Starting i3 build looking for help

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mark.moorcroft
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Starting i3 build looking for help

Post by mark.moorcroft » Fri Jul 14, 2017 12:46 am

Newbie here,

I'm hoping to build a 30 x 40 i3 clone for my first 3D printer. I would buy a genuine Prusa, but I want a steel (or alu) frame, and as much 24 volt stuff as possible. Can anyone point me at any good resources for someone in the US to get started with sourcing parts? Does anyone do steel frame kits with 24 volt upgrades? Have you seen anyone TIG weld key parts of a metal frame to stiffen it even further? I guess I'm basically doing the opposite of dolly. Building an i3 with as many of the upgrades in the build as possible, so I don't have a pile of replaced parts later. I found a lot here, but most of it looks harder to source in the US. And I wonder if there are other folks offering the same stuff. Does anyone ever use ACME threads for the Z rods?

Mark

chumm
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Re: Starting i3 build looking for help

Post by chumm » Fri Jul 14, 2017 1:36 am

2020 aluminium extrusion is really nice for building a rigid frame while still being relatively light and not too bulky. Having built a prusa clone and a 2020 printer, I don't think I'd ever go with the prusa design again, the threaded rod base is incredibly rickety and attaches to the frame in such an insecure way. The Folgertech 2020 is an example of a printer using this sort of frame:
Image

I wouldn't buy the 2020 printer for your purpose, but they sell a kit that converts their acrylic i3 clone, which is a standard prusa/dolly design:
Image
into the aluminium extrusion printer pictures above. So this kit is probably a good place to just get all the materials for a frame based on a known design:
https://folgertech.com/products/acrylic ... ersion-kit

I think that's a good all-in-one start because the printed parts for their i3 kit are all available here:
https://www.thingiverse.com/thing:647124

If you want to just build a frame from scratch, this seller ships custom cut 2020 extrusion really quickly from the US and for a great price:
http://www.ebay.com/itm/PDTech-2020-20m ... 2962366850?

You should definitely use leadscrews, Zyltech is a good US seller that ships really fast and has decent prices:
http://www.ebay.com/itm/8mm-T8x2-Lead-S ... 2101010139
I'd recommend sticking with metric and getting 8mm screws even in the US because nearly every printed part or design you find online will be metric, so it benefits us to comply to get access to all the open source goodies. Zyltech also has a nice 24v power supply, smooth rods, LCD, endstops, stepper drivers, etc. Everything I've ever ordered from then came in 2 days from Texas to Chicago with free shipping over $30.

For electronics I ended up sourcing all the 24v stuff from China. Standard RAMPS does not handle 24v well and needs to be modified in some way, so I went with an MKS-GEN 1.4 board to avoid this and it works great. If you're going for full upgrades you might want a RAMBO or Smoothieboard or something. 24v fans were kind of annoying to find, these 2 sellers shipped in about 2 weeks with the ePacket shipping option, which wasn't bad for a tiny cheap package:
https://www.aliexpress.com/item/New-2-P ... 41963.html
https://www.aliexpress.com/item/Free-sh ... 32825.html

For the hotend you only really need the heater cartridge to be 24v, but I just bought the whole thing that way:
https://www.aliexpress.com/item/1-75mm- ... 32539.html
Naturally if you're going full upgrades then you'll want a genuine E3D hotend and of course they offer 24v variants.

For the heated bed I used a standard 3mm MK3, these are pretty widely available. I'm running 24v into the 12v input and it heats up really fast, it's just important to do the PID tuning in firmware and install a thermal fuse under the bed so if the heater ever runs away and gets too hot it'll cut power.

There's lots more parts of course but I don't want to flood you with a million links, if you need help sourcing anything let us know :)

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mark.moorcroft
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Re: Starting i3 build looking for help

Post by mark.moorcroft » Fri Jul 14, 2017 1:49 am

Awesome tips. I actually have been looking for an excuse to start working with some 2020 style stuff, but the P3Steel frame looks very sturdy. I'll have a look over your links and see what brain cells fire 8-) Did you consider using 2040 on the uprights? The thing I like about the Black Widow over the CR-10 is the beefier uprights.

For the record I'm more interested in functional part and fixture printing than I am in models and "art" pieces. I.E. an Alien head not so much as a fixture for a wood router or replacement part for an old appliance.

ronka
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Re: Starting i3 build looking for help

Post by ronka » Fri Jul 14, 2017 4:07 am

hello new one!! i admire your unspoiled enthusiasm; lets make a dent into it shall we :lol:
like a parent ill give some feedback on your decision for the buildsize, here we go typing with an old man's voice..

are you shure you'll need a bed of that size? i also went big the first try having an enormous 25x25 heated bed while 20x20 is (was) the standard..
what i got was a 5mm thick 25x25 aluminium plate with a 20x20 heated bed beneath it..
and now after a lot of printing i never came close to the edge(no phun intended) so ask yourself the question: do i really need it??

have you considered the extra weight of the bigger buildsize.. the poor motor has to pull it around the y axis, resulting in bigger jerk artifacts..

because the buildsize is larger the smooth rods have to get a lot longer, resulting into bending action in the middle giving less accurate prints..
have you got the correct diameter of the rods in mind??

keep in mind: the bigger the (carthesian)printer is, the less accurate the print will be, heatingtime goes up, printing really big parts can fail more easily because of cooling difference in plastic, very long printtimes for delicate or smooth prints necesary because of speed being limited by jerk, more susceptible to shaking from the printer itself or from external sources(wobbly table, shutting doors, heavy traffic nearby, earthquakes, or worse)

-ending old man's rant-

its all in good fun, just try and love tinkering with it like i do, i could have gone with the flow but that would have cost me manny hours not beeng busy with my hobby and learning this stuff in the process, i would'nt change a thing looking back (well almost nothing 8-) )

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mark.moorcroft
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Re: Starting i3 build looking for help

Post by mark.moorcroft » Fri Jul 14, 2017 4:55 am

Assuming I stick with 20 x 20 (mk42?), it's still a question of laser cut steel frame kit or 2020 extrusions. And the best way to go about getting 24 volt gubbins.

chumm
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Re: Starting i3 build looking for help

Post by chumm » Fri Jul 14, 2017 5:54 am

mark.moorcroft wrote:
Fri Jul 14, 2017 1:49 am
Did you consider using 2040 on the uprights? The thing I like about the Black Widow over the CR-10 is the beefier uprights.

For the record I'm more interested in functional part and fixture printing than I am in models and "art" pieces. I.E. an Alien head not so much as a fixture for a wood router or replacement part for an old appliance.
2020 extrusion is so rigid that I never needed to consider anything bigger, at least when it's well fastened. Also I used all 400mm pieces of 2020 to build a frame for a 213x213 bed, so the base was much wider than the X travel area, which i think contributes greatly to the stability:
Image


I'm sure the Black Widow is a fine printer but I can't help but look a that cross frame and think that the bed isn't well-supported, and that it would tend to wobble on the diagonals without any corners present.

Also I don't know if this is just some placebo thing, but the base of the Folgertech sitting entirely on the table, compared to the CR-10 sitting on 4 feet, seems much more sturdy to me. I built mine so the z motors, y motor, and power supply case all sat flush with the bottom and it feels like it's seated very sturdily:
Image

As for the steel vs extrusion situation, I think the core problem with most i3 frames is that they're designed to be cheap to make, so they are laser cut from thin metal. As someone with a thin aluminium dolly, I can say that the design is awful and is clearly an artifact of people just continuously iterating/cloning the same designs. So the P3steel uses steel instead, which is good, but then they need to create all these cutouts to cut weight so it's not ridiculously heavy. Then it's still thin enough that any front to back force will flex the steel, so you have to add these big supports on the back to cut any Y motion. X is rigid of course bc it is thick in that direction. If you were mass producing a printer in China you might jump through all these hoops because the cheapest way for you to make a frame in those numbers will always be laser cuts of thin metal, but as a hobbyist I think the only reason people use those designs is because that's just "how it's done" or because they want to be sure they can adapt it to an existing open source design.

A much shorter thought is to imagine bending a sheet of that thin steel by hand, then imagine bending a 2020 extrusion :lol:

Edit: I would also say a 200x200 bed is plenty, the novelty of having a huge bed will wear off when you have to wait 10 minutes for your giant bed to heat up so you can print a part the size of your thumb! In a perfect shop you've got a big and a small printer so you can use the right tool for the job though, so if you think you might get that far into it maybe go for it.

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mark.moorcroft
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Re: Starting i3 build looking for help

Post by mark.moorcroft » Fri Jul 14, 2017 6:30 am

You're making way too much sense. There must be something wrong here :lol:

So as I said, I have been looking for an excuse to work with these kinds of erector set extrusions anyway. And they have the benefit of being useful to re-purpose as well. Have you ever considered welding any key spots for extra strength? What about using a 2020 cube? I was thinking from an erector set perspective it makes a lot of sense. And have the perimeter cube bolted to the bench (maybe with some isolation damping). I have seen some pretty interesting furniture designs combining 2020 and hardwoods or hardwood ply.

ronka
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Location: Holland

Re: Starting i3 build looking for help

Post by ronka » Fri Jul 14, 2017 12:56 pm

hi,
my printer is also made of 2020, and its rigid enough to use the gantry as a handle when moving..
where my printer differs somwhat from chumm's is the fact that his gantry side posts are on the frame in stead of mine passing the frame making it possible to bolt the posts in to withstand the x and the y forces.. my upper gantry bar is bigger by 10cm (mine is bigger :lol: again no phun..)
but as stated the aluminium is realy sturdy so any type is better than the plastic frames.
.
frame.jpg
frame.jpg (78.81 KiB) Viewed 2117 times
on the other hand, a tiny bit of movement in the frame can absorb some vibrations in the frame.. but thats another story...

if anything on my printer is causing trouble its the printed parts, so yeah, i'd get as many solid parts as possible.

chumm
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Re: Starting i3 build looking for help

Post by chumm » Fri Jul 14, 2017 8:08 pm

mark.moorcroft wrote:
Fri Jul 14, 2017 6:30 am
So as I said, I have been looking for an excuse to work with these kinds of erector set extrusions anyway. And they have the benefit of being useful to re-purpose as well. Have you ever considered welding any key spots for extra strength?
The weakest points are the spots where the side posts attach to the square base. I wasn't sure if just fasteners would do the job there, but a combination of corner brackets like ronka posted and L-shaped fasteners on the sides makes it completely rock solid. I lift the printer by the crossbar with a big fat 24v psu weighing down the base and there's never any play at all. If the extrusion is pretty well squared at the cut, it will sit solidly. That said, they are just fasteners and can absolutely loosen over time, so you could weld if you felt so inclined. Ronka's solution may also be more reliable since it doesn't rely on the squareness of the cut.
mark.moorcroft wrote:
Fri Jul 14, 2017 6:30 am
What about using a 2020 cube? I was thinking from an erector set perspective it makes a lot of sense. And have the perimeter cube bolted to the bench (maybe with some isolation damping). I have seen some pretty interesting furniture designs combining 2020 and hardwoods or hardwood ply.
CoreXY printers are cube-based, here's one made with 2020: https://www.thingiverse.com/thing:1313587
You could do the same thing with i3-style cartesian motion. Basically the upper side of the cube would structurally just serve to prevent Y motion on the X gantry (which I assure you is not happening :P ) but it has the added benefit of allowing you to build an enclosure for potential climate control if you're having trouble printing larger ABS parts, for example. It would also give you lots of places to mount LEDs, a camera, a multi-spool holder, etc. I think it might make maintenance a little more of a hassle since sometimes you need to do a bit of contortion to get a hex key into a weird corner, etc, but I imagine it would still be pretty roomy.

The combination of cube + bolting to bench would certainly maximize rigidity, which should allow you to increase your print speeds, but then that's the whole point of a CoreXY design so maybe if you're already thinking cube and rigid and fast printing, that's the way to go (I've never built one so I can't say for sure).

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