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Discussion Starter · #1 ·
Hey everyone,

I picked up used Leigh FMT mortise and tenon jig recently. Unfortunately, it is missing the sub-base to mount the router on. I called Leigh and the sub-base is available for about $300CAD. Before I take the plunge on a new one I thought I might try making one to at least get started playing around with this thing. So I was wondering if anyone here has one and would be willing to take some measurements for me so I could figure out the rough size and placement of the pins and the router?

Thanks very much.
 

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the FMT and the FMT Pro are different animals...
also, is it sub base for the router or for the jig???...
which is it???...
 

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Discussion Starter · #4 · (Edited)
Thanks for the replies. As I said in my original post I'm "missing the sub-base to mount the router on". What I'd really like to know is the distance between the two guide pins on the bottom of the universal sub-base that fit into the joint guides as shown in the photo below. I think I can make some good estimates about the rest of the sub-base dimensions from there.

Thanks again. I've also attached a couple pics of the used FMT I bought.
 

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Discussion Starter · #6 · (Edited)
Sorry if I did not explain what I'm looking for very well. Here's a picture that may clear things up. I purchased a used Leigh FMT mortise and tenon jig at a local Habitat ReStore, but it is missing the Universal Sub-Base that attaches to the router as seen in the photo. I would like to try making a sub-base, but would like to know the distance between the Left Guide Pin and the Right Guide Pin. The pins appear to be tapered to fit in the Joint Guides, but I have a mini-lathe and think I can make something that fits.

Hope that helps a bit. It would be great if someone can let me know the distance between the pins.

Thanks again.
 

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Discussion Starter · #9 ·
Thanks for the the pics and measurements Steve. It looks like you have the FMT Super, but hopefully the specs are the same as the Pro/Original. Doesn't look like it would be too hard to make something similar.
 

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The left pin in your first pictures is a tapered pin, with an adjustment knob on the top side of the plate to move it in and out. It is used to fine adjust the dimensional relationship of the tenon to the mortise, to get the desired perfect fit of the tenon to the mortise. An 1/8 of a turn of this knob will change the mortise and tenon fit by about 0.001". Once set, you can create mortises and tenons of the exact size relationship to fit together perfectly.

I have an early model FMT jig, but I have a knee problem that will keep me from getting to the jig to be able to measure it for a while, so I hope you can find someone else who can provide your needed measurements. They need to be quite accurate, not only for the pin spacing, but the pin to router bit center measurement as well. It would be best to make the plate from aluminum, since moisture changes in a wood plate might seriously affect the accuracy of the jig. The taper on the pin is going to be hard to measure too. It's this accuracy that is likely the reason why a replacement plate is so expensive.

How in the World did the seller manage to loose the top plate to his FMT? He likely still has it attached to one of his routers and it is some place in his shop. Maybe you could help him search for it (and maybe find some other goodies in the process). If not, deducting the cost of a new top plate should be part of the pricing for what is left.

Charley
 

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Discussion Starter · #11 ·
Thanks for the info Charley. I found the FMT in a Habitat for Humanity ReStore. It was probably dropped off there by the family of it's former owner. The router plate could have been tossed out by the family or maybe sold at the Restore with a router before I got there. I searched every inch of that store hoping to find the base, extra joint guides, or accessories, and asked the staff if they'd seen anything like it, but no luck.
 

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Discussion Starter · #12 ·
Here's a pic of my first attempt at turning a guide pin for the sub-base. Ten degrees seems perfect for the left guide, but it's a bit loose of the right side. I think 11 or 12 might be a better fit on that side. Seems odd they would use different angles.
 

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Just a suggestion, maybe you can get someone who has a baseplate transfer the size and shape onto a cardboard template,including the pin positions, and mail it to you. This will not solve the taper on the pins, unless someone can accurately measure the length of the taper for you.
Herb
 

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Discussion Starter · #14 ·
Just a suggestion, maybe you can get someone who has a baseplate transfer the size and shape onto a cardboard template,including the pin positions, and mail it to you. This will not solve the taper on the pins, unless someone can accurately measure the length of the taper for you.
Herb
A template would be amazing if someone could do that. A drawing that could be scanned or photographed would probably work just as good too.

I emailed Leigh and asked if the base for the FMT Super would work on the FMT Pro or Original and they said no, the parts are not interchangeable. Don't know if the pins are in different locations, but if anyone could check the base for a Pro or Original I'd really appreciate it.

Thanks again for all the replies.
 

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The taper pin adjusts the accuracy of how tight/loose the tenon is to the mortise. In use, the tapered pin does not touch both sides of the plastic template at the same time. You make a pass down one side and back on the other for cutting the mortise. The pin then rides against the outside of the same template when cutting the matching tenon. Changing the depth that the tapered pin fits into the template makes slight changes in the dimensional relationship of the tenon to the mortise. Once the pin is at the correct depth, the tenon cut will perfectly fit the mortise cut with the same bit and settings.

I think you should download the manual for the FMT Pro and read it thoroughly. Watch their Youtube demos and training videos too. My leg problems have not allowed me to get to my shop, so I still can't take measurements for you, but don't hesitate to ask more questions here or send me a PM. Much of every day is spent here in my photo studio at my computer, since I can't do much else. Saw the doctor yesterday, and he saw me. I still can't walk much, but I helped him pay for the new stereo for his Mercedes.

Charley
 

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Andy,

Send me a PM with your email address and I'll try to get to the shop to take pictures and scan my FMT Pro plate for you. If it doesn't happen today, it will likely be this weekend. I'm back on my feet and walking again, but my wife is now having health problems, so I have all of the chores to do, both her's and mine, as well as catching up on my own since I haven't been able to do much of anything for over a week.

I want to send high resolution pictures, so you can enlarge them to see tiny details. They won't post in this resolution here because the file sizes are too large.

Charley
 

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Discussion Starter · #18 ·
Glad you're feeling better Charley. I sent a PM with my email address. There's no big rush, so take care of yourself and your wife. I take care of my mom with dementia, so I know what it's like.
 

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I hope you, and your wife get better fast, Charlie, thats a bummer being laid up. I know what you mean about the stereo. Here our Dr. is limited to 15min per customer/patient, an expensive 15 min. too
Herb
 

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They run on the same schedule here too. If you can get a full 15 minutes with them you are doing better than me. Mine frequently runs back and forth between patients, so I get attention for just a few minutes at a time, maybe 10-15 minutes total, but I'm always afraid that they will mentally mix my problems with those in the other rooms and prescribe the wrong things for me. Hasn't happened yet, but the chances are there.

Andy, I'll do my best to get you some pictures and info this weekend, but SWMBO has quite a list of chores for me that absolutely have to come first.

Charley
 
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