Small rigid router - Design advise needed

[mitchejc]

Have you priced up laser cutting yet ?

One large dia tube is going to be much stiffer

Nope, I have not. I did get some parts laser cut about 6 or 7 years ago and at the time the price seamed very reasonable. I hope I'm not in for a nasty surprise. Until I get a design past the cnc police there's no point in costing the cutting

Yep, the big dia tube is much stiffer but there's just no practical way I've seen to make it work for a gantry router due to the reasons Silyavski listed above.

[Boyan Silyavski]

I see.

-IMO is very bad idea to lay the machine on anything else but steel. I will advice against it. I mean the orange part as you have drawn it is bad idea.

-I agree the design should please your eye. I wouldn't do it that way at all as my moto is "maximum efficiency, minimum effort" . I mean i advice against using steel tubes at all. Though as i see it the gantry could be left as it is if you insist on keeping the design, just take care the plate bellow the rails to be truly all supported, not hanging in the air.

-The sides definitely could not be as they are now


I mean, change everything, but if you insist keep the gantry

[Sven]

I haven't read this thread for some time now and I am surprised at the design of the router as it is now. It looks really nice.

Am I correct in that you will have pieces cut by laser as part of the build?

If so, why not build a steel torsion box from nothing but laser cut sections?
That would save a hUge amount of time, and be stiffer too.

[mitchejc]

Yep Sven, the idea is to have the parts laser cut. Interesting idea. I'm sure what you are suggesting would be possible and EXTREMELY stiff. Its amazing how stiff some of the light torsion box or honeycomb composite structures are like on the photo below

[Sven]

I'm currently in contact with a guy who is building an extreme fixed gantry router. He can calculate this stuff in to extremes.
He suggested to me that a steel torsion box is nearly as stiff as a solid steel one and when designed right wil only need spot welding to keep it together, but can even be glued if you have the right technology available.

[mitchejc]

Ok, now its down to bartering. A friend needed some aluminium house numbers urgently and he had something I wanted, so I cut the numbers Wednesday night and swapped this

for this


Great deal, don't you think? :-)

Back to plan A of using I-beam for the gantry sides. The beam I got was a bit higher (254x148) than I hoped for but I'll make it work. I guess for me DIY CNC is more about what I have/can get/can build rather than building the ultimate design from the best choice of material. I also listened to the advice and went with a slightly more practical approach and used 76x76 square tubing, and some 10mm and 5mm plate and also bolt or weld the X sides directly on the base. Gantry weight is +- 60kg excluding Z. I know Y rails top bottom is the better approach but I'm thinking its going to much easier for me to get them parallel and on the same plane if I put it on the front. I'm hoping the laser cutting is not going to be too expensive otherwise I'll have to go for plan B with the gantry. See pics below.
Again please comment if you see any obvious issues.

[Boyan Silyavski]

Looks awsome. Will need a lot of patience welding.