Clamping system

I’ve made a new clamping system for my MPCNC. Seems to work really nicely and the corner piece gives me an accurate (and correctly aligned) starting position so I can get consistent runs.

This is based on the design by Marius Hornberger and I really recommend it:


Love it. I am trying to get a picture frame cut today and have been thinking about how to clamp it. That kind of thing might work. I want to try an 8’ piece of piane all at once on the lowRider.

Hornburgers vid has popped up here a few times I believe. Very well explained. Such a cool idea and love the 4 size options on all the blocks and locks.

Ah man, I still need to make myself a LowRider.

I’ve finally gotten my MPCNC into the state I want (metal feet and clamping system), so today I ordered an extruder so I can look at printing out a LowRider.

I’ll get there eventually :slight_smile: Not enough hours in the day!

Oh and then there’s the DMLS build… ;-D

So, do you have endstops, or do you always start the machine at one corner? Maybe the accuracy you’re talking about is just the parallel to the axis accuracy? I usually start my machine at the same spot, so if I had this installed at 130,89.6, I could get consistent cuts after a powerdown, after I moved the machine by that X,Y, and reset the 0.

I think that kind of registration is really necessary for doing some of those joints at the end of boards.

Also, this would be very useful for the low rider, since the carriage is very wide, and close to the same height as the bit, clamps that are above the workpiece are in danger. I currently clamp a lot with screws, but having it clamped from the side would be awesome. You could also put a backer board, smaller than the work piece, if the work piece was 1/4" thick or something.

I saw a video of Adam Savage touring the Artisan’s Asylum, and they have a nail gun that shoots plastic nails. That would make quick work of clamping for the Low Rider:

I made the holes and cut the parts using the CNC, so I know that if I align to the holes it’ll (at least) be perfectly aligned with the machine.

I start in the bottom left corner, then run “G1 X21.65 Y21.65” to get to the exact starting position, then reset the home position before running the program. It seems to work well!

Before I had any clamping system I used to have a lot of trouble finding exact corner of a workpiece, especially when using larger end mills (like my 16mm one). Now I don’t need to worry, I can run multiple passes on various sizes of end mill, I can remove and replace the work, and they’ll always start perfectly in the corner.

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I would really like to know what others are using for clamping. I drilled 3/8" holes in my bed and inserted 1/4" x 20 pronged T-nuts in from the bottom at a 6" x 6" spacing. I am using simple 3D printed clamps and common bolts. This is nice but not optimal

My spoil board is 3/4" ply. I use screws through the material into the spoil board. If things are tight, I will set my origin, then move the bit to a coordinate I know won’t interfere, and use the router to mark where to screw, then more the bit away and put in a screw.

So if I know my part is 500mmx250mm, I’ll move the bit to 530,270 or something, turn the router on, and go to Z-2. Then I will finish drilling and screwing with my cordless drill. On one big job, I put a screw in a waste piece that I knew wouldn’t be pocketed. I also tend to think about the screws when I do the CAM, and try to make holding tabs close to the screws to give them the best chance.

It has the advantage of not having anything proud of the surface. I have hit a screw, but there was no serious damage.

Same here, screws. If it is big enough to hang off the edge I will use clamps past the rails, sometimes in the middle like in my most recent vid.

Like most, I just use screws.

I have gotten where on complicated designs where I need holding force close to the part, I will do guidelines in my CAD and actually design in the screw locations. Then I’ll print it out and when I get to the machine, I can mark out where the screws need to go.

The nice thing about doing it this way is in Inventor, you can flag those screws as hold downs in the CAM software. The CAM will route around them to make sure they’re never hit even on flyovers.


That’s cool. I like the idea of laying down the printout on the workpiece too, as long as you get it square to the axes.

I just pay attention but make sure I have plenty of room.
Here is the Lowrider set on a 2x2 square, the red x’s are where I put screws.

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