# Leigh FMT climb cut problems



## loked (Jul 12, 2014)

Hi,

I've recently bought myself the Leight FMT Pro jig. I've been trying to cut some tenons in white oak and I keep running into trouble with the climb cut. It grabs the router and pulls it along the edge (even leading to grinding against the jig itself). I'm trying to cut the largest possible tenon and I'm using the 1/2" Leigh up spiral bit. I'm also cutting about 1 1/2" deep. It's hard to make a light cut because the wood thickness doesnt really have much room between the bit and the guide edge, so I'm forced to take quite a deep cut (which might be what's causing the problem). Should I just be doing twin joints for a thicker piece?

Any advice would be greatly appreciated. I'm feeling like I'm A. going to damage this very expensive jig and B. like its quite dangerous having my router go flying along uncontrollably. 

Thanks!


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## Semipro (Mar 22, 2013)

N/A, welcome to Router Forums, glad to have you join us, I'm positive the members of the community would be more than willing to answer any questions you have 
One of the pro's will be along to help soon!


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## Stick486 (Jan 4, 2013)

which FMT do you have and are you using a plunge router???
I read that you are trying to cut 1.5 inches deep in one pass...
again, why is this???
you need to be trying to take seriously smaller bite climb cutting..


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## CharleyL (Feb 28, 2009)

Cut your tenon in multiple passes at increasing depths. Any attempt to cut deeper than 1/2" per pass will cause problems, not only when climb cutting, but also the chips will be too long and bridge across the vacuum port, causing it to clog up.

I also tried to cut long tenons when I first got my FMT jig and had similar problems. Since then I've begun cutting them in multiple passes at increasing depths. This also solves the problem of long chips clogging the vacuum port. The climb cutting step is necessary to minimize edge splintering, but keep it shallow. It only needs to be about 1/8" in depth. This takes practice, since it's basically a free hand cut. When cutting a tenon in multiple passes at increasing depths the climb cut only needs to be performed on the last bit depth setting to leave a chip free shoulder. You don't need to climb cut at the shallower depth settings, but it's a good idea to make a final finish cut on your tenon at the full depth using a climb cut. You shouldn't be removing much material with this last cut, but it will leave a very clean, smooth surface on your finished tenon.

The vacuum port will work very well to remove the wood chips from the back side and ends of your tenon, but it won't do well when cutting the facing side if the tenon is wide. I put some velcro along the front edge of the top plate of the FMT and have a 6" high by 8" wide piece of 1/8" clear Lexan that I have added mating Velcro strips to and I attach the Lexan so that it hangs down below the top plate. The Lexan keeps the chips off of you when cutting the front side of the tenon and it also adds a small level of protection from the flying debris, but keep your eyes and head above the jig when cutting the tenons. Don't use this Lexan to watch the cutting action. It isn't safe enough for that.


Charley


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## delmirj (Jan 10, 2013)

I take the first ( climb ) cut very thin, about 1/16 to 1/8 inch, then proceed in the normal manner taking less than 1/2 the bit diameter on each pass until the stylus is riding firmly on the template for the final cut.
This should solve your problem.
Dick


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## loked (Jul 12, 2014)

Fantastic feedback. Thanks very much! The reason I had been taking a full depth pass is because I read somewhere in the FMT manual (or maybe online) that there is no need to take multiple cuts with the up spiral bits, but by the sounds of things, that's not true. I was getting clogging of my vacuum as well, so this will also help. 

Thanks again for such in depth help. Much appreciated!


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## Jose Canha e Sa (Mar 20, 2017)

Hi There,
I have Leich FMT super for a few years.
I was not use for a few years and today I use it.
I find to move the router is not smooth.
I tried to use W40, vaseline it help but is not perfect.
Is anyone give me a solution?
Thanks
Jose


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## CharleyL (Feb 28, 2009)

Welcome to Router Forums.
Please take the time to edit your personal details. We already have too many people on this forum with the first name of N/a. Is it Jose? 

There are thin white strips of HDPE (High Density Poly Ethylene) on the top of the jig that act as bearings to make the router plate slide more easily. Are these still in place? If not, contacting Leighjigs.com Customer Service should get you some replacements 

Clean the top of your jig and the bottom of the router plate. Remove everything that you have tried (WD-40 and Vaselene) by using mineral spirits (paint thinner) or alcohol, and then apply two coats of paste wax (NOT CAR WAX), letting each coat dry to a haze before wiping it off. Johnsons Paste Wax or Butchers paste wax are good choices. Avoid using any wax that contains silicone. Repeat the wax application whenever the router plate doesn't seem to slide easily on the jig.


Charley


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## 4DThinker (Feb 16, 2014)

I you can cut 2 or even 4 smaller tenons rather than one large tenon, you'll get far more glue surface area contact in the joint. You'll also weaken the mortise side less as there will be a web of wood left between the 2 or 4 mortise slots. I've been doing several tests on this very topic and am convinced a double or quadruple tenon array does more than double or quadruple the strength of the resulting joint. 

Here is an extreme example using a tenon array on the end of cedar 4x4s: 4D Furniture Thoughts: Simple Desk Design. Tenon Array Joint.
This desk is extremely solid even with no stretchers. It is my office desk/PC station. 

4D


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## Jose Canha e Sa (Mar 20, 2017)

Thanks Charley,
I'm going to do what you say. At that moment is very hard to have a perfect control. Under the second plate it has that strip but not on the first one where is in contact with the black plastic. I saw on the pro it have that strip.
Many Thanks
Jose


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## CharleyL (Feb 28, 2009)

Johnson's Paste Wax, Burcher's Wax, or similar on the rubbing surfaces makes a huge difference. Avoid using car waxes, as most contain silicone. Silicone on your wood will cause all kinds of bad finishing problems. Silicone in any form is banned from my wood shop for this reason. Candle wax or Paraffin wax (canning wax) can be rubbed on the surfaces if you can't find the other waxes. It's difficult to get a thin amount when applied though, but it will work.

Charley


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