole with a small piece of Ali.



Problem #2.....the rod holder must be at 55 Deg meaning I have to drill the pilot hole through my Ali at 55 Deg, What is the "agreed" method of drilling a hole at 55 or any angle for that matter through a piece of steel? Fot this project it would not matter if the hole is a mm or so off as the drill is pressed to the side.

ps I know I can drill the hole in the boat square and then use the pencil grinder to get it to the desired angle that is not the point of this question.

[mklotz]

Problem #2.....the rod holder must be at 55 Deg meaning I have to drill the pilot hole through my Ali at 55 Deg, What is the "agreed" method of drilling a hole at 55 or any angle for that matter through a piece of steel? Fot this project it would not matter if the hole is a mm or so off as the drill is pressed to the side.

ps I know I can drill the hole in the boat square and then use the pencil grinder to get it to the desired angle that is not the point of this question.

Presumably you intend to do this with a handheld drill motor or something similar?

I would first prepare a 55deg angle guide block that could be clamped in place to guide the drill.

The biggest problem is getting the drill started. Once it's immersed in the material it can drill as usual but standard drills are not suited to starting hole at such an angle. A machinist would first use a (flat-ended) milling cutter to make an angled flat in the material so the (angled) drill could begin drilling on a surface perpendicular to its point.

If you don't have a milling cutter, perhaps you can grind a surplus drill such that it's a flat-ended cutter. This is done all the time to create flat-bottoms in holes drilled with conventional drills.

[Frank S]

It seems as though you are planning on drilling though the gunnel of the boat. If so these are usually quite thick so you could start the pilot hole vertical until the point has started to drill then lean your drill to the angle you want. Once the pilot is through drilling with the hole saw will require going very slow at first contact. Hole saws can grab and gouge quite unexpectedly and will continue to do so until they make full circular contact Using a hardened drill rod as th epilot guide instead of a drill bit helps some but care must still be taken

[ranald]

Hi Garage nut,

This method is a bit slower but no special tooling is required. You could try drilling the desired sized hole at 90 deg in DAR straight grained hardwood that sits neatly in the gunwale . It looks like you have a sandvik hole saw so it has no external strengthening ribs and can be continued with an extension but the waste/centre has to be removed periodically with a chisel or small router etc. Then cut at the desired 55 deg angle: continue drilling & remove a slice (10 or 12 mm, 1/2") from the block also at 55 deg : continue the hole further & cut the timber/lumber at desired angle ie 55 degrees. Then just shy of the hole depth leaving some solid wood on the shallowest part of the hole ( and quite a bit on the opposite side) cut the main drilling support block again at 55 deg. Mark out the fixing bolt holes on the gunwale directly or by stick-on template. Drill pilot holes(for screws later) . Attach the "slice" in position with double sided tape (or masking tape in loops) & mark and drill the fixing holes, all the way through, from under the gunwale. This is your template for main drilling block. Transfer the pilot holes to the main drilling block. Also use the "sleeve" as a template for a solid block or thick plywood which is attached under gunwale and main drilling block on top of gunwale :screw all together through the pilot holes. As Aluminium has a grain and is like wood in many properties there is less resistance if the gunwale is supported on both sides. Care still needs to be exercised to avoid jamming. I would remove the holesaw pilot bit for the final drilling through the aluminium gunwale. The templates/blocks can then be used for further holes for the rod holders of same model.

You have very little hardwood except olive so you may have to source from Tassie=LOL. Watch out for those Great White munchies when you launch.

Hope this helps and gives a different method to investigate.

[garage nut]

Thanks to all

I used a 6 mm endmill to create the flat as suggestedand then drilled the 4.8mm for theholesaw center drill. This gave me the perfect start for the 55 deg hole. Then the problem with the "waste center bit" was encountered. thanks for that advice. Ended up cutting the hole then at 90Deg to get rid of the waste. then the "guide" constructed to guide the drilling machine helped to clear the last little bit of waste on the other side bottom.

So can see I had to use a bit of everybodies advice for this job.

THANKS