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Re: New ORD Bot Idea

PostPosted: Wed Mar 27, 2013 8:01 pm
by Winder
bdring wrote:3. Again this compares to the original design and the other versions of folded brackets and printed brackets. Currently the Z motor is as close to the Misumi extrusion as possible. With the folded u channel, the motor can move a lot closer to the Z extrusions which has many benefits in any design.


Could you elaborate on the benefits of moving the motor closer to the Z extrusions? I'm curious because I needed to move my motors further away in order to use some Nema23 motors I had on hand:
Image

Re: New ORD Bot Idea

PostPosted: Wed Mar 27, 2013 8:09 pm
by bdring
Could you elaborate on the benefits of moving the motor closer to the Z extrusions?


The closer the motor is to the Z, the stronger it is regardless of the design. A longer bracket is easier to flex.

The same is true for the gantry plates. Ideally, you would like the lead screw right on the same plane as the wheel. That is not practical, but the closer the better. I am not sure this will have a huge benefit, with the floating Z nuts, but smaller is cheaper and lighter.

Re: New ORD Bot Idea

PostPosted: Thu Mar 28, 2013 9:14 am
by Digitalmagic
bdring wrote:2. You still have the alignment in the X direction because you are mounting to t-slots.
You get this alignement concern because you chosed flat nuts in your ORD Bot BOM.
FlatNuts.JPG
ORD Bot Flat nuts

Self-aligning nuts are available from Misumi and offer self-alignement, more expensive, though.
1 Misumi - SHNTU5 Nuts
Self-Aligning Nuts - SHNTU5.JPG
Self-Aligning Nuts - SHNTU5.JPG (11.12 KiB) Viewed 12071 times

2 Self-aligning roller-in T-slot nuts
http://www.fathinc.com/en/products/t_slot_nuts/slot_8.php?goto=303169

bdring wrote:3. With the folded u channel, the motor can move a lot closer to the Z extrusions which has many benefits in any design.
How many millimeters did you shift the motors closer?

Otherwise, why not placing the leadscrew/motor in the wheel midplane?
The Misumi/Makerslide angle is a good structure to elaborate a new motor attachment, possibly along 2 axis (X & Z).
The extruder weight is less on the wheels and more on the leadscrew.
ORD-Bot-NewMotorPlacement.JPG
New motor placement in the Makerslide/wheels midplane

Concept of plate
Motor-FoldedPlate.JPG

Here, the motor can't be more close to the Z extrusion, and symetrical to the wheels.

Re: New ORD Bot Idea

PostPosted: Thu Mar 28, 2013 1:33 pm
by bdring
I use those nuts all the time. They are handy because you can install them where you can't slide them in from the ends. They also hold their position lightly on vertical slots. They make a set screw version (instead of the ball) if you really want it to hold the position tightly. They still slide along the X direction and need manual alignment and are pretty wiggly in the slots.

In theory placing the rod where you have it is best, but in practice it is hard to do. If you try to put it behind the gantry plates, the increased wheel spacing hurts stiffness.

Re: New ORD Bot Idea

PostPosted: Thu Mar 28, 2013 3:03 pm
by Digitalmagic
bdring wrote: If you try to put it behind the gantry plates, the increased wheel spacing hurts stiffness.

The leadscrew goes before the gantry plates, not behind.

There is absolutely nothing to modify on the gantry rig, just a hole to drill across the makerslide, in order to have the leadscrew through it.
Just the pulley idler holder plate screw to shift.
Gantry-Holed-Makerslide.JPG

Leadscrew nut on the upper gantry plate to allow the gantry to reach lowest Z.

Re: New ORD Bot Idea

PostPosted: Thu Mar 28, 2013 4:10 pm
by cozmicray
With this arrangement you just reduced X travel perhaps 30 mm on each end.

What's wrong with current z-axis system?
There are a lot of other areas that could use tweaking / redesign?

This topic looks like Ordbot Hadron 2.0 design ???? mo money ????

Re: New ORD Bot Idea

PostPosted: Thu Mar 28, 2013 4:26 pm
by Digitalmagic
It is just a "New ORD Bot idea" topic, a good opportunity to "shake the concept", as usual! :)

You are right for the 30mm, but with a custom design in mind, you cut the 20x40 60mm longer, and no extremity plates.
I don't like the new U-profile, which goal is to have the motor at the closest of Z axis, so this is a mod, keeping the Misumi rigidity and getting rid of the motor plates at extremities.

Re: New ORD Bot Idea

PostPosted: Sat Mar 30, 2013 3:02 pm
by Digitalmagic
The initial motor plate can't have been U-shaped, because NEMA17 width is greater than HFS5-2040, being 40mm.

By using a HFS5-2550, having the same slot width (6mm), now a U-shaped motor plate can be quite simple, with the Z-axis Makerslide above of it.
The Y-axis Makerslide L-brackets attach onto the 2550 using the same nuts.

It meets all the goals of the proposed U-shape, rigidity and motor/wheel closeness, while increasing X-axis rigidity, using a standard profile.
MotorPlate-U-Profile-50x25.JPG
50mm wide Misumi U-Plate

Re: New ORD Bot Idea

PostPosted: Fri Jul 26, 2013 6:45 pm
by richmond
Bump.
Hey Bart, did you receive the formed channel?
Any chance to build with it?

I like the motor mount idea from Digitalmagic, could consider a hybrid of that and the original approach and would still retain build envelope flexibility by swapping out extrusion between the motor mounts.
If one is looking at forming sheet metal maybe taper down the inside end to fit current extrusions while maintaining width for motor options.