Groove routing question
#11
Let's say I have a 3/16" straight router bit and have to route a groove that is slightly wider than the bit.  What would be the safe way of doing this - where the fence is moved back or forward on the second pass?
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#12
on a router table first pass is the inner cut the second is made by moving the fence back; that keeps the cutter removing stock properly
Let us not seek the Republican Answer , or the Democratic answer. Let us not seek to fix the blame for the past. Let us accept our own responsibility for the future  John F. Kennedy 



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#13
Moving the fence back means taking new wood from the left of the existing slot, a climb cut.

You have to move the fence out (west) for a safe anti-climb cut/
Pat Warner
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#14
[Image: 99926963_03_md.jpg]

Are you sure of that? 

this illustration disputes your assertion
Let us not seek the Republican Answer , or the Democratic answer. Let us not seek to fix the blame for the past. Let us accept our own responsibility for the future  John F. Kennedy 



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#15
You're right, I'm wrong.
Pat Warner
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#16
You can make a jig that resembles a T-square with two legs.  Space the bushing so that the width will equal the desired with of the groove plus the clearance for your router bushing.  

Clamp it in place and take two passes.

This guy made an adjustable version, but instead of using a bushing he appears to be using the router base for location.  This is fine if your router base is perfectly round and evenly spaced.  Otherwise use the bushing.

[Image: 208989.jpg]
No animals were injured or killed in the production of this post.
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#17
The fact that someone of Routerman’s stature (as author of books on routers and as designer of beautiful router-fence hardware etc.) offers an incorrect answer highlights the difficulty of thinking and communicating about router direction.  Obviously, Routerman knows what he’s talking about, but talking can be confusing, and communicating can be hard.  Diagrams in books can be hard to decipher.  It’s important to think this through for yourself and to understand it.

From someone who knows a lot less about routing than Routerman, here’s what I do for the cut you describe:  I keep it simple.  

1.  I arrange the cut such that I always move from right to left on the router table with the work in front of and against the fence, and 
2.  I always keep the edge that’s being cut between me and the bit.  

If I do those things, then the direction of the cutter will oppose my (right-to-left) movement, not be a climb cut. 

To widen a groove under these rules, the fence must be moved back, away from me on the second pass, as JGrout said and Routerman agreed.  That way the fresh edge that’s being cut remains between the bit and me.  

Otherwise it would be cutting behind the bit, between the bit and the fence.  In principle, I could also widen a groove that way without doing a climb cut by advancing the fence toward me and going left-to-right on the table.  Symmetrical, sort-of -- right?  What’s wrong with that?  Several things.

 1.  It violates the simplicity-principle of planning the work so that I always move from right-to-left.  I impose this on myself because I work best as a creature of habit. 

2.  The work would be trapped between the cutter and fence.  There is no degree of freedom to back off safely.

3.  What happens if the fence should slip?  Maybe someday I forget to snug it down; maybe I just push too hard against the fence.  It immediately puts me into a sudden climb-cut situation where the workpiece may fly out of my hand and I’m left grasping for something that turns out to be the spinning bit.  

If the fence slips when I keep the cut between me and the cutter, I may ruin the workpiece, but I can also remain in control.  

Sorry this became a lot of words.  I’ll repeat that I think it’s most important to think this through for yourself so that you understand it.  Hope this helps.
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#18
(12-12-2016, 01:58 PM)Paul-in-Plymouth Wrote: The fact that someone of Routerman’s stature (as author of books on routers and as designer of beautiful router-fence hardware etc.) offers an incorrect answer highlights the difficulty of thinking and communicating about router direction.  Obviously, Routerman knows what he’s talking about, but talking can be confusing, and communicating can be hard.  Diagrams in books can be hard to decipher.  It’s important to think this through for yourself and to understand it.

From someone who knows a lot less about routing than Routerman, here’s what I do for the cut you describe:  I keep it simple.  

1.  I arrange the cut such that I always move from right to left on the router table with the work in front of and against the fence, and 
2.  I always keep the edge that’s being cut between me and the bit.  

If I do those things, then the direction of the cutter will oppose my (right-to-left) movement, not be a climb cut. 

To widen a groove under these rules, the fence must be moved back, away from me on the second pass, as JGrout said and Routerman agreed.  That way the fresh edge that’s being cut remains between the bit and me.  

Otherwise it would be cutting behind the bit, between the bit and the fence.  In principle, I could also widen a groove that way without doing a climb cut by advancing the fence toward me and going left-to-right on the table.  Symmetrical, sort-of -- right?  What’s wrong with that?  Several things.

 1.  It violates the simplicity-principle of planning the work so that I always move from right-to-left.  I impose this on myself because I work best as a creature of habit. 

2.  The work would be trapped between the cutter and fence.  There is no degree of freedom to back off safely.

3.  What happens if the fence should slip?  Maybe someday I forget to snug it down; maybe I just push too hard against the fence.  It immediately puts me into a sudden climb-cut situation where the workpiece may fly out of my hand and I’m left grasping for something that turns out to be the spinning bit.  

If the fence slips when I keep the cut between me and the cutter, I may ruin the workpiece, but I can also remain in control.  

Sorry this became a lot of words.  I’ll repeat that I think it’s most important to think this through for yourself so that you understand it.  Hope this helps.

Paul,
Thanks for your thorough explanation - it helps tremendously.
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#19
This is how I approach any straight NON through cuts on a boards face. Be it a dado, or a v, round, or whatever shaped bit. You can make a single width, or increase your width safe and accurately. Feeding against the fence when no stock has been removed is very smooth. I've felt not so smooth moving the fence to make a wider cut as Joe illustrated. I am not saying Joe is wrong, he feels doing it that way is right for him. I'm saying there is more than one way to skin this cat Wink

Plus using the jig I can use either a D handle, which I feel has LOTs of control, or a Colt, which fits in your hand, and I feel control is pretty easy with it. If you need to do a stop start cut, a plunge router can be used, it's pretty universal. If you are not making a dado, it is best to use a router template guide to "center" your v, or round bit. I am listing 3 different links to people making one of these "Router Dado Jigs" you will note none of them are exactly the same, none are critically measured for exact sizes and some have do dads, the one has about 50# of T Track on it, none of the other two have any T Track. All 3 work exactly the same, it is how much effort you want to put into it. All you need to do is insure you have adequate width to allow for your routers base, and enough room to stretch out to what you think your max width is. Keep in mind most Dados are 3/4" wide or less.

Our old hosts offered this one


Fine Woodworking says


Worst thing they can do is cook ya and eat ya

GW
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#20
I sell plans for a router Dado base that lets you do this in two passes using one straight edge setup.

I will be happy to send you the plans for free if you want, just PM me.

The base can be set using the piece you wish to set in the groove or a spacer block. Make one pass, spin the router 180, and make a second pass. You control the direction for proper cutting.
Ralph Bagnall
www.woodcademy.com
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