The Leigh Super FMT: getting to know it — Part 2, the clamp plate, and workholding in general

With the machine unpacked, set up, and ready to work, it was time to put it through its paces. But first I must learn a brand-new way of holding the work pieces properly. In other words, I must learn the basic workholding on the Super FMT, using the new Leigh F-style clamps. I will cover the use of outriggers in a later article.

Part 2 is all about the clamp plate, the new clamps, and the side-stop fence. The clamp plate is the front plate with many holes in it. The bar of the new F-style clamps is inserted from behind the plate, through the holes; a rare earth magnet holds the clamp in place while I position the work piece:

After sliding the screw handle on the clamp bar, I am ready to clamp the work piece:

It takes a little maneuvering to set up the clamps in the tight spaces that are the upper-left and the upper-right quadrants. The reason? The sides of the dust chute reduce the working space considerably. But, once the clamps are in place, they hold the work piece very well. Barring obstructions, the clamps can be rotated in the hole through a good arc, to allow the best clamping arrangement.

I used the pencil line on the work piece to set the plunged router bit depth, then moved it into position; the following photo shows an unobstructed view of a work piece as I machine a mortise:

After machining the test mortise, I prepared the jig to clamp the tenon pieces. I started by moving the clamps to holes that will allow clamping the work piece vertically (having extra clamps on hand would be better yet). I learned I could save acrobatics by moving the clamp plate to the full open position, reaching under it, and inserting the clamp bar through an opening in the plate:

In the next photo I push a clamp bar through the clamp plate – notice how the clamp on the right-hand side can now reach over the side-stop fence, to allow clamping the work piece:

After returning the clamp plate to the closed position, I have the following view, from my working position – in this photo it is clear how the clamp reaches the work piece (I have already machined the tenon):

In the following photo, taken from behind the clamp plate, you can see the clamp head below, and to the right of the dust collection hose:

In the next photo I show the tenon work piece at eye level, as I machine the tenon – the work piece is flush against the side-stop fence, it is held firmly in place, and is square to the table:

Also from my working position, the next photo shows how the joint aligning sight – the target area is huge, and allows very precise alignment of the work piece:

First impressions about the clamp plate, and workholding in general:

1. The new F-style clamps work very well-they hold the workpiece securely. I was unable to make the work pieces shift, even under heavy mechanical load (my hand, shoving hard)
2. In some areas, restrictions such as caused by the dust chute make insertion of the clamps somewhat hard. But after doing it a few times I started to get a better feel for the maneuvers.
3. An extra set of clamps will make workholding even better, as it will virtually eliminate moving clamps during a job.
4. I found that if I moved the clamp plate in any way, I had to check it for alignment, to ensure square joints. I am still working to find the best way to close the clamp plate repeatably after opening the clamp plate. I used a Wixey Digital Angle Gauge to do the measurements.
5. I love workholding on my old FMT (now the Pro), which uses cam clamps. It took me a while to get used to the new F-style clamps on the Super FMT, but now I like them much better.

In Part 3 I will cover the jig’s table features, and in Part 4 the router sub-base. In Part 5 I will cover routing technique, and troubleshooting if things don’t work out right.

Right now I must go shovel some snow off the deck, and run the tractor to remove about 4 inches of snow of the driveway – we expect an additional 8 inches later today.

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—— Al Navas