[ssturgis]

Hello, everyone! This is my first post and a search of the forum didn't turn up an answer to this this question.

When using a template with a table mounted router, what are the relative merits of mounting the template above or below the stock?

I don't have any pattern bits and I'm trying to decide if I should invest in a "top bearing" bit (bearing at the shank end of the bit - close to the router) or a "flush trim" bit (bearing at the end of the bit - away from the router).

My first project is make a round the end of a 4 1/2" wide, 1 1/2" thick maple board. In other words, I'll be shaping the end of the board into a 4 1/2" diameter semi-circle. This will be the start of a small desk clock.

 

[reible]

I was thinking about your question.... it is a good one. If your table can use template guide bushings and you don't mind resizing patterns that would be my favorite way to go. Next would be with the bearing on the end of the bit (away from the router) and the pattern on top of the work piece.... mostly because all but two of my bearing type bits are that way...... As you know if the bearing is on top (nearest the router) it has to be larger then the shaft and for a lot of bits that makes it larger then the bit then you get into the off set issues again.

For what you are doing I would go with a bandsaw cut (jig saw, or ?) within a 1/16" or so of the pattern line then use a flush cut bit with the bearing against the pattern. The pattern attached to the back of the "clock" and make sure you have a spot to start the cut on the pattern....

Before I forget:

Welcome to the forum!!!!!

Ed

 

[fredsintheshop]

I use both types in the following situations...
Pattern on top: If i'm doing one or two pieces, I'll just attach the template to the top of the stock with double stick tape or small nails if the holes can be hidden.

Pattern on bottom: For multiples (or hard to handle pieces), I generally make a template fixture with toggle clamp hold downs and alignment fences that I can clamp the stock into. This allows better repeatability, and keeps my hands further from the spinning bit.

My preference it the pattern on the bottom.

 

[Woodnut65]

Hi, welcome to the forum:
Bits that have the bearing on the end away from the motor are called flush trim bits.
When using them with a pattern the pattern is on top and it is harder to see the cut.
Bits with a bearing on the shaft, nearest the motor are usually called pattern bits, and they will allow you to see the cut better. I use both types, and I prefer to see the cut
better. but it is a matter of choice. To make a 1 1/2" cut the bit would have to be long, and it is adviseable to trim the work on a band saw leaving about 1/16" to remove by router. If I can I also use a bushing in the router base plate and size the pattern to come out the proper size. Happy routing.. Woodnut65

 

[ssturgis]

Thanks for the thoughts and suggestions, guys!

I hadn't considered using a bushing and straight bit, but I will now. Looking at other posts on the forum, it's clear that bushings are used to accomplish a variety of operations. Plus, I already have a 2" straight bit ...

Also, (although I'm not sure if this is all that important), use of a bushing allows all the side force applied to the bit to go into the cutting operation. You're pushing the stock against the cutter alone, as opposed to both the cutter and bearing. (The bushing is taking the side force of the template, instead of the bearing on the bit.)

Anyway, this inspires me to start looking into getting a bushing set.