[onri999]

Hi everyone,

Apologies if I have posted this in the wrong place.

I am looking for some feedback on my design for a small fixed bridge design. I have built a couple of drawing machines but never something this ambitious so would love to get the advice of some experienced machine builders before I bite the bullet and start sourcing parts.



Here is a quick 360º spin to give you an idea of the proposed design:



Currently got my eyes on a set of rails, ball screws, bearings etc. from Aliexpress, they are the SBR16 type. The set consists of rails at 300mm, 600mm and 800mm. I would really love to buy some HIWIN or similar square profile bearings but I just can't justify the cost. I will, I'm sure, end up making the upgrade.

The approximate travel limits are:

X: 450mm
Y: 425mm
Z:150mm

The frame of the machine will be welded from mild steel box section, with plates of 10mm thick aluminium (lighter shade of grey in the video).

All the motors are driving the screws using belts, this choice was made because I much prefer the look of machines that don't have big protruding motors, is there an advantage to coupling the motors inline with to the screws?

My goals for the project are to be able to machine wood and aluminium with good accuracy. I have good access to workshop machinery at my university, but I graduate this summer so I need to get going soon.

Any advice, suggestions, constructive criticism will be gratefully received.

I look forward to hearing what you guys think!

[KH0UJ]

If you can design a table that hides all the ball screws or linear rails that are hidden underneath the table, it`ll save you tons of headache in the future, im currently working / maintaining / programming on CNC machines on a daily basis for straight 3 years now, if you can design similar on the pillar or column type CNC machine that`s the most rock solid steady machine, it can loop a program path a thousand times and still park at the same spot all the time, because the ball screws are hidden, it does`nt require constant maintenance (lubrication /overhaul) on the ball screws, dust debris and metal chips are some of the reasons that a CNC machine gets offset or stuck.



With a pillar type design, you can easily install a coolant recirculator + drain, no need to worry about the chips getting stuck on the ball screws because it`s all hidden underneath, you can even put grease as your lubricant on the ball screws making it even more less maintenance.

[onri999]

Hey KHOUJ,

Thanks for your comment. This style of machine looks like a good bet.

In terms of the exposed rails and screws I forgot to mention I had thought about using bellows to cover them. Like this:



I get what you are saying though, the design you shared totally covers the important bits up.