Spoken like a man with great wisdom OR one who's built a airplane in their basement. Don't ask me how I know, I don't want to lie.

Larry

 

The grin on my face when that semi-truck pulled up is still on my face. It might last a loooong time too.

 

Hi Steven,

I already have the silicone pad, all 1272x1170 mm of it, etched foil, split internally into four areas. It spits out 8000 watts at 220, or 4000 watts at 110. Yes, that's a lot of power, don't want to wait forever for it to come up to 120 for ABS, and god knows what else I will be using in the future. Not decided about the glass yet, whether I should go with borosilicate or tempered. My main concern is flatness, still working on that part, and lately, your remark about it sticking to the underside of the glass. I'm thinking I should add an aluminum sheet on top of the pad, with adhesive. Other than spreading the heat evenly, it might prevent said sticking.
I have to be careful about this one last step, the glass is about the last major thing I have to buy, other than some loose ends which I can find locally, such as solid state relays, etc.

Regarding glass bowing, a borosilicate properly manufactured should not bow and be flat. The other option I was thinking about is to buy a much cheaper tempered glass. This will come with an inherent bowing in it, due to internal tensions, but if I were to place it with the concave side up, I'm thinking by clamping down the edges I should be able to adjust flatness within acceptable parameters. Perhaps I ahould mention, the glass (and pad) will be sitting on a 1 inch thick cork mat flush with the printing platform, 1332x1326 mm. If you have a look at the pic I posted previously, you can actually see the cork mat and the silicone sitting on top of it.

 

Larry, I hope your grin will be renewed every time you manufacture something on your two mini wonders.

 

How does one take out a 1500 mm cube shaped printer through a 3 foot door?
Answer: one doesn't.
Lucky me I designed it so that the side walls can be disassembled like one peels off a banana, just in case I want to take it with me golfing.
That, or tear a new hole in the front wall of my house.

 

Yes Val, blocks CAN be removed....That's as far as I'm going.

Steve & Val, guys, what about using the heat mat glued to glass and then sandwich aluminum plate atop the glass? 1/4" glass and 1/4 aluminum plate would give a very solid build platform. Unless your flux capacitor melts and crosses streams with the flow from your dilithium crystals in which case, life as we know it in this dimension ends.....

 

Hi Larry,

If by sandwich you mean using also adhesive, I believe the different expansion coefficients of the glass vs. aluminum would lead to shear forces which in turn would cause the weaker element to break apart, glass that is. I am, however, considering using an aluminum sheet glued to the silicone pad, to counter the phenomenon Steven mentioned earlier, namely, the pad sticking to the underside of glass. This would also help spread the heat evenly across the glass on top.

My flux capacitor must have gotten damaged, I suspect, when I was allegedly dropped down the stairs in childhood. This must also have been the moment when my dilithium crystals got badly bent, with the family klingon pet boldly chewing off whatever was left of them. It might explain why I went for the maximum 3d printer span openbuilds can provide, to use in the first 3d printer I ever built.
On a more serious note, flux liners are quite the thing, as the picture attached will show, namely, flight by means of electricity only, no moving parts and an insignificant amount of energy used in the process. The little triangle in the pic is aloft, no optical illusion there. But this is another conversation for another era.

 

nice work, steve and tim.
now, here's a forrest gump question: how do you plan on keeping the bed parallel to the xy plane? unless the floor of the room is extremely so, won't you need a way to adjust the base, bed that is, then adjust the xy axis on top of it so as to keep them parallel?
i'm only asking this because i had to think long and hard about doing mine back in the day.

 

and, by the way, glad to see you guys kept at least the drones...

 

will do the same for my mobile bed, except that my glass will sit on top of the silicone heater, which sits on top of a 1 inch cork mat. glass will be 1/2 inch tempered, which comes with a slight inherent bow due to fabrication. planning to use this bow to my advantage, by clamping down the edges of it until flat, all under the watchful eye of a dial feeler attached to the port extruder. already set the bottom board of my printer horizontal, since it sits on four height adjustable casters, so as not to have the weight pushing down onto the wheels. after setting the base board horizontal, i laser adjusted the top xy plane horizontal, so now the two are parallel. once the glass flatness will be ensured, manual adjusting of the four screws will set it parallel to xy plane. will post more once i get there, but right now i'm on the other side of the world, hard to work on it from 5600 miles away.

 

I'm having issue with the lead screws...they wobble all over the place. None of the lead screws I received are straight, they are bent at different places. Steve, we may need to find more solid lead screws and go to 10mm perhaps...

 

steven and tim, have you guys tried the wobbly lead screws yet?
i was looking yesterday into that, trying to figure out whether you can get away with 10 mm or if you might have to move up to 12 mm.
first thing that came to mind was the weight of the printed part. if you ever print a large model with more than the customary 4% infill, e.g. lots of ins and outs, the weight of the model will increase considerably. second, the current 8 mm screws have 4 starts, meaning you will have to 'tone' down the 8 mm lead by resorting to micro stepping, thus increasing the burden on the microprocessor for thinner z layers. if you go with a single start screw and small pitch=lead, you will solve this problem mechanically because the nut will inherently have a shorter travel per screw revolution, if my math and memory serves.
perhaps mark carew wants to look into supplying single travel lead screws in the future, the current 8 mm / 4 starts screws seem to me to be better suited for x and y axis movement rather than z axis. we could use some lead screws especially for z axis, where the movement is less frequent, methinks.

 

i stand corrected. somehow, i totally forgot your bed is stationary.

 

Nice design. I am also into doing something like this but I use the frame as my Z axis, unlike you guys.

Is that a 20×40 profile for x and y?
Have you calculated the load the hotend will have on the x axis and the amount of deflection (bending)?

I plan to use 20x60 there as I might use a direct drive extruder. I haven't decided yet.

Good luck with your build. Keep us posted.

 

good decision regarding the 12 mm screws, methinks.
while at it, how about moving the z motors on top of the screws and going direct drive with a flexible coupling?
it would mean redesigning the z axis kinematic chain, but the advantages over belt driven might be worth the effort.

 

direct drive is not about weight lifting, rather about having less moving parts in the kinematic chain.

 

that is indeed one downside to it.

 

steven and tim, how's work going lately?
any progress?