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Using lock miter bit on long boards.

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Forum topic by typing posted 10-19-2020 03:54 PM 370 views 0 times favorited 15 replies Add to Favorites Watch
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typing

46 posts in 501 days


10-19-2020 03:54 PM

I need to make a kind of a column from 1×8 pine boards using a lock miter router bit. The problem is that I only have a Kreg benchtop router table and the length of the column is 10 feet.
May it work or I should not even try and just use the table saw with the blade beveled at 45 degrees ?


15 replies so far

View PBWilson1970's profile

PBWilson1970

142 posts in 309 days


#1 posted 10-19-2020 04:20 PM

Sounds like it will be tricky to maintain the accuracy over the entire length of the board.

I’d set up an infeed roller and outfeed roller and use a featherboard to keep the stock tight against the fence right over the cutter.

Good luck!

-- I love the smell of sawdust in the morning.

View ChefHDAN's profile

ChefHDAN

1780 posts in 3765 days


#2 posted 10-19-2020 04:21 PM

If you make 100% certain that your RT is well secured to the table you have it on, and use feather boards, AND at least 1 helper you should be able to do it. The same would apply to cutting the 45’s on the TS.

The advantage of the lock miter comes into play for the assembly, gluing 10’ of a column with just 45 bevels will certainly require brads/pins to make it work, and with a lock miter you just need the clamps.

I used a lock miter to make the column in this table, and learned a valuable lesson, DO NOT put 2 different cuts on each board. The directions will say to do 1 edge flat on the table and the opposite edge on the fence. This works okay with frames or perhaps boxes that you can put a band clamp on but NOT FOR A Column.
Cut 2 of the boards, North & South, with the same profile (flat on table), on both edges. For the other 2 boards, East & West, use the interlocking profile, (face to fence), on both edges. Cutting them like this will result in only needing to apply clamp pressure to 2 of the faces. If you do what I did on my first one you will need twice as many clamps.

-- I've decided 1 mistake is really 2 opportunities to learn.. learn how to fix it... and learn how to not repeat it

View metolius's profile

metolius

260 posts in 1646 days


#3 posted 10-19-2020 04:22 PM

I have a lock miter, but I haven’t gone past an 8 inch edge. It is super sensitive to a clean and steady pass.

Seems that 10ft is a lot of feet of risk. I am sure it may work, and if I was doing it I’d expect to get it right one time out of five. :)

Lock miters are nice mechanical addition to end grain miter joints. It seems that you are mitering long grain, in which case my bet would be a glue up on a miter cut sawn may be sufficient.

-- derek / oregon

View Madmark2's profile

Madmark2

1815 posts in 1504 days


#4 posted 10-19-2020 04:28 PM

Featherboards and a powerfeeder are the only things that will keep things tight and even then you’ve got a long lever arm working against you.

-- The hump with the stump and the pump!

View SMP's profile

SMP

2868 posts in 821 days


#5 posted 10-19-2020 05:49 PM

Do you have a reliable friend or two that could help hold it in place and run it through. I have done similar and just have to explain to people what you want them to do including what to do if you need to stop etc. Do a test dry run first then go for it.

View Robert's profile

Robert

4150 posts in 2396 days


#6 posted 10-19-2020 05:59 PM

Do a miter fold just like a box. It will work on a column.

Link.

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

View splintergroup's profile

splintergroup

4128 posts in 2138 days


#7 posted 10-19-2020 06:03 PM

I did some oak table legs that required about 24” of lock miter cuts on the sides. With a router table it was doable, but took a lot of care to keep everything positioned. Pine is softer so that will go easier, but I’d pass on trying to do the same with 10’

Ten feet has a lot of long grain glue area so strength shouldn’t be a problem with a simple 45 deg. miter. Keeping alignment during glue up can be challenging, but there are ways to help.
Yo could cut a miter on the table saw or more accurately with a hand held router and a bearing guided 45 deg. chamfer bit. You can attach a straight edge (thin plywood or masonite) for the bearing to run against.

View Loren's profile

Loren

10788 posts in 4563 days


#8 posted 10-19-2020 06:05 PM

A lock miter is often overkill in solid woods. It’s useful for areas that are stressed like drawer fronts. Still, over 10 ft. getting those miters aligned might be a challenge at glue up time. I would probably use biscuits.

You can also use a 5/8” deep rabbet instead of a lock miter. I know it’s less appealing but it’s easier to align and glue up tight in my experience.

View Fred Hargis's profile

Fred Hargis

6571 posts in 3409 days


#9 posted 10-19-2020 06:17 PM

I think given the circumstances I’d just cut the miters and then use biscuits.

-- Our village hasn't lost it's idiot, he was elected to congress.

View therealSteveN's profile

therealSteveN

6648 posts in 1490 days


#10 posted 10-19-2020 06:23 PM

As suggested a LOT of jigging just to keep constant, and mostly consistent contact between the wood, and the cutter, is a must for that joint. Pine being pretty inconsistent (off the shelf) would be a poor choice, but 10’ long is stuff a legend would be made from if you got it to match tightly, and without a tight match that joint is just a failure.

As Loren suggested, biscuits, or possibly a Domino, or even dowels would allow both registration, and keep your glue up from slipping apart, while glue dries, and for the purpose of a column, would be plenty robust enough.

-- Think safe, be safe

View ChefHDAN's profile

ChefHDAN

1780 posts in 3765 days


#11 posted 10-19-2020 06:25 PM

I concede previous position and yield to the wisdom of Loren & Fred. Biscuits and glue, (or a spline), are the solution for MUCH less hassle.

-- I've decided 1 mistake is really 2 opportunities to learn.. learn how to fix it... and learn how to not repeat it

View CaptainKlutz's profile

CaptainKlutz

3831 posts in 2410 days


#12 posted 10-19-2020 08:00 PM

+1 Making long columns requires jigs/tooling, regardless of joint type.
Better question is which joint is easier/cheaper to make jigs for in your shop?

+1 Cutting profiles on both sides of long boards makes things much harder.
Any chance you can make it a 5-6 sided column?
The boat builders mastered long masts using birds-mouth joint centuries ago. Only need to profile one side of board on table saw for each joint. Here is calculator to help understand how.
https://duckworksmagazine.com/04/s/articles/birdsmouth/

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

View Loren's profile

Loren

10788 posts in 4563 days


#13 posted 10-19-2020 08:27 PM

here’s another idea that’s easy to put together. A 5/8” deep rabbet and a 45 degree bevel or roundover to the joint. Leaving it square is fine too but in pine hard corners get damaged in use so it’s good to round them off.

View Robert's profile

Robert

4150 posts in 2396 days


#14 posted 10-19-2020 09:27 PM

Didn’t anyone hear me?

FOLDING MITER!!!

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

View AlanWS's profile

AlanWS

97 posts in 4474 days


#15 posted 10-19-2020 10:15 PM

If you are gluing side grain of solid wood, a simple butt joint is as strong as the wood. Do you need a miter? The chamfered rabbet joint Loren showed would look similar and be much easier. A butt joint with the edge chamfered or rounded would be even easier, and might be sufficient.

Mitered (or lock mitered) corners are commonly used when one wants quartersawn grain on all four faces of the post—not likely the goal with pine boards.

-- Alan in Wisconsin

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