# Making a male part for a female part



## Chris Curl (Feb 13, 2012)

I have already made the holes for my new router table. They are 10x12", ani I made them with a 3/4" bit, so I have a 10x12" hole with rounded corners.

I'm sure there is a way using bushings to make a male piece that fits it, but I'm having a little trouble figuring out how to set it up.

Can someone point me to a good reference for it?


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## jw2170 (Jan 24, 2008)

Chris, I assume you want to cut a plate to fit in that space?

It is relatively easy to calculate the template if you know what cutter you are going to use.

Also, are you going to use a bearing guided cutter or a cutter in a template guide?

In this case, remember that you want to keep the "inside" of the cut.


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## Chris Curl (Feb 13, 2012)

thanks james. i THINK i may have figured it out ...

if i use a 1/4" flush trim bit to make a male template by carefully following the inside of the hole, then i use a 1/4" bit in a 3/4" outside diameter bushing/template guide, i SHOULD get a male part that fits the hole pretty much exactly.

or if i use a bushing and bit combo that gives me a template that follows the inside edge of the female XXX", then one that follows the outside of the template by the same amount will do it for me.

for my 3/4" radius rounded corners, the male needs to be at most 3/8" smaller than the female. otherwise, the corners will be malformed when i make the inserts. so in this case, XXX can be at most 3/8".

does this sound reasonable?


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## harrysin (Jan 15, 2007)

Chris Curl said:


> thanks james. i THINK i may have figured it out ...
> 
> if i use a 1/4" flush trim bit to make a male template by carefully following the inside of the hole, then i use a 1/4" bit in a 3/4" outside diameter bushing/template guide, i SHOULD get a male part that fits the hole pretty much exactly.
> 
> ...


Why not use the table saw to cut a piece the exact length and width then rout the corners round like in these shots.


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## bobj3 (Jan 17, 2006)

Chris 

How about the jig below you don't need to buy one you can make your own.

Amazon.com: Trend VARIJIG Frame System: Home Improvement

http://www.youtube.com/v/xtgbgwfBnak&autoplay=1&rel=0

===


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## jschaben (Jun 21, 2009)

What Harry said, except you used a 3/4 bit so you just have a 3/8" radius, personally, I'd just sand it.


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## harrysin (Jan 15, 2007)

Are you sure about the 3/8" radius John?


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## Chris Curl (Feb 13, 2012)

Harry and John, that was my original idea, but I thought this might be a good opportunity to learn how templates and guide bushings work and understand the math behind it.

Now that I understand it a little better, I think I can make a rectangular piece with square corners (on the table saw) that is 3/4" shorter and narrower than the opening. Then if I use a 1/4" bit with a 1" OD bushing, I will get a 3/8" offset on each side and the corners should be rounded with a 3/8" radius.

harry: yes, since i used a 3/4" wide bit, it has a 3/8" radius.

bob, I'm not seeing how I can use that to make the male part with rounded edges. That would result in a piece with square corners.


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## mgmine (Jan 16, 2012)

Chris I'm not sure what you are trying to do are you trying to make your plate lay flat on the table? Is the plate larger than the hole in the table? If so then you need to use a rabbiting bit to make the recess in the top to accept the plate.


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## bobj3 (Jan 17, 2006)

Hi Chris

Any time you use a round cutting tool or a round guide on a inside corner of a frame/template jig you will end up with round corners like a 3/4" or 1" guide and 1/2" router bit..

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## Chris Curl (Feb 13, 2012)

Art, my router table will be 2 pieces of ply glued together.

The top piece is 1/2" ply, with three 10x12" rectangular holes cut into it. These holes have rounded corners because I used a 3/4" straight bit. They are all the same size, because I used a template to make them. Since the bit was 3/4", the radius of the corners is 3/8".

The lower piece is 3/4" ply, also with three holes in it, but these holes are smaller than the ones in the top piece, such that when I glue the two pieces together, they will create a quasi-rabbeted edge that will support the insert plates.

So my task is to make insert plates that fit in the holes in the top with the smallest and most uniform gap around the edge as possible. 

I realize it doesn't HAVE to be perfect, but I will have projects in the future where I will want a professional looking finish. And it is time for me to start learning how to get there.


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## Chris Curl (Feb 13, 2012)

bobj3 said:


> Hi Chris
> 
> Any time you use a round cutting tool or a round guide on a inside corner of a frame/template jig you will end up with round corners like a 3/4" or 1" guide and 1/2" router bit..
> 
> ===


right. i get that. that is how i made the holes i have now in my top. but the part in the middle that comes out has squared edges.

what i need to do is make the male part that fits inside the hole. 

i think my approach is right ... make a rectangular piece with squared edges that is 3/4" smaller length and width and use a bushing/guide combination that puts the bit 3/8" away from the edge. then going around it should result in a male part for my hole.

does that sound right?


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## bobj3 (Jan 17, 2006)

Hi

It comes down to putting the kart b/4 the horse, I would suggest you buy 3 plates from Grizzly and re cut the hole to hold the plates,then you have a lip to support the plate and the router ,they are only 13.oo bucks...and come with the inserts..

===


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## Chris Curl (Feb 13, 2012)

bob, i am not interested in buying plates from grizzly. i am interested in making plates that fit nicely in the openings that i have already made.

are you saying that there isn't a good way to do it, and that i am basically screwed and should scrap this and start all over again?


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## bobj3 (Jan 17, 2006)

Hi

No I'm sure you will get it done but you doing it the hard way backwards you could say, no need to make it into a hard job 
You have the holes for the router to drop in you just need a lip to hold them.

==


Chris Curl said:


> bob, i am not interested in buying plates from grizzly. i am interested in making plates that fit nicely in the openings that i have already made.
> 
> are you saying that there isn't a good way to do it, and that i am basically screwed and should scrap this and start all over again?


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## Chris Curl (Feb 13, 2012)

bob, you don't know me very well ... i almost ALWAYS make my woodworking tasks harder than they need to be!


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## harrysin (Jan 15, 2007)

Chris Curl said:


> Harry and John, that was my original idea, but I thought this might be a good opportunity to learn how templates and guide bushings work and understand the math behind it.
> 
> Now that I understand it a little better, I think I can make a rectangular piece with square corners (on the table saw) that is 3/4" shorter and narrower than the opening. Then if I use a 1/4" bit with a 1" OD bushing, I will get a 3/8" offset on each side and the corners should be rounded with a 3/8" radius.
> 
> ...


Please stand or hold a 3/8" bit in your rounded corner that was made using a 3/4" bit!


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## Dmeadows (Jun 28, 2011)

I agree with Harry, that will not give you a 3/8 radius. Had to really think about that, but it can't, it will give you a 3/16" radius on a board 3/8" larger than your template. or maybe just a board 3/8" larger than your template. Remember that cutting on the outside of a template the inside edge of the bit is giving you your finish cut, not the outside!


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## Chris Curl (Feb 13, 2012)

i must not be explaining it well. 

obviously, a 3/8" diameter bit (which has a 3/16" radius) bit does not fit in a corner made by a 3/4" diameter bit which as a 3/8" radius.

but going around the OUTSIDE of a 90 degree template corner with a bit in a bushing will result in a rounded corner on the output piece, won't it? and wont the radius of that corner be the same as the distance that the outside of the bit is from the template? after all, the bit is 3/8" away from the template AT ALL TIMES, so around a square corner, that corner becomes the center of a semi circle, the radius of which is the distance to the bit.

is there something wrong with my logic?

so when you take a bit/bushing combo that puts the outside/cutting part of the bit 3/8" away from the template, then when you go around a square corner on the template, you should get a rounded corner on the result that has a radius or 3/8", (which just so happens to be the same as the radius of the rounded corner of the female part).


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## Dmeadows (Jun 28, 2011)

Chris Curl said:


> bob, you don't know me very well ... i almost ALWAYS make my woodworking tasks harder than they need to be!


I think we all do, sometimes. But that doesn't mean we should _design_ them to be harder.:laugh:


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## Dmeadows (Jun 28, 2011)

Chris Curl said:


> i must not be explaining it well.
> 
> obviously, a 3/8" diameter bit (which has a 3/16" radius) bit does not fit in a corner made by a 3/4" diameter bit which as a 3/8" radius.
> 
> ...


You are making the male part(the router mounting plate), no? The INSIDE piece is the one you want! Not the outside one. The outside of the bit is cutting scrap, not your finish piece! Try it see what happens. It's too early to think clearly!


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## Dmeadows (Jun 28, 2011)

duplicate post


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## Chris Curl (Feb 13, 2012)

sorry, i misspoke a little here ...

going around the OUTSIDE of a 90 degree template corner with a bit in a bushing will result in a curved corner on the output piece, won't it? and wont the radius of that curve be the same as the distance that the bit is from the template? so, since the bit is 3/8" away from the template AT ALL TIMES, around a square corner, that corner becomes the center of a semi circle, the radius of which is the distance to the INSIDE of the bit (3/8")


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## Dmeadows (Jun 28, 2011)

Yes, you are right. Must be to early in the morning to think right! That's my story and I'm sticking to it!


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## Chris Curl (Feb 13, 2012)

Dmeadows said:


> I think we all do, sometimes. But that doesn't mean we should _design_ them to be harder.:laugh:


Believe me, I'd much rather make them as simple as possible. My inexperience is usually the reason why I do things in the wrong order. The other cause is that I tend to jump into things before thinking them out fully.


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## mgmine (Jan 16, 2012)

To make the plate fit the hole is difficult so why not make the hole fit the plate. Cut what ever size plate you want then lay it on the table and trace it. Now cut the hole with a multitool using a straight edge. If you were only using one layer of plywood it would be necessary to support the plate from below. For that you could use either a thin piece of wood, strap metal such as used in construction (available in the joist hanger section of any building store) or clips that hold a storm window in an aluminum frame or even a butterfly latch.


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## Chris Curl (Feb 13, 2012)

Art, it is a little late now for me to change up. I have already glued the 1/2" to the lower supporting 3/4" ply and cut the holes. I don't really want to start over again:


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## jw2170 (Jan 24, 2008)

I see you are making great progress, Chris.


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## mgmine (Jan 16, 2012)

mgmine said:


> To make the plate fit the hole is difficult so why not make the hole fit the plate. Cut what ever size plate you want then lay it on the table and trace it. Now cut the hole with a multitool using a straight edge. If you were only using one layer of plywood it would be necessary to support the plate from below. For that you could use either a thin piece of wood, strap metal such as used in construction (available in the joist hanger section of any building store) or clips that hold a storm window in an aluminum frame or even a butterfly latch.


Okay with a table saw cut the plate to fit in the hole, turn the table over and trace the inner hole size onto the plate, remove the plate and trim off the excess wood so that it sits flat.


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