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.

I see your point. So are you thinking of something more like the extruded box-beam this fellow uses?

Regards,
John

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

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! :)

Todays fun!
Attachment 3538

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.

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.

...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.

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).

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

Vibration.
 

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.

My try
 

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.

bbq ready to start cutting
 

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

Attachment 3980

Attachment 3981

Serious Z
 

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

Uau :)

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! :)

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

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 . . .

...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.

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

Suspect it has to do with the speed control?:

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.

Z installed
 

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.

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.

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

Extended Z-slide summary
 

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:
Attachment 5762

Attachment 5763

Attachment 5764

Attachment 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

Attachment 5766

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