Printed CNC clamps (sideways): feedback welcome

Snapmaker 2.0
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Hey all,

I’ve been planning a cnc project for a while in which I can’t clamp the material from the top. So as a nice entry project into 3D printing I’ve designed some alternative clamps for the CNC wasteboard to make this possible.
The idea is to use the “dogholes” in the wasteboard to clam the material from the side. There are some challenges as the depth of these holes is very limited, nevertheless, I’m making an attempt :slight_smile:

Just wanted to share where I am so far and get some feedback.

To be clear: I haven’t used it in real life yet! :slight_smile: There are still some optimizations to be made and the downwards pressure is a bit too small to my liking. Still pondering on how to improve that one.

A quick picture showing some of the the components.

DSC_1694
DSC_16945504×3096 2.52 MB

I’ve added it a public github repo so everyone can have a look at it:

And below the intro text with some explanations, or just go directly to the stl files on github: https://github.com/brvdboss/Snapmaker-cncdogs/tree/main/stl (they also allow them to be previewed in the browser). Also to be found on this thingiverse link: https://www.thingiverse.com/thing:4669020

Everything was designed using OpenSCAD and the code is available as well. (needs a bit of cleanup still, but I can live with it for now)

Snapmaker-cncdogs

clamping dogs for the cnc wasteboard of the snapmaker2

This provides a set of clamping tools to secure your stock on the snapmaker cnc wasteboard.
There are variants for the small holes (where the screws go to mount the wasteboard) and the larger holes where the provided clamps fit

The spirals are used to put additional pressure on one side and come in different sizes to adjust for all your clamping needs
For these the “keys” are used to make them universal for every type of hole in the wasteboard. The smallest spiral is designed so it can be used on the holes closest to the side and still clear the vertical axes.

To tighten the clamps a handle is provided to make that easier with the same keyhole.
This handle can also be used as a wedge to secure your material.

Why use this?

If you have a piece of material that you can’t clamp from the top down or need to secure from the side, for example to align it more easily.
It’s from plastic. If your bits do drill in to this, they probably won’t get damaged.

Overview of elements

  • cornerdog: element to fix the corner of your material. Both in large and small hole variant
  • dog: align on the side of your material. Both in large and small hole variant
  • spiralhandle: handle to tighten the pressurespirals. You can also use this as a wedge in combination with a dog to the fix the material.
  • turnkey: the “key” that locks in the holes. Both in a large and small hole variant
  • turnkeyspiral: the actual pressure spiral, insert a key, put it in the hole and turn with the spiralhandle. Different sizes available

Where possible all objects are parameterized so they can easily be adjusted in size

What to watch out for when using this

  • These clamps only apply pressure from the side. Depending on the material, tolerance in your dogholes. Often the material has a tendency to be pushed upwards.
  • The holes in the waste board are small and not very deep, in addition the waste board is rather soft. Don’t put huge amounts of pressure on it.
  • When fixing your material also push it down while clamping and check you push the dogs down to make sure everything is secure. You could use one of the snapmaker provide clamps to push down on the pressure weels to get some more downforce on the material.

How to print

Printing everything using the defaul fast profile in Luban seems to work fine and everything fits snuggly together. (tested with snapmaker provided white filament)

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You could use M4 pan head screws and print a counterbore (instead of actual boring it). This wouldn’t raise the dog height at all and would eliminate the dog popping out of its hole because of vibration. It would be significantly stronger, admitting much larger clamping forces.

The spacing of the clamping nuts within the table is regular. If you were to print fences spanning two or more nuts, you’d protect against rotation of an individual dog. It would also give you a perhaps-adequate registration to the axes of motion. It’s only perhaps-adequate because of how the machines are constructed. A slot instead of a hole on one end of the fence would allow fine adjustment of angle.

I would be cautious about the cam clamps vibrating loose. These machines are not stiff. You can improve the resistance of the cam against vibration by printing a circular slot whose radius is the distance to an adjacent clamping nut. Use one clamping nut as a pivot and the second to forestall vibration-induced rotation.

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The limitation is real, but this doesn’t adequately describe the problem. It’s defective-as-manufactured. In addition, at least on mine, some of the inserts are mounted askew, not aligned normal to the surface.

The insert nuts that SM puts on the work table are mounted on the wrong side. They’re meant to be inserted on the side opposite to screw tension, not the same side. The flanges on the insert are supposed to bear against the body of the material, not against air.

The best amelioration I can think of for this problem is to use an adhesive to glue the inserts in. It would not help as much having them mounted correctly to begin with, but it’s better than nothing. I’d use a two-part epoxy, heavy bodied for as much strength as is available.

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Thanks for the feedbakc @eh9!

After posting this I also came to the conclusion that adding through holes to allow using M4 bolts would be a good addition. If not for all, at least for some clamps. But what I was hoping to reach was to reduce the amount of screws as well. Making it a “toolless” experience.
But after posting this, I already added a feature request for myself to add the holes for m4 bolts. It would still be possible to use them without too.

Dogs using more than one hole were on my list as well. but thanks for the reminder, will add it to the enhancements requests on github as a reminder for myself :slight_smile:

And I came to the same conclusion that the insert nuts were mounted incorrectly after already pulling on out accidentally :sweat_smile:
Maybe I’ll just remove them and screw them back in from the opposite side as meant to be. Shouldn’t be that much work. It’s just a standard hex nut and the holes are all the way through already.

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Hey,

quick one:
I very much like the idea and gave it a test print on a snapmaker 2 with default fast print settings.
Yet for me the turnkeys dont fit the spirals.

Turnkey as well as the dogs fit in the wasteboard quite nicely.
I would say tight enough to look promising

Regards

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It’s a really tight fit for mine too. I could adjust it a bit. Before I do: Did you try pushing the key in hard enough? :grin:

If you have a little bit of an elephants foot that might already be enough to block it (it did for me the until I pushed it through). Could you make sure that you face the top sides towards to each other and then try to squeeze it through? Then the little brim from the elephant’s foot shouldn’t be the problem and once you push it all the way through, that will just break of. (or you could give it a quick rub with a file or piece of sanding paper)

Let me know how that goes. If that doesn’t work and I’ll see to make the fit a bit less tight in the model. (Or you can resort to using a hammer :wink: )

As a quick workaround, the easiest modification is to scale the spiral up by 1% in your slicer (Luban?) and I would assume it would fit. If you have a caliper you can always measure. You shouldn’t scale the key down as that will make the fit in the holes less tight as well, which you don’t want.

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Hey there.
Thanks for the quick reply.

So I ended up trying the hammer thing as well as scaling up the spiral 1% … still no luck.
I might have to do it the tedious… and actually measure :grin:

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One additional question: Which Luban-Version did you use?
(I am at 3.11.0… )

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Just checked and that was still 3.10.2 but that shouldn’t make a real difference.

I’ve added an issue to my github repo (see it is my todo list :wink: ) to make the tolerances a bit bigger. It shouldn’t be necessary to have an extremely tight fit. So it won’t harm to have it a bit looser.

There are some other changes listed as well and would like to combine some of them and would like to combine it with the other change I’ll do to the spiral. I’ll make sure to measure the ones I have printed as well and see how accurate they really are on my printer. (absolute sizes)

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Looks interesting, love to see some pictures of it in use!

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I might have a fundamtal issue with my printer currently. Inner structures like the cross-shaped whole in the spiral for the key are way of measurement … I will have to do some further testing…

So… perhaps you ignore my earlier feedback. I wasn’t aware…sorry.

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Hello,

I’ve made some updates on the clamps and a new version is available on github. Files have been uploaded to thingiverse, but it seems really slow. Not sure when the update (with previews) will finally come through.

Most important change: I’ve added through-hole versions that you can screw down with M4 screws (you can use those included in the snapmaker).

@666.hellroad: I have played a bit with the tolerances and have made it a tiny bit more forgiving, but not by much. Reprinted some samples and everything fits nicely (also still with the previous versions.)
Maybe you should try doing some more calibration. For example, if you print this calibration cube: https://teachingtechyt.github.io/calibration.html#baseline what measurements do you get?

@eh9 I have tried remounting some of the insert screws by unscrewing them and screwing them back in from the back. very easy to do and not that much work. However, the little flanges are very small and not strong at all. When manually screwing them in from the back they actually tear of. (just using a manual screwdriver, now powertools, and the wasteboard is basically thick cardboard).
Main disadvantage of screwing them in from the back: they sit a bit deeper which requires slightly longer screws. On the other hand, more wasteboard to, uhm, waste :sweat_smile:

@StumbleRunner: I hope to be able to test some “real” cnc projects in the coming weeks and will post some pictures when I get some real world usage.

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I have been experimenting with insert molding (3D print to a STOP point, add HEX HEAD metric screw of specific/required length and thread, then restart printing to capture the bolt inside the 3D printed form. Still working on this to help with torque, but looks promising. Why bring this up, because side loaded clamps work better with CAM action and you would need to put in a metal lever in the mix to operate the off-centric CAM to lock the clamp into the side of the work piece. If you need additional ideas for reference or parts, check out McMaster Carr catalog online https://sophiesew.com/SS2/the-software/ and also CARRLANE https://www.carrlane.com/en-us/product/clamps-accessories
for some cool bits and accessories. I worked 35yrs for a multi-axis machine tool builder and we used these catgalogs to custom fit workholding, clamps, etc when needed. I’m thinking that just gazing at whats already out there will inspire us to go farther with things like side clamping. (Hence, why I am looking at a CAM action side clamp for the same reason. Cannot/willnot take downward force. :sunglasses: Jim

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Sorry, McMaster-Carr link is here. https://www.mcmaster.com/

The SophieSew is freeware embroidery software for generating laser images more clearly.

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OK…I’m obsessed with this idea. in the CARRLANE catalog they make a side-edge clamp that can be bolted down to the wasteboard. Problem is that M8 is smallest bolt size. However, we can still do this with M4 or M5 if you add metal thread inserts into the wasteboard. If needed you can add shims to the side clamps to allow you to clamp various sized workpieces without moving the clamps from there insert positions.

Another key factor in side-clamping is that if your workpiece has enough strength, you could secure the workpiece, while it is sitting above a buffer (like cardboard) and allow you to run mills a little deeper without screwing up a tool when it leaves the workpiece and dives into the wasteboard. I have attached a schema of the clamp from CARRLANE. (Also you can download an 3DXML file free from CARRLANE)CAM SIDE CLAMP

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Hello @JAMMER862

thanks for the feedback. I have been looking at existing solutions, getting inspiration is always very important :slight_smile:
One of the issues is the available space. SO putting handles on things is a challenge to avoid consuming too much space and running in to the vertical axes when the bed is traveling. That’s the reason for the spirals:
forces

With the small handle (used as a wedge in the picture in the orignal post) you can tighten it, and using the the through hole version of the cross-part (turnkey) it can easily be tightened.

Having two sides using the simple dogs it’s easy to align it straight for machining. with the spirals (and or wedge) on the other two sides it can be safely secured.

I’ll try to have some more pictures and maybe a video in the weekend.

I’m not sure if I understood everything you said correctly, let me know if I missed something

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Howdy, I saw the small handle and the spiral/wedge (CAM) and think this is the best way to go for side clamping. Your models show a fence/wall on opposing corner of a square workpiece. This is the perfect setup for side clamp. In your model you are relying on “friction” to hold the spiral in position after clamping.

The CARRLANE type device uses a 1/4 turn to tighten and lock the cam. This method is only affective when the CAM is locked. Depending on work piece size, shims are used to bridge the distance between the CAM and workpiece edge. This is done to preserve the 1/4 turn CAM lock.

For side clamping, I am also visualizing the CAM clamp being used on a taller workpiece where the SM2 would be working at a height of 150mm or more. It would be important to hold the workpiece securely if you wanted to do some intricate milling at the top of the tall workpiece.

Your ideas have inspired me. You are approaching this correctly and I am only a newbie. I am just adding my “metal” work experience to further your idea for a side clamp that might be universal to all widths, shapes and heights of work pieces. Workholding is considered the MOST BASIC ELEMENT when working on CNC projects. If you cannot hold the piece securely, “nothing else matters”. (Metallica) :sunglasses:
I will try to draw some schemas to help visualize my idea.

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Correct. And I think the clamp you refer to does the same. As I understand it the handle is turned and creates pressure against the “gripping piece” which in this case also pushes down a bit. but the handle also stays in place thanks to friction I think?
I do like the way it creates the downforce and was thinking about putting small teeth on the sides but in the end din’t as it would be more difficult to print accurately.

I don’t understand the locking mechanism yet I think :thinking:

I also have in my mind “spacers/plates” possibly with curved sides to use in combination with the spirals to clamp non square pieces. But at this point I don’t have a project planned yet for which I would need those :slight_smile:

The other alternative that I actually thought of first was to simply create a vise that bolts down tot the wasteboard

Do keep the feedback & suggestions coming! I’m just playing with both 3D printing and CNC and CAD designing. So it’s afun new project :stuck_out_tongue:

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Hallo Bruno,
image
Wie Gehts!

Here is a model of CAM clamps that I hope to build with M4 or M5 bolts and modified 3D components for clamping workpieces. This should better visualize what I am thinking. JIM :sunglasses:

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CAM CLAMP MODELS
CAM CLAMP MODELS1608×1060 165 KB

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