Speeding up routing & drilling of keyhole slots in ply chisel racks?

[ian maybury]

This to see what comes up - it's mostly idle curiosity/playing with methods so don't go to a lot of trouble.

The job is cutting the keyhole slots in the 18mm (we're metric this side of the Atlantic) ply shelves for a wall mounted tool cabinet to hold chisels - each chisel location is the fairly classic conical hole with 15 deg (a bit less angle might suit some chisels) off vertical sloped sides reducing to 13mm (roughly 1/2in) dia by the bottom/lower surface of the shelf. Then a 13mm wide slot cut in at right angles in from the front edge of the shelf lined up exactly with the conical hole, and just breaking through into the hole.

The narrow/circular part of the shank of the (mostly Japanese) chisels slides in through the slot, it's dropped when the conical hole is reached so that the steel male conical socket for the chisel handle drops nicely into the hole and locates in it - very similar to the arrangement in the photos here by David and especially Derek C: http://www.sawmillcreek.org/showthre...or-chisel-rack

The question isn't about finding a method to cut the keyhole slots - it's just to explore whether or not there may be a straightfoward way to speed the job up a bit. It's proven possible to do it nice and cleanly by first drilling a 13mm through hole in the shelf using a very sharp Famag HSS brad point that has really sharp nickers, then plunging a conical/bevel/chamfer router cutter in the hole to a depth stop to create the taper hole. (one like the T1943-1/2 here: http://www.wealdentool.com/acatalog/..._Bevel_79.html ) The bit has a 13mm dia guide bearing fitted which is a nice sliding fit in the drilled hole, which means that the bit is guided and can't damage the sides of the hole as the plunge is retracted. The edge to hole slot is then cut on the router table to break into the conical hole and top on its centre with the using a 13mm straight bit with the shelf clamped (bottom face down on the table) to a cross cut fence guided by a mitre bar in the mitre table slot.

It's worked fine for a run of trial slots, and cutting the 35 this way is perfectly do-able - but a faster set up would be nice. Especially given the need to accurately align the 13mm slot/router cutter and conical hole for every cut - it's slow. CNC would be the business, but isn't an option. It'd be easy to cut accurately spaced edge to hole slots first using a dado cutter or with the shelf vertical on the router table using a locating pin (like for a finger joint), but then the problem becomes how to bore the conical hole accurately located over it, and with part of one wall missing as a result of the slot… (could be done against the fence on a drill press, but the router cutter would need more rpm than the available 2,800 rpm to cut cleanly i think?)

Thoughts anybody? It's maybe worth saying that neither a shaped spade bit nor a conical reamer proved able to cut the conical hole without causing a lot of tear out in the ply. The conical router cutter also has the advantage of being carbide so it won't blunt so easily cutting ply.

[Jamie Buxton]

There are chamfering router bits. They have a pilot bearing at the tip, and some of them cut 15 degree chamfers. You could make a template which clamps to the bottom of the shelf, and guides the pilot bearing. The outline in the template would be keyhole-shaped.

For instance http://www.rockler.com/15-chamfer-router-bit

Or, the outline in the template could be a simple rectangle, but you get a little tricky with the router. You'd run the router at one depth to cut the access slot, and plunge the bit somewhat deeper to cut the round hole at the top of the keyhole. Finally, a use for those doohickies on plunge routers that offer several depth stops!

[glenn bradley]

I drilled stepped holes with Forstner bits and then used the bandsaw to cut the slots. For the files I just ran a dado back about 1/2" from the front, cut the slots and they drop into the dado behind the lip.

Plane Till (54).jpgPlane Till (53).jpgPlane Till (55).jpg

[Dan Clark]

It turns out that I'm creating racks for my chisels right now and am wrestling with the same issues. Cutting slots with bandsaw is a very interesting idea. For the chamfers, you might consider something like these chamfering bits:

http://www.amazon.com/flute-degree-C...=drill+chamfer

I have a small set that is similar. I used them to chamfer holes for screwdrivers.

Regards,

Dan.

[ian maybury]

Thanks guys, think you have helped me to see a way forward using the set i've built so far.

The bandsaw is a definite option to cut the slots. Imagine it needs a good (carbide?) blade to get nice clean cuts, and that their placing takes care. Plywood compared to solid ups the ante in this regard...

The UK sourced router cutter i have Jamie is pretty much identical to that Rockler item.

That pattern of countersink works well on wood Dan - i have some too. There's a really clean cutting version in hardened cobalt HSS sold in toolmaking places. They were branded and quite expensive, and lasted for ages - but i think there's a lot copying them now.

The forstners have the great advantage Glenn that they can be run in the drill press, and will happily bore a hole at the end of an already cut slot - and it wouldn't be hard to make a small fixture to pick up on the slot to align the hole over it.

[Edward Oleen]

From what I gather drilling/routing the holes is easy, and so is routing the enryway, but you want to speed up the process. I wouldn't cut the entry way on the router table: I'd do it on the band saw. I'd make a jig which would ride in the miter slot and have a conical post to align the work-piece and yet allow it to swivel from side to side. I'd have two stops: one for the left side cut and the other for the right side cut.

Making the entry-ways would consist of putting the workpiece on the conical post (for each hole, of course) swiveling it first one way and cutting, and then the other way and cutting. A stop on the sled would prevent cutting through the work-piece.

This way you'd have one guy drilling the raw hole, a second making it conical, and a third on the band saw cutting the entry-ways, thus allowing each tool to do what it does most efficiently.

[ian maybury]

Hi Edward, i only saw your post just now. I ended up doing something very similar to what you describe - but used the router table to cut the slots and not the bandsaw as it's fairly cheap ply and i wasn't sure I could get a clean cut. My Agazzani also has no mitre slot. There's a series of pics below. The fixture mounted on the mitre bar worked pretty much as you describe to speed up the cutting of the slots and give some accuracy.

There's actually a few pitfalls, so for anybody interested here's a few thoughts and some pictures. US cutter sizes and tool dim differences etc may require some adjustments. Who would have thought that such a basic part would require so much thought...

1. Spade bits and conical reamers didn't give a clean enough hole in the ply - they might be OK in solid wood.

2. The 13mm dia holes are drilled on a drill press using a fence to locate the work - the key to getting clean holes was to use a very sharp high quality brad point with scoring wings.

3. The holes are opened out into cones (except for the bottom 3mm or so) using a conical chamfering router cutter in a plunge router with a 13mm dia bearing that fits snugly in the drilled hole, with the depth set using the stop on the router. http://www.wealdentool.com/acatalog/..._Bevel_79.html

4. It's worth doing some test pieces to optimise the slot width and a socket layout for your tools. I had to accomodate Japanese, traditional Euro and a few other oddball types of chisel in mine, hence the 15 deg cone and a 12mm wide slot - but a 12 deg taper and narrower slot might be a better and a bit more stable if e.g. you are using Japanese chisels only. Try to make sure that the slot is narrower than the bottom of the cone, this greaty imporoves chisel location. The other option is to get into customising slots for specific tools, but i wanted freedom to change locations for tools if required.

5. The ply fixture on the router table is screwed to the mitre bar. The 3/16 ply piece at the end is super glued to the fixture, and the slot in it then cut with a router cutter of the same diameter as the bottoms of the sockets. (13mm in this case) The block at the end is important - the cutting forces will deflect the ply and result in a too wide/uneven width slot if the ends are not tied together as it's cut.

6. Quick clamps (2) hold the work tight against the fixture, the slot provides a reference by which to line up the slot cutter with the sockets/holes in the racks.

7. It's worth making up some small sanding blocks to de-fur the slots. A piece of sponge abrasive pad works well to clean up the edges of the sockets.

8. The racks are going in the doors of a wall mounted tool cabinet. Chisels racked in this way take up scary amounts of cabinet space - it's important to sort out a layout that works before cutting wood. Don't forget that a chisel has to be lifted before it can be removed from the rack, it's likewise for safety advisable not to have the sharp edges end up too close to the handles of the chisels in the row below.

finished chisel rack 12-2-14.jpg chisel rack after drilling 12-2-14.jpg chisel rack after routing 12-2-14.jpg chisel rack slotting fixture 12-2-14.jpg chisel rack fixture loaded 12-2-14.jpg chisel rack in use 12-2-14.jpg

[glenn bradley]

Those came out just fine Ian. The holders you see in my previous post were done with a miter gauge on the bandsaw so the method is similar to what you've done, just a different tool ;-) I was using a 3/4" steel 2-3 variable pitch blade that I normally use to resaw. I keep a finer tooth blade on the smaller saw but needed the throat depth for the holders. Your move to the router table solved any throat depth issue ;-)

[ian maybury]

Yours worked out fine too Glenn - you got nice clean cuts with the band saw. As above i wasn't sure i could manage it with my less than top quality ply. These things often come down to very detail considerations.....