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The Super FMT: Part 2 cont’d – more on the clamp plate

December 15, 2009 By

The weather is just about back to normal – we expect 4°F tonight, with (again!) winds around 15 mph. However, today was a good day to be in the shop; the furnace kept the shop at a toasty 65°F. I had a dovetail saw in hand, cutting dovetails for some drawers I must finish. And then it struck me: I had to resolve an issue I ran into with the Super FMT the last time I used it.

I like to check the joinery as I work, because it saves me headaches at dry-fit, and at glue-up time. So, checking each and every single joint is a hard-to-kick habit. After playing around with the Super FMT, moving clamps to and fro as I made mortises and then tenons, I found a misaligned joint:

mis-aligned-joint

See the light under the straight edge of the square? This means the joint is misaligned; there should be NO light under the straight edge. Take a deep breath, and start looking for the cause of the problem. My immediate thought: the table and the clamp plate were not at a perfect 90° angle to each other.

Now I must get ahead of the plan I mentioned near the bottom of an earlier thread. As I mentioned in that earlier post, I planned to cover troubleshooting in Part 5 of this series. But I now chose to ignore that part of my plan, and to give you the benefit of my findings right away. So, let us reason this out together – I will wing it:

  1. I moved the clamp plate several times, to remove and insert clamps as I switched from routing mortises, to routing tenons.
  2. The table moves only on one plane, in the X-axis (left-and-right) and in the Y-axis (front-to-back, and back-to-front). The table is, therefore, a good zero angle reference point.
  3. Both mortise and tenon pieces are machined with the same face facing me (I mark these surfaces with chalk).
  4. If the clamp plate is misaligned, and both tenon and mortise are machined with the work piece clamped flat to the plate, then the error introduced by a misaligned clamp plate (that is, with the clamp plate at an angle other than 90° ) is essentially doubled. This means that a 1° misalignment of the clamp plate relative to the table will result in a 2° misalignment of the joint. And even such a small error will be blatantly obvious.

Question: Why is the error doubled, as I mention in #4?

Answer: It is doubled because the top faces on the work pieces in the photo above are facing me while I machine them – let us assume each piece will have an error of 1°; the joint later goes together with the marks on the work pieces facing me. Thus, a 2° misalignment results; this is visible without the need for any measurement. But it is impressive when back-lit, as I have shown in the photo above — and it is a good way to for me to show you the results. Once again, the eye can tell and it can see the results of a slight joint misalignment; trust your eyes, and check joint alignment, always.

Solution: Align the clamp plate such that is at 90° to the table.

How to do this: My Wixey Digital Angle Gauge to the rescue. Simply set the clamp plate surface 90° to the table surface every time that the clamp plate is moved. First, the table is made the 0° (zero degree) reference surface:

table-zeroed

Then set the clamp plate at a perfect 90° to the table:

clamp-plate-90-deg

After routing the tenon and the mortise, the result is a perfectly-aligned joint when the clamp plate is set to 90° to the table:

well-aligned-joint

I double-checked, and my eyes were correct; I believe you can also tell that this joint is perfectly aligned, by simply looking at the photo above. Trust your eyes, but confirm it with a straight edge — always!

As I kept trying different things, I ran into the following – and when it happened, I felt serious vibration on the router itself, like a strong shudder:

ouch-table-loose

A little more troubleshooting revealed that I forgot to properly tighten the table; I had moved it to align a new work piece.

Edit to add: In addition to remembering to tighten the table, I suggest you also move the table as far left (or as far right) as possible, while still allowing sufficient space to route the mortise. This allows you to move the work piece closer to the clamps; the net result is that the mortise work piece will be better supported by the clamps, and less prone to vibration. And, before I forget, always use two clamps to support the work piece.

After resetting the table, and properly tightening it, I got the following result:

good-mortise

I will continue work on the drawers, aiming to finish them this week. Then on to the rest of that project. And, in between, a little more work with the Super FMT. Hang in there with me!

.

—— Al Navas

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Filed Under: Blog, Education, Joinery, Leigh jig, Mortise, Super FMT, Tenon Tagged With: , , , , , ,

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

December 8, 2009 By

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:

2-using-sfmt

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

1-using-sfmt

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:

3-using-sfmt

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:

6-using-sfmt

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:

7-using-sfmt

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):

8-using-sfmt

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:

5-using-sfmt

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:

4-using-sfmt

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.

.

—— Al Navas

Filed Under: Blog, Education, Joinery, Leigh jig, Mortise, Sponsor, Super FMT, Tenon Tagged With: , , , , ,

The new Leigh Super FMT: Unpacking it, and getting it ready to work – Part 1

December 4, 2009 By

Download this video in Quicktime format
Duration: 43 seconds (NO audio)

Disclosure: Leigh Industries, one of my blog sponsors, sent me the Super FMT to try.

Imagine this: Super-accurate mortises and tenons in a jig costing a fraction of the original FMT, but with all the features of the original FMT (now called the FMT Pro). That is what the new Super FMT will deliver – and I am working to learn its ins and outs.

In an earlier post, I mentioned I was on the road – and that the new Super FMT arrived the day I left! Now I am back, and it is time for several things; but first I must unpack the new machine, try it out, and compare it to the earlier model I have used for years.

First thing to do: unpack the box, check that all the contents are correct, and read the User Guide. I recommend everyone heed the instructions, especially when installing the router on the router base. Taking your time to align the router on the router base is key to getting the results you yearn for in your mortise and tenon (M&T) work.

super-fmt-unpack

I started assembly by installing the optional dust collection box; this was a snap. I suggest you get this accessory, as it will make your experience much better – this means very little wood dust and chips to clean up later, or during and between machining of both mortises and tenons. The only way to get the dust chute in place is by loosening the knobs on both sides of the body of the jig, and fully opening the front:

super-fmt-unpack6

The chute is secured using two nuts provided in the kit:

super-fmt-unpack7

Making a base is a basic requirement, as it allows holding the jig in place. I used the Leigh clamps, in the same fashion as I did with the FMT Pro:

super-fmt-unpack4

With the Super FMT in place on the workbench, I can proceed with the remainder of the assembly:

super-fmt-unpack5

The side-stop fence needed just a bit of tuning to make it perfectly square to the jig body – it uses a screw, similar to that available on many table saw fences:

super-fmt-unpack3

I will have a detailed procedure on installation and centering of the router on the router sub-base in another article in the near future. It was surprisingly easy to do all the alignment with the new clamping arrangement designed for the new sub-base:

super-fmt-unpack2

The first of two minor glitches I ran into was, surprisingly, preparing the plywood base for the jig. The instructions and their accompanying illustration in the User Guide showed the base slots to be 3-5/16″ front-to-back, with a spacing of 15-3/4″ between the left and right jig body supports. The actual dimensions I measured were 3-17/32″ and 13-7/8″, respectively. At first I thought jet lag caused me to mark the dimensions wrongly. Out came the tape measure… Leigh Industries has already published an Important Correction notice, available for download from the Leigh Customer Support page; print it, and keep it with your User Guide.

The second glitch: The side-stop fence is designed in such a way that it is virtually impossible to get a try square close to it while keeping the square’s body tight on the jig body (see the photo below). The reason: the cutout on which the adjustment screw is mounted is too close to the front of the jig. I solved this by using a metal square with a 45° bevel – problem solved!

I am impressed with the fit and feel of the Super FMT. It went together flawlessly; all surfaces are coated with something I believe is a fusion-bonded coating, and similar to the FBE (fusion-bonded epoxy) used on external surfaces on buried pipelines in the oil and gas industry. It is a very tough, durable coating, and as such should do well in a shop environment.

The clamp plate, which is the front of the jig most visible from the front, was remarkably smooth in its operation. And setting any angle was repeatable. The knobs on the side of the jig held fast; this will be very useful when machining angled joints. I will cover the clamp plate in greater detail in a future article.

I found that, once unlocked by slightly loosening two clamp knobs, the table glided effortlessly both to the left and to the right, and from the front to the back. The table movement can be limited by using the X- and the Y-axis Limit Stops, an essential feature to precisely align multiple mortises and tenons. The table also accepts the guides, the joint aligning sight, and the router sub-base, which holds the router for all operations. More on all the table features in future articles, as I work with this new machine.

First impressions:

  • The touch-and-feel of the new Super FMT is excellent; thick steel telegraphs “sturdy”, “beefy”, “good!”
  • The protective coating on the steel was in great condition as-received — not even one ding on any surface, whether exposed or hidden.
  • The clamp plate worked effortlessly, and clamped well – I must mention that I did not detect any movement, even when loaded.
  • The table worked extremely well; loosen two clamp knobs, and the table will glide to a new position without effort. Lock the knobs, and the table stays put extremely well.
  • The joint aligning sight was very new to me, but I am geting comfortable with it. Already, the circle around it seems to make the targets more easily readable, as it gives the impression that it is larger (or maybe it just feels larger?) than the sight on the FMT Pro.
  • Installing the joint guides was easy, although the guide recess itself has a totally different feel from the recess in its FMT Pro brother. I had to learn a new way to remove the guides; but my fat fingers learned it quickly — the table itself has a larger opening.
  • The guide pins in the router sub-base make the sub-base feel quite different from the sub-base on the FMT Pro. But I suspect that, with a little use, I will get accustomed to this new feel as the sub-base pins ride in the tracks.

I am very pleased with the Super FMT thus far. As I put it through the paces, I will report my findings. And if you have any questions about this much-awaited machine, please leave it as a Comment here. I will address all questions as they arrive – and even if I don’t know the answer, I will work to get you an answer!

.

—— Al Navas

Filed Under: Blog, Joinery, Leigh jig, Mortise, Super FMT, Tenon Tagged With: , , , ,

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