For strength of a beam the resistance to bending is 1/12widthheight^3 in cm4
So for just a Z backplate of 1cm thick and 10cm wide this adds up to 0,83 cm4
The riser of 1,2cm wide and 3,2cm high is 3,28 and there are two of them totalling to 6,56 cm4
But when you bolt a steel rail on one side of the riser and the aluminum backplate you get a combined beam of 65,77 cm4 ten times stronger than the individual components.
The strength comes from the steel rail and aluminum backplate mounted to the risers, not the risers itself, so there is no reason to go to 20mm.
If the carts are mounted above and below the ballscrew mount they can be mounted even closer together.
For this short axle I would use a 1204 ballscrew in order to save some weight.
That is actually what I ordered but did recieve1605 instead. There is a weight penalty but sizewise there is not much difference, just height being 3mm or so more.
True, but this would impact total travel. So the mounting block will be carved to clear the carts.
I know, the mounting block will be carved to fit - it should clear the M5 holes - just about. Initially I did space the risers so the block would clear but thought it would be better to butt them up against the BK/BF blocks and modify the ball block to fit instead.
Another nice thing about the 1204 is that the 4mm pitch in direct drive plays well with multiples of 200 (0.02mm resolution @1:1 ustepping, 0.01mm @1:2 ustepping and so on).
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Good point, not a deal-breaker at the moment. I might go imperial…! JK 
BTW Elias, do you do your own anodizing? Ref. your Brake-Fox
Or is it painted?
I tried anodizing last year but it failed, and without a decent primer / technique spray paint chip far to easily…
I wish. I’ve read several howtos but always postponed for later with the excuse of not having enough time.
You go first 
Perhaps I might!
My main issue is sourcing proper acid, battery dealers dont sell battery acid any longer over here…
More progress have been made over the weekend, to date my most massive aluminium carve. Several passes. tools and paths - the CNC got a serious workout 
Front side is done, will face the rear side of the mounting plate tomorrow plus do the screw holes/recess.
The 1605 mounting blocks fit perfectly. (checked dy eye only as I haven’t tapped the holes yet)
One thing is for sure, it will be strong! Only actual use will tell me how the SBR16 & MGN12 rails/block hold up with their narrow spacing.
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That is as narrow as you can possibly make it. The SBR have a cage supporting between 600 and 2200N, the MGN12 3720N which is a lot more than a Makerslide wheel at 27N. You should be safe here.
Thank you for that data Erik !
SBR16 center-center (CC) distance is 100mm
MNG12 CC = 80mm and I will use 4 blocks to give a mounting surface W100xH80mm
Just an update after running this bit a few hrs this weekend:
It is performing very well, I suspect I gave it a solid 4hr workout on Sunday and it seems like it would do it “forever”
550mm/min @ 22k RPM and DoC 1mm / WoC 3-2mm
Didnt seem to struggle one bit.
I also ran contouring of 16mm alu plates, but used a strategy of two passes (0.5mm stepover) which worked very well. It takes time obviously.
With one pass contouring the bit shank rub the material making it wobble, the dual pass made that less of an issue.
During facing I also jumped the feed rate a little (<50%) with no audible change in sound / tool noise.
Impatiently awaiting for the 6mm bit to arrive 
Update #1
Just ran an hr with DoC1,2mm and feed at 670mm/min, no sweat
This was just a simple Easel facing operation at 80% stepover (2,4mm WoC)
Update #2
The 3mm bit will not survive taking a 4mm DoC straight pass in soft steel with X-rapid. Insufficient safety height caused that… 
It did take a nice chunk of it tough…
More progress:
The risers are mounted, faced flush after assembly and drilled / tapped to accommodate the MGN12 rails.
Structually this is very rugged… moving on with the smaller carriage plate that will hold the Makita mount.
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Machined the router backplate today, also tried for the first time a 6mm 1F end mill and it worked like a charm
The right edge with parallell facing tracks is a 1mm recess to accommodate the 25mm spindle clamp which is up next. With a recess I also have a flange to mount the bracket to ensuring it is true relative to the back plate.
3mm 1F for pockets/screw holes and 6mm 1F for facing and contour.
Carve data for the 6mm:
1100mm/min 22k RPM and 1mm DoC.
Weight of the unit as shown here 3.4kg (about 7lbs)
Also very nice to see the bolt holes matched the rail blocks…phew…!
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Although this plate looks impressively strong it is rather flexible in Y and unbreakable in X. With the long lever to the spindle mount this may introduce shatter.
Sorotec in Germany has a comparable setup and sells side plates as an add-on when you want to cut aluminum. For reference: https://www.sorotec.de/shop/Performance-Kit-f-r-Basic-Line.html
If you put 50x10 sideplates the carriage becomes as strong as your rail plate. Maybe it is worth to make the threaded holes before making the assembly to your machine so you have the option open.
Yes, I have given that some thought and is something I will keep an eye out for. Adding a pair of side rails for the lift plate is the go-to solution should it be required
Another “tool” is to add a second and higher spindle mount so the rotation is not at the bottom edge of the lift plate alone.
Not much progress this weekend as I have been occupied with aircraft maintenance but hope to start the Makita mount tomorrow
A minor distraction:
I have earlier been very active within RC model aircraft and the itch have come back. Currently designing (copying rather) a very potent DLG glider to make moulds for a full composite project
My 4yr old love planes so decided to make him a model to chuck around, so I put the CNC to good use
The DLG wing was scaled down to 25% and I 3D carved the top curvature out of 3mm balsa using a ball nose bit. The remaining flying surfaces are flat sheet balsa (1mm).
I increased the chamber of the wing by making full span flaps.
It flew 25minutes after I hit “Carve” on the CNC
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Although the ShapeOko2EVO takes a lot of work out of my hands 25 minutes is unbeatable. It took me 8 weeks to deliver the woodwork ready on this years airplane.
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Cool @ErikJanssen - that is a C/L model correct?
I designed and kitted a EDF MiG-29 almost 20 years ago, when batteries were NiCd and NiHM was emerging… Boy have the E-scene changed since then Dropped out from R/C in 2006 when I got my glider license.
My MiG29 is still today available as a kit from RBC Kits in Holland 
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Yes, Minifan 480 for this one / RBC Kits. I also made a larger version for the Wemotec Midifan but this was never kitted.
Back then the Wemotec Minifan was the go-to fan in that size and 90mm EDF was “limited” to the JePe and DS fans (which I also used a fair bit) Had several high performance EDF such as JePe A4, Ralf Dvorak ElBandito, Aeronaut Panther.
Good times
The Hawk is sweet! Love doing “old school” building in balsa&ply…
