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3D printer build log
spuddevans:
A little more progress made today. I started working on the Y-Carriage blocks to whittle them down a bit for mounting the bearing-pulleys for the belts to run round. So I milled off a "T" section, drilled for tapping M3 for mounting the bearing-pulleys (the centre hole) and drilled two holes 15mm either side so that I can make a little bracket to fix the top side of the pulleys.
Another view with the bearing-pulleys put in place,
End-on view,
I reckon that, compared to the plain Ali' blanks, these are now at least half the weight, and I'm not done yet!! I still have a fair bit more I can mill off, but any major milling will wait until near completion as it gets hard to accurately hold in the vice when you don't have a couple of the original squared faces untouched.
Onwards and sideways,
Tim
awemawson:
That's going to be one nice solid machine when you've finished Tim. Most of the 3D stuff out there on the web looks very flimsy so it's nice to see a proper build :bow:
spuddevans:
--- Quote from: awemawson on May 07, 2017, 01:40:40 PM ---That's going to be one nice solid machine when you've finished Tim. Most of the 3D stuff out there on the web looks very flimsy so it's nice to see a proper build :bow:
--- End quote ---
Thanks Andrew, solid is what I'm going for.
Like you say, some of the 3d printers being built have been quite "elastic", and seem to be quite lacking in basic engineering good-practice. There's some more being built now using Ali' extrusions, but many seem to make the joints out of plastic printed parts :doh:
It's a slow build due to limited time in the workshop, but I'm really enjoying the challenge of figuring this out as I go.
Tim
nrml:
In my experience (albeit limited), super rigidity isn't particularly necessary for a FDM printer. Vibration and resonance control are far more important and having a rigid all metal frame doesn't automatically eliminate this. In fact it might even make it more difficult to manage. I suspect (but can't prove) that having dis-similar materials in the frame might help break up resonance and might actually be advantageous. The forces and loads on a 3D printer are not really going to stress the frame and joints unless it is really poorly designed and / or put together.
I have no doubt that the care and effort you are putting into your project will result in an excellent printer, but I doubt that it will perform any better than a well designed and carefully built printer with plastic joints. I presume building it to your standards is more important to you than rather than just aiming to get a half decent working product in the quickest time possible.
I will be watching your build with interest as I have an ongoing corexy build (aluminium extrusions and aluminium corner brackets) which is currently on the back burner. My problems started with bearing issues. I found that igus drylins had far too much play for my satisfaction and oilite bushes were binding at the slightest hint of dust. I have reluctantly decided to scrap the smooth rods and use linear rails instead but this means a Z axis redesign, which is where I am stuck at. Your thread is a good motivation to pull my finger out and restart my project.
How is your Z axis implementation going to be? IMO it is the most challenging part of a corexy design.
spuddevans:
--- Quote from: nrml on May 07, 2017, 08:08:03 PM ---In my experience (albeit limited), super rigidity isn't particularly necessary for a FDM printer. Vibration and resonance control are far more important and having a rigid all metal frame doesn't automatically eliminate this. In fact it might even make it more difficult to manage.
--- End quote ---
That's true, at the moment my frame does have a little "ring" to it, but I have a cunning plan to deal with that (mainly involving kiln-dried sand part-filling some of the hollow sections
--- Quote --- I suspect (but can't prove) that having dis-similar materials in the frame might help break up resonance and might actually be advantageous. The forces and loads on a 3D printer are not really going to stress the frame and joints unless it is really poorly designed and / or put together.
--- End quote ---
You could well be right about the dis-similar metals, my concern would be the differing thermal expansion properties (I am intending to enclose my frame for ABS printing) I bow to your (and others) experience regarding the stresses experienced by a 3d printer, I was assuming that the moving mass of the print-head/extruder/stepper (I intend to use a direct extruder) would benefit from a more rigid/stiff frame to absorb the movements when the direction changes (unless printing really slow)
--- Quote ---I have no doubt that the care and effort you are putting into your project will result in an excellent printer, but I doubt that it will perform any better than a well designed and carefully built printer with plastic joints. I presume building it to your standards is more important to you than rather than just aiming to get a half decent working product in the quickest time possible.
--- End quote ---
A lot of what I am doing is based on the materials I have access to and the techniques I am familiar with, rather than any thought of it being a better way of doing things. You're probably right about the end result being no better in performance than others, especially as even the most flexibly built printers can be run slow enough to not wobble when printing.
--- Quote ---I will be watching your build with interest as I have an ongoing corexy build (aluminium extrusions and aluminium corner brackets) which is currently on the back burner. My problems started with bearing issues. I found that igus drylins had far too much play for my satisfaction and oilite bushes were binding at the slightest hint of dust. I have reluctantly decided to scrap the smooth rods and use linear rails instead but this means a Z axis redesign, which is where I am stuck at. Your thread is a good motivation to pull my finger out and restart my project.
--- End quote ---
That's interesting about your bearing issues with the smooth rods, I have seen that many others have moved over to linear bearing rails and blocks instead of smooth rods. I probably would have done that myself if I hadn't already bought the smooth rods and bearings.
I'd be interested to see your progress when you restart your project.
--- Quote ---How is your Z axis implementation going to be? IMO it is the most challenging part of a corexy design.
--- End quote ---
I plan to use 3 8mm smooth rods (1 at each front corner, and the 3rd at the centre of the rear of the print bed) with linear bearings for keeping the printbed from moving in the X or Y axis', and lift will be provided by 3 10mm leadscrews located in roughly the same areas. The 3 leadscrews will be driven by a continuous GT2 belt with one stepper moter. The leadscrew pitch is 2mm, multiplied by 200 steps per rev of the stepper gives a vertical resolution of 0.01mm without resorting to microstepping or "gearing down" using different pulley sizes.
Hopefully all of that will give me a printbed that is very stable from movement in X and Y, and also that can be levelled relative to the print-nozzle, and won't sag or bow with weight from the print or from just the weight of the bed itself.
Of course, until it's actually built, all of that is subject to change :lol:
Tim
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