This Old Machine: Re-purposing an Engraver as a 3D Printer

I think thats a bit rougher of a lead than most use (for instance my O2 uses a m5 with a 0.8mm pitch. You should still be fine for layer heights though - .12 and .24ish mm layers are perfectly acceptable for quality on a toy boat for our needs. Your lack of fine control on Z though does mean you're going to have to work extra at making sure you've got your bed level and zero'd mechanically. I would see if I could make it work with what you've got though.

 

I've printed down to 0.1, but typically work around .2. I'm reasonably certain I could print thinner layers but don't see a need. Practical layer height is also a function of your hotend. Its a bit dodgier to try to lay down a .1 layer with a 0.6mm nozzle than it is with a 0.4mm. I've put together prints with 0.3mm layers as well. Visually at 2+ feet its all pretty much the same for a lot of parts.

 

I don't understand shelling out for the very nice Smoothieboard but then limiting yourself with a generic J-head? Why not an E3D?

 

Now I'm really confused; the E3D has active cooling, and the J-head does not. There are some new all-metal J-head variants but they're basically the same as the E3D Lite hotend, which still has a PTFE liner.

You are correct about the cost, it's pricey.

 

What sort of feedrate can you achieve on those leadscrews&steppers?

 

I would think that you've got plenty of feedrate with those numbers Most of my printing has been at 60mm/sec or less.

 

I have experimented with faster, but the GT2 timing belt has enough elongation under load that I can see artifact on the printed object. It looks kind of like ripples at corners in the print. They can be smoothed out in post-processing and certainly wouldn't be visible from 10 feet on a combat model, but still...

I had considered doing all-leadscrews on my i3 variant, but I wasn't sure about getting similar artifact from leadscrew inertia. But since I plan to use a smoothieboard on the i3 variant, I can take the stepper voltage up which could mitigate the artifact (if it would happen at 12V with leadscrews...) with greater motor torque.

I already bought into redesigning the Z and X axes because I decided to use real leadscrews and nuts (on the Z-axis) vice the threaded rod that most printers are using these days. Changing out the printed parts of the Y-axis is fairly trivial at this point. X-axis parts aren't done being redesigned yet, so that wouldn't be a new burden.

I don't know what the maximum extrusion speed on the RRP hotend is, nor for the E3D that will be on the i3 variant. Time for some research I do know that delta printers with J-head extruders are capable of very high print speeds with 0.5mm nozzles. My E3D hotend currently has a 0.4mm nozzle for finer detail; I want to do a gearbox that is entirely printed, apart from shafting and a few M3 nuts and screws to lock the gears to the shafts.

 

I run 50-60mm/s on my O2 with the e3d 0.4
I can run faster, but I'm not sure exactly how much faster. Too fast on smaller parts and you just end up with a big gooey mess.

 

Generally you use a fan to cool PLA prints, but not ABS. ABS will firm up fairly quickly - in my experience a 10sec layer time is generally enough if your hotend doesnt radiate metric f*cktons of heat (very scientific number). Cooling ABS tends to lead to warping and delamination problems - problems I hoped to resolve by moving to pet-g, but since I can't reliably print that with my current hot end, I'll be trying HIPS next.

 

After scratching some drawings on scrap paper at work today, I'm ordering two more 8mm leadscrews with the fancy brass nuts for them, so that I can move the X and Y axes with leadscrews. My i3 is relatively experimental anyhow, and I can always retrofit it with belts.