Lowrider2 questions

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This topic contains 6 replies, has 5 voices, and was last updated by  Zsolt 3 months, 1 week ago.

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  • #105298

    Zsolt
    Participant

    Hi all, I have a couple of questions, any tips and answers that would point me in the right direction would be welcome and appreciated!

    A bit of a background: my only CNC experience stems from 3d printing. I’m quite capable with hardware/software/firmware, electronics, mechanics and hacking it all, however this is a fairly new endeavor and I would love to learn as much as possible before taking the next step.

    So far I’ve only been doing research and ordered the kit from the store with the mini Rambo board. I’ve been browsing the forums for quite a while now, and for some reason I have a hard time figuring these out:

    • How does the homing/sending past end values really work without end switches?
    • If you end your job at a random location and power off, next power up will think that the position you’re in is [0,0,0] so how do you home from there without grinding the motors/sending coordinates past ends?
    • Y movement on rails without any guiding groove. If I assume correctly, the fact that there are belts on both sides with synced motors pulling on them simultaneously will assure that the movement stays square on both ends? How likely is for the Y axis to get out of square after repeated moves? What about crashes?
    • Z movement – am I to assume correctly that if you send the axis past its end value, the whole assembly would slip apart somehow?
    • Is there a comprehensive guide to build a solid table for 4’x8′ cutting area?
    • Does the bottom side of the spoil board equal to Z0? Or is it the top of it?
    • Should the top of the spoil board be level with the top of the side rails the wheels are running on? I guess I’m just not really aware of how the spoil board comes into play when it comes to a CNC machine.
    • Any advantages using metal rails for the sides? Or is that even the right thing to do? How about a V slot metal groove for the wheels to run in? Or is it totally unneccessary?
    • Are 2×4 beams ok for the entire table? Should they be of more premium quality? Would more expensive 2x4s have advantages over regular ones? Or rather use 2x3s so it would have some extra space for the sides to fit properly?
    • Joining the parts for the table, is it better to use a joining jig (like the Kreg jig) or is it better to just drive screws perpendicularly?
    • For the stainless steel rods, is it ok if they run a tad bit longer than necessary? Also, what’s the key metric for them, the type of steel, the type of seem, wall thickness?
    • I’m planing on printing the parts in carbon fiber PLA, which is pretty much my go to filament for practical prints. Any downsides to it?
    • I’ve seen mentioned a couple times the use of water cooled spindles instead of the DeWalt router, mainly because it’s quieter. I haven’t bought a router yet, is it worth going the water cooled spindle direction? What are the drawbacks?
    • What bits should I start out with? What are the brands, materials that are worth going for?

    I’m sure I’ll have more things to ask if you nice people don’t mind 🙂

    I’m very close to finally create a shop for myself and I’m super excited to build this machine — I have so many things I want to make!

    #105301

    Jamie
    Participant

    Homing will set the coordinates relative to the extreme point of your machine, but it’s generally inconvenient to precisely position your workpiece in the workspace and build this offset into the CAM.  It’s easier to “home” relative to your workpiece by disengaging steppers, moving physically to a known location on your workpiece, and then energizing steppers and issuing G92 X0 Y0 Z0.  Or some other Z value if the known point on your workpiece is not at Z=0.  It depends on your CAM.  Z0 could be the top of your workpiece or the top of your spoil board but it will usually not be the bottom of your spoil board.

    Assuming your CAM doesn’t send the tool far outside your workpiece, you are generally safe from running into the limits of the workspace, but you do have to take care because Bad Things (like self-disassembly) can happen if you exceed your working volume.

    I can’t say much for table construction…

    3 users thanked author for this post.
    #105324

    Jeffeb3
    Participant

    As long as your software isn’t configured for dual endstops, you should be able to go into negative coordinates.

    I set Z=0 at the top of my workpiece. If I’m cutting through 1/2″ material (12mm) I will set the total depth to 13 or 14mm and the final Z depth will be -13mm, which is inside the spoil board.

    My LR does drift in Y, or at least it did before I installed some wood to keep it straight. If you crash, the whole job is done and needs to be reset, just like skipping steps on a 3D printer.

    The Z will fall apart if you drive it to the ceiling, but leaving those screws and pipes long won’t hurt. The higher your Z gets, the less strength it has in x and y. So you don’t want to cut at 4″, but you can lift it to 4″ to put your work in, or change bits.

    You don’t have to have the rails and spoil board at tge same height, but it plays into the length of Z you have extended while cutting. My only concern with 2x4s is they aren’t straight. Metal rails are fine.

    I don’t see any benefit of pocket screws unless you’re joining thin material, like 3/4″ material.

    The tubes can run long. For a 5′ span, you will want stainless steel. Ryan has some suggestions on the parts page.

    Any PLA is fine. What are you using? I have wanted to try some CFPLA.

    The noise of the bit and the vac will make the router noise a non issue. You’ll need hearing protection no matter what. The dewalts are useful as shop tools, have warranties, and have good performance per dollar.

    The V1 shop stuff are theright bits. Ryan used to recommend these when he wasn’t selling them and they make a big difference in performance. Try these first. Pretty much nothing at home depot works well for CNC bits.

    3 users thanked author for this post.
    #105431

    Greg
    Participant

    Good luck with your build! For tracks I routed 1/8″ deep grooves for the wheels in the table top seems plenty deep enough.  I also just experimented with putting 1/8″ grooves into 1/4″ hardboard and putting that under the wheels.. worked great too.

    Re: carbon fiber PLA… in my experience it is very rigid but also brittle.  You might have trouble with the parts that clamp on the tubes since I think they work better with a little flex… but they also need to be strong since they have stresses.. I wound up reprinting these parts from PLA in PC+ filament since the PLA started failing.

    I would try with the dewalt router first.. unless you soundproof your dust collection it will be as loud as the router anyways.  The mill bits from Ryan are high quality and work best so I would get a few of these to start with.  I wound up switching to cheaper packs from ali express so I could have a large variety. No horror stories so far.  Just make sure you are getting 3.175mm (1/8″) shanks and not 3mm shanks

    2×4 you would want to run through a jointer since they will not be flat on the side.

    Yes ‘bad things’ happen if you send your machine past the Z extents.. too low and it will stretch your threaded rod adapter apart .. you can put it back to normal by clamping it in a vise.  Too high and the pipes will fall out of the bottom clamps.

    Z=0 just has to match what you have setup in your CAM software.   I use the top of my stock as Z=0 but if you were trying to make something a certain exact thickness and removing everything from the top I could see using the bottom of your stock (top of your spoil) as Z=0.

    Buying extra tubing length doesn’t cause any problems at all.. I think buying it a couple inches long gives you some more options.

    For instructions on making tables just google ‘torsion box’ there are lots of articles.. many of them are kind of overbuilt and heavy though.  I made one out of 1/2″ MDF and 1/4″ skins and it’s fine.  The taller you make the box the more rigid it will be.

     

    1 user thanked author for this post.
    #105448

    Barry
    Participant

    Good luck with your build! For tracks I routed 1/8″ deep grooves for the wheels in the table top seems plenty deep enough. I also just experimented with putting 1/8″ grooves into 1/4″ hardboard and putting that under the wheels.. worked great too.

    Re: carbon fiber PLA… in my experience it is very rigid but also brittle. You might have trouble with the parts that clamp on the tubes since I think they work better with a little flex… but they also need to be strong since they have stresses.. I wound up reprinting these parts from PLA in PC+ filament since the PLA started failing.

    I would try with the dewalt router first.. unless you soundproof your dust collection it will be as loud as the router anyways. The mill bits from Ryan are high quality and work best so I would get a few of these to start with. I wound up switching to cheaper packs from ali express so I could have a large variety. No horror stories so far. Just make sure you are getting 3.175mm (1/8″) shanks and not 3mm shanks

    2×4 you would want to run through a jointer since they will not be flat on the side.

    Yes ‘bad things’ happen if you send your machine past the Z extents.. too low and it will stretch your threaded rod adapter apart .. you can put it back to normal by clamping it in a vise. Too high and the pipes will fall out of the bottom clamps.

    Z=0 just has to match what you have setup in your CAM software. I use the top of my stock as Z=0 but if you were trying to make something a certain exact thickness and removing everything from the top I could see using the bottom of your stock (top of your spoil) as Z=0.

    Buying extra tubing length doesn’t cause any problems at all.. I think buying it a couple inches long gives you some more options.

    For instructions on making tables just google ‘torsion box’ there are lots of articles.. many of them are kind of overbuilt and heavy though. I made one out of 1/2″ MDF and 1/4″ skins and it’s fine. The taller you make the box the more rigid it will be.

    Just don’t go over 4 inches with your spoil board!  Unless you’re running them on metal rails bolted to the sides.

    #105450

    Greg
    Participant

    Yep.. there is only like 1/8″ of room left over if you have a 4 inch table. I found it really helpful debugging everything on just a simple table made out of 2 by four feet of 3/4″ MDF.. plus you have the option of cutting taller Y plates or other pieces if you need them before making your torsion box.  My wheels don’t run on my spoil board so at least that didn’t affect my maximum table height.

     

    #105556

    Zsolt
    Participant

    Thank you for the answers!

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