# How to route a long and thin beam?



## alfie_m (May 31, 2017)

So I am somewhat new to woodwork. The situation is this:

I need to route a 6mm wide and 5mm deep 'slot' in the middle of timber beams that are 44mm wide and 44mm deep and 2000mm long. I have attached a sketchup model of what I need to beam to look like.

I just dont know what kind of set up I would need for this? Would it be easier to pass the beam under the router or move the router over the beam? I need to have perfetly straight lines. What kind of router would be best for this?

I'm helping a friend build a photobooth and the timber beams will form the 'skelton' of the booth, while the routed 'slots' are for the mdf 'walls' of the booth, the mdf 'walls' will slot into the routed beams if that makes sense? I know it would be easier to just screw the mdf to the beams but the photobooth will be built up and taken apart many times and we decided that consently screwing and unscrewing the mdf to the beams would mess up the wood after a long time.

Any advice would be very much appreciated!

Thanks a lot


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## Steve Neul (Sep 2, 2011)

That would be probably be easier done on a table saw with a dado blade. To do it with a router you could improvise a sub-base for your router with a edge guide on it. It could just be a piece of 1/4" plywood with a straight edge glued to it.


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## woodnthings (Jan 24, 2009)

*If you only have a router ...*

A self centering guide would be best because it can not wander from side to side:











Your beams must be straight in order for your groove to be straight if you move the router along the top edge using the adjustable guide.

If you have a router table, then you would use the fence to make the groove the appropriate distance from the edge.

If you have a tablesaw and dado set, then you would use the fence on the table saw.

There is no machine commonly in use where you pass the work under the router. It is called an over arm router or pin router, but they are not that common. 

A radial arm saw could also be used with the dado set parallel to the table, but a bit scary to use that way, and the setup would be tricky .... not recommended.


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## 35015 (Nov 24, 2012)

From my perspective (and someone that works in large timbers on a regular basis) it is neither safe, nor logistically plausible to try to move a piece of wood as massive as something you are suggesting over a moving powered bit or blade.

Like most traditional work (even with power tools) in your case it will be the tool going through material...not material through tool...

You can cut the groove (dado) several ways with either hand tools (e.g. planes, chisels, or even saw methods) or with a powered router or saw, and the appropriate sized bit (take several passes, as removing all the waste at once can be a bit daunting.)

For layout of the lines, I would most likely a traditional Ink Snape Line...and perhaps back check (if new to snap lining timber) with a long straight edge perhaps...


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## ducbsa (Jul 6, 2014)

You could take another look at bolting the mdf sheet on, using some variety of these https://www.amazon.com/b/ref=s9_acsd_hfnv_hd_bw_b16rAj_ct_x_ct02_w?_encoding=UTF8&node=6909192011&pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-3&pf_rd_r=ARVWCQNY7KS3GVW9C0CM&pf_rd_t=101&pf_rd_p=abe37c29-f04d-5e97-816a-129ee9136bfc&pf_rd_i=16410701

As mentioned above, the beams must be straight so that any fence or jig as mentioned above will help you cut a straight slot needed for the very straight mdf.

These are used for rough boards to rip a straight side, maybe something similar could be used to cut a straight groove in a slightly bent beam? http://www.woodworkersjournal.com/how-to-cut-straight-edge-rough-board/


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## GeorgeC (Jul 30, 2008)

That is a very small piece of wood to use a router on. Hopefully you have a table saw. You might even do that one in a drill press.

George


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## woodnthings (Jan 24, 2009)

*good catch George!*



GeorgeC said:


> That is a very small piece of wood to use a router on. * Hopefully you have a table saw*. You might even do that one in a drill press.
> 
> George


The workpiece is 1 47/64" wide and 78 47/64" long and the slot is 15/64" wide :surprise2:

The word "beam" has thrown everyone off. These are not beams as known in timber framing or construction. :frown2:

A table saw would be a logical machine to use for this operation. A router is another good choice.


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## alfie_m (May 31, 2017)

Thanks for all the comments, so I'm now thinking maybe it would be easier to make the dados with a table saw. If I instead used 3mm thick mdf instead of 6mm then I could use a table saw blade with a Kerf of 3mm and have the saw blade protruding 5mm from the table, the MDF sheets would slot into the dado? My only question then would be do most table saws allow you to set the fence as low as 22mm?


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## woodnthings (Jan 24, 2009)

*The fence is set away from the blade ....*



alfie_m said:


> Thanks for all the comments, so I'm now thinking maybe it would be easier to make the dados with a table saw. If I instead used 3mm thick mdf instead of 6mm then I could use a table saw blade with a *Kerf of 3mm* and have the saw blade protruding 5mm from the table, the MDF sheets would slot into the dado? My only question then would be do most table saws allow you *to set the fence as low as 22mm?*


The fence is not a height adjustable unit. The blade is height adjustable. The fence is set a distance away from the blade. You sound a bit confused here...? 

You are complicating things also here by using metric measurements. In order to understand you questions we have to convert them to what we most commonly use... inches. 
A 3mm kerf would be 1/8" inches or "full kerf" no problem there.

Where will you find 3 mm MDF? There is certainly 1//8" thick plywood. I don't know of any 3 mm MDF.


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## Toolman50 (Mar 22, 2015)

When cutting a large dado with a router, do it in steps. It's usually better than trying to cut it in one pass. 
Also you might consider assembling the photo booth using dowel screws with wing nuts. Quick to set up or dissasenble.


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## alfie_m (May 31, 2017)

woodnthings said:


> alfie_m said:
> 
> 
> > Thanks for all the comments, so I'm now thinking maybe it would be easier to make the dados with a table saw. If I instead used 3mm thick mdf instead of 6mm then I could use a table saw blade with a *Kerf of 3mm* and have the saw blade protruding 5mm from the table, the MDF sheets would slot into the dado? My only question then would be do most table saws allow you *to set the fence as low as 22mm?*
> ...


Sorry I'm over here in Endland that's why I'm using metric, and MDF comes in 3mm thickness at all major places that sell wood over here.
No I know the fence is not height adjustable, I was wondering if there is a minimum distance the fence has to be away from the blade...


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## ducbsa (Jul 6, 2014)

I guess I wouldn't want the blade closer than 6mm from the fence. A sacrificial board clamped to the fence protects it from the blade, if needed. http://www.rockler.com/universal-fence-clamps


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## 35015 (Nov 24, 2012)

Thanks WoodnThings...I read this too fast and saw "beam" also...Since I work in metric..."I thought" (silly me...ha, ha,) the OP meant 440 mm...not 44mm...???...That's a long "twig"...ha, ha...

As such, your first post (if using a power tools) was the best advice thus far other than a "capture jig" for a Router to do the job at hand...

I would add that a simple Plow Plane sharp and tuned would have this job done before you could get a Router bitted, set up, and plugged in...haha...We use them all the time and for just a few pieces like this. It's better than the noise, dust, almost as fast (over all) and much less chance for error...

Thanks again WnT...


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## rcheli1 (May 20, 2017)

A table saw and dado blade are going to be your best bet. If you do not have access to a table saw and dado you might consider a glue up of three pieces that would result in a dado'ed beam.


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## regesullivan (Jan 26, 2007)

6mm wide would only be a couple of passes even with a thin kerf blade.... Really not worth setting up a dado unless you were doing a bunch of them. I think the op is on the right track with the table saw solution.


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