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What bit to use for edge jointing slabs

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Forum topic by bhacksaw posted 10-22-2015 08:08 PM 1033 views 0 times favorited 16 replies Add to Favorites Watch
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bhacksaw

161 posts in 1286 days


10-22-2015 08:08 PM

I’m going to glue up two 8’ long 2” thick slabs. I don’t want to rip joint two edges straight and glue them together, however. I’d like to make it look a little more interesting. Here’s my plan:

-find a grain line on one of the slabs to cut along. cut to the waste side of that line with a jigsaw.
-cut a long pattern piece to that sinuous line and double-edge tape it to that slab.
-Transfer that line to the other slab and jigsaw cut on the waste side.
-Place the slabs almost together with about 1/4” space in between.
-Use a router with a 1/2” diameter bit, running along the pattern, so that the bit is cutting both slabs simultaneously to ensure a matching seam

My question is whether i should use a pattern bit or a flush trim bit. I suppose I should go with 2 flutes rather than 3 to lessen the load on the motor. The slabs are 2”thick (hopefully just under 2” when i’m done planing/sanding because 2” is the longest cutting length i can find for a bit) and I’m a little nervous about that length. I could use this setup with a 1 1/4” pattern bit and then flip the slabs over and finish each individually with a flush cut bit, but doing the edge in 2 passes opens it up for more inconsistencies between the two edges.

Any advice would be greatly appreciated!


16 replies so far

View bigblockyeti's profile

bigblockyeti

3668 posts in 1182 days


#1 posted 10-22-2015 08:23 PM

The 1/2” bit idea sounds good, but it would have to be a flush cut & not a pattern bit as you wouldn’t be able to find a 1/2” pattern bit that long, it would break. 3 flutes would actually be less load on the router as you would not have all flutes engaging wood at the same time as you would with a 2 flute bit. A spiral fluted bit would work best for reducing the load, but a 3 spiral fluted bit that long would be expensive,

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Yonak

979 posts in 983 days


#2 posted 10-22-2015 08:31 PM

If the cut were straight, it would work fine but, as you follow along the curve of your grain, the gap will get larger and smaller, depending upon the angle of the curve, which would leave gaps between the boards when you glue up.

It seems like a very creative idea and would work if you were very proficient with your spindle sander instead of using a router bit.

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bhacksaw

161 posts in 1286 days


#3 posted 10-22-2015 09:18 PM

Yonak, I think I see what you mean. Hopefully, though, the curves will be subtle enough that the difference between inside/outside diameters will be negligible. Definitely going to do a test run. I WISH i had the setup that would allow me to run an 8’ slab on a spindle sander, but my shop consists of a shed from which i wheel all my equipment into the carport when working. And i don’t have a spindle sander. Someday…

Yeti, thanks. I know the flutes thing was counter-intuitive to the way i thought, i must have double-counter-intuitived myself.

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Yonak

979 posts in 983 days


#4 posted 10-22-2015 09:57 PM

Here’s another idea : once you find your grain profile, make a template that shape. Use the template to guide your routing. Then use the template to make another template as a negative of the first. Use second template to guide the routing of the other piece.

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bhacksaw

161 posts in 1286 days


#5 posted 10-22-2015 10:04 PM

That’s what I was thinking, too. It will certainly make for a less cumbersome routing job. And thanks for saying “grain profile”. I think that’s a phrase i’ve been struggling to find since i thought of this job.

View BasementShop's profile

BasementShop

69 posts in 762 days


#6 posted 10-22-2015 10:32 PM

I am really looking forward to pictures of your final, glued slab!

Two questions from the “Wowers!” arena:

1) Is matching grain profiles, and finishing two pieces to that profile, done to hide the seam inside the grain???

2) How many of you lumber jocks are motivated to go to this level of effort to make a seam invisible?

Thanks in advance for your answers!

Basement Shop

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bhacksaw

161 posts in 1286 days


#7 posted 10-22-2015 11:58 PM

Bsmt, I only work one day every other weekend, so don’t hold your breath for the pics! ;) I heard it was a method to hide the seam. This is the first time I’ve ever done such a big glue-up. Probably foolish, but what the hey!

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BasementShop

69 posts in 762 days


#8 posted 10-26-2015 07:39 PM

I’m still impressed… and waiting impatiently for the pictures!

View rwe2156's profile

rwe2156

2190 posts in 942 days


#9 posted 10-27-2015 11:42 AM

+1 on making a pattern and routing a positive and negative.

How about instead of hiding the seam, accentuate it with a 1/8 thick strip of contrasting wood?
What the heck, how about several strips?
You already have a bending mold!

-- Everything is a prototype thats why its one of a kind!!

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cutmantom

389 posts in 2497 days


#10 posted 10-27-2015 12:10 PM

Maybe regular bit and a guide bushing

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jkn09

49 posts in 776 days


#11 posted 10-27-2015 01:48 PM

I’ll add a +1 to the template idea. I want to say I saw somebody do that here on LJs not too long ago. Cut along your grain profile, put MDF/plywood under it and trace the profile, then carefully cut along your line. That should give you a template for each piece of wood. If you cut carefully enough, then you can run your router with a bushing along the template for both sides. Should be a perfect fit.

As far as the bit goes, I used a 2-1/2” flush trim bit to make the outline for a walnut guitar body a while back. Worked like a charm.

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bhacksaw

161 posts in 1286 days


#12 posted 10-29-2015 02:43 PM

Found this beaut on Amazon. It’s 2.5” but only 2 flutes. I got a 3 fluted 2” Whiteside last week but at the low cost I figured why not get this one, too.

http://www.amazon.com/gp/product/B00KZM1JK8?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

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HokieKen

1744 posts in 600 days


#13 posted 10-30-2015 09:00 PM



Here s another idea : once you find your grain profile, make a template that shape. Use the template to guide your routing. Then use the template to make another template as a negative of the first. Use second template to guide the routing of the other piece.

- Yonak

I think I’m missing a subtlety here :) If you just flipped the first template over, wouldn’t that be the same as making a second template that’s a negative of it?

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

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Yonak

979 posts in 983 days


#14 posted 10-30-2015 09:22 PM


I think I m missing a subtlety here :) If you just flipped the first template over, wouldn t that be the same as making a second template that s a negative of it?

- HokieKen

..Only if it’s symmetrical.

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HokieKen

1744 posts in 600 days


#15 posted 11-04-2015 02:29 PM


I think I m missing a subtlety here :) If you just flipped the first template over, wouldn t that be the same as making a second template that s a negative of it?

- HokieKen

..Only if it s symmetrical.

- Yonak

Duh. I don’t know why I assumed it would be. For some reason my mind went to a yin yang symbol to evaluate the situation. :-/

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

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