1800 x 1500 x 500 work area CNC build log

[marbles]

X & Y steel frame build.

I’ve designed a frame which can taken apart including the gantry and supports. The advantage is the flexibility of the design but the downside is the loss of rigidity which will need compensated by additional cross bracing in all directions. (certain interior sections of the steel had been packed out with timber where theres cross bolting to reduce compression).

All mild steel in the following profiles
60x40x3mm, 40x40x2.5mm, 100x30x2.5mm, 60x20x1.75mm ERW & 40x40x1.75mm ERW

Steel advantages: infinitely adaptable, cheap, long lengths, readily available.
Disadvantages: profile deformity, heat distortion when welded, 3mm wall thickness for rail bolts is a bit thin, takes longer to prepare than alu extrusion.

The uprights have 10mm holes at 50 and 100mm centres which allow the bed to be lowered. As I carve blocks of PU this is a requirement. The disadvantage of this system is that the x rails need bracing which I have still to put in but will be essential.

As i’ve never worked with profile rail or R&P before I wanted to see how everything would run on the build and then adapt the framework accordingly. Then take the whole thing apart, spray it and put back together. I hooked the machine for its first time up to the controller and ran it through mach3 and it worked fine but obviously there is much still to verify and add before i can confirm all is within the limits I require.

[marbles]

Z axis Design

700 x 152 x 9.5mm alu plate x 2
25.4x12.7mm alu bar x 2
HG20 rails 700mm x 2
HG20 blocks x 4
1605 C7 ballscrew
coupler
4nm stepper

The design of the z axis carriages is one i’ve not seem before but i’m hoping will work for me. I’ve mounted the rails on two alu risers that screw directly into the 700 x152 travel plate. The blocks for the Z are fixed to the Y axis plate and the rails travel.This adds more weight (8kg total) but some additional rigidity. The idea of this design is to give as much support as possible to a B/C head, or infact anything when the Z is extended and expected to have any substantial forces against it. By placing the rails on 12.7mm alu bars it actually gives the perfect spacing for the ballscrew and all the supports to ride just behind the travelling plate.
(I just noticed is that I have to add extenders to the grease points to get access for the gun. Just sourced some on ebay there)

[routercnc]

Looking good. For carving big chunks of foam that will be fine. Spacing out the rails is less popular vs a solid plate with pockets machined to clear the ballscrews as it is a bit stiffer. But the spacer is going to be more economical for such a large Z and I think will be ok.

[marbles]

Just for comparison here's Mk1 machine. T5 belt drive and still going strong-ish after 4 years..Needs a wee holiday soon for repairs and an upgrade to geared chain drive and RM2-2RS Bearings and rails, which i have already but have just never fitted.