Why can't you joint both sides of a board, using a router?

[LFS19]

I was watching a video today on YouTube.
It was a tutorial of how to "square up" or "joint" the edges of a board with a router and an offset fence.

The guy explained that you couldn't just flip it over and joint the other edge, but he didn't explain why.
I was wondering why this is and asked here, as I'm sure you'll all know.

He proceeded to take the other edge to the table saw and joint the edge on there...

Thanks allot.

 

[Racers]

On a router table you can't get the edges parallel.

You need a fence to set the width.

Pete

 

[RobinBHM]

It is possible but a table saw with a fence will naturally create a dead parallel cut without much effort.

 

[LFS19]

Thanks for your replies.

Forgive my idiocy on the topic, but I'm not really sure what you mean by parallel.
Obviously I know what parallel means, but not what it refers to in this instance.

Thanks

 

[mseries]

can you post a link to the video ?

 

[novocaine]

in this instance, same width plank at both ends. you'll end up \ / or / \ not | | which is what you want.

 

[bertikus_maximus]

So, imagine you draw two lines on a piece of paper. If those lines are parallel, the distance between them will be consistent along the length of the lines. Draw two 'ends' (by joining the right hand end of one line to the right hand end to the other, and the same for the left hand ended) and you've effectively drawn a piece of timber in 2D. This shows that having parallel edges on the board ensure a consistent width all the way along its length.

Hopefully this explains what's meant by having the edges parallel and why it's important?

 

[mseries]

Usual router method us using a split fence with the trailing face inline with the cutter and the leading face a mm back. By leading I mean the face that contacts the wood first and leads the cutter to the wood. This then is referenced from the edge to be jointed. Swapping the wood round will still reference from the edge being jointed so their is no guarantee that it will be parallel to the first edge. To make it so you need to reference the second face from the first (such as the first running along a straight edge as in a table saw)

 

[Monkey Mark]

As said above. You could use a router to do this, first face (face A) done as above with the leading edge in a mm. But then you would need to turn the piece around. Run face A along a straight edge allowing face B to contact the router cutter.
Same as using a table saw, just a little more set up time.

 

[Monkey Mark]

This video shows the first stage. https://youtu.be/H6nql7mlSOo
Second stage he uses the table saw but could instead use a straight edge/guide in the t-track on his router table. Exactly the same process, just a different tool.

 

[LFS19]

The video is titled "squaring up board edges with a router" and it's by Steve Ramsey.
I'm not able to provide a link because using YouTube in the iPad browser just defaults to the app, meaning I can't copy and paste.

I understand what you all mean by paralel. The little diagram Novocain was what I'd envisaged you meant, but I just didn't understand how, from jointing both sides against a straight edge you could end up with / \.
I think I get most of it now, though.

The method you described using the router is indeed the method in the video.
I unscrewed the right hand side plastic plate on my fence, and placed a mm thick piece of wood between the plastic plate and the part it was screwed onto.
This created a mm difference in once side.

Monkey Mark - that makes sense. I guess that's what I'll do then.

That was actually the video I watched, by the way. :mrgreen:

Thanks everyone

 

[WellsWood]

As said above. You could use a router to do this, first face (face A) done as above with the leading edge in a mm. But then you would need to turn the piece around. Run face A along a straight edge allowing face B to contact the router cutter.
Same as using a table saw, just a little more set up time.

If I understand that correctly what you are suggesting here is the equivalent of running the piece through between a straight fence and the bit. This is extremely bad (and dangerous) practice as the work will be drawn into the cutter and away from the fence, risking ruining the edge as well as catastophic kickback.

 

[Monkey Mark]

As said above. You could use a router to do this, first face (face A) done as above with the leading edge in a mm. But then you would need to turn the piece around. Run face A along a straight edge allowing face B to contact the router cutter.
Same as using a table saw, just a little more set up time.

If I understand that correctly what you are suggesting here is the equivalent of running the piece through between a straight fence and the bit. This is extremely bad (and dangerous) practice as the work will be drawn into the cutter and away from the fence, risking ruining the edge as well as catastophic kickback.

Which is why people use a table saw.

If i was to do it in the router table i would have the main fence set only just back from the cutter with finger boards to help.
It should, with correct rotation, try to push the piece away rather than pull it in.

 

[LFS19]

Well, I've put up a thread about getting a straight cut with a circular saw because I don't have a table saw.
Maybe I could just use that.

Most of the jigs for it, though, are for cutting sheet wood, so I'm not sure what I'd use just to take of a thin piece from a narrow board.

 

[WellsWood]

How about this: use your router table in "planer mode" to generate a straight edge on your first board (or one edge on all your boards) then use that as a guide rail to get the second edge on all subsequent boards. There is no safe cut that can be performed with a router that will push the work away from the cutter.

 

[LFS19]

How about this: use your router table in "planer mode" to generate a straight edge on your first board (or one edge on all your boards) then use that as a guide rail to get the second edge on all subsequent boards. There is no safe cut that can be performed with a router that will push the work away from the cutter.

Sorry but I'm not quite sure what you mean.
How I'm envisaging that in my head is similar to what you were saying was dangerous earlier, so I must be getting it wrong! Haha

Thanks

 

[WellsWood]

Sorry, was a bit cryptic there, let's have another go.

Once you got your boards with one jointed edge each (using your router table as previously discussed) you can use that edge to dictate the second edge on all your boards by doing the following with the router used handheld:

1. calculate the offset between the edge of your router base and the cutter with this formula:- diameter of base minus the diameter of cutter divided by 2
eg: if your base is 150mm and cutter 12mm then your offset is (150 - 12) ÷2 = 69

2. Decide what width you want your board to finish and subtract this figure, for a 200mm finish board this will be 131mm. Mark this from your already established edge and clamp a second board with it's straight edge on this line.

3. You now simply run you router handheld along this straight edge, effectively using the base as a large guide bush, to cut the second joited edge on your first board.

4. Repeat for all subsequent boards

This method is much much safer than trying to use your router table as if it were a tablesaw to define a set width, as the cutting action will always pull the router TOWARDS the guide edge of the board on top - effectively your "fence".

Make sense now?

 

[Eric The Viking]

Wot Mark just said.

I managed for a number of years without a planer/thicknesser, using the router table to plane stock...

... BUT... not for the whole process.

Tall (75mm) cutter + split fence (bit of Formica stuck to the outfeed side) = nice result, usually*.

Then use that new face flat on the table to square up one of the adjacent sides (I was doing some small window frames, mostly).

At that point it's down to hand tools and careful measuring / marking out. Plane to the line and check for squareness and flatness in the usual way.

I didn't own a tablesaw, but I did have a small bandsaw. That's a great tool for dimensioning long stock. It's relatively safe ("kickback, wot kickback?"), and once you have two nice true faces, squaring off the other two is straightforward.

Any operation that puts the stock between the cutter and the fence on a router table is inherently unsafe. You might, just, square a parallel face with a sled (clamping your known good face parallel to the track), but you'd have to make one, contrive adjustable clamps on it, and put up with the reduced cutter height.

It's do-able, but not elegantly. But for small stock it's a good way of making use of old kitchen worktop cutters - it's one of the few applications that doesn't wear the end of the cutter more than the bit near the shank. Otherwise-worn-out worktop cutters can be 'recycled' that way, but frankly it's still a lot of faffing about.

E.

* You'll never get as nice a finish from the Router table approach as a proper planer (even small planers), because the cutter diameter has to be a lot smaller, and the split fence approach usually makes a mess of gnarly grain, even if the cutter is razor sharp.

 

[LFS19]

Sorry, was a bit cryptic there, let's have another go.

Once you got your boards with one jointed edge each (using your router table as previously discussed) you can use that edge to dictate the second edge on all your boards by doing the following with the router used handheld:

1. calculate the offset between the edge of your router base and the cutter with this formula:- diameter of base minus the diameter of cutter divided by 2
eg: if your base is 150mm and cutter 12mm then your offset is (150 - 12) ÷2 = 69

2. Decide what width you want your board to finish and subtract this figure, for a 200mm finish board this will be 131mm. Mark this from your already established edge and clamp a second board with it's straight edge on this line.

3. You now simply run you router handheld along this straight edge, effectively using the base as a large guide bush, to cut the second joited edge on your first board.

4. Repeat for all subsequent boards

This method is much much safer than trying to use your router table as if it were a tablesaw to define a set width, as the cutting action will always pull the router TOWARDS the guide edge of the board on top - effectively your "fence".

Make sense now?

Ah I see, thanks very much for the explanation!

 

[LFS19]

Wot Mark just said.

I managed for a number of years without a planer/thicknesser, using the router table to plane stock...

... BUT... not for the whole process.

Tall (75mm) cutter + split fence (bit of Formica stuck to the outfeed side) = nice result, usually*.

Then use that new face flat on the table to square up one of the adjacent sides (I was doing some small window frames, mostly).

At that point it's down to hand tools and careful measuring / marking out. Plane to the line and check for squareness and flatness in the usual way.

I didn't own a tablesaw, but I did have a small bandsaw. That's a great tool for dimensioning long stock. It's relatively safe ("kickback, wot kickback?"), and once you have two nice true faces, squaring off the other two is straightforward.

Any operation that puts the stock between the cutter and the fence on a router table is inherently unsafe. You might, just, square a parallel face with a sled (clamping your known good face parallel to the track), but you'd have to make one, contrive adjustable clamps on it, and put up with the reduced cutter height.

It's do-able, but not elegantly. But for small stock it's a good way of making use of old kitchen worktop cutters - it's one of the few applications that doesn't wear the end of the cutter more than the bit near the shank. Otherwise-worn-out worktop cutters can be 'recycled' that way, but frankly it's still a lot of faffing about.

E.

* You'll never get as nice a finish from the Router table approach as a proper planer (even small planers), because the cutter diameter has to be a lot smaller, and the split fence approach usually makes a mess of gnarly grain, even if the cutter is razor sharp.

I see, that makes sense.
It certainly sounds like a considerable amount of faf, haha

Thanks