DIY straight edge with Epoxy+ aluminum profile. Will it work?

[Clive S]

Then what are you going to do with them? You will end up with two rails that will bend when you move them.

One of the reasons for using epoxy is so that the rails that are fixed to the frame will be on the same plane.

Imagine a trough on the top of your rails that you fill with water it will be level in all planes it does not matter if the frame was twisted a little or out of level with the opposite rail.

[ba99297]

Then what are you going to do with them? You will end up with two rails that will bend when you move them.

O

I dont want to use them for constucting a machine, but to check the flatness of a machine, just the way i would do with a straight edge
The use of these rails is to use them as straight edge so that you can chek the flatness of a machine.
My question is if these aluminum tubes are reliable straight edges?

[GTJim]

Are you thinking of using these to get your rails straight?

[ba99297]

Are you thinking of using these to get your rails straight?

I already have a 1200mm long straight edge
It is enough to messusre my machine (1800mm long, 1160mm wide) between left and right sides.
For the distance of 1800 i will use the same straight edge in parts
If the above solution is reliable it will make my life easyer about messuring the flatness of 1800mm long rails
It is just a thought and i ask if somebody has an opinion about this
I dont think i am the first that has this idea
For me it sounds logical that it will work, unless i miss something

[GTJim]

Any straight edges above 1200mm that I have seen are very expensive. So I hope your suggestion works as I have yet to come up with a better one.
Jim

[mekanik]

Hi Don't see much of a problem here, you say width of rails 1160 so your straight edge will span that distance, to ensure the 1800 rail is straight set the master rail onto the grout leveled frame member and lightly clamp both ends, drill and tap the frame for the hole in the centre of the rail, work your way from the centre of the rail to the ends drilling tapping correcting and fixing the rail as you go, you will have a section of rail that can be verified straight with the straight edge, all you have to do is extend the straight edge 200mm each end to set the remaining portions of rail. the second rail can be set using a fixture with carriages set on the master rail and on the one your trying to bring into spec, most find that using the gantry works OK.
Regarding drilling and tapping you need a couple of jigs that will align in the countersunk holes of your rail, one to align the drill and one to keep the tap vertical.
Regards
Mike

[toomast]

Hi,
I have had exactly the same idea in my head for a week now :)
I will try to make my straight edge out of the "bridge" when leveling my long axis.