evilc66 published a new build:

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All Openbuilds parts showed up yesterday, so hopefully I can get a start on the mechanical build this weekend. Everything else will be trickling in over the next two weeks.

 

This bad boy showed up today, which is about a week and a half faster than anticipated. I don't think I'll have temperature issues with this guy

 

So, here's the CAD model in it's current state. There is still some more to add, like all the corner brackets, all the hardware, extruder. hot end, etc... At the very least, I have verified that I can get greater than 300mm travel in all directions. Pretty happy with that. Still patiently awaiting the updated belt reduction plates for the X and Y-axis.

 

Nice! That certainly seems to be workable. The 1:2 ratio though would make it fly.

I put the heater mat up against my Two-Up earlier today, and it just as big as it's footprint. This sucker is huge!

 

Managed to get the X and Y axis rails assembled on Sunday. I would have got further with the assembly if I didn't find my order short 4 of the 8mm locking collars for the lead screws The team at the OB store have me taken care of though, and the missing parts will be here tomorrow. With the Misumi order that showed up today, I will be able to have it mechanically assembled this week! I do have to trim the 20x60 extrusions though, as they were all cut 10mm too long for some reason.

I think I have everything but the controller now on hand. I have an extra Ramps 1.4 board and drivers that I can use in the mean time, but I'm thinking of going to a Smoothieboard for the smoother operation. The Azteeg X5 Mini was on the list too, but I'm not thrilled about it only having 4 stepper drivers. Other suggestions are welcome.

 

Progress, and pictures!





That's the base and Y-axis done for now. 8mm lock collars should be arriving today, so that will allow me to get some more done tonight. You can see the Misumi t-brackets and the 45 degree support extrusions that came in yesterday. Everything fit together as expected.

As you would imagine, even this part of the printer is not light. I don't think I'll have much in the way of vibration issues with this beastie!

 

All mechanical parts now assembled!





This thing is stiff and heavy, both of which I find to be good things. I'll have to get it on a scale once it's all said and done, but I'm estimating this thing is currently tipping the scales at about 40lbs. Certainly overkill for a 3D printer, but anything worth doing is worth overdoing

Next thing on the list will be the heated bed. I have to get the mounting plate sorted out first (the part that mounts to the Y-axis carriage), which I'm still trying to decide on the material for. I had initially ordered two 1/4" thick MIC-6 cast tool plates (one for the mount, one for the build plate), but that's an awful lot of weight to throw around at high rates of speed. Then I thought about 1/8" aluminum plate. Much less weight, but I worry about it flexing under the weight of the build platform, which will be the 1/4" tool plate. I also thought about 1/4" MDF, as it's pretty rigid all by itself, not too heavy, and shouldn't have the same resonance issues the thinner aluminum would. I dunno...

Thoughts?

 

G10/Garolite might be a good choice for the bed mount. It's lighter than aluminum and much stiffer. I'm pretty sure I have a decent sized sheet of carbon fiber kicking around the house too. I've had it for years, so I might as well put it to good use.

 

Thanks Kyo!

I literally just found my sheet of carbon fiber seconds ago. I think I'll be using that, even if it's only for the bling factor

 

Just make one. Lots of places will cut material to size if you don't have the tools to do it yourself. I use Online Metals a lot, and they will cut to any size you want. My build plate is 1/4" thick 12"x12" cast tooling plate and was cut to size by the vendor I bought from on ebay. The bottom plate was just a 12"x9" sheet of 1/8" carbon fiber that I had laying around. I used a C-Beam gantry plate as a template for the mounting holes, then laid out the mounts for the build plate adjusters by hand. Took about half an hour to do and all I needed was a ruler, a pencil, some masking tape (to mark on so you don't mark up the plates permanently), a drill, a few bits, and an M5 tap (and handle).

Speaking of, I did get the build platform done over the weekend. I just haven't posted pictures yet (I will tonight). I'm going with a 3-point mount, but rigid (no springs). 5mm shims of varying thicknesses are readily available in the R/C car world, so I picked up a set of 0.5mm, 0.35mm, 0.20mm, and 0.10mm shims. with how rigid this machine is, I think I will only ever need to level the bed once, until I take it apart

I had to do a little surgery on the heater mat. Turns out I wasn't paying attention to the dimensions when converting from metric to imperial, and didn't realize that there would only be about 2mm clearance around the heater to the edge of the build plate. That's not really enough room to get a standoff and screw in there, so out came the xacto and the soldering iron. The heater mat I bought is made with nichrome wire (versus a kapton heater), and the wires do end up coming quite close to the edge of the mat. As a result, the wires were exposed when I cut into the mat to allow clearance for the three standoffs. I cut the nichrome wire and crimped a section of regular wire (you can't solder nichrome wire) to the ends to re-route everything around the standoffs. Everything was then sealed back up with high temperature red RTV silicone. Looks a little ugly, but gets the job done.

The PEI sheet came the other day (took forever to ship due to an issue with the vendor's ordering system supposedly), so that's going to get mounted to the build plate here shortly. Once that's done, the Y-axis will be complete. Next up will be the extruder mounting plate.

 

That's madness! I paid $25 plus shipping for the 1/4" tooling plate! Try these guys. This is where I got my plate

diamond plate aluminum tread 3003 6061 7075 2024 7050 5052 items in Metal store on eBay!

The other alternative is Online Metal. More expensive than the ebay option, but they will cut to size (1/8" increments) if you have an oddball size that you need.

See if you have any places locally that deals with used tools. I have a place down the street from me where I picked up my drill press (the recondition them before sale). It's a 3ft bench top unit (variable speed, 1/2" chuck), but it's built like a floor standing unit (much thicker column) and weighs over 150lbs. Looking around, I'd have to pay close to $400 for an equivalent, and picked it up with a vice for $150

 

Either way, it's insane.

 

It's almost like they are planning to CNC machine it for those prices. How much do they think it costs to operate a drill press for crying out loud!

Out of curiosity, where are you located?

 

Some pictures. They aren't very exciting, but pictures none the less.







That last picture isn't the clearest, but it's one of the spots where I had to tweak the heater mat. Having the mat come that close to the edge will be good though, as it should offer pretty even heat across the whole build surface, especially once that big slab of aluminum reaches equilibrium.

 

Carbon is pretty easy to cut and drill. The only thing you need to be worried about is the dust, as it's not really that nice to breathe. As long as you wear a dust mask or respirator and wet the cut a little to keep the dust at bay, you shouldn't have anything to worry about. For saw cuts, just use the same blades as you would for non-ferrous metal. Good sharp drills cut through it like butter.

As for the heater, 250W can work, but it will just take longer to get up to temperature. The heated bed on my Two-Up is a pcb based 6" heater (about 150W IIRC) and that would get up to 120C, but it took an age, and certainly wouldn't have gone much higher. If you are going to use an aluminum build plate, a little more wattage wouldn't hurt.

 

Why don't you want to use an SSR? That gives you so much more flexibility than relying on keeping the MOSFET cool enough to conduct enough current.

I haven't run across many boards that have MOSFET outputs that can handle more than 12-15A, but then again, I haven't been keeping track of all the different offerings and current limits due to deciding to use an SSR right out of the gate. Keeping your current MOSFET cooler with a beefy heatsink and a fan will help you eek out a little more current. You could even try running MOSFETs in parallel for greater current capacity.

 

Fair. While the MOSFET can handle a healthy amount of current, the board may not. 15A requires some pretty thick traces, even though they are very short. If you really want to beef up that portion of the board, you can scrape off the solder mask that lead to the drain and source (incoming power and outgoing power) and add a healthy bead of solder to them. That will help carry more current. Heatsinking the MOSFET is still a good idea, but with the tight packaging of the Ramps board, that's not so easy. Mounting the MOSFET remotely will allow you to cool it better with a beefy heatsink and a little airflow. If you decide to try this, just make sure you use appropriately sized wire.