Template Routing-Help!

[Brett Bobo]

Maybe I'm overthinking this but I'm trying to make the templates for routing mortises for bed hardware (Rockler's heavy duty bed hardware), particularly for the mortises in the legs. I'm using using a 3/4" MDF template to register the jig at the correct distance from the base of the leg and on top of that, I offset 3/4" MDF scraps for the router bushing to follow to correspond to the correct opening for the hardware. My plan was to remove the 3/4" MDF scraps and only use the template and a router bushing cut the mortises in the legs but with any router bushing, the size in the legs won't be correct now. A couple of thoughts:

1. The total depth of the MDF template and the MDF scraps is 1 1/2" so I can't use this combination since the router bit is just at 1 1/2" in length. Since I used 23 gage pins to hold the scraps to the template, I can't plane down the MDF scraps but I can plane down the template probably just enough to allow the bit to remove the correct amount, ~3/16" or so.

2. Using the same router bushing, make two offsets from the template with the scraps so that the when I place the template on the legs with the same bushing, the mortise comes out to the correct size. My only concern here is the amount of accuracy lost in moving the template scraps and routing twice for the final product.

3. Remove the MDF scraps and use a router template bit with a top bearing to create the final mortise in the legs. I'm not sure of the available cutter lengths for a router template bit but it would need to be fairly short, say 1/2", in order for the bearing to follow the template and still provide a shallow mortise with the hardware thickness only being ~3/16" thick. Woudl a router template bit be the correct choice for a mortise application? Does a router template bit like this exist with a shorter cutter length?

I think what's throwing me off is that unlike mortising for hinges, this template is enclosed on all four sides and not open on one side like for hinges. At the same time, I'll have to rout mortises in the legs for the male hooks from the bed rail so unless I have a smaller router bit that offsets correctly to correspond to the male hooks, I'll need another template for that too.

What am I doing wrong here or missing? What option do you suggest as the best solution or what solutions do you recommend? Thanks in advance!

Brett

[Jamie Buxton]

What is the shape of the opening in your guide -- a rectangle? If so, here is how I make the template: plunge cutting up on a table saw. The rip fence gives me very precise control of the dimensions of the rectangle. The kerfs penetrate the edges of the the template at the corners, but this is okay because the round template guide doesn't actually touch the corners of the template's hole. To make the template, you want to start with a big enough piece of MDF or plywood that when you plunge the blade all the way to the top surface, there's still material holding the template together.

Plunging up on the table saw sounds a little scary, but I've doing this operation for decades. MDF is so soft that it cuts easily without catching.

[Kent A Bathurst]

If - if - I understand, then these observations. If I misunderstood, then ignore all this noise:

1) I use 1/4" MDF for templates, for the reason you have discovered - router bit length. I buy a 2' x 4' sheet at the BORG and leave it laying around so I have some when I need to fab a template.

2) A number of the templet guide bushings in my set have [had] a barrel longer than 1/4" - I never understood why, assume there is a good reason I am missing. NBD. I mount them to the dis-assembled router base plate, screw the router base to a block of wood, and then cut off the guide barrel to 3/16" or so on the CMS - they are brass - no serious problems with the CMS blade. With the templet guide bushings, I don't need to worry about bit bearings - just need to do the math for offset to accomodate the bushing v. bit distance.

3) I don't understand the use of the 2d layer of MDF scraps. You lost me there. I just use the one layer of 1/4" MDF with the template hole cut out. I screw a block[s] of wood along the side [+end] to register it - they are attached to the "underneath" side of the MDF - kinda like a ledge projecting down. There's only 1/4" of material between the router base and the target.

4) FWIW - I cut out the template holes on the bandsaw - cleaner and more accurate for me than a jig saw. I drill a hole near each end of the cutout. Run the 1/4" bandsaw blade into a hole. Use the holes to turn + twist the MDF under the bandsaw blade. Then, cello packing tape on the MDF to hold the bandsaw kerf in line - but usually I cut in with the BS on the side of the MDF that will have the registration blocks screwed to it - holds everything together.

[Lee Schierer]

Go to a machine tool supplier and buy a 1/2" end mill that is about an inch longer than your current router bit. They come in longer lengths and will work in a router for limited use.

[Brett Bobo]

[QUOTE]What is the shape of the opening in your guide -- a rectangle? QUOTE]

Jamie,
Correct, my opening is a rectangle. In order to follow the rounded corners from the router bit, I rounded the corners of the bed hardware on the grinder to match.

The table saw technique is interesting as I hadn't thought of that. Actually, that would be very accurate and provide smooth side walls for the bushing to ride against. My only reason for not using the bandsaw was due to not have smooth side walls of the template for the bushing to ride against, even with using the fence to adjust for each cut. I'll have to try the table saw technique.

[QUOTE]3) I don't understand the use of the 2d layer of MDF scraps. You lost me there.[QUOTE]

Kent,
The reason for two layers of MDF was to make the initial cut into the template before placing the template on the work piece. As mentioned above, I was trying to use the bushing to provide as smooth of side walls as possible, instead of using a bandsaw, jig saw, etc. Just a preference as I don't trust myself to make clean and accurate cuts--ha!

Thanks,
Brett

[Kent A Bathurst]

Brett -

From a distance, it seems you might be overdriving your headlights a bit. Hard to tell from here, tho...........

You don't need to route a dead-nuts mortise. You need to route a "pretty good" or a "not bad" mortise. Then use chisel[s] to clean the sides as needed to fit. Unless you are going into production on a large number of units, you just need to get it hogged out then clean it up, not create the world's most perfect template.