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Construction Boring on a Flip-flop

Maximizing accuracy and minimizing setups requires using as may constants as possible. With my flip-flop boring machine the constants are the distance between the stops on the back fence (or between the side fences), the distance between the drill head and table, and the location of the back fence. It is possible to drill all holes on all panels with with the only adjustment/setup being the location and angle of the drill head. Since 3/4" material is the most common I will use it as an example.
With 19mm (3/4") material the drill head is set to 9.5mm (3/8") off the table for end boring. To account for variations in material thickness all end boring is done with the outside face of the panel (typically the top and bottom of the cabinet box) against the table. You can use 18mm plywood and/or 19+mm melamine and your end bored holes will always be 9.5mm from the outside of the cabinet. Face boring is done with the inside face of the panel (typically the sides of the cabinet box) against the table. The head is set 9.5mm from the back fence (or stops on the side fences?).

Unless your panels are all sized in increments of 32mm (requires a very precise setup and panel size) you need a consistent reference point to insure a flush joint at the front of the cabinet box. Using the front/edge-banded edge as a constant makes the most sense. Using the front edge allows you to bore panels of different sizes without changing any bits - the distance from the back of the panel to the first hole can vary (e.g. bigger or smaller when drilling 12 and 24" panels with the same setup). Using the front edge also works better if your parts are not precisely the same width, e.g. made at different times.

The added benefit of outside/inside face down boring (second paragraph) combined with front/edge-banded edge against the stops (third paragraph) is that your stops or side fences don't have to be perfectly the same distance from the right and leftmost bits because both pieces of each joint get bored from the same stop. Both pieces of the top-right and bottom-left joints get bored from the left stop or side fence, top-left and bottom-right from the right.

I have almost no experience with side fences, mine were pretty crappy and I removed them a long time ago. One thing I like about doing all boring from stops on the back fence is that parts do not need to be perfectly square. If the back fence is parallel to the boring head all holes will be parallel to the edge. Using a side fence that is not perfectly square to the head and/or boring a panel that is not perfectly square will result in a row of holes that is not parallel to the edge, i.e. create a joint that is not flush along its length.

I've set my back fence and stops to be a constant for both face and end boring. The only adjustment I make when switching from face to end boring is the location of the boring head. Moving the boring head is the only adjustment I can make on my boring machine that is easy and precise (digital position indicator), using the above methods it is the only setting that needs to be.

I always mark my panels before boring, marking the back edge of all panels helps to keep track of which side goes where. I used to draw a line near the good side face, but the good side is not a constant (sometimes the good side goes out). A line can be an "I" for inside and a dot/circle an "O" for outside. If you're line boring unbalanced panels put the mark near the end that goes against a stop (top or bottom constant). If you're boring for nailer to box top joints, pick the left or right stop as a constant and put your marks on that end. For nailer to side panel joints the nailers should be sized so that the the first hole from the banded edge is the same as all other end boring.

Comments [ new ]

Re: Construction Boring on a Flip-flop
Posted by mels on Saturday, 15-Mar-2014

i'am having problems getting the boring aligned for my backs. I am using a fully recessed back so no edges of the back are exposed. I bore my holes in the tops and bottoms and sides. I am having to move my flip stops in order to do the holes for the backs, only on the sides. evidently my set up is wrong because from everything I have read, if I understand it correctly, I shouldn't have to move my stops. should I? tks, :)

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Re: Construction Boring on a Flip-flop
Posted by Dave on Sunday, 16-Mar-2014

Re: Construction Boring on a Flip-flopMels,

You could use a scrap of your top/bottom stock as a spacer when boring the sides of your backs. All my stops are tapped and I'd use a screw in spacer. With plant on/full overlay backs, spacers would have to be the default - only removed to bore the holes on the back of the top and bottom.

Unless you're only using the machine to bore the four corner joints, e.g. when using 1/4" dadoed backs and hangers, moving stops is probably inevitable. My stops register to holes in the fence (32mm apart) so that I can keep my setting when moving them.

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Re: Construction Boring on a Flip-flop
Posted by mels on Monday, 17-Mar-2014

never thought of using spacers! I am using fully recessed 3/4" backs. doweled on all edges. not a fan of 1/4" backs. stock fence is a good HD unit but has no way to index it. will remedy that. tks for the info. :)

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