Not quite wire pr0n, but the #FB2020 has had a rebuild bringing it up to current designs and getting rid of badly printed/cracked parts and a damn good tidy. The plug bundle is getting ready for the final tweak on this design. This will be a quick swap magnetic hot end assembly as taking the hot end out is a bit of a bitch.
How are you going to do the magnetic quick changer?
Not exactly sure as yet. I have a rough idea of using the existing carriage design but flipping the mount 90 degrees as there’s space to do so. I’m probably going to end up using 10mm x 2mm N42 or N52 Neodymium disc magnets which have a 1.4 -1.6KG pull or 20mm x 10mm x 2mm N42 bar magnets, which have a 2.1kg pull. I need to see what fits. Unless something really stupid happens, like the nozzle catching the bed badly, that should be enough force to hold the whole assembly in place. At the same time I’m probably going to make the layer fan magnetic so it’s just a case of pulling the layer fan off, pulling the plugs removing the hot end and repeating that in reverse for the new hot end.
You might want to look into printing a cover for that SSR - the terminal screws do carry live mains, after all.
@Thomas_Sanladerer - Hadn’t even thought. They’ve only just been put on both the FB2020s to allow M80/M81. It is very rare, if at all that my hand goes anywhere near the mains at the back of the printer, but knowing myself and having had a tingle from a few mains related items, I’ll get on to that now.
You should use round magnets that are half as thick as their diameter. This way a magnet has the maximum holding force to size ratio. I did a magnetic quickchange holder, too, and used 8 round neodym magnets 10x5mm. https://youtu.be/yqk5P5jW644
@Rene_Jurack - yeah, I’ve seen. It was what made me think to do it. Unfortunately I don’t have enough material on the carriage to use decently thick magnets (it’s about 5mm thick). The thing is, even if I use 8 N42 6mmx 3mm disc magnets at 1.1kgs pull force I’m getting a similar force on each side. It’s all about the pull force, the shape is whatever I can fit in. 1.4-2KGs of force on each corner is well enough to hold something with good strain relief that shouldn’t ever be knocked. You’re talking needing around 1 & half to 2 UK sized bags of sugar to actually be able to detach it which is well enough.
i’m about to finish my own design of a quick changed head (i can use both direct and bowden remote extruders). the carriage part is a simple plate with to dovetail slots on the sides and moving bar on the bottom to lock the attachment. there’s also 5 round small magnets (still working out which are best to use and how many, so that detail is not final).
the attachment part has two dovetail extrusions on the sides and a small part for the lower bar of the carriage to lock, and of course the corresponding magnets. so far it’s working really really well, but i’m trying to tweak it to get it as small and thin as possible without loosing mechanical stability.
the version i’m testing now is about 6mm thickness for both the plate and the attachment (together, not each). i have ~0.1mm clearance for the dovetail and it’s working very well when printed, slides in but no room for movement.
regarding the SSR, can’t clearly tell from the picture if it’s grounded or if the frame is grounded… considering it is attached to the aluminum extrusions, if they are not grounded - i’d definitely both ground it and enclose it.
btw - did you use any crimping connectors for the connections to the power supply? and are those black jst connectorts on the left?
a beautiful job indeed!
@Tom_Keidar Thanks. It’s all grounded via the earth wire on the PSU. All PSU connections are crimped. I’ve found it gives a much better electrical connection, especially on the DC side. I had an issue where the temperature on the hot end was fluctuating about 1.5˚c either side, as soon as I added the crimps, it dropped to 0.5˚c.
The Connectors to the Hot end & Carriage are 2 pin JST SMs - https://www.amazon.co.uk/gp/product/B019JPOWH8/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
As for the cover for the SSR, it’s just finished printing…
Quick update, now designed and added http://www.thingiverse.com/thing:1713742 for a bit more cable management and strain relief
It’s amazing the wire size difference from a 12/24v heated bed to mains with SSR.
That bundle’s a bit off tbh as there’s a couple of soldered joints reducing the 14AWG to 16AWG. I didn’t have 16AWG to hand at the time and had all the fun of trying to stuff the 14 AWG into the board connectors on the RAMPS, so I basically bodged it when I got the 16AWG and just reduced it down. I need to rewire it properly. It’ll be a lot smaller then tbh.