An approach to extending Z-Axis.
 

Hi Gerald,

Can you critique the following approach to extending the z-axis. (My application is 90% foam cutting).

Is it possible to add height to the parts 1020451PA and 1020456PA in such a way that torsional stiffness is not comprimized? Is there another way that makes more sense?

Thanks, Greg

btw the parts from domino11 are works of art! Thanks Heath.

I wouldn't do it.

Greg, Why would you want risking rising the gantry assy & felx when you could just conceive a lower table ( Lowering the X-bearers ) ??
Playing with flex, I would say !!

Greg,
I actually have a bolt together table so I can remove the center of the table and cut up to 48" below the Gantry as designed. I am currently remaking my Z-slide with a few Gerald suggested changes to accommodate a 36" stroke z-slide.
I have taken a few pages from the SB forum by raising the machine slightly off the floor to allow for a complete 48 x 48 x 96" billet of EPS foam for mold making.
I trust this is a similar approach you are considering.
Let me know...maybe we can compare notes.

Sean

Ahhh nice,

So if I keep the upper structure as designed, and put my energy into lowering the table center I can achieve my goal?

Thanks for the Info Sean.

here we go.. I think it'll work great!

Greg,
No problem , glad you like the parts. :)

Sean, Greg,
Hopefully you will compare notes in a build or mod log so the rest of us can chime in? :):eek:

Chiming in will be no problem.
I have already sent the new, longer and larger spider to laser cutting.
I hope to have it back in a week or two. It's on the LOW priority list at the cutters. They said they would put in the works when the table had a large enough drop to accommodate it. Nils was kind enough to order the eccentric bushings and additional bearings for me with his order, thus I have most everything I need on hand now.

Sean

This sounds really interesting. :)

I sent Sean a "doodle" I found on PC. Can't remember when or why I did it. To use entirely at own risk . . . :)

Change the attached extension to .dxf when you save it, open with CAD. Wonder if the holes still line up?

I did change a few holes, added a few to match the Mamba carriage and extended the open area for the gearmotor stepper clearance.
pm me if you want the cadfile i can't get the revised version under my kb limit sean

Okay Sean, you finish the development on that, and then we will place your drawing in the set. :)

...I LOVE being the guinea pig:D

Wow, now that's nice! Is there a bending schedule or does it pretty much follow the smaller spider plate?

The bending schedule is identical to the regular spider plate.
Nothing on that front to change. I have attached the plate with modifications as a general reference of the idea.
Sean
Attachment 1849

Sean,

That is one strange looking plate but I am looking forward to seeing you use it.

Maybe we can call it the "pirate" plate - a skull with an eye-patch?

yeah, I can't say I understand what I am looking at.

I'm in Marc's camp. :confused:

Shouldn't the holes for the V-rollers line up with the long axis (up/down in the drawing).

It is a way of getting 2 more z-rollers above the z-motor. Bottom half is the standard spider.

Does this give the hint?:

Oh, the z motor "peeks" through the big hole????

This might help clear things up, based on Geralds original drawing.

Attachment 1851

You can see why Sean had to make some changes, the motor bracket would foul the spider and the holes dont line up with the car, thats why its called a doodle :)

Thanks Alan and Gerald,

Nice models.

Thanks Alan!

I'm impressed.

Impressive,
Maybe we could call it the super spider.:)

Tarantula

Looks great! Now how long a z-slide can you have before it needs reinforced?

And once you get a 36" z-slide are we going to put on a little baby cable chain for the router's cord?

I suppose a 4:1 reduction on the gas spring will be needed as well so that it doesn't need to be 24" long...

wait..wait..wait...you know what we really need? Neon!

Matthew,
It's nice to see you finally paying attention to us little people in florida.
I have made allowances for the z-slide. For one, I am using alum flat bar with the machined rails for the vertical. Baby e-chain is already sitting on the bench for the air line and spindle power cord. I have also come up with a machined billet of aluminum for the back ribbing instead of 1x2 box for weight and rigidity. Additionally, I have given serious thought to a multistaged telescoping balanced cylinder for the z-stroke balance. I found a really affordable one at Skycraft the other day!

On another note, I don't intend on cutting anything but foam with this long z-slide....so, the moment arm of the z-slide "should" relatively stay in plane (I hope :) )
Neon....what color do you want? Blue or Green? :)

So, Alan. I haven't modeled the spider yet. Did I get it right?

I would maybe dump the back ribbing in favour of front ribbing, if I knew I could get a good connection at A. . . . which is easy with a spindle:

send me the dxf file and I will check it out...

dxf file
 

Can you send me a copy of the dxf file? I will model it probably from plywood. I have a free gear reducer coming that I want to test. I want 9" of travel which is more than any gas shock I can find and the gear reducer is a 20:1 which is extreme but it is free and I am hoping that with it I won't need the gas schock.

Here are two images of the re-worked tall slide, every thing seems to be OK. I can see why you had a hard time getting the file size down, lurking in your file is a 3d version of a motor, not visible in the dxf file but appears when I import it into sketchup :confused:


You might want to check a small detail on the drawing as shown in the image below, the arcs and vert line dont line up properly and there is an extra arc where the two meet.

That extra arc must be from when I stretch it! I knew there was something in the file but I couldn't find it. I even try to reset all layers to 0, and purge. Heck, the file should only be about 50k at most. Thanks for the quick review Alan. I will be cutting a quick sintra PVC mockup this week to double check everything before the final laser part is cut.

Thanks again.
Sean

The cutout for the motor is rather severe. I would be tempted to improve the bracing of the top rollers....back to the furthest corners of the y-car.

Snapper

Why don't you just rotate the z motor 90degrees and mount the rack on the side of the 1x2, that way you don't need the big cut out for the motor and the left side could look just like the right?

Plus wouldn't it be better to have the motor forces pushing against the vee roller axis instead of perpendicular to it?

The "sideways" motor is to leave space in the y-car for a dust hose, or for a second similar z-axis back-to-back with the first one. Motor force direction is not really a factor - this is much less than the cutting forces.