Play in linear bearings

[Ross77]

Should have guessed from the 200x200mm foot print that it was an engraver....:whistling:

Oh well that will teach me to start rambling without asking all the facts

There are ways to reduce deflection in unsupported rails like adding centre supports and if you can make the end fixings for both rails out of 1 piece and give it a good 50 to 100mm grip on the rail then the fixed end moment is able to help resist the deflection as well.

the only problem is the more you add the more it costs. Have you seen this site http://www.students.tut.fi/~kontkant/jv2.php.html

fixed gantry and only one rail and one block for the x and y axis. got to be comparable in cost to 2 round rails and 2 blocks and definitely much stronger.

[leadinglights]

Hi Irving,
Most of the jobs I want to do will need cutters smaller than 3mm, and resultant high cutter speed so there shouldn't be too much load on the rails. However, I am beginning to be impressed by the advantages of precision profile rails - more for the reduction of free play than minimising deflection. It would be nice though if the manufacturers of the various rails gave us real numbers as well as drawings.

Mike