# Climb cut on a 45 lock miter bit?



## Finleyville (Feb 28, 2010)

Anyway...


I am trying to make my first box using a 45 lock miter bit. I am using BB plywood since I do not own a planer to use solid stock. When I feed the vertical pieces through I get major chip out on the inside face. 

So can I ease the fence little by little into the bit and not change the profile to reduce/end the chip out?


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## derek willis (Jan 21, 2009)

You could try that, but, personally I wouldn't use ply as yu will always get a bad break-out, try M.D.F. for better results.
Derek.


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## LexB (Apr 12, 2010)

Finleyville said:


> Anyway...
> 
> 
> I am trying to make my first box using a 45 lock miter bit. I am using BB plywood since I do not own a planer to use solid stock. When I feed the vertical pieces through I get major chip out on the inside face.
> ...


I haven't tried ply with my lock miter bit, but when I get chip-out with ply I first try supporting the fibers with blue masking tape along the cut line. Really burnish the tape firmly when applying it so that it bonds firmly with the wood. Be careful when removing the tape--pull in a direction that minimizes the tape pulling splinters out of the wood. The "low tack" painters tape (often called "delicate surfaces") works well.


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## harrysin (Jan 15, 2007)

derek willis said:


> You could try that, but, personally I wouldn't use ply as yu will always get a bad break-out, try M.D.F. for better results.
> Derek.


Welcome back Derek, long time no see. I agree with you that plywood is a poor choice for the lock mitre joint, I'm also not keen on MDF either because it's difficult to maintain a sharp edge and if the joint is a good fit, the tongue easily breaks off if a dry fit is tried before glue-up and if going straight to glue-up, you have to bring the two pieces together EXACTLY because there is no chance to re-align them. For "real wood" the lock mitre is a superb joint.


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## derek willis (Jan 21, 2009)

Harry,
couldn't agree more, but Michael says he has no way to handle real timber.
Derek.


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## Ralph Barker (Dec 15, 2008)

Lowe's and HD sell "craft" woods as thin stock - 1/2" and less, that are suitable for boxes, and such. My local Lowe's store carries Poplar and Oak, for example.


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## bobj3 (Jan 17, 2006)

Hi

The Climb cut works well for plywood..with the LM bit..
Just flip your fence around..to the other side of the bit.  make small cuts with bit, 3 or more the norm.
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## jschaben (Jun 21, 2009)

bobj3 said:


> Hi
> 
> The Climb cut works well for plywood..with the LM bit..
> Just flip your fence around..to the other side of the bit.  make small cuts with bit, 3 or more the norm.
> ======


Bj - can you explain this a bit more. "flip fence around.. to other side of the bit"?


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## harrysin (Jan 15, 2007)

bobj3 said:


> Hi
> 
> The Climb cut works well for plywood..with the LM bit..
> Just flip your fence around..to the other side of the bit.  make small cuts with bit, 3 or more the norm.
> ======


Bob, adjusting the fence to make small cuts isn't, in my humble opinion the way to go because as you well know, there are two adjustments in setting up for a perfect lock-mitre, the height of the cutter and the position of the fence, both generally require at least a couple of test cuts, so just moving the fence back a few times doesn't strike me as a method of achieving a perfect joint. The better way, again in my usual humble opinion, passing all the sides over a 45* bit so that about two thirds receives a mitre makes the work of the lock-mitre bit much easier. Having said this, most of the things that I make these days using lock-mitres are made from about 3/8" which is no problem in one pass.


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## bobj3 (Jan 17, 2006)

Hi Harry

I see you have the same error as most do, to get the Fine edge..
And in my usual humble opinion it takes the fence to be moved in and out and to make more than one pass..and the best way to do that is with the climb cut..it's like using your sanding disk trick but with the router bit..

see video below, take note about using plywood, they don't show the climb cut way but I use it all the time on the fine cuts.
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_lockmiter.html
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harrysin said:


> Bob, adjusting the fence to make small cuts isn't, in my humble opinion the way to go because as you well know, there are two adjustments in setting up for a perfect lock-mitre, the height of the cutter and the position of the fence, both generally require at least a couple of test cuts, so just moving the fence back a few times doesn't strike me as a method of achieving a perfect joint. The better way, again in my usual humble opinion, passing all the sides over a 45* bit so that about two thirds receives a mitre makes the work of the lock-mitre bit much easier. Having said this, most of the things that I make these days using lock-mitres are made from about 3/8" which is no problem in one pass.


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## jlord (Nov 16, 2009)

No need to flip your fence to the other side of bit to make climb cuts. The description sounds like you will be trapping your material between the bit & the fence. Great recipe for a missile in the shop. Just run your material left to right & hold on using pressure to backup the front of the piece. It will want to go faster than you do. You should not get any or very little tear out using the right way if your bit is sharp, router has enough torque for the cut, & router speed is set right. If climb cutting be careful it can be a dangerous operation & possibly damage your material if it gets away from you. Do not suggest doing if you have little experience with the router or table


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## bobj3 (Jan 17, 2006)

Hi 

The Climb cut is *Not* for the *Novice* router table user !!!!!
But it's one you want to *master* .
Why you want to flip the fence around, it gives you a bigger foot print to work on the norm.
You want all the help you can get...when making the climb cuts , you must hang on to the stock or have a way to keep it in place with a sled if you want to..and a tall fence, same thing bigger foot print.

You will not see why you need to flip the fence around until you try it..
I use the fence below with the push block when I use the LM bit, it's makes it very safe..and dead on every time..
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## KenDarga (Feb 18, 2011)

Very Good info---
thanks for sharing


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## Finleyville (Feb 28, 2010)

Alrighty then...

It seems that I may have mislead some posters with "my" definition of a climb cut on a router table. It probably is my fault that I am using the wrong word.

I didn't have any tear out on my ply when feeding the face flat on the table. I was only having problems when feeding the mating boards vertically. 
So after I mark the proper fence position can I move the fence INTO the bit so I remove a small amount of wood like you would a deep rabbit? Then incrementally move the fence back to the set stop? Will this result in the same final profile needed for a proper lock miter cut?

I know on some profiles this method will not work. Is a lock miter one of them?

BTW, I personally would never trap a work piece between a fence and a bit. However, I do not have nearly the experience as some other members here.


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