Square dog holes with a plunge router
So I got to the part of my bench building project where it was time to make the square dog holes. Now, I’ve seen plenty of articles on various ways of doing this from table saw sleds to routers with template bearing guides. I decided to go with a bit of a hybrid approach. Nothing in what I’m about to describe is particularly original, but for the intermediate woodworkers out there who might appreciate a more detailed description than “now cut your dog holes with your router” found in some bench building articles, I offer the following. It was straightforward and produced good results.
I made two simple jigs designed to guide the router’s base-plate (like those used routinly for router dadoing with two strips that hug the work piece and two that control the width of the groove) for each direction of 2 degree sloped hole (the one in the vise face toward those in the bench and vice versa – four jigs in all) – one for the slot and one for the “blip” that houses the dog’s head. But no worries, these are very simple jigs. I built them from 3/4″ birch ply scrap I had around. Pics are worth a 1000 words: http://home.comcast.net/~samson141/dog_hole_jigs.bmp I happened to be using the smaller metal dogs sold by Highland Hardware, but this method would work for any dogs (just make sure you have one in hand before starting as you need them for making the holes the exact size you want).
1. I ripped some approximately 4″ strips and some near 2″ strips. The ripping was important to make sure that the edges of the strips are smooth, straight and parallel.
2. I took the 4″ strips to the miter saw (SCMS in my case fwiw) and set the table to cut a 2 degree mitre. I chopped the strips into about 6 inch lengths (the length will vary some depending upon the thoickness of your top; you want them long enough to span the top laminate board width and the two 2″ runners that will hug the workpiece. You now have parallelograms with two 92 degree corners and two 88 degree corners.
3. The 2″ runner strips should be around 15 inches long, but length is not critical. Place one on each side of the work piece even with the face you are going to route the slots into and pin them there with a clamp.
4. Take one of your parallelogram pieces (pay close attention to the direction of the slope (2 degree slope towards the tail vise) and place one of its short edges flush with the edge of the bottom runner. Screw it in place.
5. Now take your plunge router, chucked with a 3/4″ straight plunge bit, and place it with its round base pressed to the parallelogram you just placed. If you trapped teh router with the other parallelogram, you’d get a 3/4″ groove, but you need one slightly wider. Use brass setting bars or wood scraps of known dimensions placed against the already screwed down parallelogram to achieve the desired groove width, make sure the base of the other prallelogram is flush to the runner (i.e., makes sure you have parallel edges for your groove) and screw it down.
6. Now make a test route on a scrap of the same width as your work piece (take a 1/4″ at a pass until you reach full depth). To set the bit depth plunge the router to the point where the bit touches the work piece and place your dog sideways right on your depth stop and adjust the depth scew just a hair proud of the top of the dog. This will give you a slot just a hair deeper than your dog is wide with no need to measure and fidget. If the test reveals that the slot is too loose or tight in either dimension, make adjustments and retest until the fit suits you.
7. The test is also useful because it demarcates the edges of the groove to the extent you’ve necessarily routed out U shapes at the inner edges of your runners. Place the jig on your work piece where you want the first slot, clamp it in place and route it out.
8. Now cut a scrap the same width and slightly shallower than your slot. Cut it a 1/2″ or so shorter than the slot is long. Put it in the slot and put a little blue tack poster hanging stuff or double sided tape on it. Carefully place the jig where you want the next hole to be pushing down over the old slot last to engage the blue tack/tape. Carefully pull the jig off and the scrap will be attached where ti needs to be for setting your spacing. mark it with a pencil, remove the adhesive and then screw it on from below. This will now make spacing the rest of the holes a snap.
9. For the blip, it’s the same jig with the righthand side parallelogram moved out as far as necessary to widen the slot at the top and a couple of scraps added to limit the router base’s travel as shown in the diagram.
Hope this is useful to some others out there. It’s simple, easy, and effective.
I could have cut the slot wit a sled and dado blade, but I would still have had to get out the router for the blip. And I didn’t like the upper bearing template guide method for several reasons including that the bearing might not engage for the first few passes – it’s had to see what you’re doing when the slot fills up with chips – and the chips tend to get int he way of the bearing and (for me at least) leave less than perfect results as far as clean straight walls, etc.)
Replies
Why didn't you just use a square bit?
Heh heh.
Mike
I learned in the manhole cover thread that there are indeed bits that can drill nearly square holes, but the chuck axis has to be able to move. All my drills have stationary chucks? In short, I had to work with what I had. ;-)
Sorry is my simple procedure seemed long-winded in the description. It's amazing how hard it can be to convey even the simplest things with words alone (hence the cheesy diagram). I also wanted to throw in all those little things that often get glossed over or assumed in WW mag articles.
lemme try to make it simpler:
Step 1: Buy round bench dogs.
Step 2: there is no step 2
:)
Depends what you want. I wanted square.
And even with round, you have to bore straight, evenly spaced 3/4" holes through a thick hard benchtop. No matter whether you use a drill with a forstner or spade bit or a plunge router to make these holes, you are going to need a jig if you want them straight (i.e., perfectly perpendicular to your top) and evenly spaced. So there's actually a lot to Step 2. ;-)
I checked ebay for you:
http://cgi.ebay.com/Developing-a-SENSE-of-HUMOR-NEW-Hypnosis-CD_W0QQitemZ5931246771QQcategoryZ3149QQssPageNameZWD1VQQrdZ1QQcmdZViewItem
Hey, thanks, I got a link for you too http://www.aqguide.com/abbr-n.html
But if you don't want to spend the money -
;-) means "wink" (note that it was at the end of my last message)
Jokes are funny and clever when there is kernel of truth in them; yours unfortunately fell down there. Unless you were just going for the absurd - i.e. that if you just buy round dogs, perfect holes just appear in your bench. Yeah, I guess that is funny.
I didn't use a jig unless you call a drillpress a jig. I just set the fence, marked off the increments and drilled. My problem was when the bit went through the other side that it took these big slivers with it. How can I avoid that? I did use the round dogs.
You can avoid the splintering by placing a sacrificial piece of wood below the board you are drilling. Then the bit will make a nice clean exit hole from the first board. Any splintering will occur only when the bit exits the sacrificial board.
I assume you drilled these holes in strips before lamination? If not, did you manuever the drill press around the bench - or even more difficult, bring the assembled slab to the press and wrestle it around? On assembled benches, of course, depending upon where you want the holes, a drill press may not be able to reach the spot (e.g., a 15" DP is not going to reach the middle of a 24" wide bench).
All that said, I agree that if one is drilling holes in lamination boards before glue-up of the top, it is indeed a simpler procedure than mine for making square holes.
There was two of us to move the whole slab so that wasn't hard. The drill press is a twenty inch and I was only drilling next to the edge so that was not a problem. Used a support with five rollers and it was easy to move. Even had a sacrificial board under it so I don't know if the slab wasn't down flat or just what. I was pretty well done before I noticed the problem. I am wondering if it would have helped to drill a larger hole 1/4 inch deep, or so, from the underside so that the 3/4 inch bit from the top would have drilled into it.
I didn't see your original post of drilling with a router. Does that take a special bit? and how deep can you bore that way? The slab I had was 3.5 inches thick
I have not yet had the need to drill 3/4" bench dog holes with a router, though I may eventually add some to my new bench (maybe for clamping small panels across the end of the bench where the front vise is). I think one of the recent issues of FWW had an article (tips and tricks or advice blurb?)about drilling such holes with a router by using a jig or baseplate to locate your router on the top and hold it perfectly stationary for the cut. My recollection is that they used a 3/4" plunge bit to get most of the way through the slab, then drilled a 5/8ths hole and finished off from the bottom with a fluch trim bit - i.e., the end bearing rides on the edges of the 3/4" hole to make a 3/4" hole all the way through. Fairly complicated way to proceed. I think there was a whole thread on this procedure here not too long ago with some folks taking issue with it for various reasons (needlessly complex, etc. IIRC).
I think when it comes time for me to make some, I may just do my best to drill a stright hole with a forstner bit and some blocks or squares - crude jig of some sort - to help me drill reasonably straight and true.
Wow, never expected such an articulate set of instructions. Puts a whole new light on the subject as I was prepared to use my table saw sled with dado blade and struggle with 8-foot boards, etc. Thanks much for the great help!
I've been considering this method, but thought there would be some chip/tearout at one end or the other as the router bit entered/exited the wood. Was this not a problem?
You need to go in the right directions as usual with a router, I guess, but I had no tearout in the maple I used. The runners on the jig also help. Here is the result:
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Edited 7/30/2009 10:27 pm ET by Samson
Hello! If my dados look like that I will consider it a job well done! Nice work, Samson!
Samson,
You ended up with a beautiful bench. Did you build it from a purchased plan or your own?
I have been waiting to get my new bench going. I have a rather large pile of Hard Maple sitting out in the shop, that will soon become a work bench. Seen as I am moving my shop over this next week, I have been holding off till after the move.
I love the contrasting colors you have used. Is that Purple Heart that you used?
Well done, thanks for the well written explanation of the jig you used to cut the bench dog holes.
Taigert
Hey, Taigert. Thanks for all the kind words. This is a version ( I varied some of the dimensions to suit myself) of the Fortune/Nelson bench described in Taunton's Workbench Book. The tail vise is padauk. Most of the rest is maple, with a few bits of walnut here and there. Been using it for a few years now, and have no complaints at all.
I use a router with a large spiral router bit and another to hog out the corners with a small spiral bit..
Then I use a corner chisel with a wooden plug that forces the chisel into a corner.. Yes it takes four different sized wooden plught to do it right..
I just drill a round hole!
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