Routing mortises using an edge guide

[Geoff Harris]

Hi, I'm fairly new to this forum but have been reading it for several months now. I'm a weekend woodworker and have been on a fairly steep learning curve for about 2 years now (with no end in sight :-)

I am trying to route a mortise using a plunge router with an edge guide. I built a small jig I found here:
http://www.tools-for-woodworking.com/index.asp?PageAction=Custom&ID=29.

It mostly works well except for the initial part of the cut. It seems that there is some play in the edge guide system because the slot moves a bit away from where the bit was initially set as soon as I start to move the router (I'm assuming the fence gets pulled tighter against the jig). It's only about 1/16" but I'd like to figure out how to eliminate it.

I'm using a PC 690 with the PC edge guide, I've attached a 10" long wooden fence to the guide. The bars that hold the edge guide are a bit flimsy so that may be where the problem is. I did make sure the fence attached to the edge guide was flat and square to the jig.

Is this slight movement normal with edge guides or is there a trick I don't know?

[Mike Vermeil]

Geoff,

I believe there are two different PC edge guides, but I'll assume you have the most common one that I also have/had. I was never able to get decent resuts with it until I made the following changes:

1) I changed out the whimpy phillips-head bolts that secure the guide to the base. I tapped out the holes to SAE 1/4 fine and used regular bolts to get some decent clamping power.

2) I ground away the portion of the guide that was interfering with the base, not allowing the flats of the guide to contact the mating flat surfaces on the base where the mounting studs pass through.

But the best change I made was to switch to a Bosch router! I struggled with the shortcomings of the PC router for way too long, and now kick myself for it. The newer model PC routers have fixed some of those shortcomings, but after comparing them side by side with the Bosch, I still feel the Bosch is a completely superior product. I can do things with it successfully that I was either not able to do at all, or at least struggled with on the PC.

Mike

[Bruce Overholt]

There, was a good video tip in Fine Woodworking a while back, but I cant find it now. I hope in the future to build one also, so I got the better micro adjustable edge guide with my new PC router.
The heart of the jig I want to build, is a good surface of at least 2 to 4 inches wide for the base of the router to ride on. Incorprated would be a T-Nut track for T-Nut mounted stops to mount in. While the Edge guide adjust one axis, the track mounted stops would adjust the other axis.
When I get one built, I'll post pics.

Bruce

[Nick Gattuccio]

You might also consider a little different approach. I frequently cut mortises with a router, but I put the router in a router table and mount a spiral up-cut bit. They're expensive bits (I use the Amana), but they perform beautifully. Add a decent fence and you'll really be able to stabilize the workpiece and get perfect results. For deep mortises, you might need multiple passes, depending on the hardness of the wood.

If you don't have a router table, they're not that difficult to build. Using MDF cuts costs (also adds weight, for stability). You can find plans all over the web.

Good luck!

[Dennis McDonaugh]

Geoff, remember that when you move the router one direction it pulls away from the fence and when you move the router in the other direction it pulls into the fence. I can't remember which is which, but I had a hard time using the fence because I didn't consistently move the router in the same direction.

[Alan Turner]

I don't care for a router use which traps the bit in the wood, such as you are describing. When I build a jig, I try to design it to use a collar, and use a bit smaller than the desired opening so that it is not trapped for the final cut. To me, a trapped bit always chatters.

[Mark Singer]

Geoff,

Alan is correct...you can use the same jig in combination with a template guide on the router and a smaller bit. Take smaller depth bites and it will be easier to control. A compressor with a blower tip will help eject the chips as you go...


I don't care for a router use which traps the bit in the wood, such as you are describing. When I build a jig, I try to design it to use a collar, and use a bit smaller than the desired opening so that it is not trapped for the final cut. To me, a trapped bit always chatters.

[Doug Shepard]

Here's my $0.02. I do a fair amount of this with a DeWalt 621 and a Microfence edge guide. The initial plunge cut has a tendency to grab a little and sometimes shift your cut. You can't really keep pressure on the edge-guide fence to stop it since your hands are busy pressing down on the router and locking the cutting depth. What works well for me is to clamp the edge-guide fence to the board with a QuickGrip clamp with just light pressure. Once you've plunged in and your hands are free to hold the guide to the work, pop the clamp trigger to release it. Then proceed to move the router through the cut. You can have the same problem at the other end if you take your hands off the guide to try and raise the bit out of the work. Better to let it come to a stop in the cut, then raise the bit out. An On/Off footswitch is a big help doing this too. It's basically a problem of just not having enough hands to deal with keeping the fence snug to the board while messing with the plunge mechanism or power switch at the same time.

[Geoff Harris]

Thanks for all the replies.

I was thinking of using a template at first but I wanted something that didn't require a custom jig each time. My understanding of using templates is that it needs a template cut for each shape of mortise I would be cutting. Mark, I'm not clear on how you meant to use the jig I have with a template guide. I can imagine building an adjustable jig for this but the edge guide jig seemed to be a simpler solution if I can get it to work satisfactorily.

Do spiral bits chatter? I suspect they do. I've been doing 1/4" passes and they seem to go fairly smoothly.

I'll try clamping the guide for the first pass and see if that changes anything. I suspect a more rigid edge guide system would help a lot.

Is the 690 micro adjustable edge guide that much better?

Thanks,

Geoff.