How to get everything square?

[MrArmyAnt]

I'm almost done with my 5x10 table, but I was curious what are people using to get x and y perfectly square and to get rails that are about 6 feet a part perfectly parallel?

[vacextar]

Getting the rails straight and parallel shouldn't be too bad. I'm using a piece of fishing line stretched tight next to the rail, and adjust the rail so it is striaght with the fishine line (it is far from straight out of the box!).....then measure what you have for appox gap between the rails and cut yourself a chunk of anything (I'm using a piece of 1x1 tube) cut to that dimension.....then just work your way up the other rail using the 1x1 butted between the rails to make them parallel.

[WSS]

This thread helped me out quite a bit.

http://www.cnczone.com/forums/cnc_pl...get_table.html

WSS

[MrArmyAnt]

Sweet. Getting flat and level isn't something I really have a problem with, I just can't get these rails exactly parallel

[WSS]

Does your design have a master/slave set-up? You can hold one side tight (master) and let the other float/follow(slave), your tolerance will be set to the rigid side. Spend your time getting that side straight and the anti-parallelness (a new word?) will be very very minimal. Our machine rides on v rails on the master and floating followers on the other. Cuts really accurate parts.

I remember setting our rails up and I cut a square tube to length and set it in between the rails and squeezed the rails against at each bolt point before tightening. It got everything within a 20 or 30 thousandths if I remember right. then tapped around with a dead-blow hammer.

WSS

[MrArmyAnt]

MY rails are beefy as hell and are on precision ground bar stock that follows the underside for the full 13ft. They were in the GM plant where the equinox was made, so they are already true. It's going on a platform that also already been machined flat. I think I'm going to do the rigid method. I wish I knew my gantry was square first though.

[MrArmyAnt]

If I just base it off the edge of my platform I would be at .0625 over 8ft. I'm thinking I'll just do the getting one side down thing. Hopefully that will work. Then on to squaring that gantry up.

[MrArmyAnt]

I still have deflection in my gantry if I force it to. What the hell. I don't want to have to rebuild a gantry, this one was expensive as hell.

[WSS]

I was worried about sag and weight and deflection too. All said and done, my THC eliminates 99% of the troubles. remember also that plasma cutting is a non contact sport for the most part. Initial sensing is about the only time the gantry is subjected to a shift in load. Try it first before you determine the deflection is excessive.

WSS

[MrArmyAnt]

I built my table to be able to use a router on mdf for making composite molds too. and maybe some light aluminum in the future..

The problem is if I grab the motor (the large gear) and do jerky movements I can see the other side not responding. I might need to do some gusseting. Also the bar stock that the rails are on are only tac welded partially on one side and other rail is c clamped for testing...

[WSS]

Ahh! Router changes that theory for sure. Can you post some pics to look at? Is it a dual drive or cross shaft with single driver?

WSS

[MrArmyAnt]

Here are two photos. The goal was to get the machine up and running then cut new brackets and mounts and such that are a bit more accurate.