A question for Ellis

answer

Ian Neuhaus

Ellis suggested

To make a complementary template, you'll need to use two bushings.

For example, for the first curve use a 1/4" bit in a 1" bushing, and for the other, use a 1/4" bit in a 1/2" bushing.

1" - 1/4" = 3/4"

1/2" - 1/4" = 1/4"

there is the 1 to 3 ratio recommended by Stumpy Nubs

Re: answer

Tom Norton

Thanks Ian. I think the "little gray cells" are starting to get it! I made a 1"odx1/2" I'd wooden bushing out of cherry. I will post the results!

Fascinating post - thank you

Howard in Toronto

My brain seems to be hardening up (plus all the Bushmills 10-year old single malt) and I appreciate this practical info. Howard

A problem!

Tom Norton

So I set up to make the patterns but they do not mesh together. Here is how I did it. I took 1/4" play and attached it to a backer board,the I attached my pattern to the 1/4" material. I made the first cut with the 1/2" bushing then , without moving the material, I followed the pattern with the 1/2" bushing.

The patterns do not fit together.

Am I missing something??

Re: A problem!

John in NM

Bit diameter. If you are using two patterns rather than one, they will not fit together because they are offset by the diameter of the bit you intend to use them with. Mark's post has some good pics that illustrate this.

Re: A problem!

Barry Irby

Tom I have been thinking about this for several days. I think the key is you need to use a bushing for the second cut that is two bit "diameters" larger than the first bushing. So if you make the first one with a 1/4" bit and a half inch bushing, the second cut needs to be with a 1/4" bit and a 1" bushing.

Go on You Tube and Watch "IMPORTANT ROUTER SKILL: Complimentary curves and making positive and negative templates" and other similar videos.

Scott Grove has an entire book on this technique *LINK*

Stephen Roth

https://www.amazon.com/Hardwood-Edging-Inlay-Curved-Tables/dp/0764351184/ref=sr_1_1?ie=UTF8&qid=1544735950&sr=8-1&keywords=scott+grove

It seems simultaneously more simple and more complex than you would think!


https://www.amazon.com/Hardwood-Edging-Inlay-Curved-Tables/dp/0764351184/ref=sr_1_1?ie=UTF8&qid=1544735950&sr=8-1&keywords=scott+grove

Re: A problem!

Tom Norton

Barry, thanks for your reply. What you suggest is what I did but it did not work. I think the part I am not understanding is the order of cuts.

The you tube videos are using bits with bearings not bushings so they are not helping me.

Ellis is the first that suggested the bit size and 2 different bushing sizes but I am lacking the procedure for using them.

I did it! (I think)

Barry Irby

Just went into the shop and worked this out with the aid of a couple of scraps.

I used a 1/4" bit, a 1/2" OD bushing and a 1" OD bushing.

On a 1/2" thick scrap of MDF I drew a wavy curve and cut it out on the bandsaw. Gave the edge a really quick sanding with 80 grit by hand.

Laid the pattern on the "lower" piece of stock and traced the edge. Cut that quickly with little care on the bandsaw. Double stick Taped the pattern on top of it with the edge projecting about a 1/2" everywhere. Routed the edge with the 1/4" bit and the 1" bushing.

Remove the Lower piece and set aside. Without changing the orientation tape the pattern to the "upper" piece. In my case, the upper piece was wide enough to project under the pattern and the piece that was cut away was the keeper piece. If your pieces are narrower you will have to figure out how to hold them still in relation to each other. Change to the 1/2" bushing and the same 1/4" bit and route the curve.

It fit.

I'm sure there is a way to make an upper and lower pattern so that each one could be laid on top of the keeper piece, but I haven't worked that out in my head. At least not using bushings. With a pattern bit it would be easy.

I like doing it with bushing because the bits are cheaper and I keep burning up the tiny bearings. I practiced on 1/4" thick scraps and was impressed with the ease of using the 1/4" bit. I am usually skeptical of 1/4" bits, fearing they will whip and make a sloppy cut. Not so this time, the bandsawing of the piece was a waste of time.

Re: I did it! (I think)

John K Jordan

Will this work for a wavy semicircle or closed curve, one that goes around and the end connects to the beginning (such that if you cut it out you get a hole)?

I could probably figure it out on paper but maybe someone already knows.

Re: I did it! (I think)

Ellis Walentine

Good explanation, Barry. I was all set to do some drawings of the setup I use, including a second method using a pattern bit as you suggested. I think you've given a good enough explanation without them.

To elaborate on routing the second piece, I was going to suggest a setup that includes a plywood platform (or your bench) to place your workpiece and a complementary spacer board on. The router template goes on top of the spacer board and everything gets clamped to the platform. Sounds complicated, but it really isn't.

There's also a little intermediate step if you want to create an exact replica of a particular curve. An edge that is 3/8" from your template will not match the template precisely, so you'd need to create a different template that includes your router offset from your master template and work from that.

Ellis

Re: I did it! (I think)

Tom Norton

Ellis, since I am a visual learner is there any way you might post a drawing? Barry any chance of a few pics?? That would help so much. Thanks!!

Re: I did it! (I think)

Barry Irby

I have a kit I got with a used router. It has a 1/8" bit and a collar with a ring/bushing. Have not used it, but the way it works is lets say you want to inlay a bowtie across a crack. You make or buy a bowtie template. With the bit and the bushing with collar, you route away the "field". Then you put the temlate on the second piece for the patch, remove the collar and route the outline only for the bowtie. Then you free the bowtie and Insert it. You do have to round off the corners or square them up in the field.

The "trick" is the collar is 1/8" thick on each side and so is the bit, so the collar offsets the bit by the diameter of the bit.

If you do a blob shape you don't have to do the rounding or squaring. You can buy kits that have multiple templates and precut inserts to match. Or you can make your own.

See if this helps

Ellis Walentine

Re: See if this helps

Tom Norton

Thanks Ellis!! I made a screenshot and will print a copy for my shop notebook!

Re: See if this helps

Joseph Bradshaw

I used a variation of the method that Ellis showed to make a clamping jig for some steam bent pipe stems. My work piece was to be 3/8" square. I drew my ogee curve on my template material and carefully cut it on the bandsaw. I smoothed the cut edges. I then cut a matching curve on the jig pieces. I clamped the jig pieces down with a 1/4" gap. I used a 1/2" bushing and a 3/8" bit. I set my template up so that the router would center on the gap that I left. My jig pieces were 3/8" plywood and I cut the shape in one pass. I am using oak for the stems and this setup has worked well.