An approach to extending Z-Axis.

[bradyaero]

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.

[Gerald D]

I wouldn't do it.

[Robert M]

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 !!

[smreish]

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

[bradyaero]

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.

[bradyaero]

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

[domino11]

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:

[smreish]

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

[domino11]

This sounds really interesting. :)

[Gerald D]

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?

[smreish]

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

[Gerald D]

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

[smreish]

...I LOVE being the guinea pig:D

[bradyaero]

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

[smreish]

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
1849

[sailfl]

Sean,

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

[Gerald D]

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

[Marc Shlaes]

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

[Greg J]

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).

[Gerald D]

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

[Gerald D]

Does this give the hint?:

1850

[Marc Shlaes]

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

[Alan_c]

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

1851

[Alan_c]

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 :)

1852

[Greg J]

Thanks Alan and Gerald,

Nice models.

[Gerald D]

Thanks Alan!

[Marc Shlaes]

I'm impressed.

[domino11]

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

[Marc Shlaes]

Tarantula

[Leko]

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!

[smreish]

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? :)

[smreish]

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

[Gerald D]

. . . . a machined billet of aluminum for the back ribbing instead of 1x2 box for weight and rigidity. . . . .

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:

1860

Even with a router, that point A could be on the router bracket.

[Alan_c]

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

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

[Art]

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.

[Alan_c]

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:

1888

1889

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.

1890

[smreish]

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

[Gerald D]

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.

[Leko]

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?

[Gerald D]

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.

[Gerald D]

Good bracing would be something like this:

1893

[smreish]

Snapper....hmmm (old college humor for you in the cheap seats)

Matthew,
I did consider it...then forgot everything I was doing because I am do darn busy to think clearly lately. You do have one good point to rotate the motor. I could keep the sides intact and still add the "kickers" Gerald suggested. All these ideas and little time this week to do anything about it!
Everyone Thank Alan for doing the quick sketchup model. :)

[domino11]

Sean,
Any new developments on the new spider design? How did your laser cutout come out? :)

[smreish]

...nothing new. Still trying to push the 3" of water out of my shop at the moment. I really don't like hurricane season.

[domino11]

Sean,
Hope your water problem goes away soon! :)

[lolailando]

Hi,
I am new to the forum and I am also interested in cutting foam only and a long z axis.

[domino11]

We are still waiting anxiously for Seans update on the Super Spider long Z. :)

[smreish]

Heath.
Should be this week. Trying to fit the MM upgrades in the the production schedule, Santa and other projects (okay - honey do list). :)

Banter on domestics moved here (http://www.mechmate.com/forums/showthread.php?t=1246).

[servant74]

. . . .

This may be off topic, but if two Z carriers were used, what would be an appropriate way to hook up dust hoses? Over the side of the car around the Y axis frame?

[Gerald D]

. . . . . .

Jack, dust hoses for twin Z's are a major headache - they have to fight for space with the y-motor or with the y-cable chain. (They cannot pass outside the y-car. between the gantry tubes without reducing the y-travel)

[Art]

I have never been really happy with the Z axis. For flat work it is great but most of my work is in lathe mode and ocasionaly it can be driven down a tooth or 2 on the rack. Think of a 14" square by 10' piece of fir running at 100 RPM and being cut slightly off TDC. Not what Gerald designed for. Also had problems with the A axis when running at 4.5:1 but since I installed the 10:1 gear box it is doing fine. I am working on a Z with 10" of travel using a lead screw with 10 TPI Acme thread. It is being prototyped from plywood and will post prictures once I get it running.

[Gerald D]

Current discussion at ShopBot forum:
http://www.talkshopbot.com/forum/messages/312/37276.html

[domino11]

Heath.
Should be this week. Trying to fit the MM upgrades in the the production schedule, Santa and other projects (okay - honey do list). :)

Sean,
Any update on the super spider project? Was wondering if you got it together yet? :)

[smreish]

3489

3490

Closer....maybe next week I'll be done with upgrades

[Gerald D]

That's got my attention!

[domino11]

Sean,
Wow that looks interesting, cant wait to see the end results! :) Sorry for the push. :o I know others are intereseted, as I had one cut for someone on the forum. :eek:

[sailfl]

Sean,

Wow, I like it. When you get it done I will be at the shop.

[jhiggins7]

Sweet!

How much Z-travel are you planning?

Regards,
John

[smreish]

Usable travel is about 36". Mechanically able to stroke 42", but we will see what I get actually.

[jhiggins7]

I love it!:) Really looking forward to your progress.

Looks like that aluminium (UK spelling) I-Beam should be stiff enough. Are you beefing up the Y-Car/Gantry in some way to keep them from tilting?

Regards,
John

[Gerald D]

The I-Beam is stiff for bending, but it is quite flexible for twisting. If the router had to go on the face furthest from the V-cap rails, the cutter would be quite far offset from the rails. Looking down on the table from the top, cutting force in the y-direction would cause the I-Beam to twist clock/anti-clockwise. Unless you can get the cutter placed between the v-rails (still looking from top), the torsion becomes an issue. Generally, a box-section (hollow profile) is the most desirable for long overhung z-axes.

[jhiggins7]

...Generally, a box-section (hollow profile) is the most desirable for long overhung z-axes.

I see your point. So are you thinking of something more like the extruded box-beam this fellow uses (http://www.cnc-toolkit.com/gantry_router.html)?

Regards,
John

[smreish]

Actually,
When fabrication is complete, it will look very similar to Geralds post #33 in this thread.
The web and outside flange will be removed to allow for the router/spindle to be in the same position as the original z-slide. Thus, to reduce the twisting both of you are very keen to notice. Instead of manufacturing a long back bone, I just happened to have an I-beam the right dimensions.
Sean

[Gerald D]

Sean, I knew you had thought that one through already. My last post was for the wider audience who might have been tempted to go and buy some I-beam. Yup, first use what you already got! :)

[smreish]

Todays fun!
3538

[sailfl]

Today I was able to see the modifications that Sean is making to his machine and I am eager to see the new Z and Indexer in action.

[Gerald D]

The plot thickens! :)

Notice that the traditional wrong_way_bending of the the 2 small tabs in the spider have reared their head again, but you are surely not using both of them.

[smreish]

...yep. Noticed it. Not using either of them so I really didn't care. Keen eye Gerald!
Did you notice the extended "leg" on the diagonal. I had the laser cutter leave an arm on each side so the back gauge on the brake press would ensure a parallel bend without trying to "visual sight" the bend.

[Gerald D]

Smart thinking on the gauge tabs for the back-stop - I thought they were for the red braces in post #41. What have you got under your V-rollers? Look a little small, the roller may "wobble" a bit (cantilever overhung from the spider).

[smreish]

Machine drill index pin collars the same diameter as the bearing race. Temporary.

[glintid]

Hi Sean,

Do you anticipate any vibration on the extended Z arm passed on by the router? I know that aluminum has a tendency to vibration. I'm looking to build a similar machine with an extended Z and your solution seems to be the simplest.

[Art]

Because of the laterial and vertical force involved the rack and pinion on the Z gets lost. I replaced it with a lead screw I have 10" of travel with the Z plate between all V rollers and up to 15" if I go past the top ones. Will have it installed and running next week.

[smreish]

Today's installation.
Z-slide, balancer, and cable work well. Next stop....4th axis cutting!

3980

3981

[Art]

Nowthat is a real serious extended Z! You gota show the whole machine in one picture amd working.

[YRD]

Uau :)

[domino11]

Sean,
I noticed in one of your pictures that the lowest set of rollers is now missing?
Is this a mod? Just curious, or perhaps the picture is of a non complete unit?
Looks awesome though! :)

[smreish]

Heath,
I had a problem with the hole on the that side of the slide.
I needed to get cutting, so I left 1 bearing off. The threads were tapped slightly not square and was causing the bearing to not seat properly, so I left it off.
Thanks for noticing! :p

[Gerald D]

Good work Sean!

I still think it would be good to bridge the gap. You could even go as far as the second router bracket . . .

3983

[smreish]

...Planned, just not installed yet!
That's todays metal working challenge. For the life of me I couldn't wrap my head around that electrical cord exit, so I just said I will cut something to fit in the field.

[J.R. Hatcher]

Can't you rotate the router 90 degrees so the cord will be on the right side???

[Gerald D]

Suspect it has to do with the speed control?:

3985

[smreish]

Gerald and JR.
You are both correct.
I have 2 router heads. One is the 7518 model which is single speed (for foam) and the 7519 model which I use for wood, metal, etc. So, you both are correct. I will try both heads today and see if I can't make it work. i'll be honest and say I didn't spend to much time on it yet.

[Art]

I got the Z installed and rinnind and it looks great. With the Z all the way down ithe plate is still between all V rolers.

[smreish]

Nicely done Art.
Today I was able to rotate the router 180 degree's and have the cord exit the rear next to the slide. Final stiffener bracket is in the works.
I have to add "one more rotation" on the cable balancer tension spring and I think my slide will be dialed in for vertical travel.
I have a small challenge with my indexer at the moment, but I will address that later this week.

[sprayhead]

I got the Z installed and rinnind and it looks great. With the Z all the way down ithe plate is still between all V rolers.

Hi Art

My project has a similar setup as yours, with a lighter (shorter) gantry and I am at the moment a bit worried about my gantry not being heavy enough and lifting out of the tracks.

Have you made any attempts on testing how much force you need to put on the router bit with the Z fully extended (down) until the whole gantry starts to flip (wheels start to lift)?


Ultimatelly I would like to be able to calculate the exact force needed to start lifting wheels out of the tracks, but at this moment it's probably still out of my knowledge base.

thanks,
Francis

[smreish]

To All,
I have received a few emails lately on the performance and details on the slide extension I have modified for foam cutting.

In summary:

What is the Z-slide made of?
- W6" x 4.7#/ft Aluminum I - Beam
- custom z-spider
- BWC Vee Rail
- 8 - BWC #3 Rollers
- 1 35# constant force spring/cable balancer
- porter cable 3.5HP router
- 3dcutting.com 12" x 14mm round nose bit


Usable cutting distance
0 to -36" Z
0 to -12" Z you can cut all normal MM materials (ply, plastics, etc)
-12 to -36" you can cut foam upto about 22# density...I haven't tried more dense materials

In use for about 8 months with no issues.

Pictures for review:
5762

5763

5764

5765
DO NOT PAY attention to the small little bushings behind the VEE wheels, this was a temporary set up for alignment use only. Use the MM specified bushings

5766

[Doug_Ford]

Cool Sean. I'm amazed at the innovation on this forum.