Sunday, September 16, 2007

Trim Router Offset Base v0.1 (Part 2)

In Part 1 I showed the plan I drew, how to make the template, and using the template and my router to cut the base from a sheet of acrylic.

Here in Part 2 I'll make that bare cutout functional.

Once I had the acrylic cut and the template removed, I started on the holes. I needed 4 small ones to match the base mounting on the router, a big one for the router bits, several small ones for pins, jig mounting, etc, and another small one for mounting a knob.

First I clamped the small square baseplate that came with the router to the new base. I marked the 4 holes, and removed the small base. With the new base clamped to a piece of scrap, I drilled out the 4 holes then used my Bosch countersink bit to let the screws mate flush.

I did a test-fit of the new base and found the stock screws just barely fit. They only caught one or two threads, not enough for my comfort.

I ran across the street to Ace Hardware and got some longer screws. M4 is the size. They only had screws that were the same length, or ones that were double. The double length ones bottom out, but are workable. I may grind them down a bit later to get a more perfect fit.

In the photo you can see the quality difference. The one from the Harbor Freight tool just looks like crap compared to the new ones from Ace.

Test fit completed, I figured out where I wanted my knob. Because this baseplate is also going to be used as a plate in a router table, I went with a small, 1" diameter, wooden knob. $1.29 for two at Ace. The screws that came with them were 2" long, way too long for my use. I dug in my screw drawer and found some 1/2" screws of the same diameter that would work fine.

I measured the hole to mount the knob 1 1/2" away from the small end of the baseplate. I drilled and countersunk and tested the fit.

To make the pinholes, I chose a location approximately 30 degrees from the centerline, at the edge of the large circle. Then I measured the center of the large circle to 1 1/2" along the centerline and made new holes every 1/2".

The line of holes wandered a bit... My 4 year old daughter helped me make the marks. Since this is just a prototype I used her marks. Made her day, which is way more important than whether the holes are in a straight line.

Anyway, the reason for the single hole in the big circle was as a guide. A pin in there combined with a pin in the first of the other holes will allow me to lock the router bit on a center line when cutting grooves in board edges. Keeps things aligned nicely.

One place I really blew it here was the bit opening. I figured since the router did such a wonderful job on the outside edge, why not just plunge the bit through the base using the router?

I found out why. For some reason it cracked and chipped its way through the plastic instead of cutting smoothly through it. I'll use a hole saw on the next one...

I am happy with the end result. It's comfortable to use, and helps stabilize the router when working on narrow boards like picture frames.

The next version will have a stepped cut for the bit opening so I can mount a template bushing. Plus the circles will be rounder, and the holes in an actual straight line.

Feel free to ask questions if I skipped any point. I loved making it and would be happy to share details!

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