Comments sought on new build: A CNC Router for RC Gliders and Planes

[njhussey]

I've been wanting to build a CNC Router for some time now to help with building RC Gliders and planes. After much searching and looking on forums I've been recently collecting bits to make a CNC Router. I'm going the "skinflint" way at first to get into it before upgrading/re-designing later once I've had a good play! Bits I've bought/collected so fare are:

• 3 x Nema 23 Mineba Astrosyn 23LM-C355-P6V 1.5A/winding 550g/cm torque Steppers
• 250W 24V 10A Switching Power Supply
• 3 Axis TB6560 Stepper Motor Driver Board Controller
• TR12x3D Trapezoidal Spindles for the X & Y and TR10x2 for the Z Axis
• 6 x V£ type micro switches (limit & home)
• Emergency stop switch
• Delrin for antibacklash nuts (will make them myself from homemade tap)
• Performance Pro 701W Rotary Cutter
• 24V fans for cooling electrics
• 300x20x120 Plastic enclosure for electrics
• Screened Cable for wiring (from Work)
• Armoured cable sheath for running the wires in
• 100x100x19 block of Aluminium for making the router holder/mount

The frame is going to be made from 40x40x5 RHS steel (sourced from the scrap bin at work), the X axis rails are going to be from 1" NB CS Sch40 pipe (again from the scrap bin) the Y & Z rails from 3/4" NB Sch40 CS pipe (scrap bin raiding again!! ) The bed will be 18mm MDF. The Y Axis sides and frame are going to be from either 5mm steel or 10mm Aluminium. I'm going to use skate bearings for the runners, a combination of skate-o-rail (Z & Y Axis) and joes2006 design (Z axis)

I've had the electronics together and working, see => http://www.youtube.com/watch?v=eJ9uujaey-0 so now I'm just drawing up the machine and starting to dimension the parts.

I'm going to make as much as I can. We have a Colchester Bantam lathe and Bridgeport milling machine at work so If I can remember how to use them (it's been over 20 years since I was last in a machine shop) I'll make all the bearing shafts, machine the leadscrew ends and drill/tap all the plates etc.

I've uploaded a PDF of what I've drawn so far (minus all the scrap bits round the side) for you all to comment on. All I want to machine is balsa and ply and possibly some plastic. Not sure it will be up to doing Aluminium so maybe that will be phase 2!

Cheers,

Neil

[Ross77]

Hi Neil

Looks like you have it all planned out, and realistic with what you want to cut, and will be good to see a machine using skate bearings take shape.

I couldnt see any reference to dimensions or table size so its a bit difficult to check, the main bit I can see you might have a problem with is the close spacing of the bearings on the x axis gantry plates. also is it possible to design the bearing holders with a slot in the bottom? that way you could support the rail with a small plate on its edge, similar to the supported round rail design.

Any way good luck

[njhussey]

I couldnt see any reference to dimensions or table size so its a bit difficult to check, the main bit I can see you might have a problem with is the close spacing of the bearings on the x axis gantry plates. also is it possible to design the bearing holders with a slot in the bottom? that way you could support the rail with a small plate on its edge, similar to the supported round rail design.

Hi Ross77

The table is 1190 x 470. I haven't dimensioned much up yet, was just looking at the plates for the skate-o-rails and they were odd sizes so I guess things will change a bit once I start getting the dims to round numbers. I was wondering whether to do that but left it for the time being as I was getting the design roughly finished. I thought of welding a 6mm plate between the two rails to stiffen it but wasn't sure quite how accurate I'd get it, I was then thinking of how to make an adjustable design so decided to leave it for the time being. The plan was then to get all the experts out there to comment on it and see what modifications were recomended!!

I've attached a dimensioned sketch of the gantry bearings. One of the things I need to do is make at least one of the bearings adjustable (see other attached drawing) so I can take up any slack when setting up.

Cheers

Neil

[routercnc]

Hi njhussey,

Sorry to jump in with a sales pitch (!), but as an upgrade could I interest you in some bits to replace your pipe and skate bearings:
http://www.mycncuk.com/forums/showth...l-and-bearings
I noticed that the sizes were close, so may be an option. Still open to offers . . .

As for the design, reasonably traditional layout so good start. But the gantry sides look too thin. Consider welding angle iron onto the 5mm plate, or some other upgrade. Same goes for the flat plates holding part of the Z axis rails on (if I understand the dwg).

Otherwise, for balsa and liteply it should get you going . . .

Barry

[cooliced]

Nice design,

Whats the exspected Outgoing costs of this build so far and projected?

Stu

[Ross77]

The table is 1190 x 470. I haven't dimensioned much up yet

So you have approx 1200mm long rails on the x axis? I feel they could do with some support really. I also noticed that the bearings are quite a bit lower than the table, could this be reduced to help with the gantry stiffness?

I guess with a design like this it will be a work in progress and you will tinker and tweak the parts as you make them, you'll soon get a feel for what works and what doesn't, allowing for adjustment is always a good idea.

[njhussey]

Sorry to jump in with a sales pitch (!), but as an upgrade could I interest you in some bits to replace your pipe and skate bearings:
http://www.mycncuk.com/forums/showth...l-and-bearings
I noticed that the sizes were close, so may be an option. Still open to offers . . .

As for the design, reasonably traditional layout so good start. But the gantry sides look too thin. Consider welding angle iron onto the 5mm plate, or some other upgrade. Same goes for the flat plates holding part of the Z axis rails on (if I understand the dwg).

Otherwise, for balsa and liteply it should get you going . . .

Hi Barry

I think I'll stick to my pipe and bearings as I've already got the bearings thanks. Also I'm doing this on the tightest budget ever...well trying to anyway! For my next machine (oh noooo I sound like everyone else on here now, not even built my first and already planning the second!!) I'll use fully supported precision ground rails or linear rails as I'll probably want to cut ally. I'm going to stiffen up the gantry, just not figured out quite yet how. Was thinking of a back, top and bottom welded to the sides from 6mm steel. Guess with all the weightI'll need to support the rails!

Neil

[njhussey]

Nice design,

Whats the exspected Outgoing costs of this build so far and projected?

Cheers Stu, I reckon I've spent just a smidge under £180 so far, as I'm making the rest out of scrap bits from work I don't think there's too much extra to come in terms of expense. I've an old PC that I'm planning to use, might get a 15" flat screen to save space. All the machining I'm planning to do myself, might pay to get the steel plates cut for me by one of our work suppliers, been quoted £17 per gantry side and £6 per skate housing side which comes to £130...but still might do it mysef yet. Will probably try the first one and see how it goes!

Neil

[njhussey]

Just gone through my purchases to date and costs are as follows:

30 x 608 2RS 8MM BALL BEARING SKATEBOARD = £11.91
6 x micro switch V3 type microswitch 16 amp = £4.19
1 x Aluminium Plate 105x103x15mm = £4.80
1 x 3 Axis TB6560 Stepper Motor Driver Board Controller = £41.67
1 x Acetal plastic sheet 215x110x20 = £10.23
1 x 10mm Round Bright Mild Steel = £2.10
1 x 250W 24V 10A Switching Power Supply = £21.29
1 x 1000mm TR12x3D Trapezoidal Spindle - Acme Ballscrew Leadscrew = £20.30
1 x 500mm TR12x3D Trapezoidal Spindle - Acme Ballscrew Leadscrew = £5.70
1 x 100mm TR12x3D Trapezoidal Spindle - Acme Ballscrew Leadscrew = £3.08
1 x Performance pro 701w rotary cutter = £15.00
1 x 8mm Round Bright Mild Steel = £1.65
1 x 200mm TR10x2D Trapezoidal Spindle - Acme Ballscrew Leadscrew = £3.96
3 x Stepper Motor MINEBEA Astrosyn 23LM-C355-P6V = £23.99

Total so far....£169.87

I'm back at work tomorrow (had 2 weeks off) so will begin machining and turning (in my lunch times) to make a skate-o-rail housing to test the theory! Been doing more draughting today, looking to support the 1" NB pipe by welding to 40 x 40 angle and also to put a 6mm steel web betwen the 3/4" gantry rails for support. should stiffen things up a bit!!

Neil

[GeorgeD]

Where did you obtain the power supply from at that price? HongKong?