Using Router Guides to Make Template and Insert Opening

[Hoosierpopi]

I have a set of Porter Cable Router Guide Bushings.

want to make a router table. I have a nice insert already drilled for the PC Router base. I want to fit this insert into the table blank I also have prepared.

My thought was that I should be able to use the insert to form a template, then, use that template to cut an opening into which my insert will fit "perfectly."

It seems to me that using the appropriate (Spiral Bit?) and two of the bushings should work.

That's as far as I've gotten to date.

Has anyone sufficient experience using these guides to offer a solution?

I also have the "Router Inlay Set" (Similar to Woodcraft

but that bit is too short to cut a decent template.

Of course, if there's another, better approach I need consider, please advise.

[Morris Dovey]

| I have a set of Porter Cable Router Guide Bushings. (http:// |

) | I want to make a router table. | I have a nice insert already drilled for the PC Router base. | I want to fit this insert into the table blank I also have prepared. | | My thought was that I should be able to use the insert to form a | template, then, use that template to cut an opening into which my | insert will fit "perfectly."

Sounds like a good plan. Why not try it out on a piece of scrap to see how well it'll work?

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Tom Veatch]

Using a male pattern (your insert) to rout a female template will result in a template in which the cutout is oversized an amount equal to 1/2 (guide O.D. + bit diameter). If you use a pattern following bit, the guide diameter = the bit diameter, so the opening is oversized an amount equal to the bit diameter

Routing the opening in the table using the template opening you just made requires that you select a guide and bit combination such that

1/2 (guide o.d. - bit diameter) is equal to the specific amount the template is oversized. (note that here the calculation is guide MINUS bit. before, it was guide PLUS bit)

Sounds more complicated than it really is.

Tom Veatch Wichita, KS USA

[dadiOH]

)

Easy to avoid problems, just make template from strips of ply butted to edges of router plate.

[Father Haskell]

My preferred method. The insert will drop into its recess like silk. This works best with a top piloted flush cut bit, not the collars, however.

[Tom Veatch]

If I understand what you are saying, create an undersized replica of the router plate and use the replica as a template to rout the recess in the table top.

Is this what you have in mind?

1. position plate on template material

1. butt strips to the plate and clamp/tape strips to template material.

2. remove plate and guide on inside of strips to create an undersized replica of the router plate. The replica will be undersized by an amount equal to 1/2 (guide o.d. + bit o.d). Also the replica corners will be square while the router plate may be rounded.

1. clamp/tape replica in position on table top for use as a template to rout the recess.

2. rout recess in table top guiding on outside edge of replica using the same guide and bit as was used to create the replica. Be very careful not to overshoot at the corners. (I always find following the corners to be a little dicey when routing a recess using a male template.)

Assuming the bit is well centered in the guide, the recess will be oversized relative to the replica the same amount the replica is undersized relative to the plate. So, the recess dimensions should match the plate dimensions except possibly in the corners. Matching the corners of the recess to the corners of the plate may require some chisel work if the plate corner radius is smaller than the bit radius or some gap filling if the plate radius is larger than the bit radius.

Tom Veatch Wichita, KS USA

[Jim]

No, you create an oversized template to cut the recess with a router and bushings. You create an exact size template to cut the recess with a router and top control trim bit.

If you make the template as dadiOH mentioned, you can use the brass measuring sticks to make a template for use with bushings.

The guys on "Router Workshop" discussed these methods lots of times. Jim

[Tom Veatch]

Obviously! And the amount of oversize would be as I stated in my first post in this thread.

keying off the inside of strips butted against the router plate, the recess in the work/template will be smaller than the router plate if guide bushings are used and the same size as the router plate if a top bearing template bit is used - except possibly the corners, of course. Using the template bit is preferable, but the OP is talking about using guide bushings.

I don't know what the "brass measuring sticks" are, where they came from, or how you propose they be used. However, if their width is the same as the diameter of the bushing and are used as spacers between dadiOH's strips and the router plate, then the resulting template will be oversized the right amount as long as the same bushing and bit diameters are used to cut both the template and the recess for the router plate.

and the "Router Workshop" is ....

Tom Veatch Wichita, KS USA

[dadiOH]

Stop here, the rest is just extra work and totally unnecessary.

Remove the plate and use the strips as guides to cut the hole in the table; said hole will wind up the same size as the router plate. If you are worried about rounded corners on the router plate, use a bit the same radius as the corners. No big deal if you use a smaller bit, just means there will be a small gap twixt plate and table at corners, just a place for sawdust to fall through.

Much easier and more accurate this way. And no problems following the corners on a male guide.

dadiOH ___________________

[Tom Veatch]

You won't get any argument from me on that as long as you're using a top guided pattern bit.

But, if, as the OP was wanting to do, you're using guide bushings where the bit diameter is necessarily smaller than the bushing diameter, the recess will wind up too small in overall length and width by an amount equal to the difference between the bushing diameter and the bit diameter.

Tom Veatch Wichita, KS USA

[Tom Veatch]

Sorry about the slight error there.

The width of the spacer has to be the same as the difference in diameters of the bushing and the bit if you are cutting a template for routing a recess to contain the original item (the router plate). The width of the spacer has to be equal to the diameter of the bushing to cut a template to use for duplicating the original.

As others have said, and I agree, it's much simpler and straight forward if you can use a top guided pattern bit and route the recess directly.

Tom Veatch Wichita, KS USA

[Morris Dovey]

| Sounds more complicated than it really is.

I think you're right. :-)

I put together a web page (link in sig) that attempts to develop a formula for working with possibly different bit sizes and different sized bushings - I'd appreciate if anyone would let me know of errors...

Thanks!

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[dadiOH]

All he really wanted to do was make a damn hole in the table for the freakin' plate :)