View Full Version : Longitudinal beam options for 350mm Z-axis

Tue 06 July 2010, 00:09
I'm building an extended (350mm) z-axis, so am planning for 300mm tall "sides" (formally 'main longitudinal beams').
It appears that this height in PFC (Parallel Flange Channel) only comes with 90mm flanges. This falls within the range given in the plans.

If I go the 300 x 90 PFC route, then I can pinch 15mm each side from the table (from the space between the beam and support board) without affecting any other plan measures? i.e. I keep the overall width outside long beam to outside long beam at [cross-bearer length + 2x5mm] for welds. In my case [1220+420+10]=1650

Or have I seriously miscalculated somewhere?
Much appreciated

Gerald D
Tue 06 July 2010, 02:12
When the y-car is at the end of the gantry, against the stop, the 90mm wide flange of the beam will encroach onto the side of the router and/or dust foot. If your router/dust foot is no wider than 150mm, then you are about okay.

Tue 06 July 2010, 18:42
Thanks for the quick response, Gerald.

Sheesh - the things it's possible to miss.
150mm seems pretty standard width for the foot and sometimes router plus mount, so I'd be cutting it fine and be thinking about moving stops, etc.

Seems a better idea to plan the table at 1260 (1250?) to cut 1200 wide if the flanges are 90mm.

Gerald D
Tue 06 July 2010, 21:34
The dust foot would spend most of its life inside the channel (below the upper flange), but I have seen some designs that ride high up.

Thu 15 July 2010, 07:16
I recalculated the cutting list as below to allow for the bigger flanges.
The machine should cut 1200 wide and 2.4m long. With 90mm flanges on the 300mm tall PFC I've extended the table size to 1250.
Without CAD I'm relying on hand drawn, non-scale drawings and arithmetic, so it's possible that I've blown something.

Please let me know if you see mistakes.

Table: 2440mm x 1250mm x 350mm: Bolt together ends and longitudinal supports.

75 x 40 x 4mm PFC = 4 @ 720mm (legs)
50 x 50 x 3mm SHS = 4 @ 1634mm (End cross supports: Y axis top & bottom cross rails - with allowance for welded plates to bolt to legs)
50 x 50 x 3mm SHS = 2 @ 1940 mm (Longitudinal Axis lower brace X axis bottom side rails)
50 x 50 x 3mm SHS = 4 @ 800 mm (Longitudinal angle supports: X axis diagonal braces)
50 x 50 x 3mm SHS = 4 @ 700mm (Y axis diagonal braces - to be cut to size in situ)
50 x 50 x 3mm SHS = 2 @ 520 mm (Longitudinal upright supports: X axis)
100 x 50 x 2mm Rectangular tubing or Box = 2 @ 1750mm (Cross member tube Y axis gantry rails)
76 x 40mm PFC 7kg/m3= 8 @ 1670mm (Y axis cross supports)
300 x 90mm PFC 22.9kg/m3= 2 @ 3040mm (Longitudinal Beam X axis main beams)

65 x 50 x 6mm Angle = 2 @ 3400mm (X axis v rails) NOTE 65 x 50 max dimension
65 x 50 x 6mm Angle = 2 @ 2200mm (y axis v rails) NOTE 65 x 50 max dimension
20 x 6mm strip = 2 @ 1700mm Y Rail Clamp strip,

50 x 25 x 3mm Rectangular tubing = 1 @ 700mm (Z-tube support)
25 x 25 x 6mm angle = 2 @ 75mm (stopper base)
15 x 15 steel bar = 1 @ 300 mm (x,y stopper block, stopper base)
35 x 15 x 6mm plate = 2 @ (stopper lip proxy extension)
76 x 38 x 5mm plate = 4 @ (foot closing plates)
460 x 77 x 5mm plate = 4 @ (beam closing plates)
150 x 55 x 5mm plate = 8 @ (plates for bolting frame together)

570 x 100 x 6mm Gauge Plate Ground Stock = 1 @ ( Z slide)

Laser Cut Parts

Thu 15 July 2010, 19:27
Corrections on the above cutting list:
beam end closing plates 460 x 90 x 5mm
300 x 90 PFC weighs in at 40 kg/m3

I'll have to see whether upright supports are needed within the 300mm tall PFC

Mon 16 August 2010, 08:04
The 300x90 PFC was delivered and seems really stiff. At this point is does not look as though internal supports will be needed - especially with the rails carrying the y-carriage hanging outside the vertical face of the PFC. Time will tell...

Mon 22 November 2010, 07:12
After looking at building walkways suspended on the same PFC I don't think I need worry about beam sag. I've had the support board and cross supports bolted on the beams and been clambering all over it and there's no indication of movement. I don't believe that the flanges flex at all and neither does the beam. I think other parts will flex before big PFC does.

Mon 22 November 2010, 07:38
the feeling is mutual, I end up used mine for nearly 6 month before I decidedd to weld the internal crosses. Just because I was too free...