Stabilymod for top and bottom brackets

Hi,

Im building a 50x100cm Cherry-Pi/Wolfstock hybrid with Vslots and Im thinking of ways to stabilize the frame besides cross bracing.

Since the backside of the extrusions is free I though about extending the top and bottom brackets.

[www.thingiverse.com]

What do you guys think? Is it worth spending the extra material?

Anchoring the vertical extrusion at the top of the Kossel/CP seems to be the Achille's heel of both designs. Anything that you can do to shore up that joint is most certainly NOT a waste of material, IMHO.

Personally, I would use even more material and extend bracing fillets from your addition along both sides of the extrusion and put two more screws into it from the sides. I don't know if boxing the top of the extrusion completely solid is worth the material, but I had considered printing another set of bottom brackets to use at the top to shore things up.....

Edited 1 time(s). Last edit at 02/02/2015 10:05AM by vreihen.

Ok good. I have to check how far down my arms reach in the maximum position, then I have some space to anchor it in the sides as well,

Maybe I am confused about the part. I was thinking that you were mounting it with the added portion up, lowering your build height by 20mm or so by having the vertical extrusion extend up above the bracket. If your idea was to put the added portion facing down, then blocking the side slots is obviously a problem and your design makes sense just catching the outside slot of the extrusion. If you have a piece of spare/scrap extrusion to test it with, I'm curious if it makes a difference if you print a test part as designed.....

yeah this part is meant facing down because its the top bracket. the bottom bracket would have the extension facing up.

your right that if the top bracket is facing down and has reinforcements on the side it would block z height. that wouldn't work, but on the bottom bracket you could reinforce the sides as well, because the sliders shouldn't go so far down anyway. i think I have at least 10cm for side reinforcements on the bottom parts. Ill design a bottom bracket with sides tmr.

Ill have extrusions shipped soon then I can test it out

I'm not sure the extra plastic will actually achieve anything. At design size for the towers (600mm) the machine is quite rigid in normal use (I normally print between 80 and 100 mm/s). As you increase the towers then rigidity drops off but it's more to do with the twist in the extrusion. If you hold the base and turn the top you will get 5 to 10 degrees of movement with 1000mm towers. That's why I went for 2040 extrusion for the towers on my Cherry Pi 4XL design (thread called A Larger Slice Of Pi).

aha interesting point. ill keep an eye out for that. unfortunately i couldn't order 2040 from my European supplier. I guess cross bracing combats twisting better than reinforced brackets

There's always this thing (I've not tried it myself yet)
[www.thingiverse.com]

or this:
[www.thingiverse.com]

Edited 1 time(s). Last edit at 02/03/2015 09:37AM by Zedsquared.

ah yes, thats looks similar to what I had in mind.

I received my 1m 2020 Vslot and tried carefully to twist it and is doesnt move one bit, which leads my to assume that the reinforcements can actually help make the connection between extrusion and bracket stronger.

Quote
sungod3k
I received my 1m 2020 Vslot and tried carefully to twist it and is doesnt move one bit, which leads my to assume that the reinforcements can actually help make the connection between extrusion and bracket stronger.

My post was unclear. I didn't mean to twist just the extrusion. What I should have explained was that once the machine is assembled if you put the base on the floor and stop it from turning with your feet, then hold the top like a steering wheel, you can 'twist' the machine by a fair amount

Ah I see, but then the 2nd part on my last sentence still holds and I can add more contact surface between brackets and extrusion and expect a gain in stability.

Quote
Zedsquared
There's always this thing (I've not tried it myself yet)
[www.thingiverse.com]

or this:
[www.thingiverse.com]

An honor to have my "stabilimod" noticed and shown here.

Can you talk about you experiences with these mods?

You mean this bracket I made ? -> [www.thingiverse.com]

And I thought you didn't want cross-bracing... Anyway, the cross-bracing definitely stiffens the whole frame. I can grab two of the bracing rods and lift the machine and shake it about without fear of twisting or bending the towers.

It adds quite a bit of a bulk to the printer but anything that would reduce vibration will surely improve the performance and durability of any machine.

As for the print quality, the waves that appear on perimeters (resonance) when it was still stock disappeared too. Now I can go as fast as my steppers/drivers would let me. This mod stays.

You just have to measure the offset clearance so no part of the effector would hit the cross braces. The shorter the offset, the sturdier the brace will be. I have 3 different offsets. You can enter the offset parameter in the scad file.
This mod is cheap too. I bought the 3/4 inch curtain rods for about the equivalent of $2 for 2 meters.

From what I learned about seeing my machine in action Im designing a bigger bracket, that will have a double row of vslots like on the bottom.
Also I think we need to increase the contact surface from the vslot to the bracket. I think adding screw holes on all sides would get more of the wiggle out of the construction. The same btw also goes for the bottom bracket Since we have more space around the slot on the bottom bracket it will also get a higher sleeve.

Crossbracing works very well be limits the print size to within the basetriangle so Im trying to find solution that either move the anchor for the braces outside of the printbed, which will results in a pretty hefty anchor OR design the brackets to be stable enough without cross braces.