New T-slot Pre-Design Questions

I've been following the 3D printer scene for a while waiting for a really accurate fast 3d printer. The Ultimaker seems to fit the bill however I'm not a huge fan of the plywood cabinet since I tend to move around a bit which lands me in humid locals sometimes. In short I'm looking at a t-slot bot in ultimaker fashion with a bigger build area/heated bed. I do realize that there are limits when dealing with a bowden extruder in length but I'm fairly certain some... creative engineering can fix anything.

Looking to use RAMPS 1.4 setup since it seems to be the most hack-able atm. Might add some goodies like an auto x/y/z so hackability is a big plus. I have some concerns with only putting 12v to the steppers and lacking acceleration for those ultra fast movements without losing steps. I read I can hook a bigger powersupply to the board but I'll lose the ability to run PC-less which I would eventually like to do. Is the 12v accel issue even an issue?

I'm also looking for the size of the linear rod and the material (alum, steel, stainless, etc). I'll have to go bigger but I'd like to know what works for them. The last mystery is the gear ratios on the x/y I assume they are similar to Mendel.

Lastly those of you who have built larger printers, what is the practical limit on build area for on of these machines before warping goes out of hand even with a heated bed?

If anyone can answer some of these questions it would be very helpful.

If you are printing with ABS then you need a printed heated bed - period.

When printing with PLA it depends on the shape and size of the object but anything that gets near the limit of the Mendel print bed size of 200mm x 200mm you also need a heated bed.

Edited 1 time(s). Last edit at 01/23/2012 11:10AM by rhmorrison.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

rhmorrison Wrote:
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> If you are printing with ABS then you need a
> printed bed - period.
...
I think you mean heated bed, eh?

Yes - that is what I meant to type.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Hmm, so it looks like the benefits of a larger build platform are balanced with power consumption of the heated bed as you can't have one without the other.

I think I've found info for the rest of my questions about the mechanics. From what I read about the Bowden extruders there is a problem with compressing the filament. Has anyone tried mounting a encoder to measure and control filament feed rates?

200mm is about the practical limit for good prints with abs or pla. Anything bigger always lifts/cracks without a heated chamber unless it is very short.

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www.Fablicator.com

Heated chamber,maybe one day but not today.

I'm having some issues tracking down a MXL 20T pully with a 8mm bore. Misumi stops at 6mm and McMaster-Carr seems to only carry imperial bore sizes. Any one know a vendor that stocks these or should I just bore them out.

Have you tried Stock Drive Products? I didn't look for your particular size, but they're a good resource.

They have some nice pillow blocks that I won't have to fab now , but not 8mm timing pulleys. Looks like I'm running low on options, might need to bore out some smaller ones which is a bit of a bummer.