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  1. #1
    Hi,

    I have a design for some coat hooks I want to use in a few places around the house. This uses some rough green oak for the 'base' and 30mm bought-in machined dowels for the 'pegs'. I'm not much of a woodworker :) but I did a rough little prototype to check the design and figure out a fixture to drill the 30mm holes at a 30 degree angle on a drill press:

    Click image for larger version. 

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    (Please ignore the peg at 90 degrees - that was only done to check the dowel fit.) I was pleased to find that the 30mm Forstner bit I used gave a clean entry cut even being used at a 30 degree angle. The problem was that the '30mm' dowels are slightly bigger that the '30mm' Forstner bit I used. The discrepancy is about 0.3mm with the dowel being ~0.2mm too big and the holes ~0.1mm too small. I would be happy making the holes 0.5mm bigger than the dowels giving an easy fit and room for some glue.

    The question is how? I don't have a lathe and anyway this would be tricky because of the 30 degree angle. Some kind of adjustable bit would work. Or I could buy a bunch of different bits to find one that cuts oversize - but I would need a bit that was happy with an entry angle of 30 degrees without tearing out the side of the hole. In one example I want to put about 30 'hooks' in a line so manual adjustment with a sander isn't looking a great way to go (and the dowels are quite hard anyway.) A trimming router and an oval template - I could cnc machine that in aluminium I guess? Any other ideas? (And yes, I know my mitre saw blade is blunt :) )

    Ta, Alan

  2. #2
    As you say , a Forstner bit is the ideal drill type to drill your angled holes - however they don't come in fractional sizes. However just as in metalwork, precise holes are reamed after drilling, so you want to open out your initial hole just a little. I would be tempted to get a cheap 30mm Blacksmiths bit that has a reduced shank so you can chuck it in a power drill. Then just use it to ream out the holes a bit by hand to get the fit you want.

    You say the base is 'green' ie wet - as it dries this wood will shrink making your holes smaller. If your dowels are too snug a fit, then you might get splits, however get ot righ and you will get a tigher fit that will last better than any glue!

    Hope that helps

  3. #3
    Thanks and good point about the shrinkage of the green oak.

  4. #4
    Kitwn's Avatar
    Lives in Exmouth, Australia. Last Activity: 3 Hours Ago Has been a member for 2-3 years. Has a total post count of 595. Received thanks 78 times, giving thanks to others 15 times.
    Sandpaper and elbow grease!
    Engineering is the art of doing for ten shillings what any fool can do for a pound.
    Wellington.

  5. #5
    Hi
    If the dowel wood is green you can try putting the dowels in an oven or micro wave ( you'll have to experiment a bit on how long and how hot, but it should get you out of trouble. If you have any kind of table disc or belt sander you could rig up a v block jig and roll the dowels against the sander.. One final method take a piece of your dowel, screw a woodscrew into the end of it (as central as possible) leaving15mm stickng out, cut the head off ,chuck it in a drill and run it against some coarse sandpaper making a very slight taper till it's small enough to fit your holes plus a bit extra for the thickness of your sandpaper , super glue some sandpaper on the dowel and enlarge your hole to taste .
    Cheers
    Andrew

  6. #6
    If you have a lot of holes to do might be worth investing £5 in one of these Abrasive Sanding Flap Wheel Mop 30mm KLINGSPOR

    The other way to do it is put a sawcut across the dowel and press fit it into the hole.

    Phill

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  7. #7
    Hey you guys are smart :)

    I'll try to remember to report back after I try those methods.

    Thanks, Alan

  8. #8
    This is cute but not available atm:

    https://www.amazon.co.uk/Forstner-Bi.../dp/B01GRN28QW

  9. #9
    You can get an adjustable flat bit from Screwfix. https://www.screwfix.com/p/adjustabl...questid=832185

  10. You can make a circular sanding mop easy with a bit of metal rod, put a sawcut across the diameter wide enough to slot a strip of sandpaper in it then tear of a short length 2-3 inches, put it centrally in the slot and wind it the oposit way a drill spins, put the other end of the rod in your drill, put the sandpaper end in the 30mm hole and spin it with the drill. I use this method on the lathe to get very smooth good fitting internal bores and if held straight it will not oval the hole.

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