1086 Tube Vise

Over the last ~year, 1086 has been working on streamlining our machining process for machining aluminum box tube. Our new tube vise is able to hold tube in both the 1" and 2" orientations, allows for machining all the way through the tubes, and streamlines the work coordinate system.

The clamp is cut from 1x3 6061 bar from Xometry and uses a set of Eccentric Hex Clamps. They’re definitely a bit overkill, but we had them on hand. Some small changes could make any of the other sizes on McMaster work fairly well.


Clamp in 2" orientation: When machining the 2" wide faces, the tube rests on the upper “shelf” of the vise. This allows the lower area (highlighted in blue) to serve as a relief so that you can drill/mill all the way through the part without cutting the fixture.


Clamp in 1" orientation: When machining the 1" wide faces, the tube rests on the lower “shelf” of the vise. This allows the lower area (highlighted in red) to serve as a relief so that you can drill/mill all the way through the part without cutting the fixture.


WCS: In both orientations, the clamp provides an end stop in X and a fixed Y position. Because of this, we can avoid re-zeroing in between different operations, and even between entirely different parts


While the clamp was designed for 1" and 2" tubes, it can accomadate anything smaller than those sizes using parallels to shim the gap between the clamp and tube. Pictured above is a 1.5x1.5 tube shimmed with a 1/2" parallel.

Strength: So far, I’ve had no issues with it. I’ve only pushed a 1/4" end mill to around 100 IPM (.075 radial, .125 axial), so I certainly wouldn’t expect to, but the clamps are rated for 2k lbs, so I expect to be able to push pretty hard on this in the future.

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Tube Ends: Prior to making this, I generally machined tube ends using a 3/4" end mill full depth through the end of the tubes hanging over the vise. Because there’s now material directly under and next to (on the X- edge), this is no longer possible. In order to cut the edge all the way, I cut the top .800" in the first op, then flipped the part over for op 2 and slip the now-finished shoulder (red edge) into the hard stop so that I could cut the remaining saw-cut edge (blue). This ended up working extremely well, and there’s hardly any cusp from the overlap.

Price: One of (in my opinion) the biggest strengths to this design is the price. We paid $32 for a 30" piece of material and cut a 20" version and 9" modified version (see photos below for modified version). Even if we purchased 10 clamps instead of using ones on hand, we be spending right around $100, which ends up being pretty cheap compared to some of the COTs options.

CAM: When programming parts, I imported the clamp body into Fusion360, mated it to the part, and set the origin based off of that. It’s an unnecessary step, but I find it to be quick and a good way to double check my WCS.

CAD release: The STEP file in GrabCAD works, but has every single clamp in both the open and closed position for a 20" version. The Solidworks files are set up parametrically; edit the “Length” variable in the “Parametric Body” file and the assembly will automatically update. I chose to cut a 20" one due to machine travel distances, but it could easily be extended to suit whatever length you want.

Holding the clamp: Originally, I was planning on boring holes for 1/2-13 holes to bolt to the bed of the mill. However, because the mill belongs to our sponsor, it makes more sense to put the tube vise into the mill vises than to remove their vises every time we have to machine tube. It wasn’t the solution I had hoped for, but we lose no noticeable rigidity (the 1" bar is plenty stiff for the forces involved in cutting tube, even when mildly cantilevered). Additionally, the WCS is still constant between operations, so even if I take it out at the end of every day, I’m still only edge finding once per day, a massive improvement over our old tube system. I have CAD with the 1/2-13 holes if anyone is interested.

GrabCAD: https://workbench.grabcad.com/workbench/projects/gcPFJZ-iSBCNiG8LbrgaABY6A_pAsCSEkPWQXsevqvkQbp#/space/gcFfrH8BBHpMrCtUvA5qmtKu1ufo6dsIm7ZtYD_524VZTr

More Pictures: https://drive.google.com/file/d/1XWqlOufPlk60Fqyj1uqpR9t4gngaUNvX/view?usp=sharing

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$100, pretty cheap compared to COTS

I think that’s validation that cots tools are near their price floor at approximately $300, and I won’t be able to wait for a better deal.

This is a sweet design. Very thoughtfully executed.

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Once you take into account things my $100 estimate didn’t (tooling, time, etc), I think you’re probably spot on.

Thanks!

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This thing looks pretty legit.

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These fixture clamps are awesome.

For the curious, the common supplier of these is mitee-bite, a brand name that has become somewhat synonymous with any type of cam style work holding clamp. Bonus points for being a New Hampshire based business!

The miteebite website includes part numbers as well as some application data for these style of clamps. A quick search of the part number on Amazon will yield parts sans Mcmaster tax.

Just because I always dig photos of work holding, here’s another use of these fixture clamps from a recent project;

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Have you tried 2" tall 1/16" wall thickness tube yet? I’ve found that even when supporting the entire vertical face on both sides while clamped in a vise, its extremely easy to buckle thin wall tube being clamped in a “tall” configuration, unless you really drop your depth/width of cut and feedrates. Something to watch out for.

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Yep - I’ve definitely been loving them a lot recently. Here’s a fixture plate for some elevator blocks a few months back that uses them.

Not yet, but hoping to soon.

In what way did it buckle? The only way I could imagine it buckling (the two long faces coming together) shouldn’t be an issue here since I only clamp on the bottom 1/8" of the tube. However I haven’t done much milling in the “tall” orientation, mostly drilling, so it could be worth testing how aggressive I can get milling in that configuration.

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Is there any real benefit to machining tubes on a mill instead of a router? I’ve heard some claims relating to improved accuracy because of greater rigidity and the like, but since you can machine a lot more tubes at once on most routers, it seems like a pretty small thing to get caught up on.

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We use a mill because it’s what we have. I don’t know for sure about the accuracy claims, but they sound valid. As far as rigidity, I know mills are almost always significantly more rigid, and I’ve definitely pushed faster than most router posts I’ve seen here. I’m not sure how big a difference that makes in FRC, however, since we aren’t exactly doing production runs.

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Cool, makes sense. We’ll probably stick to using a router for now (or hoping to use a router anyways, don’t actually have one just yet), just because it’d be nice to free up our mill for some neat billet parts, but if I find out there’s any significant benefit to using a mill over a router in practice we might just switch. Thanks for your help!

On a slightly different note, any reason you didn’t design this jig to hold more than one tube? Just wondering since it looks like you had the space make it a bit larger.

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I certainly could have, but we don’t really do enough tube work to warrant it, and what we do do is usually somewhat spread over build season. If I were to do it, I’d probably honestly just hit the mirror or linear pattern button in solidworks since the design is (somewhat?) tillable in Y.

The benefit to machining tubes on a good mill is flood coolant and rigidity, the RPM range, and tool changing. We would much prefer to cut our tubes on the Haas with a 3 Flute endmill at 10k RPM than on the router with a 1 flute endmill at ~20k RPM. Plus, if you have anything to drill, you can do it all in one program. Don’t have to babysit the mill quite as much either, again, thanks to flood coolant. Router does have bigger XY travels though.

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We have access to a Haas and a couple of Bridgeports, but we still do almost all of our tube work on our Omio. Partially this is because we own the Omio and are guests in the shop with the “real deals”, but also:
(1) We just don’t do that much, we’re not a production shop,
(2) It’s simpler and easier for the students (who aren’t machine shop pros),
(3) We aren’t working to the tenth,
(4) Most of what we do are one-off or two-offs, so the quicker setup on the Omio beats the faster speed of the big machines,
(5) We just “drill” with our end mills to avoid the tool change on the Omio.

YMMV

For our setup, which is mainly 1/16" sheets of aluminum, we like to drill all our holes with a regular drill. It saves so much time, especially when I get all lovey-dovey with the rectangular pattern tool and some rivet holes…

drillbitsunlimited.com has a ton of super cheap drill bits that work really well on routers.

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Its not buckling because of clamping force that you need to worry about. Its buckling due to tool pressure. If you have a 1"x2" tube with the 1" dimension clamped in your fixture, the 2" wall wants to cave in when you cut it. Your fixture is actually more prone to it since its only supported at the very bottom (and it wouldn’t surprise me that despite having a boatload of clamping force per miteebite cam clamp, you could actually tear the whole tube out/fold it over if you were too aggressive).

You can address this in a couple ways:

Conventional instead of climb cutting (virtually a must on thin wall tube like this)
reduced axial depth of cut
reduced radial width of cut
reduced feedrate.

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We’ve seen this plenty of times. It’s easily mistaken for over clamping but doesn’t show up until after the milling operation. Going really light on the vice seems to reduce the issue for us and we never had to back off from our pretty aggressive feeds and speed.

Cory,

Have y’all ever see similar issues if you are drilling holes on the 1” face with a 2”x1” vertical in the tube fixture?

I’m wondering if a #10-32 1/2” linear hole pattern would buckle if drilled using the tube jig setup.

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No, I wouldn’t expect you’d have an issue with that. Your holes are small and the tube is strongest in that orientation.

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It makes a huge difference. Turnover time throws everything off; FRC teams tend to struggle with logistics to begin with (the tight build season schedule does not help), and if you machine a part wrongly when the turnover times are long you can throw everyone out of sync.

Routers are great tools, but they’re not a panacea.

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