Tool Mill table edge clamps

[PeterT]

Coincidentally I was looking at some AliExpress mill table clamps that Cliff was mentioning around 3-min mark. And I have to agree with his assessment of them. Ever since the Great T-nut Thread I find myself being a lot more mindful of different table mount do-dads in terms of T-slot loading. I've seen some home shop clamp systems that what I'd call an 'anchored' T-nut, basically a set screw that pokes out the bottom of T-nut to prevent skidding along the T-slot axis under load so that something else can be mounted to another part. Those to me are almost asking for trouble. Usually the anchor screw is finer thread which means more vertical for for given torque & thus putting the cast iron table lip in tension which we know is bad news. But thats another subject.

Despite some rambling on, Cliff did some very interesting real world clamping tests. Before seeing this I was wondering how successful shop made table clamps in this style would be, because the commercial ones are typically hardened & ground (and as shown in video) and seems to me depend on a very good sliding fit between the tounge on movable jaw, however its accomplished. Some have dovetail, his has plain rectangular. some Ive seen something like pin slides. Maybe the rectangular tounge profile could be milled with conventional milling & lapping. I like the idea of setting the work on paralells which now requires thicker jaw, chunkier clamps which is a good thing. Vs the thin nose typically associated with work mounted on the table when you need to mill beyond the edge of work & obviously a protruding clamp is now in the way.

Interesting note in the comment section:
most of the clamps of this type that I have seen use an incline angle of 45º. It's possible to increase the mechanical advantage significantly by using a steeper incline, say 55 or 60º. Thanks for the feedback. My previous version/video was at 60 deg. Actually, I was surprised to see the toe closing lateral forces tending to skid the body away, even at 45 deg, they are already on the high side. I also copy my comment below: "Interesting subject. My last video/design used a front bolt into the table also, but there are downsides. I found with my checks the bolt tension of the front bolt has to be quite low because of the wedging effect, too high and it skids the body away. So really two body bolts are needed to avoid a skidding jaw. " I agree reducing the slot width would help with the guidance ratio, and slightly with crabbing resistance, if there is enough metal to allow this without weakening the structure. Cliff

My other idea was basically a cross table bar bolted on multipe T-nuts with a series of Mitee-Bites. This might be better for irregular surfaces, each Mitee-Bite is clamping to wherever the surface happens to be. Withe the elevated work mode (part sitting on parallels) this becomes dead simple. My friend who runs a CNC is not fond of MiteeBites though.
Just curious, what do you guys use?

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[PeterT]

Or you just cut a Gerardi in half LOL. Bison has a similar system


These Saunders are (I think) a flexure type jaw system but I feel are meant for more nicely machined edge surfaces.

 

[Arbutus]

Or you just cut a Gerardi in half LOL. Bison has a similar system

These Saunders are (I think) a flexure type jaw system but I feel are meant for more nicely machined edge surfaces.

The SMC free vice you show has a fine serrated jaw face that is slightly inclined. It grips really well! As an alternative there are MiTeeBites (sp?) available as the gripping faces.
The pressure is from the large countersunk screws which allow the jaw to float and each allow about 2mm of offset jaw travel.

 

[PeterT]

I should have clarified, MiteeBite makes a few styles. These are the edge clamps which clamp via the eccentric screw. But now that I see how they coupled to a T-nut, maybe they use that same anchoring screw into the bottom of T-slot? Their website is not responding right now, I'll look tomorrow. Anyway I was proposing using the clamp (gold part) but mounted to a decent bar & bar scured conventionally with T-nuts underneath it. Normally this would sit high, not suitable for table mount. But if part was supported on parallels like video, it should work.

 

[Susquatch]

I've seen some home shop clamp systems that what I'd call an 'anchored' T-nut, basically a set screw that pokes out the bottom of T-nut to prevent skidding along the T-slot axis under load so that something else can be mounted to another part. Those to me are almost asking for trouble.

This is the real problem I've tried to highlight. Most users just don't know or don't really understand the problem.

It's nice to see that you do.

That aside, I appreciate your commentary on the video. I only have one set of miteebite clone clamps I got on Ali. I don't like them. They arrived all rusty and they don't really work well. I'd return them if it made sense financially. But the shipping would cost me more than the clamps did.

The day may come when I might spring for a set of genuine miteebite clamps, but so far I have not really needed them. I've always managed to find another way.

 

[Maker Mike]

The Saunders modular vises are designed to be used with their baseplate, although you could make a baseplate. They have pins on the bottom to hold and align them. I was having difficulty with them until I took the time to look up the torque specs. The miteebites clamp on very little of the part.

 

[Sqought]

I was proposing using the clamp (gold part) but mounted to a decent bar & bar scured conventionally with T-nuts underneath it. Normally this would sit high, not suitable for table mount. But if part was supported on parallels like video, it should work.

If the bar extends below the part, it effectively acts as a parallel, and would be a lot less fiddly. If you need tight precision you could surface grind the bar to your preferred size or make a matched set of bars/miteebite fixtures.

 

[PeterT]

If the bar extends below the part, it effectively acts as a parallel, and would be a lot less fiddly. If you need tight precision you could surface grind the bar to your preferred size or make a matched set of bars/miteebite fixtures.

Thats true. On one hand, a part raised off the table allows operations like through holes. And related to this thread, allows more robust edge clamps because they can be thicker. OTOH sitting on parallels could allow the part to bow in the unsupported middle depending on size & positioning of parallels. Thus far I havent had to do anything that big. For simple 'raised' machining I've used a slab of MDF spoiler board underneath which is supports the entire underside, as long as the thickness consistency & clamping strain is acceptable which so far hasnt been an issue.

 

[PeterT]

only have one set of miteebite clone clamps I got on Ali. I don't like them. They arrived all rusty and they don't really work well.

Maybe you saved me a $$ gamble, Ali can be hit & miss. I have one set of actual MiteeBite clamps but they are small (8-32). Thus far they have worked fine but have been confined to smaller aluminum parts. I made myself a clone with a larger clamp body just to see if I could replicate the eccentric action. It works the same. But there is a reason the throw is relatively short on these. If you make the eccentric too large you dont get the mechanical wedging & it can come loose. There is probably a formula in there related to thread pitch but anyway, fine pitch is better than coarse pitch.

Next one I would do differently. Press/Loctite a SHCS into an oversize steel disc. Thread that into an offset jig held in lathe chuck & turn the OD to size. This yields the eccentric throw & matched size to the counterbore clearance of whatever clamp you want to use.