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9th June 2012, 10:26 PM #1Intermediate Member
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Drilling 19mm Work Bench Dog-Holes Experiences - Advice Please
On a previous bench build, I drilled 108 dog-holes (19mmx62mm) in the MDF worktop of a MFT-ish style bench (Multi-Function-Table). For holding 19mm TasOak dowels, the diameter of these dog-holes is fine, although possibly a tad loose. I first drilled +-25mm with a 3/4" (19.05mm?) Forstner bit, and then drilled through with a 19mm Irwin Spade bit which has since grown legs and run.
However, I recently drilled about 40 dog-holes (19mmx50mm) in another worktop comprised of 18mm MDF and 32mm laminated chipboard, and have a wee problem... the diameter of the holes is a tad too narrow!!! These were drilled through in one go with a 19mm Irwin Power Auger bit.
The dowels are binding in the top MDF layer even before they reach the chipboard.
I am hoping somebody can please suggest an easy way to solve the too narrow dog-holes?
Stupidly I drilled all of the bench dog-holes before checking the resulting holes, as I had recently used the same Power Auger bit to drill 24 holes in 70x70 pine, when making a horizontal timber rack, and the 19mm TasOak dowels fitted nice and tight in those holes. With hindsight maybe too tight for bench dog-holes, and I should have drilled the first 5-10mm with the Forstner bit!
Out of interest, a digital calliper measures our current three nominal 19mm bits as follows:
18.95mm = Irwin Power Auger bit, although it is somewhat difficult to measure this type of bit accurately
19.03mm = Forstner 3/4" bit
19.40mm = Spade bit from a cheapish combination bit set
By the way, for the layout I used a sheet of pegboard that was clamped to the worktop while all the dog-hole positions were centre-punched at 4 pegboard holes/inches apart. I used crayon to pre-mark the shiny white side of the pegboard to know where... and more importantly where not... to drill.
Key to me drilling the dog-holes straight was using what I call a drill-through "jig" that I built around a cheap drill-press-stand thingy, that I find works well for this purpose. I am sure others have better ideas for getting the holes straight....
Attachment 211692
And whereas I felt very much in control with the Forstner bit, and to a lesser extent with the Spade bit, I found that with the Power Auger bit I had to set the drill speed high enough to prevent it stalling, and once it bit (no pun intended) into the work piece, there was virtually no stopping it and the hole was done. I am guessing that this is because of the screw-thread-point?
Thanks,
Andy
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9th June 2012 10:26 PM # ADSGoogle Adsense Advertisement
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10th June 2012, 01:45 AM #2
Proberly to put the pegs in a lathe and with a strip of emery sand the daimeter down , if you only sand up to where the chuck gripe the larger diameter will stop the dowles falling through
For my layout I took a strip of wood as a template and drilled three holes in a straight line 300mm apart
Drilled the first hole in the bench , dowel through first hole in guide and bench top and used the template to drill the next two and so on , only had to get the rows of holes at rt angle to the first row and all was good using a forstner bit.Ashore
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10th June 2012, 02:13 AM #3GOLD MEMBER
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What Ashore recommends is the quick way, as long as you don't need to fit any special hardware.
The alternative is to do the opposite - wrap/glue some medium to coarse sandpaper to a length of undersized dowel - say 16mm - chuck it in a drill after reducing one end, then sand out the holes until they fit a dowel. Lots more holes than bench dogs if you are like most people. Tried using a slightly larger drill bit and guessing the hole centre, not reccomended, I also don't think making a fairly loose plug with a centre mark & hopeing the drill pushes it through is any better.
Most metal hardware intended to fit dog holes is a bit undersized and has some sort of spring or wedge to stop it dropping through. I have been looking for small (<1/4 inch) ball catches to put in 3/4 dowels so they stay put, but the smallest I can find at Bunies etc are over 1/2 inch in diameter
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10th June 2012, 09:04 PM #4Intermediate Member
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Thanks for the advice guys. Can see that both approaches will work, but will try the sandpaper on an undersized dowel in a drill chuck, as I sometimes make doghole-secured jig thingies that are meant to be interchangeable across two different benches in two different sheds. The one bench has undersized dogholes and the other has correct sized dogholes.
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