Thread: Source of thick wall RHS cut to size in Melbourne

I'm trying to build my own small foot print mill. I like the idea of using thick wall (9-12mm) RHS (rectangular hollow section), but I can only find sources in Melbourne that sell full lengths (8m). Does anyone know of a source that sells short lengths (1 or 2m). It appears this isn't a common size, so nobody wants to keep part lengths in stock.

My design is currently using 200x100 and 100x100 sections. If I'm force to buy and 8m length, then I'll have to redesign to use 50x50 (or thereabouts) and stack them up (weld or bolt together).

Thanks,
Frank

I went through the same thing for a lathe I'm building.

I'm in Newcastle. Eventually found a place that did 200x200x9 RHS, cut to 1.1m long, for $2.3 a kg.
(Newcastle Steel Distributors if anyone from Newie wants a good source of steel, prices mostly $2.2-2.5/kg)

Got a CAD model of your design? Are you going to use linear bearings?

I got some 200 x 100 as seconds ( rusty ) from the local steel supplier, I have a few offcuts you are welcome to, longest would be 80 cm or so...

Ray

Frank,

Try ROBOT Trading in Notting Hill - just off the Freeway in Ferntree Gully Road have had various steel cut by them previously, inc RHS..... give them a call first and ask the question 9543 3666..............Lee

If they are still there Ungar metals on Warrigal Rd Chadstone http://www.ungarmetals.com.au/

Thanks for the tips, I'll call around.

As for my design (I've also posted this on cnczone)...

I got a Sony Robokid and like the way it had an extended gantry. I thought I could use it with a tool changer, or a 4th and 5th axis.

I put together a design, but the robokid is pretty flimsy. It's body (about 250x300mm) looks like a small desktop PC with a gantry, has 1 linear rail on X and Y and is belt driven by small steppers. It doesn't come with a Z, but it does have stepper drivers for Z and A. I think it would struggle to cut wax. I may use it for a 3D printer.

5axis1.png5axis2.png

So I've started playing around with a more rigid design. I've just laid out some surfaces and rails to start with...

5axis4.png5axis3.png

The design includes an 85mm BT30 ATC spindle, and a FR-50-80 harmonic drive gear for the B-Axis. Rails are Hiwin-25. The table is what I guess Machinery House's SCT-240 240 x 425mm compound table top (https://www.machineryhouse.com.au/M2061) to be.

This is a 3D pdf of it...

mini mill.pdf

I'd like to say the base is a new hi-tech design (middle support? Cooling?), but that is what I'll do if I can't find a source of large RHS - those pieces are 100x50x6. I'm not sure if I'll try and weld them or bolt them. I was planning to fill it with epoxy granite.

My design is still in flux...

• I'm concerned about flex when the Z-Axis is extended so an option is to have a standard 3 axis gantry and the 4th and 5th axis can be a trunion - that way I can add those bits slowly.
• Originally I was aiming for continuous 5 axis milling of steel (yes I know CAM software is an issue), but my calculations of cutting forces seem to indicate I'll need a gear box with huge torque to hold the 4th and 5th axis - the one in the picture is supposed to do about 600Nm. So I may scale back my requirements so I add a brake for roughing, and then a smaller gearbox for continuous finishing operations.
• I'm also thinking of just doing a small machine, maybe restricting it to aluminium. That would allow me to actually complete some of the machining operations at home (fly cut the surfaces). Although I do have the BT30 ATC spindle (actually it is in the mail) and the only other size I've seen that's afforable is an ISO20.

I have very limited space in my workshop. I want to be run cnc jobs with out sitting next to the machine squirting WD40 every 10 seconds. I don't have the space to encase my router (and it's design exposes the ballscrews anyway). I want to encase the small machine in a box and use flood coolant.

Any constructive comments on the design are appreciated.

Thanks,
Frank

Last time I tried UNGARS, several years back they weren't that helpful unless they had an off cut the size you were after and would not cut to size for me.....most of their off cuts are out in the weather and rusted...didn't seem to affect their prices any ...just my opinion.....

If you are over that way and get stuck call in and see the lads at East Australian Engineering at 913 Riversdale Road Surrey Hills..enter from the back street, plenty of parking.....they may be able to help but I can guarantee you'll have a hard time leaving when you see their setup.....not sure if they are still doing it but as hobby they make trains .....got to see them to believe what they can do and the quality......nice blokes as well.....try then first on 9836 6406

Handy Steel in W Heidelberg cut whatever they stock at a couple of days notice.

Kearney & Trecker (K&T) who developed today's common model of ATC made a RHS framed 4 axis machining centre about 30 years ago, you could worse than make a scaled version of that with a 5th axis spindle in a nodding head like an SNK aerospace mill. Couldn't find the K&T on google images, will check if I still have a photo.

http://www.techspex.com/cdn/cms/snk_cmv50.jpg

Originally Posted by dave4

a 5th axis spindle in a nodding head like an SNK aerospace mill
http://www.techspex.com/cdn/cms/snk_cmv50.jpg

I like that design (and name). It makes it easy to position the drive motor and gear box inline with the axis.