Lowrider CNC

moebeast

Member
I really like the look of this - but it seems the distance between the rails is smaller than the stock Lowrider design too, right? That'll mean a redesign of the all the other parts as well...

Right. Since Z is on the carriage, the side plates will be much simpler. The cross rails will be fixed, but need to be adjustable in height for various material and leveling. I am also using 3/4" emt since the span is shorter and doesn't need to support a router. Attempting a print today.

compact z.jpg
 

rockyboy

Skill Collector
Mentor
Right. Since Z is on the carriage, the side plates will be much simpler. The cross rails will be fixed, but need to be adjustable in height for various material and leveling. I am also using 3/4" emt since the span is shorter and doesn't need to support a router. Attempting a print today.

Very cool!
 

dkj4linux

Elite member
That is very cool, Mark. I recognize the motor/pineapple/bearing/leadscrew Z-axis setup from MPCNC combined with back-to-back rollers. I've been playing in Onshape with similar back-to-back roller parts, sized to the gantry rail spacing (~70mm) for my existing CoreXY machine, which I retained from the MPCNC Z-axis. From your picture it looks as though you did, too!

dkjCarriage.png

I can't see any detail regarding the leadscrew nut/lift assembly but I don't think it'll be difficult to figure out... you've already done the hard part. I may add slide rails (long 5/16" bolts) on both ends of the carriage and play with printed linear bearings, just for the fun of it. -- David
 
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moebeast

Member
That is very cool, Mark. I recognize the motor/pineapple/bearing/leadscrew Z-axis setup from MPCNC combined with back-to-back rollers. I've been playing in Onshape with similar back-to-back roller parts, sized to the gantry rail spacing (~70mm) for my existing CoreXY machine, which I retained from the MPCNC Z-axis. From your picture it looks as though you did, too!

View attachment 93041

I can't see any detail regarding the leadscrew nut/lift assembly but I don't think it'll be difficult to figure out... you've already done the hard part. I may add slide rails (long 5/16" bolts) on both ends of the carriage and play with printed linear bearings, just for the fun of it. -- David

David, I am planning to use 8 mm rods for the Z axis slides. I have some bearings from my old printer, but I also want to try printed ones. It will be tricky to make my moving part printable in one piece with the bearings integrated.
 

moebeast

Member
David, I am planning to use 8 mm rods for the Z axis slides. I have some bearings from my old printer, but I also want to try printed ones. It will be tricky to make my moving part printable in one piece with the bearings integrated.

Something like this.
z axis.jpg

Still have to figure what to do for the lead nut, and I may beef up the bottom plate.
 

dkj4linux

Elite member
Very nice, Mark. I'm really impressed that you managed to fold this carriage up into such a nice compact unit. And you are really making some great progress. Did you print anything yet?

I've also made some progress but not really thought it through completely... I know I'm facing imminent collision of corexy belt terminations and Z-lift assembly on my version. I'm also thinking laser rather than needle-cutter at this point although their needs for Z-lift range are really quite similar. But, impatience wins, and I couldn't resist printing the main carriage body last night. I seem to work better printing some physical stuff for fit-check and looksee ;)

Worked most of [rainy] yesterday on the CAD stuff... I'm still quite awkward while learning my way around in Onshape... but I finally got to the point I could create an STL

Screenshot_2017-08-15_09-38-25.png

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Then I started printing late last evening... it was at 48% when I went to bed. Woke this morning to a finished print... took about 6-1/2 hours (0.25mm layers, 15% infill, and 3 perimeters)

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I'll try to populate a basic gantry mockup to see how well things move mechanically before migrating it to my current CoreXY machine. It'll be a trick, I think, getting all the belts attached so I can drive it around... but I really don't have anything better or more pressing to do, so I'll keep piddling with it to see how far I can get before crashing into the wall... ;)

20170815_102138.jpg

-- David
 
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moebeast

Member
Very nice, Mark. I'm really impressed that you managed to fold this carriage up into such a nice compact unit. And you are really making some great progress. Did you print anything yet?

I've also made some progress but not really thought it through completely... I know I'm facing imminent collision of corexy belt terminations and Z-lift assembly on my version. I'm also thinking laser rather than needle-cutter at this point although their needs for Z-lift range are really quite similar. But, impatience wins, and I couldn't resist printing the main carriage body last night. I seem to work better printing some physical stuff for fit-check and looksee ;)

Worked most of [rainy] yesterday on the CAD stuff... I'm still quite awkward while learning my way around in Onshape... but I finally got to the point I could create an STL

View attachment 93071

View attachment 93072

Then I started printing late last evening... it was at 48% when I went to bed. Woke this morning to a finished print... took about 6-1/2 hours (0.25mm layers, 15% infill, and 3 perimeters)

View attachment 93076

View attachment 93073

View attachment 93074

View attachment 93075

I'll try to populate a basic gantry mockup to see how well things move mechanically before migrating it to my current CoreXY machine. It'll be a trick, I think, getting all the belts attached so I can drive it around... but I really don't have anything better or more pressing to do, so I'll keep piddling with it to see how far I can get before crashing into the wall... ;)

View attachment 93077

-- David
Yours looks about the same as mine except the bearings are spread a little wider. That should be more stable. I also like the idea of making the top plate separate for ease of assembly. The motor has to be mounted to mine before the horizontal bearings. I do recommend adding rod holders to that plate to keep your rods vertical.

I printed my carriage yesterday. It took 8 hrs. at .2mm layer, 3 perimeters, and 35% infill. I need to make some tweaks. My Fusion360 model is a huge mess since I was just trying to learn as I went. I wasn't paying attention to which component was active when I created sketches, and then when I moved stuff around, I ended up with stray bodies and internal voids. I should start over now that I sort of know what I'm doing.
 

dkj4linux

Elite member
Yours looks about the same as mine except the bearings are spread a little wider. That should be more stable. I also like the idea of making the top plate separate for ease of assembly. The motor has to be mounted to mine before the horizontal bearings. I do recommend adding rod holders to that plate to keep your rods vertical.

I printed my carriage yesterday. It took 8 hrs. at .2mm layer, 3 perimeters, and 35% infill. I need to make some tweaks. My Fusion360 model is a huge mess since I was just trying to learn as I went. I wasn't paying attention to which component was active when I created sketches, and then when I moved stuff around, I ended up with stray bodies and internal voids. I should start over now that I sort of know what I'm doing.

Yeah, there's still work to be done for sure. My basic "4-eared" rollers were some I did when I was building my CoreXY machine and IIRC the spacing is the same as the MPCNC rollers, whose "mesh" model I used for reference. It was then I discovered the value of laying out just one "ear"-quadrant and then mirroring it to get the other three... I do love symmetry!

I saw pretty quickly that mounting the motor would be a real aggravation in a one-piece design so decided to make the separate motor plate for it. I couldn't tell from your model... but thought maybe those "depressions"(?) in the side, immediately under the motor-mount plate, were nut traps. I planned to add rod-holders/guides to the motor plate, directly above the ones on the main carriage, but that's such a simple part I knew I could add those pretty quickly when it came time to print.

But, for now, the Z-lift stuff is on the back burner. I want to fit-check what I've got now and just make sure all the mechanical movement is okay. I really like your carriage design but I'm afraid this corexy configuration may need to go... those belts are just in the way of almost everything good about your design.

I've about decided to mock up this gantry design on the camera slider setup (in the background) I did last year and continue pondering whether I really want to retrofit the CoreXY machine... or, build a totally new, conventional, relatively light-weight machine... or, maybe even start a Phlatprinter-inspired design...

20170815_112009.jpg

I really want to see your Z-lift/carriage idea work. I hate that big green monstrosity that's on my CoreXY machine now... and would LOVE somehow/someway to get this design integrated into that machine.

Later.
 

jhitesma

Some guy in the desert
Mentor
Been thinking about the Z-lift....I like the way you guys are going...just...I'd love to get away from the 8mm rods. They're harder to source and more expensive...but EMT would be way overkill for such a small Z axis. I'm also not sure if rods that short are easy to find and they're really hard to cut down. I've held my tongue though since I haven't had any better ideas.

But...like I said I've been thinking. What about a 3D printed track that skate bearings could ride in. It wouldn't really be smooth and accurate enough for a traditional CNC (I don't think) but for a foam cutter should be fine. Maybe I need to fire up some CAD this week and start putting my own ideas down :D
 

dkj4linux

Elite member
Been thinking about the Z-lift....I like the way you guys are going...just...I'd love to get away from the 8mm rods. They're harder to source and more expensive...but EMT would be way overkill for such a small Z axis. I'm also not sure if rods that short are easy to find and they're really hard to cut down. I've held my tongue though since I haven't had any better ideas.

But...like I said I've been thinking. What about a 3D printed track that skate bearings could ride in. It wouldn't really be smooth and accurate enough for a traditional CNC (I don't think) but for a foam cutter should be fine. Maybe I need to fire up some CAD this week and start putting my own ideas down :D

Jason,

I personally think these guide rods we are talking about are so short that common 5/16" bolts (up to 7" or 8" or so) from Lowe's and printed bearings would be just fine... especially with a leadscrew lift that's driving the movement in both directions. Also, printed rack/pinion could easily be used...

20170815_164356.jpg

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Those printed herringbone racks are about 8" long with a 1/4" hole through the middle. String them together on a 1/4" threaded rod and they butt together in such a way as to appear continuous... you could easily make a full-size machine with rack&pinion drive. I've often entertained thoughts of building a 2' x 2' r&p machine just to see how good/bad it would be... my guess is that it would be entirely fine for the kind of stuff we do ;)

-- David
 

moebeast

Member
Been thinking about the Z-lift....I like the way you guys are going...just...I'd love to get away from the 8mm rods. They're harder to source and more expensive...but EMT would be way overkill for such a small Z axis. I'm also not sure if rods that short are easy to find and they're really hard to cut down. I've held my tongue though since I haven't had any better ideas.

But...like I said I've been thinking. What about a 3D printed track that skate bearings could ride in. It wouldn't really be smooth and accurate enough for a traditional CNC (I don't think) but for a foam cutter should be fine. Maybe I need to fire up some CAD this week and start putting my own ideas down :D

I was going toward the 8mm rods because this Hobby King printer I as thinking of scrapping has seven of them that are twice the length I need. I will try using 4" x 5/16" carriage bolts for the rails and see if it works. Obviously more friction, but nothing the screw drive can't handle.

I also found this today at Lowes. The back lash is horrible, but it should work for foam cutting, plotting and vinyl cutting.
t-nut.jpg
 

dkj4linux

Elite member
I was going toward the 8mm rods because this Hobby King printer I as thinking of scrapping has seven of them that are twice the length I need. I will try using 4" x 5/16" carriage bolts for the rails and see if it works. Obviously more friction, but nothing the screw drive can't handle.

I also found this today at Lowes. The back lash is horrible, but it should work for foam cutting, plotting and vinyl cutting.
View attachment 93120

I second the idea of 5/16" bolts for this.

T-nuts: use a couple of them, with a spring lightly compressed between, and then trap the whole nut assembly in a holder of some sort :black_eyed:
 

jhitesma

Some guy in the desert
Mentor
I hadn't thought of bolts...probably because I mostly go to home depot and their bolts are all full thread. I learned this while shopping for low rider bolts without going to my favorite wholesale bolt shop since they're only open on weekdays. It seems Lowes near me has the shoulder bolts with smooth sections, while HD only has full threaded bolts. I think Lowes also had the full thread for more $$$ but don't remember for sure.

I do like that idea.

And like David says a spring between two T-nuts could give a good anti-backlash setup...though the threaded coupler on my mpcnc has been fine so that seemed like an obvious option. On something this small and light it would probably be better to use a 1/4" for the drive thread though..5/16 is probably overkill and 1/4" was what my printer came with and worked fine with before I swapped to lead screws. That could help keep the weight and cost down....

Though I was also thinking about printed gears/racks like David is demoing.

Oh I can't wait to see where this all goes :) Wish I had more time to play with CAD :p
 

moebeast

Member
Almost there. Needs x and y motors plus z height adjustment. My z shows 14mm of travel. The table is 28" wide and it shows that it will cut 20", so I should be able to use a 30" x 6' 8" hollow core door ($30) for a 22" x 62" cut area.
foam ripper.jpg
 
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jhitesma

Some guy in the desert
Mentor
Looking good mobeast!

One thing...14mm is a bit more than 1/2". Should be fine as long as that's above the spoil board not above the table. Unless you plan on cutting into the table and mounting the waste board inside it...which could be tricky with a hollow core door as a table.

Of course you don't need more travel - just may need to make the sides a little higher to allow for a spoil board. I'm assuming you've already accounted for that but it isn't obvious from the rendering so thought I'd mention it :D
 

dkj4linux

Elite member
Looking good mobeast!

One thing...14mm is a bit more than 1/2". Should be fine as long as that's above the spoil board not above the table. Unless you plan on cutting into the table and mounting the waste board inside it...which could be tricky with a hollow core door as a table.

Of course you don't need more travel - just may need to make the sides a little higher to allow for a spoil board. I'm assuming you've already accounted for that but it isn't obvious from the rendering so thought I'd mention it :D

I must admit I find it a bit disconcerting to have so little travel from the same basic components/mechanism that lifts far heavier loads, much higher, with the MPCNC. I know it's just the configuration -- the length of the leadscrew and guide rods -- that limits the amount of travel with this design but I would really like to see at least a couple of inches of travel to help address the concerns Jason brought up... to allow for sufficient adjustment for varying thicknesses (within reason) of the workpiece/wasteboard/etc.

Maybe you have more travel available, Mark... how did you come up with 14mm? I guess we'd need to see the bottom of the carriage with leadscrew, nut, and guide rods in place?

-- David
 
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moebeast

Member
The 14mm clearance I was looking at was the upper area of my y-z carriage. Now that I have the two pieces printed, it is actually only 6mm because I didn't check the bottom (probably 0 if I had a bolt installed). I can cut away to get most the travel back. For foam board, 10 mm is enough travel and I have put adjustment in the x carriage for various thickness of wasteboard, vac table etc. But I should stretch the two pieces to get more travel. This would look more like David's. Should make the motor plate separate while I'm at it.
printed z.jpg

foam ripper.jpg
The bottom of my x carriage is so deep so it can be used on a table from 3/4" to 4". Probably don't need that much if it is purpose built.

No more progress for the next two days:(
 
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dkj4linux

Elite member
Some thoughts on Z travel...

I recognize that the LowRider gantry may sit quite close to the work surface... maybe far closer than I plan with a more conventional machine with legs. And I see that Mark is showing use of the guide rods between the upper and lower guide rod holding tabs...which is where all the restriction is.

I don't know whether LowRider is going to give sufficient leeway but since you are reworking all the Z-lift mechanics and rail spacing maybe it will...

I'm thinking that 5/16" smooth-shanked bolts from Lowe's (up to 8" long) extend far enough below the bottom holding tabs (nearly 4-1/2" ) that easily 3" or more of travel is available there...

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[I know I'll jinx myself saying this... but things seem to be going pretty well when I can dig through old projects (I think it was an original Printrbot) and find random pieces that fit so closely what I'm playing with... :eek:]

That little trolley/shuttle that encloses the printed bearings (yellow) is about 1" high... leaving over 3" of available travel. Make it 2" high and attach it to the back of the needle cutter body (or laser) and it should provide plenty of stabiliity, little/no binding, and still have over 2" of travel. I suspect the trolley/shuttle could simply enclose a 5/16" coupling nut for attaching to the leadscrew... many MPCNCs actually seem to work quite well without the original spring-loaded backlash compensation.

I'm satisfied with what I see so far but sadly I don't see it as a retrofit for my CoreXY machine any more... all this Z-axis stuff sits right where all the belts terminate. I've just installed the carriage assembly on the camera slider rails and hope to start testing the Z-lift mechanism... moved from 8" bolts to 5" bolts for clearance on that jig. I really see a Phlatprinter-style machine mounted that way...

20170816_231256.jpg

but I'll probably just build a basic 2' x 2' X-Y machine first. Anyway, that's my roadmap for the moment... :D

-- David
 
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dkj4linux

Elite member
Sneaking up on it...

I've used Onshape to create a double-ended, ~1" thick, leadscrew shuttle that printed bearings and the coupling nut pressed into tightly. I've made no provision for attaching a tool... I'm really more interested in adequate travel and smooth operation for now. It should be straight-forward to attach a *skinny* tool (~ 45mm between rails) to the shuttle when the time comes. I made it double-ended (I love symmetry!) primarily so that bearings and guide rods at both ends might be used to give more rigidity and smoother travel with less binding, if needed. I also thought that with some tools one end might be preferable to the other and/or possibly two tools might be mounted sumultaneously(?)...

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Shuttle at lowest position with the 5" bolts for guide rods...

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at an intermediate position...

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and top-most position...

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gives a hair over 20mm of total travel (max). Obviously, with the same shuttle, ~25mm of travel is gained for each additional inch of guide rod... and these bolts are available up to at least 8" in length; i.e. so more than 3-1/2" of travel should be easily realized.

I need to find/print a 5mm to 5/16"coupler now and cut a length of threaded rod for a leadscrew and it should be ready to test. It may be a couple of days, however... I'm also spending a lot of time in Onshape, still learning and trying to work out some details for a simple machine based on this gantry/carriage. -- David
 
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I'm not sure I understand, but won't the bolt block some of the travel ? If I look at the pictures with your fingers undeside, even if the shuttle is at its highest position, the bolts would hit them at the gantry slides sideways.

Would'nt it make more sens to block the bolt on the shuttle, and have the bearings on the gantry ? that way, as the shuttle is lifted, the bolts don't scratch/limit the surface underneath.