1800 x 1500 x 500 work area CNC build log

Hi,

I’m starting a build log half way through a build to get your feedback, share processes and problem solve issues which are still to arise. This is my second build the first is being run daily at the moment but will soon get reconfigured for non contact tasks like plasma and clay extrusion based fabrication when No2 is proven to work. What I’m hoping to build is a machine that will allow me to form complex shapes whether thats throughout reductive or additive process i.e. milling or extrusion processes.

Clients are asking me if I can produce large scale forms for them which have complex geometries, undercuts for formers, molds and such like. I can do that currently by dividing models up into parts but its a pain.

Ideally i’d like this No2 machine to have the abiltiy to carve materials with the density of oak. However if its more successful just in foams and tooling board that will just fine too. Since the No1 CNC currently cuts foam board and thin ply and has a water table and plasma i’m designing this No2 machine to take adapter plates onto which I can attach various tools and add axis to make the machine adaptable. It remains unclear whether i’ll be able to get everything i’d like out of this build with the resources i;ve got to hand but i’m damned well going to give it a good go :).

I’m lucky that most of the jobs this will do will be one off design prototypes where there is an amount of flexibility of the outcome however we all aspire to accuracy, reliability and repeatability in our machines especially when there is a deadline!

As you can see this design has 450mm of travel on the Z for deep carving. The intention is to be able to attach different tools for different jobs one of which will hopefully be a B/C head for 3D carving. I have three different spindles I often use. A 900w 240v Kress, a low rpm 12v RC brushless and a 2.2kw 3ph spindle. They all have their own uses and the new machine will have plates for mouting different tools.

I expect to use fusion 360 for 5 axis CAD tasks but there is much to learn and understand there with the additional axis. I currently work with Vectric & Sheetcam software for XYZ CAM.

The machine has a work area of 1500 x 1300 x 450 with a workbed I can raise and lower depending on the material volume. You can see the same principal in the machine in the background. The design will allow me to work right round a 1200 x 1200 x 500 block of foam for prototypes using a BC head.

4 x 2DM556, 2x M542, 4 x 566oz in 4nm steppers, 48v PSU, 2 x 5 axis breakout boards. HTD 4:1 gearing on the motors, Rack and pinion drive, HG20 rail and blocks. Mach3 etc

I’ll post some more info tomorrow just introducing the project tonight. Much still to do...

Cheers

Attachment 24770

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.

Attachment 24775

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)

Attachment 24776

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.

Quick pic of the control box. I'm still wrestling with broken pins and dodgy connections on one of the 5 axis BOB. I can tell you now that a Gecko 540 is a lot more straightforward to install but there we are. Probably will swap out the dodgy chinese bob for another. The second BOB is to accomodate all the extra proximity and limit switches for a BC head and or 4th axis rotary head. The second big PSU in this case is a 12v 1000W supply for the brushless spindle I have made from an RC motor. There's four 12v fans you cant see in this pic to bring air in and expel at the top.
Attachment 24788

Rack & pinion geared drive units on the X, Y & A.
MOD1 rack and pinion, 12t pinion. HTD belt 15t and 60t 4:1 ratio
Two press fit flange bearings sandwich the 60t pulley on the inside and two UCF bearings on either side for extra support. M10 shaft

I used my No1 machine to laboriously mill out the pockets for the steppers in the alu plate. 0.5mm each pass but got there in the end!

I had to totally guess the type of spring tensioner and opted for a medium duty die spring. No idea what sort of tension its supposed to be at though, any ideas?

Attachment 24789

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.
Attachment 24787

Quick pic of the rino geared steppers for the BC head. 30:1 gearing and apparently even though they are wormscrew very low backlash, which will do me for now. I just have to figure out the cross roller bearings and frame for these. I have three of these I bought from America a couple of years ago, one can certainly be used for a rotary 4th axis
Attachment 24791
Attachment 24792

Now painted orange.

Cross bracing steelwork still needs to go in and the detachable mount head various tools to go on the Z. Also realised I have to strengthen the x axis plate for the Z at the back with 30mm alu bars. At full 450mm extension of the z axis there is too much opperchancity for flex. Getting there!

Attachment 24834

As a 3 axis its working fine and its happily just cut out this large map in 18mm birch for a client. Phew

Haven't atached the cross bracing across the y axis but as I lower the bed height it'll need a spacer bar at the end of the Y rails to keep the linear guides true.

Once i've finished a few jobs i'll set it up to cut the aluminium parts for the B/C head and then get stuck into the 5 axis software side of things. Might go for a rotary axis first and build up to the B/C head.
Attachment 24928
Attachment 24929