LowRider v3 CNC - Tool-less Quick-Change Accessory Holder / Tool Holder - for laser, drag knife, pen, etc (v3.0)

Thanks. The potential problem whenever the cam lever does not hold, is a problem no matter which way the wedge is tapered. Tapered one way, the cam keeps the tool from falling. Tapered the other way, it keeps the tool from being pushed out of the mount by upward force from the material (pen and drag knife, for example).

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Gravity is a relatively weak force. My logic in turning the taper of the wedge the way I did, was because the potential for upward force from the machine pressing against the material, seemed to me to be potentially greater than the force of gravity.

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To add to the previous comment, of the two provided ways to constrain the tool from unwanted movement, one, the friction block of the tool holder pressing against the mount base, and, the other, the friction block of the cam lever, the tool holder against the tapered wedge is the stronger, more dependable. That’s why I targeted it on preventing upward force from dislodging the tool, and the less trustworthy, on keeping gravity from causing a fall.

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Update: so, @jamiek 's mention of the word “kinematic” sent me down that rabbit hole. I found numerous successful creations of kinematic tool changer mount systems, including this one that’s amazingly fast on the changes and seems very solid: Cable-Driven Tool Changer System by poofjunior - Thingiverse

Here’s a video of the above one in action:

Also, this other one seems more economical in its design, and has also been proven in real world use:

… However I don’t see a link to design files or printable models. I’ve begun some dialogue with that maker in the comments of his video, and I’ve asked if he has shared them or would be willing to.

In the meantime, I can use the same principles and examples to design something similar. While we would all like to avoid buying hardware and just go with printed plastic where possible, this seems like an instance where the hardware could be warranted, depending on your need for repeatability between changes of tool/accessory.

Just wanted to give a clue to what’s happening in my brain while this project is on a bit of a hold.

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While using your latest version I’ve encountered a problem:

The Pen Accessoire mount is too long.
Can you shorten it?

Example:
While using the squareness test in the official V1E tutorial, the pen crashes into the Y rail because the attachment is too long.

In other words on the maximum length of the X rail it’s not possible to use a pen because the attachment is too long / to far out.

Picture:


Hey! Couple points on this.

The docs exercise you’re referencing assumes use of a pen with no “springiness feature” by virtue of being attached either by lashing it directly to the router, or using it in place of the router. The offset length of this design is intended to provide springiness, and yet also allow semi-permanence, leaving added tool on without having to replace the router. This design’s thin “spring leafs” feature has to walk a tight rope to balance between having enough strength not to break, and yet having enough bend to achieve springiness. The length of the leafs was initially set by whoever came up with this approach. (This is now quite a few iterations down the road from the original.) One could certainly shorten the leafs, but doing so would defeat the purpose of it having springiness. This means any use of the pen or drag knife etc, needs to account for the offset.

Second point is this: there are other ways to achieve springiness, including— you guessed it— use of actual metal springs. There is s trade off in using printed plastic as the spring. I recently released a video showing a way to modify a ballpoint pen to add a spring from another pen, to give the pen built-in springiness.

Assuming one’s table surface is flat enough, one can go without any springiness. But the real world table is often not flat, and the bigger the table the more the need of springiness.

Also note, there are other pen mounts that don’t worry about providing springiness, and that decision gets the add-on tool closer to to core’s center (less offset).

Finally, this remix itself is being overhauled majorly to achieve a kinetic style of attachment which should give much, much better repeatability on positioning during tool switching. I’ve got the prior version on hold since I’m overhauling it. :slight_smile:

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Thank you for that explanation, like suggested I used x-10mm as an offset to use the squareness code generator.

Another solution would be to to change the angle for the mount or pen attachment.
Its really not much, with that change the whole length of the x axis could be used.

Thank you for your work, I’m looking forward to your new version :slight_smile:

This would be a valid approach. My original logic in the orientation was to have an equal number for both X offset and Y offset (45 degree offset). If the angle was turned so that the offset was all in one axis, Y, with zero X offset, it would provide full range on X axis, but would increase the deficit to usability in the Y axis.

Pros and cons either way.

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I was nearly done implementing a remix when you posted. Here is the result:

https://www.printables.com/model/477219-modified-pen-mount-for-dougs-tool-less-quick-chang

I am following this with interest…

I am also looking at maybe a combination DW660 + quick-change accessory for the Primo, since I need a new DW660 lower bracket anyway.

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At RMRRF I heard Ryan describe to someone the design process for this pen holder. Suffice to say the design embodies some optimization as far as stiffness and printability, so casual changes to the flexure are likely to make it somewhat worse.

Having said that, maybe there could be an inverted version where a rigid arm sticks out a few inches and the flexure is pointed back toward the router (or whichever mounting point). Then you could have the same function with the pen a bit closer to the router. If that matters.

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Ok I just added an “inverted” one too. (Same printables link)

image

I haven’t tried it but it should be able to hold the pen closer to the router. So you get back a tiny bit of Y range.

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@jamiek

Thanks! Cool stuff!

Also, your suggestion of a kinematic mount has led to me having a new mount, almost ready to unveil.

More soon.

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Just followed you on Printables!

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Any news Doug since the last 9 days? Can’t wait :slight_smile:

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I got a kinematic mount designed and in place that uses magnets. I would like to do some testing with it. I could go ahead and post it without testing, and I suppose let others test it with me.

Tool-less Kinematic Accessory Holder for LowRider 3 CNC 4.0 (BETA)

Ok, here is a link to where I posted the new KINEMATIC tool mount, tool-less quick change accessory holder. Printables

It’s in beta. Testing needed! Help requested.

This is an adaptation of a Maxwell Kinematic coupling. You can read about that here: Kinematic coupling - Wikipedia

Inspiration came from Workshop Feedback channel’s posting of his custom CoreXY printer and it’s electromagnetic tool-changer. My design is a freshly created thing from the ground up, and I don’t at this point utilize his concept of having flexible printed mounts for the magnets, but I drew heavily on his excellent work on his tool changer.

Summary of Kinematic coupling: “fixtures designed to exactly constrain the part in question, providing precision and certainty of location.… consists of three radial v-grooves in one part that mate with three hemispheres in another part. Each hemisphere has two contact points for a total of six contact points, enough to constrain all six of the part’s degrees of freedom.”

In this case, I’m combining use of disk magnets for the coupling force, common M3 x 16mm screws arranged in a 3D-printed “mobile base” to form the “three radial v-grooves”, and common ¼"-20 acorn nuts (aka cap nuts) arranged in an opposing 3D-printed “fixed base” to serve as the “three hemispheres” and thus is achieved an easy, affordable Maxwell Kinematic coupling.

Note: this project is in BETA. Testers needed. I will link to separate Printables listings for various specific tool holders, intended to serve for testing attachments. I’ve already created a pen holder for this, which is a “remix of a remix of a remix of a remix” (with the most recent being an “inverted” one by Jamie, @ jamiek on the V1 Engineering forum, which served for my first tool holder for this new accessory quick-change mount system).

This system affords a one-to-many relationship between a “fixed” side (you need one set of it) and as many “mobile” side sets as you want.

  • The “fixed” side is comprised of two parts:
    • new Main Mount that is merely a new iteration of my previous pen-mount / tool-changer designs, which gets attached to a LowRider v3 using two (2) M5 x 45mm screws), and
    • new Fixed Base that gets attached to the Main Mount using at least three (3) M3 x 16mm screws. The Fixed Base has one of two disk magnets.
  • The “mobile” side is comprised of two other parts:
    • new Mobile Base that gets a specific tool holder attachment on one side, and which has the second of two disk magnets in it on the other side, allowing it to be magnetically bonded to the Fixed Base, for what we hope is a suitably strong hold for using add-on tools.
    • A specific add-on tool holder, for items such as pens for plotting/drawing, drag knives for cutting vinyl signage, and diode lasers, while other possibilities include a depth finder I’ve been pondering conjuring for a while that would be a bit like a BLTouch, except for LowRider CNC work.

Aside from the two M5 x 45 screws, and two tapered head M4 x 10mm screws and nuts (or M4 x 12mm, depending on your situation), so far pretty much everywhere else I’m using M3 x 16 mm screws (and nuts). The M4 screws are serving to hold the magnets in the bases, and thus are optional as you could opt for epoxy glue instead.

The magnetic force of attraction seems possibly adequate — if I try to manually pull apart the Fixed Base and the Mobile Base, it takes a good bit of force to separate them. However, when the length of an attached toolholder / tool comes into play, then that add leverage, which means, honestly, I’m not sure the magnets are strong enough, and testing is needed to see if the magnet approach is viable. I’m trying to get to the process of both designing additional tool holders as well as testing what I already have. Help is welcome.

PRINT INFO:

  • Print as oriented.
  • Prints with no supports needed.
  • Use the same number of perimeter walls and same infill as most of the LowRider 3 parts.

BUILD STEPS & NOTES:

  • Print all the parts.
  • Insert three (3) nuts, M3, into three of the nut capture slots on the back side of the Main Mount. I chose to use the holes at 12 o’clock, 6 o’clock, and 9 o’clock. I left other holes just to allow for future possibilities not even on the radar. The upward protrusion on the main mount signals which hole is 12 o’clock.
  • Use of pliers can help with squeezing the nuts into the capture slots. Optionally you can insert screws through from the front, and tighten them until the nuts get pulled into the slots. It’s important for the nuts to be properly oriented for a straight approach by the screws, later, when attaching the Fixed Base.
  • If you plan to use epoxy or some other glue to hold the disk magnets in the Fixed Base and Mobile Base, you can skip this step. Otherwise, for use of M4 screws to hold the magnets in place, insert two (2) nuts, M4, into the back sides of the Fixed Base and Mobile Base. Use an M4 screw, inserted from the front, to tighten until the nuts are in place.
  • Install the disk magnets into the Fixed Base and Mobile Base.
    • NOTE: The two disk magnets have to face in a way that attracts. This means either that one of them has to be “chamfer up” while the other is “chamfer down” or else it means you have to pry out one of the magnets from its metal cup, and flip it over and reinstall it. If you choose to flip one as “chamfer up” then either it has to be glued in, or else the screw hole will need a counterbore area opened up so the M4 screw can be counter sunk. If you choose to pry out and flip, then be aware that neodymium magnets are brittle. It’s easy to break them. However, I broke some and still used them. They are squeezed in between the screw lip and the edge of the metal cup, and they stay in place. Also, their brittleness can become apparent if you screw them down too tightly, or if you use too much clamping force in pushing them into position. The metal of the magnet is both hard and brittle. I found that attempting to drill out a counterbore hole in the magnet itself, was a futile effort given my available tools.
    • NOTE: In order for the kinematic coupling to work, the spheres, in this case the caps of the acorn nuts, must all make firm contact with the M3 screw troughs before anything else touches. Also, in order for the magnets to provide enough coupling force, the magnets must be almost touching, aka practically touching, by the time the acorn nuts get seated into place against the M3 screws. This means the M4 screws need to be totally flush, not proud at all. You may need to pre-grind the top of a screw off it’s sitting proud.
  • Install three (3) acorn nuts (¼"-20) into the three capture slots on the “star points” of the Fixed Base. I found it easiest to hold them straight with pliers, with their hexagonal bottoms positioned for straight entry, and then press them into the opening. Once they are “started” in, they can be tapped in the rest of the way with a rubber mallet or dead blow hammer. Avoid use of a regular metal hammer, or you will flatten the tops of the acorn nuts.
    • OPTIONAL: use of glue can ensure they dan’t come out, but if you have a tight fit, it may not be needed. If you later need to remove them, say to move them to a new print, you can force them out by inserting something slender, like an allen key tool, through the holes on the bottom of each star point, and tap with a hammer.
  • Install six (6) screws, M3 x 16mm, into the Mobile Base, two into each of the “star points.
  • On your LowRider v3: Remove two M5 screws — one from the right side of the lower router mount, and one from the right side of the dust shoe mount.
  • Replace the above M5 screws with longer ones (recommend M5 x 45mm), inserting them though the Main Mount part, then back into their original locations. Tighten pretty snug.
  • Attach the Fixed Base to the Main Mount using three (3) screws, M3 x 16mm. This corresponds to the above mentioned nuts at 12 o’clock, 6 o’clock, and 9 o’clock.
  • Attach some specific printed tool holder of your choice to one of your prints of the Mobile Base, presumably with the tool. :slight_smile:
  • Magnetically click the Mobile Base onto the Fixed Base. Check alignment and grip. Test out use of the tool. Report back here in the comments! :slight_smile:

Q&A:

  • Q: What’s the purpose of the upward protrusion on the Main Mount?
  • A: It’s sole purpose is to aid with assembly, by offering a visual cue for alignment of the Fixed Base

BOM:

COMPATIBLE TOOL HOLDERS:

  • coming soon

UPDATES:

  • May 18, 2023 — Quite a few design/print/test prototype iterations preceded this beta release. Video forthcoming. If I can get one hand free.

Change log:

  • May 18, 2023 — initial release, in beta.

My PayPal tip jar: https://paypal.me/design8studio

Various LowRider 3 CNC remixes:

View all my models and remixes on Printables:

*Amazon product links are affiliate links.

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Discussion about the new kinematic mount can continue over here:

Newly released, a new, improved version 4.1 of the inverted pen holder:

LowRider 3 CNC - Add-on - KINEMATIC Pen Holder - designed for LR3 Dust Shoe (v4.1)

Download: https://www.printables.com/model/484869-lowrider-3-cnc-add-on-kinematic-pen-holder-designe

Description from the Printables listing:

This is made to go with the LowRider v3 CNC - KINEMATIC Tool-less Quick-Change Accessory Holder - supports laser, drag knife, pen, etc (v4.0).

NOTE: June 8, 2023 — improved new release, v4.1, accomplishes two goals:

  • The pen is located closer to the center point of the LR3’s router (less offset from the cutting bit)
  • The offset distance is equal in both X and Y axes: ~52.043 mm for each. That’s from the center of the router bit to the edge of the mount where the side of the pen rests. To calculate your actual offset, be sure to add on the radius of your pen body. See example below. (For anyone curious, the 45-degree diagonal measure of offset from router bit center to the edge of the holder where the pen body rests, is ~73.6mm.) Having X and Y offsets be equal hopefully makes it a bit easier to handle coordination between drawing and cutting in the same project.

IMPORTANT ASSEMBLY TIP:

  • Insert your two zip ties through the pen holder, before attaching the pen holder to the Mobile Base from the linked other listing!

Diagrams showing the X & Y offsets, and an illustration of calculating offset with a common Sharpie marker:

Here’s a helpful video I made about this (the video shows older v4.0):

OTHER COMPATIBLE TOOL HOLDERS INCLUDE:

  • Laser mount for NEJE A40640 Diode Laser: Printables
  • Pen Holder, not inverted, v4.0 - generic design for pens on LR3 Dust Shoe, made for this v4.0 kinematic system: Printables
  • Drag Knife Holder v4.0 - 1.0mm spring leaf (for drag knife such as sold by V1 Engineering): Printables

Print, attach to the Mobile Base in the listing above, using three (3) screws and nuts, M3 x 16mm.

Install a pen using zip ties. Attach this and its Mobile Base to the Fixed Base on the LowRider v3, and draw something. Post results in the comments here.

Change log:

  • June 8, 2023 — improved new release, v4.1. See above.
  • May 18, 2023 — initial release, labelled v4.0 (because so many previous mixes).

My PayPal tip jar: https://paypal.me/design8studio

Various LowRider 3 CNC remixes:

View all my models and remixes on Printables:

*Amazon product links are affiliate links.

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I’m having some issues in my lowrider and I wanted to ask you guys some questions.

Has anyone succeafully used the “old” (pre kinematic one) toolless quick mount with a laser and, if so, what speeds did you use? I’m seeing some wobbling and i think it might just be the mount.

@pastitas

I have not personally used that with a diode laser. Maybe if someone has, they can chime in here.