The Railcore spare parts are interesting. The bed seems to be custom made for 3 hold points, and a little bigger than I can use at 450mm rail size. Clearly, they know what they are doing, but I am also trying not to spend $1600, or I would have just bought the RC.
Using just the heater is an interesting option. Are there places that just sell 3mmx300mmx300mm aluminum that is reliably “flat”.
https://www.banggood.com/Creality-3D-3103203mm-Aluminum-Alloy-Heated-Bed-Platform-Plate-For-CR-10CR-10SPRO-3D-Printer-p-1422828.html?cur_warehouse=CN Maybe something like this, with a good heater underneath, and glass on top with PEI or something on the glass (or, if I was printing on glass, I suppose I could go back to glue stick).
https://www.midweststeelsupply.com/store/castaluminumplateatp5?gclid=Cj0KCQjwoPL2BRDxARIsAEMm9y-rxk40eH8TxQGntWfzXQ_aO1K-ur7gnKinNicioJZRAEj0lOFgOcUaAj3IEALw_wcB These guys have quarter in plate for around $30 for your size.
Only $10 in shipping too, unless I want it to come straight via a truck, then it’s $350, because I don’t have a loading dock 
this is the last 24v bed I purchased. finding a reliable supply of heated beds turns out to be difficult. I have many bed configurations. Mirror tile (pack of 6) with BuildTak on them works great. The Anycubic tempered glass plate, also good. Just recently got a WhamBam flexible magnetic detachable plate. So far so good.
In all cases, I have a cork tile under the heated bed. Really helps it heat faster and retain heat.
I elected to laser cut most parts from acrylic after getting a Glowforge. The CAD model reflects this. Earlier versions of GridBot were all 3D printed parts. So I recommend if you print them to combine the pieces pictured in white as a single piece so that they’re more rigid. Also make them solid or mostly solid.
Your library still have a lulzbot TAZ? That’s got a 300x300 bed. If you can get into the library these days. I haven’t checked to see if they are open or not in CO.
Instead of cork I use foam core (foam sandwiched between cardstock paper) from the dollar store. Cheaper and works almost just as well. I saw a comparison study on it a few years ago.
Bed choice. That is the main thing stopping me from building one. That’s why I decided to wait for the Prusa XL to be released. I was going to buy the bed from prusa. But that has been delayed by COVID 19. I have just come to LOVE the magnetic PEI powder coated steal sheets.
The WhamBam surface I purchased is the first time I’ve used such a system. Parts don’t stick as well to the PEI (requires more heat I guess), but the rest of it works as advertised.
One trick I have learned about these beds is to clean it with soap and water on occasion. When PLA starts to have a hard time sticking. Throughly dry it before it can rust on the edges. Then it’s amazing again.
They are drive up only (and I think that is meant for books). I would like some part of it to be milled by the low rider, to continue the generation aspect of my machines. So NBD.
Regarding the spring steel sheets. I have a no name one that is totally junk. It just doesn’t stick well, even at high temp. It is supposedly PEI, but I think it is just paint. So I’m a little vary of some of the cheaper offerings. The one I have that I like now is from th3d. I have a textured one too, but it doesn’t stick as well, and I think it is because the bl touch is so sensitive it feels the peaks and valleys and the height gets all messed up.
Maybe with the cork, and a short pause before prints, the fysetc one will be heated evenly enough to work. It seems worth a try, and it is in stock.
Those photos are really helpful. I am looking at the cad, the bom, the comments on openbuilds, and the few photos there. I am piecing it together, but these help a lot.
What orientation do you print the extruder mount?
I’m having trouble finding the 1/2" square aluminum too. I can find 3/4" at the home depot. Or 1/2" steel. I might have to cut a big piece of plywood from leadscrew to leadscrew. My big concern there is that it might be stiff, and bind the Z.
here is an old BOM for the v1 GridBot. has some relevant links. I used this 1/2" cross bar to support the bed. Great stuff. And cheap.
different part, but printed in this orientation. requires support material be removed. (found on the floor so covered in a bit of dust and carpeting)
Well, I’m thinking something like this right now. It’s all hypercube bits and bobs, except I want to replace the aluminum extrusion with an mdf box. I haven’t really changed anything else except extending the pieces to contract the box, which will have holes that line up with holes in the pieces, which will have heatset inserts for easy assembly.
That gets rid of all the extrusion and specialty hardware in favor of cheap hardware and cheap mdf. And I do have a cnc, sooooo, that part will probably be more accurate than I could have cut the extrusion anyway. No doubt the grid bot is superior, but I’m just looking for “good enough” for the money.
Here’s a quick snap of the modeling progress, still have to mirror some parts and the rest of the box, plus the compartment down below, and no print bed here either, but I think you can get the idea if you’ve seen a hypercube.
Building your own printer is worth every penny. Just for the enjoyment.
The devil is in the details with a cube like that. You need to make sure everything move the direction it is supposed to, and not in the other directions. And when the bed raises, it will be a rigid length, so the sides need to be very close to parallel.
I have a lot of confidence that you’ll figure it out and getting it to work. But I think it would save you some trouble to flush it out completely in CAD, and play a bit with assembling it too. I think Ryan said something like, “make mistakes in cad or in make mistakes in wood”. Things like, how are you going to fasten the corners of the mdf? How are you going to encourage them to be square and parallel?
FWIW, the prusa i3 design is champion for a good reason. If you are trying to get the best value, that style is very effective.
However, I like this and I like your cnc. I think this has real potential.
Thanks for the feedback. My plan is to start with a square cnc and make dadoed square panels, like on my spray can shelf, for the top and bottom. The sides will finger-joint together, at least in my head.
Might not be a bad idea to include some provision for printed corners. If I can make sure that my printer is square enough, that could be an effective aid.
Upside is that mdf is cheap, so if I have to scrap the first and second attempts it won’t really hurt. My CAD leaves a LOT to be desired, but I’m getting better all the time. Still giggling over that CNC, lol.
Sounds like a plan. You might also enjoy looking at the itopie, which is focused on using a CNC to build a prusa style printer.
That looks neat! Might have to build that one TOO.
Got the primo together, so I’m getting back to this. Since I’m using MDF to box this thing in, maybe it wouldn’t be so hard to heat it, too. I’ve seen that even getting it up to 40-50 would be useful for ABS. I’m not really sure I have a use for anything beyond ABS and TPU (in addition to the PLA and PETG that my ender can run OK). Seems like 50C is a no-go for pla parts. These pieces are kinda small, so I might be able to get them to run on the ender, and I already have a roll of ABS sitting around waiting. Should I got that route, or would PETG be good enough? Thinkins?
Well, a lot sure does happen fast around here. Turns out that to build the house we WANT, we have to sell the house we HAVE. Not too happy about it, but it is what it is. So we get to cleaning and painting, then BOOM water all over the floor under the kitchen island. Had to rip it all out and scrap everything below the counter down to the studs.
Waiting on State Farm to argue with us about what a “slow” or “intermittent” leak is and whether or not we had one. We had the guy who did the demo talk to them 3 or 4 times. Short story, it was enough water that one night the cabinets were dry, and the next night they were wet. We called the warranty plumber because I couldn’t see the leak and he found that everything was throroughly soaked. Then they wanted to talk to the plumber that fixed the crack because the other expert wasn’t expert enough for them, even though the plumber that actually fixed the leak showed up 4 days later after everything was clean and mostly dry. Topper, they ended up talking to somebody from the plumbing company’s dispatch, not the plumber, and finally “approved” coverage (don’t get me started). But hey, thanks for wasting a MONTH State Farm. They still haven’t cut a check because they want to haggle over the estimate.
Anyway, in the middle of all that I had the idea that maybe most of the parts I need for this printer are already available in the Anet A8. Certainly has enough motors, bearings and rods. Well, wouldn’t you know it, somebody else already had that idea (as happens with most of my good ideas!). He redesigned the parts to work with a standard Anet A8 kit, in hypercube fashion. Best of all? He has a 3d model of the entire assembly available in FUSION 360. Lucky me!
Too many things were jointed together or copies of components, so after fudging up and starting over 3 times, I asked fusion to convert the model to stp and made my changes through direct modeling. Lots more nasty, but I don’t know enough to do it the “right” way.
So, here’s a quick pic. I’ve moved away from finger joints and into tab/slot, and I still have to
Simple single piece of threaded rod clear across for that front corner connection. You don’t need a turnbuckle, just sandwich each side between a pair of nuts and washers - 4 nuts and 4 washers total. Turn the inner nuts independently of one another to get the spacing you want, then tighten the outer nuts to hold the side panels in place against the inner nuts. If you want it to look extra fancy, use acorn nuts on the outsides.
Many of the original RepRaps used threaded rod for the entire frame structure and it was fiddly, but very easy, to get things square and parallel and on pretty much whatever spacing you wanted.
Well, just about got to the end of stage 1. Got my Anet last week, and the whole thing looks a lot better than I thought it would. Guess I was expecting a monster to pop out of the box, lol. Several things preassembled, and not bad at all.
Looks like the lead screws are a wee bit longer than in the model, but I can cut those. I thought about just moving the xy stuff up, but I don’t really think I need the build height. On the other hand, I’d hate to need the extra 20-30mm later and be mad I don’t have it…plus it would make access to 2 of the screws a lot easier. Just a bit tired of working on this model right now. Time to get working on that 660 speed control, I think.
I ended up relying on printed parts for squareness, mostly because I trust my primo to place the holes more accurately than I can work a tape measure. Judge me if you must :D.
I haven’t modeled in the controller or power supply. I think I’ll put both of those on the back and run the display up to the lid in a box like we use for the MPCNC. That means I don’t have any screws for those in the model, either. Oh well. Got all the rest of them, though. Thanks @jeffeb3. It was a super pain, but I learned something, and it helps a lot when I think about ordering parts. I would have certainly got the wrong number of a couple items and missed at least one other all together. Also let me see where I could change some of the printed parts to get rid of a unique size or two. 25 of this and 25 of that turned into 50 of that which is probably the same price as 100 of that at Bolt Depot so I’m either going to save some money or at least have a bunch of extras for the same price.
I’ve linked to my dropbox, where I’ve exported the model as f3d and stp in case anyone wants a look. I haven’t learned how to use joints in Fusion yet, so none of it moves. I do have the entire thing duplicated though, one organized by assembly, the other by where I get the parts (to help make sure I order what I need), color coded by source for fun, too. Black=printed, orange=Anet kit, white=CNC’d, red=bought. I’ve used components for organizing rather than however components are supposed to be used, lol. Maybe one day I’ll get that together, too.
