# New Z-Axis Assembly for Probotix Asteroid



## HDVideo (Mar 8, 2018)

Well, I'm finally getting around to building a new Z-Axis assembly for my Probotix Asteroid. I've had a terrible amount of slop in the stock setup since I purchased this machine used a year or so ago and have had this design in mind for awhile now. I know there will still be some flex in the gantry, which might be a project for another day, but the Z bearings are my biggest headache. I have made a new plate that replaces the stock piece that connects the upper and lower X axis bearing plates, so this will be a direct bolt-on replacement without having to cannibalize the stock assembly. It should be up and running in another day or two. All milling is being done on my Sherline CNC mill. 

The first drawing is the original Probotix setup.


----------



## RainMan 2.0 (May 6, 2014)

Nice work Ed . I’d love to have a cnc mill


----------



## difalkner (Jan 3, 2012)

That looks _*far *_more robust, Ed! Did you measure the flex before so you can do a before/after comparison?

David


----------



## HDVideo (Mar 8, 2018)

difalkner said:


> That looks _*far *_more robust, Ed! Did you measure the flex before so you can do a before/after comparison?
> 
> David


It has been hard to measure the gantry flex because I had so much slop in the Z. With the router near the spoilboard, I could hold the collet in two fingers and move the bit .030" or more. There is no doubt that will be fixed and if gantry flex becomes my next issue, I've already got plans to address that. Won't be able to mill gantry risers on my little Sherline though. lol I was pushing its limits with this Z plate. Had to mill the bottom half then reposition to finish off the top and maximum Y travel was only .5" more than the width of these plates. It's been a fun project though.


----------



## MEBCWD (Jan 14, 2012)

Looks like it would be better and should solve some of the slop. You might also check to see how much twist you might have in the gantry plate.


----------



## RainMan 2.0 (May 6, 2014)

Looking at your Z carriage build, with your skills I’m suprised you didn’t just scratch build an entire cnc router table .
I suspect it would be pretty heavy duty


----------



## HDVideo (Mar 8, 2018)

RainMan 2.0 said:


> Looking at your Z carriage build, with your skills I’m suprised you didn’t just scratch build an entire cnc router table .
> I suspect it would be pretty heavy duty


Thank you, Rick. I have created CAD drawings for several CNC Routers and would love to build one of them if I could afford it. lol


----------



## BalloonEngineer (Mar 27, 2009)

You will notice that Probotix has moved from 30mm x 60mm to 60mm x 60mm gantry extrusions, make sure you set up plate to allow the same change when you can, that will correct most of the rest of the flex.

Looks great!


----------



## HDVideo (Mar 8, 2018)

BalloonEngineer said:


> You will notice that Probotix has moved from 30mm x 60mm to 60mm x 60mm gantry extrusions, make sure you set up plate to allow the same change when you can, that will correct most of the rest of the flex.
> 
> Looks great!


They came out with that change right after I purchased my Asteroid. The only change necessary would be a taller plate between the two X-axis bearing plates. One thing I probably should have done is increase the Z travel a little to accommodate a taller gantry in the event I ever do the upgrade (if/when they offer one) or build my own. Some form of gantry upgrade may be necessary simply due to the added weight. This assembly with a Dewalt 611 router and mount is going to weigh close to 25#.


----------



## 4DThinker (Feb 16, 2014)

Excellent work! I've also drawn up a few alternatives to their Z axis design. I asked Len why they don't change it and he stated that the current design was the product of several revisions and is used because it can be produced more precisely with less needs to remount parts after milling/drilling operations. 

I've drawn up parts to make something similar to your solution, but will likely prototype the parts in 1/2" BB plywood to verify alignment before trying to get them cut in aluminum plate. 

4D


----------



## HDVideo (Mar 8, 2018)

4DThinker said:


> I've drawn up parts to make something similar to your solution, but will likely prototype the parts in 1/2" BB plywood to verify alignment before trying to get them cut in aluminum plate.
> 
> 4D


I have been pleasantly surprised with how well parts have gone together, but you kinda expect that when designing in CAD. After considering 1/2" plate, I finally settled on 5/8" cast tooling plate (MIC-6) for the Z and Spindle plates. The primary reason for using 5/8" was so pockets deep enough to create necessary clearance and alignment was possible without using spacers between rail cars and spindle plate. In hindsight, 1/2" would have worked as well and been a little lighter; would just have to use the spacers to get everything aligned. 

I'm looking forward to getting it finished and installed, but unfortunately, have to be out-of-town next week so work on it has been suspended for a few days.


----------



## HDVideo (Mar 8, 2018)

I finally had some time to work on the new Z assembly for my Probotix. It's pretty much finished, just need to drill and tap some holes in the attachment plate and I'll be ready to see if it was worth all the trouble.


----------



## MEBCWD (Jan 14, 2012)

Hopefully, the extra weight of the 5/8" plate won't add additional problems. Did you add any adjustment to tram the spindle if needed?


----------



## HDVideo (Mar 8, 2018)

MEBCWD said:


> Hopefully, the extra weight of the 5/8" plate won't add additional problems. Did you add any adjustment to tram the spindle if needed?


I'm concerned about the weight, but will know when the attachment plate is finished. I haven't pulled the original off yet to measure the difference. There is some adjustment for tram, but making the adjustment might be a PITA. lol


----------



## HDVideo (Mar 8, 2018)

MEBCWD said:


> Hopefully, the extra weight of the 5/8" plate won't add additional problems.


It looks like the complete assembly will weigh about 5# more than the original. I thought it would be more than that. Had to order some new limit switches so as soon as those are in I'll be able to test it out.


----------



## MEBCWD (Jan 14, 2012)

If it turns out that the weight is a problem you might be able to cut some pockets in the plate to get rid of at least some of the extra weight.


----------



## HDVideo (Mar 8, 2018)

MEBCWD said:


> If it turns out that the weight is a problem you might be able to cut some pockets in the plate to get rid of at least some of the extra weight.


Z Plate and Spindle Plate both have pockets to create proper alignment and clearance for ballscrew , nut and bearings. I could whittle away some more if necessary, but with no more difference in weight than that, I'm sure I'll be OK. Thanks for the suggestion!


----------

