Evan, this is most helpful, thank you!
Not being a mechanical engineer means I really have to rely on others when considering upgrades such as this. I’d prefer to do it right the first time, so I’ll continue to monitor others progress!
Whilst in theory you can use off the shelf components for this, that one won’t work - its too long. Both my design and Tommys use custom length ball screws. You could still do it, but you will need to re-design the back plate.
If you use a support kit like the BK/BF you will also need to custom design the rail support - then you are making your own kit.
Belt drive in theory is safer, because you can slip a belt as you mention there is the chance of skipping. I doubt you would have an issue driving a ball screw directly - I don’t unless I try to jog at 4000rpm.
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No problem. I’m not Mech E but I did stay at a Holiday Inn Express last night…One thing that the above link doesn’t take into account is the linear rails on either side that would be needed to keep things steady. So there is that part not accounted for. I don’t know about purchasing from this site, but here is a nice place with explanations of what BF/BK 10 means and the bearings involved.
http://www.controlresourcesinc.com/bs_end_supports.htm
This is a VERY rough estimate because I haven’t entered individual materials for most of the fixtures and fittings but Fusion is listing the new design as weighing 6.4kg (that includes the two stepper motors) and the original Z-Axis assembly as weighing 6.9kg (again including two steppers).
It’ll be an interesting experiment to actually weigh it to see how it compares.
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Yep, design is easily modifiable to suit your own mount. If you look through the files for one called “Spindle Plate” and then edit the sketch called “Features” you can change the spacing of the spindle mount holes by changing the constraints on the bottom left mounting hole. I’ve setup the sketch to use symmetry around the X and Y axes so this will modify all four holes. This is shown in the image below.
The way I constrained these wasn’t the easiest for making this change though. What I’d recommend is deleting the two linear dimension constraints highlighted above and putting in two new constraints between the bottom two mounting holes and the left two as shown below. Then you just need to enter the values for the spacing of your mounting holes and symmetry will automagically do the needful.
I’ve recorded a screencast of the process, it should be at Screencast Title in a few minutes. At the end of the screencast I update one of the sub-assemblies but it doesn’t update with the new layout because I forgot to save the original part.
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This is the drawing I submitted to them. I’ve no idea if they can/will mill the flat edge requested but they didn’t come back to say they couldn’t. Mine shipped yesterday so I’ll find out soon enough.
It was just a case of placing the order and then sending a message to the seller. I originally just sent the dimensions as text as per Luke’s specifications but it didn’t get made before the Chinese New Year holiday so I’d time on my hands. I messaged them again asking if I could change the specs and they said fine and asked for a drawing. One quirk was I had to save it as an image as Aliexpress wouldn’t allow me to upload a PDF.
p.s. the forum is telling me to stop hogging the topic 
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Well, I suppose you’re entitled to your own opinion 
I admire your faith, I wish I shared it
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Thanks TommyG, for the explanation and F360 lesson!
Really? Are they suggesting you start a new topic? It would certainly be my preference to keep everything about Luke’s design and your refinements to his design in the same thread. I may go for a hybrid of the two so I can stick with the direct drive ballscrew.
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Quick question @Luke
I’m about to start milling the main base plate. I’ve stock to hand that’s 1/4" (6.35mm) thick but also 10mm thick stock.
What’s your experience with the 6mm plate for the back plate? If doing it again would you stick with 6mm?
thanks
tommy
I felt 6mm was more than suitable. Over a 30cm span there is no flex. It’s got supported rails on it and a ball screw. The only reason I went to 6mm was because I used a 3mm counter sunk holes. If I didn’t I’d have gone down to 5,
I used the superglue and tape method to mill it which make it quite easy.
Thanks Luke.
Getting there slowly but… well just slowly really.
Had a nightmare with the carriage top due to multiple issues including over-optimism regarding the powers of the superglue & masking tape method (I know, I was warned) and the evergreen classic “this is going to take two hours, surely I can speed that up… two days later…”. Hence the awful finish on the front of it. Oddly it was the second piece I cut, the bottom mount went like a dream.
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Cracking effort. Has the ball screw come?
I’m a suckered for ramping up the speeds but patience is a virtue. Usually if you keep them low and the aluminium stays cool the marking tape method is great…
Nope, still waiting for the ball screw.
I’m not having a lot of luck with the tape method, even the 6mm base plate came off just as I was getting to last few passes on the cutout but I was able to file it off.
In that case though, I had only had a few mm sliver on the bottom of the part and it was that which pulled loose and snagged the bit. Just experience I guess.
I’m sticking down to MDF, possibly not the best surface?
EDIT. Sorry, my bad, this should be addressed to Luke, I’m cutting his file. DOH!
Tommy, I’m test cutting the largest plate now in wood.
I see several Setups in CAM. For this first test I am using setup 2, I’ve left all the parameters the way you set them up. I’m curious why, on some of the bores in the second step plunge so fast? I know that would break a cutter if I was doing aluminum. I’ll probably add a step that cuts those as pockets instead of bores.
There is still much more that I don’t know about CAM as what I do 
PS, tapes working ok on mdf.
Thanks again for your and Luke’s hard work.
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I found that MDF was great to build a test with - I wanted to make sure everything fitted before I took the mill to a sheet of ali.
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I’ll jump in just to “vary” the input for the forum’s sake. Nothing to add just another voice chanting “keep this topic alive”. Tommy and Luke are sharing mind blowing workable concepts and we fellow Shapeoko’ers (at least me) need their enlightenment and encouragement. They have not tried to profit from these concepts and deserve (for their prolific sharings) room to “muse”. Keep talking guys, Evan and Griff are adding tremendously also. Keep it up guys and THANK you all for sharing. Jude
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Thanks Jude.
A quick tip for anyone playing along at home. If you’ve ordered a ball screw and if it has arrived and if you know bugger all about how ball screws work… DO NOT take the ball nut off the screw.
The screw is what’s keeping the ball bearings in the nut and if you take the screw out they all scream “We’re FREE!!!” and jump out all over your desk. You then have to learn how to re-stuff a ball screw and discover some new uses for Vaseline that aren’t anyway nearly as much fun as other uses you may already have for Vaseline.
This is simply a public service announcement and not in ANY way based on personal experience 
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It will be quite a while before I’m done with the house and back up and running, so I’m keeping up w/ this thread and learning. Hopefully, you guys will have this process trouble shot and someone will compile a step by step … hint hint… I doubt I will be able to glean the correct instructions from the 3 topics already in motion. So all the hope of the CNC free world is riding on your shoulders, but no pressure, no worries, you have my support and good wishes… I for one do not have the machinist ability to sort this out. Thanks for all the input and effort all of you are providing. The ball screw Z axis initiative shall succeed and the conquering heroes shall be acknowledged. Go forth young men and conquer. Jude
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I’m moving my work over to the linear slider version of this design as well. Will continue on that thread
http://community.carbide3d.com/t/new-linear-z-rev-2/8176
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