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Router table parallel rip in 2 passes

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Forum topic by Dzhaughn posted 04-11-2017 01:29 AM 1557 views 0 times favorited 22 replies Add to Favorites Watch
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Dzhaughn

9 posts in 1031 days


04-11-2017 01:29 AM

Topic tags/keywords: router table safety rip parallel

I am a beginner. Here is a crazy idea that occurred to me to do this parallel “rip” in 2 passes. I think it uses only standard, usual operations. Any objections?

(1) Ensure one side of the board is straight, joint if necessary.
(2) Set router table fence to desired width
(3) With straight bit, rout a dado 1/4” deep, parallel to the jointed edge. This is not a through cut, just a dado 4” from and paralell to the jointed edge.
(4) use a jig saw or hand saw to crudely cut through the middle of the dado
(5) use a flush trim bit to trim off excess, referencing the remaining wall of the dado. (No fence on this step.)

Any safety concerns about this procedure?

Next, with the hope of smaller off-cuts, reverse steps 3 and 4? That is, trim the board to roughly parallel + and extra 1/8”, then rout a rabbet referencing the jointed edge against the fence. (Still not a through cut.) Then flush trim. Is that different? Why?

The point of this idea is to be able to do good quality, repeatable parallel rips without a table saw. Just for beginners, not for heavy duty production


22 replies so far

View bondogaposis's profile

bondogaposis

4478 posts in 2188 days


#1 posted 04-11-2017 02:09 AM

Yes, it would work but very slow compared to making the same cut in one step on a table saw. It wouldn’t take too many cuts like that to convince you get a table saw.

-- Bondo Gaposis

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Danpaddles

573 posts in 2149 days


#2 posted 04-11-2017 02:27 AM

I’d use a circular saw with a straight edge, them hand plane to take out the blade marks. Your way, yes technically would work. But you will have a large pile of sawdust, and a dull bit when you get done.

-- Dan V. in Indy

View BurlyBob's profile

BurlyBob

5057 posts in 2102 days


#3 posted 04-11-2017 02:48 AM

I agree with Bondo and Dan. A table saw is the best tool for the job. A router table is intended for other things not as a saw!

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HokieKen

4512 posts in 975 days


#4 posted 04-11-2017 05:07 PM

Why not just cut to rough width with jig/hand saw then set router fence to final width and clean edge up in a single pass? Same as the process you laid out but eliminates step #3 and the need to use 2 different bits.

-- Kenny, SW VA, Go Hokies!!!

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Dzhaughn

9 posts in 1031 days


#5 posted 04-11-2017 07:58 PM

@everyone Of course, the table saw is a better way to do this. My question mainly is whether the procedure is safe, and then academic interest. How can you do a parallel rip with only portable tools?

@Danpaddles a straightedge involves measuring and marking, isn’t repeatable, and hard to do on small pieces, say less than 4” wide. I’m sure its more saw dust, but all of Europe cuts dados with router tables and they aren’t buried in saw dust and worn bits, or are they? But, okay, I won’t do the kitchen cabinets this way :) But how about a jewlery box?

@HokieKen Good question, this is the crux of the matter. If I understand correctly, some say your suggestion is unsafe, as the motion of the bit pinches the board onto the fence. (Or, if you go the other direction, pulls the board out of your hands.) That said, I am not quite sure I see the problem, and would like to understand better. Your method is essentially using the router table as a very narrow thickness planer that has been turned on its side.

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HokieKen

4512 posts in 975 days


#6 posted 04-11-2017 08:10 PM


@HokieKen Good question, this is the crux of the matter. If I understand correctly, some say your suggestion is unsafe, as the motion of the bit pinches the board onto the fence. (Or, if you go the other direction, pulls the board out of your hands.) That said, I am not quite sure I see the problem, and would like to understand better. Your method is essentially using the router table as a very narrow thickness planer that has been turned on its side.

- Dzhaughn

You understand correctly. I’m not sure I see a safety issue as long as you rough cut the board before routing so you’re only taking a light cut (1/8” or so depending on size of your bit). The pinching that can occur at the back of a blade on a table saw can’t occur on a router table. Since your cutter is rotary, as long as you cut in the right direction, I can’t see a problem. I have done this many times when I find I need to trim a board width by more than I want to shave with a hand plane and less than the kerf of a table saw blade because the blade can deflect if it’s not engaged on both sides. Never had a problem.

-- Kenny, SW VA, Go Hokies!!!

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Dzhaughn

9 posts in 1031 days


#7 posted 04-12-2017 04:49 AM

For reference, here are some internet discussions where some raise safety objections.

Below, they describe it as a “rocket launcher.” I wonder why they do not complain about cutting a groove that way. (some reserve “dado” for a cross-board cut, the long edge supported with a miter gauge or sled. Is a lengthwise groove on a router table something that is not-done?)

http://lumberjocks.com/topics/27072

Below, I can’t tell if they are trying to make the faces parallel, rather than the edges. That seems much worse than what I propose. While the physics is somewhat similar, it involves more of the bit and with only the edge as a reference surface it looks very tricky.

http://www.routerforums.com/table-mounted-routing/23980-using-router-table-make-two-flat-edges-parallel-bad-idea.html

View HokieKen's profile

HokieKen

4512 posts in 975 days


#8 posted 04-12-2017 12:15 PM

I can see what they’re saying but it seems unlikely to me. Since the bit is rotary and cuts on all sides, I don’t see how the board could get “pinched” between it and the blade. If it gets pinched, the bit’s simply going to remove the excess material. Now, the “rocket launcher” is very possible IF you make climb cuts (cut in the opposite direction). But, if you cut in the proper direction, don’t take cuts that are too heavy, and make sure you have a good grip on your board, I think it’s a perfectly safe operation. Like I said, I’ve done it several times with no issues at all other than some burning on the edges of some woods. All this is based on the assumption that your first step is done – the edge riding the fence needs to be jointed.

Face jointing I don’t think is really practical. I can see the “pinching” being an issue if your cutter isn’t as long as your board is wide and you have a guide bearing on it. Pinching could occur between the fence and the bearing.

I think if I were you, I’d just do some trial runs with light cuts and see how it goes. I think you’ll find it’s not a problem.

-- Kenny, SW VA, Go Hokies!!!

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HokieKen

4512 posts in 975 days


#9 posted 04-12-2017 12:22 PM

One other thing I forgot… if you’re concerned about the pinching, make a shim plate for the leading half of your fence. That way, your only using the fence to guide it before the cut and there’s no fence there to “pinch” it after the cut. European table saws come with those types of fences for the same reason. To me, while it makes sense with the table saw, it’s unnecessary for a router table though.

-- Kenny, SW VA, Go Hokies!!!

View a1Jim's profile

a1Jim

116576 posts in 3414 days


#10 posted 04-12-2017 12:51 PM

Of course, this can be done but as a woodworking instructor I find in most cases, beginners have table saws before the have router tables even though they’re low-end table saws they would in many cases do a better more efficient job in ripping wood, Even a circular saw with a clamped on fence will do the job quicker and cleaner than the process you describe as long as the circular saw can be clamped in such a manner that it’s securely held upside down,this of course is not the safest approach to ripping wood.
All said and done there are many ways to rip wood but some make more sense than others.

-- http://artisticwoodstudio.com Custom furniture

View bbasiaga's profile

bbasiaga

1009 posts in 1832 days


#11 posted 04-12-2017 01:17 PM

You could also take the router out of the table and get yourself one of those straight edge guides for it. I know on my little router table the fence doesn’t go back very far, making your rip cut procedure limited to narrow boards.

Brian

-- Part of engineering is to know when to put your calculator down and pick up your tools.

View Dzhaughn's profile

Dzhaughn

9 posts in 1031 days


#12 posted 04-15-2017 07:25 PM

To answer my own question: Google “router table trapped”

Bill Hylton’s Router Table book was the 4th result, and gives the best exposition.

The 3rd result, page (a manual on a commercial router fence) is succinct, see page 2.

“http://go.rockler.com/tech/22032013040934-49298-Router-Fence-Inst.pdf”

TL;DR it confirms that my step 3 is a “common router table operation” when not a through cut and done in the correct direction. However, widening a dado may create a trap, think about it. It labels HokieKen’s method above dangerous, because the bit pulls the workpiece away from the fence in the proper feed direction, or pulls the workpiece through the wrong feed direction.

Of course, nothing in the world is “safe,” and it makes sense that HokieKen can avoid problems by taking small cuts with a slow feed rate, because then the force away from the fence relatively small. Theorietically, 2 strategically placed featherboards, placed like rollers in a thickness planer, could also work, but that does not look practical at first glance.

View HokieKen's profile

HokieKen

4512 posts in 975 days


#13 posted 04-15-2017 10:13 PM

I can see the point about pulling away from the fence. Never really even noticed a problem with it though.

Featherboard would indeed solve that problem. Not sure why you would need two though. Just one right ahead of the cutter.

I would never suggest someone do anything that they felt was unsafe. I would suggest you go ahead with your original plan. Let us know how it works for you!

-- Kenny, SW VA, Go Hokies!!!

View EEngineer's profile

EEngineer

1089 posts in 3450 days


#14 posted 04-16-2017 01:44 AM

Below, they describe it as a “rocket launcher.” I wonder why they do not complain about cutting a groove that way

Because, when you are cutting a groove, you have equal and opposite forces on either side of he bit. Forces balance and you have no net force to throw the board. When you are cutting one side of the board, there is force in only one direction and it truly becomes a “rocket launcher”.

Until you truly understand this idea of forces in cutting, may I suggest you refrain from using power tools?

-- "Find out what you cannot do and then go do it!"

View shipwright's profile

shipwright

7779 posts in 2635 days


#15 posted 04-16-2017 02:50 PM

Not to pass judgement on any of your advice or sources but finding advice online does not make it good advice. There is a wide range of “advice” available to the inexperienced. Unfortunately it is often given by other inexperienced but well meaning woodworkers. Or sometimes experienced woodworkers who have enough knowledge and skill to safely do what they suggest don’t realize that it may not be as safe for someone with less experience.
I realize this isn’t much help. ...... just sayin’

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees. http://thecanadianschooloffrenchmarquetry.com/

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