Matchfit clamp slides in dovetail track

[Beechwood Chip]

I built a miter saw station with fold-out wings, and I put MatchFit dovetail slots in the wings for stops.  But when I clamp a piece of wood to the wing with a MatchFit clamp to act as a stop, I find that it slides in the track no matter how hard I tighten the clamp.  There may be some sawdust in the track, but still I wouldn't expect it to slide when it's clamped down.  I used a MatchFit router bit to make the slots.

Also, when I use the MatchFit dovetail track nuts I find that they bind up into the dovetail, and in order to move them I need to knock them back down into the track.

All in all, I'm getting kinda frustrated with the MatchFit system, and reconsidering my decision to go with MatchFit instead of T-track.

Any advice, thoughts, comments?

[Von]

Weird. I'm planning something like this as well so I'm interested in your experiences. 

Have you checked your wings for cupping or bowing?

[Beechwood Chip]

No cupping or bowing.  I tried blowing out the track with compressed air, no help.  Using a stop block made with MatchFit hardware worked good enough.  It would move slightly if I knocked it with a piece of wood, but would stay still if I was gentle.  I often slide the workpiece down to the stop; I'll have to train myself to be more careful.

[Von]

I popped out to the shop to check mine work like I remember and they do - rock solid when I tighten them and move smoothly when loosened. I took a couple of photos in case they give you any hints.

Edited to add: One thing I did notice is the bottom of the Matchfit knob doesn't have a lot of surface area, so if I push inline with a slot (see 2nd photo below), I could get my stop blocks to slide a little if I really tried. But I think you are talking about the green wedge sliding, so that's a different issue.

[Beechwood Chip]

I tried a different clamp and a different block of wood, no luck.  But, I think I figured out the problem:  I think I cut the track too shallow, so the runner/base of the clamp can lift up slightly above the table.  The block gets clamped tightly between the clamp's screw and base, but the clamp and block is free to move in the track.

Tomorrow I'll try cutting deeper tracks and see what happens.  I think I'll test it on a piece of scrap plywood before I start hacking on my miter saw station.

Thanks for the help, Von.

[Mark J]

If your stop block still slips after deepening the track, you might try applying some self adhesive sandpaper to the back side of the stop block, or maybe better, along the fence.

[Mark J]

@Beechwood Chip, thinking about this a little more.  If you haven't re-cut the track, yet,  you could test your theory by interposing a few sheets of ordinary paper between the stop block and fence.   

[Beechwood Chip]

On 4/30/2024 at 10:22 AM, Mark J said:

@Beechwood Chip, thinking about this a little more.  If you haven't re-cut the track, yet,  you could test your theory by interposing a few sheets of ordinary paper between the stop block and fence.   

Great idea!  Thanks!

[Beechwood Chip]

On 4/30/2024 at 10:22 AM, Mark J said:

@Beechwood Chip, thinking about this a little more.  If you haven't re-cut the track, yet,  you could test your theory by interposing a few sheets of ordinary paper between the stop block and fence.   

Yup, putting a couple playing cards under the block solved the problem.  For now I'll just use a dedicated stop block that has a cut out for the MatchFit track nut.  I was thinking I'd route out the track, inlay a piece of wood, and cut a new MatchFit track at a better depth, but seriously, I'd have to be really bored before that happened.

Thanks, Mark and Von for the support.

[Von]

@Beechwood Chip would you mind sharing a photo of the workaround? I'm sure I'll do this at someone and am not following what you did. TIA.

[Beechwood Chip]

On 4/30/2024 at 7:36 PM, Von said:

@Beechwood Chip would you mind sharing a photo of the workaround? I'm sure I'll do this at someone and am not following what you did. TIA.

Here you go!

Testing with playing cards

Before

Cutting recess

After

[Mark J]

Using a Forstner bit was good thinking.  I was thinking you'd route/chisel a groove.  This was much simpler.

[Beechwood Chip]

On 5/1/2024 at 9:07 AM, Mark J said:

Using a Forstner bit was good thinking.  I was thinking you'd route/chisel a groove.  This was much simpler.

I started thinking about a groove, but I wanted to be able to rotate the block.

[Von]

Thank you - I get it now.

[gee-dub]

Late to the party.  You guys have already figured out that due to the geometry you can cut the dovetail a bit too deep but not a bit too shallow.  Great solution with the Forstner bit.  Well done.  I have also noticed that the nuts can get wedged and require a downward push to pop them loose at times.

[Von]

 

On 4/30/2024 at 7:36 PM, Von said:

@Beechwood Chip would you mind sharing a photo of the workaround? I'm sure I'll do this at someone and am not following what you did. TIA.

Sigh, I called it. I was using a plunge router to make the dovetail slot below and apparently I didn't get it pushed down far enough when I made the cutting pass resulting in the oops you see and dovetail clamps that don't grip. Fortunately I just remembered this thread and will try Chip's trick of using a forstner bit to put a recess in the bottom on my stop tomorrow.

In case you need a little help like I did wrapping your head around the situation: since the slot is too wide at the top, the green Matchfit dovetail clamp thingee don't get pulled tightly enough against the side walls of the slot. If I route again at the correct depth, the extra depth doesn't help since the slot will still be too wide at the top. Putting a recess in the bottom of the stop allows the green clamp thingee to protrude above the surface and fully contact the slide walls.