You may want to use a set of punches to mark your steel. Easy to paint over the numbers and forget where you are .... wont say how I know these things :o :D

You are right Mark. It didn't come to my mind they would be covered.:o. You saved me a lot of messy time. Thank you.

It is a horrible weather with rain these days, weather forecast says it will be so whole week. So painting delayed.

Beast took apart and assembled on it's legs. Bolts hard tighten.

Here I come guys to the discussion we had at the beginning of this thread.

We have the situation here.

You can see what happens with top flanges of my 'I' beams. Not laying in the plane.

Choosing a relatively flat beam lowers the cost and saves time later.

Only two solutions now are to mill it flat or level with epoxy, none of them are cheap as 100$ a beam or easy as taking a look at couple of pieces for level

you could make rails with small leveling screws threaded in far side so you have two pints of contact and can set the rails level and then fill the void with "filler" of your choice

Yesterday I went through completely different way for resolving this 'headache'.
I got this idea from far beginning and here's what I've done:

I precisely "plastic surgery" cut line all along the beams 25mm under the top flange ( this height come from position of the angle grinder ) with 1mm steel cutting disk.

Future angle iron rail set as a beneath support for cutting disk and one screw of the grinder sliding to the top flange surface.

Levelling epoxy isnt that expensive to avoid levelling with this method. I just bought to me some. Price was 15,50€+VAT per kg.

My comment for belt drive is: use HTD profile, it doesnt have backlash. My first mechmate uses HTD5M profile. With T5 i think problems are quaranteed.

The "Surgery" took 2 hrs with most time used for inside cut ( I jumped over the cross members with some small hurts between the legs:o).

The another beam cut done easy. It was from outside.:D

The cut depth is 4mm.

Next, I made these "special tools" (two of them) from scrap parts laying around with few welds and with the help of the future Mechmate user applied force on the top flange at the same time.

End plates will fix it, and to be on the safe side I put small welds in the groove along the cut.

Voila, flanges are in plane, we are back in the game.:D

I honestly have not seen that done in all the 100+ builds of a MM. Unique solution. Are you planning on welding a few spots to keep the kerf from separating?

My suggestion is to weld crosswise on I beam some reinforcments like on picture
Attachment 15753
And then weld the cut.

Ivo, imo better don't suggest to weld the cut entirely, the main beam will go bananas on him, bending all over the place, even with the helpers.

Sean he writes it just above your question, that he already did little welds along the groove.

I do not think this was the best solution nor the simplest, shimming the beam would have been easier and better imo cause you kept the integrity intact. Now you introduced weakness where you did not want it in your main beam, where you want a perfect solid place to mount your rails.

But with small, say 10 mm welds or so and alternating ( from side to side and front to back etc) welding sequence along the cut on both ends of the beam, it should become strong enough once again without distorting. Make sure you let it cool in between, let's when you have 4 welds ( 2 each side) on, 8 welds on, 12 welds and so on. When one beam is cooling you can weld on the other etc.

Good welding sequences save the day when it comes to keep things straight, or making them straighter for that matter.
See Gerald's straitening techniques for example where he advised to weld along a bend beam to straigthen it out, to see how much influence a little welding( read heat) can have on a piece of straight (or bend) steel that weighs a hundred kilo.

Sean, either without spot welds the beam has it's integrity. The main role in this case will fall to 'end plates'. In addition, the kerf is only half of the vertical section of "I" beam( 4mm from 8mm). With kerf, I removed material for 'line guided torsion'( that's why the torsion is done in the same momentum in 1/3 of beam length from ends) I applied to upper flange. 2-3 strikes with homemade 'lever tool' did the job.

Ivo, there will no be need for reinforcements, 'end plates' will do the same. Welding all along the cut will make strong deformations. Only spot welds 250mm between.

Fox, The biggest force that strikes the beam is sum of ( half weight of gantry + Y car and everything that goes in it), when the Y-car is nearest to the beam. So beam is generally affected by vertical force and small moment of that force created by linear rail distance to vertical axis of the beam.

So, we've got beams back to the plain without putting thick shims, resins or similar that make rails standing on 'glass legs' or that's what I'm feeling about.:)

After welding beams kept very straight and strong too.

Thank you guys for the comments and not letting go out of the right way.

Pics will explain everything.

This weekend I continued with cutting down angle iron 60 x 60 mm to 28 mm. Used one disk 1mm thick for one rail.

It's very important to open slightly ( bend ) cut off part just before breaking through ( opposite, there is danger of disk to be catch inside the kerf and at cca 11.000 rpm:eek: flying parts of disk that are life dangerous), or just stop grinding before breaking through and separate the top part with pliers with twisting. I had very unpleasant experience that make me aware.

I want to share with future builders.

I used 'sandwich' system, plywood inside and console surface for angle grinder sliding.

Pics worth thousand words or some others tell me:)

It took 4 hours to cut all the rails.
I'm satisfied with cut quality.

Rails final grinding did with 40 grit sanding discs mounted on grinding disc 6mm thick. Height monitored at single pass in multiple points along the lenght. All done within 0.2 mm tolerance.

Skate worked perfectly. It took a little bit more time for the first rail but when you get experienced...It's easier.

Don't forget cutting forces my friend, and you'll be amazed how much even a big table will be shaking ( sideways !) when the thing is rapidly moving along it's axes, because you're stopping and accelerating your entire Z +gantry.

I'll keep that in mind, thank you Fox.

Y-car parts assembled and tightened with clamps. I needed scrap metal parts to fold and tight the Y-car. Threaded rods are perfect for fine tuning. Everything square and welding started.

Granite tile is reference surface.

X-rails marked and drilled.

Here's the pic of welded and tag welds grind Y-car.

Here's what happened when I took out clamps and threaded rods. I got difference of 6mm.

What do you think guys should I leave it this way ( I think when Z-assembly will be put in, screws will fix it, Or.. ?) Pls I need your comments.

6 mm is a lot ! Or do you mean 0,6 mm ( cant read the drawing )

I double measured. It's 3mm.
Fox, see the pic.

Fill it with shims between spider plate and y car

Throughout this whole thread we can see lots of problems that are common to novices, maybe some of them could not even happen if the wealth of information on this forum has been used.
My advice is to stop now and slow down, read some of the more documented build histories and save time on repairs later.

It's to addicting Danilo, can't stop right now, I read and work both, I want to finish 'crude' metalwork just before fine adjustment and kitchen project.

I used afterwork hours for gantry assembling.

Main beams pilot drilled and tapped.

Gantry is riding on the main beams.:). It's rolling very smooth even rails are not precisely mounted.

Y-car found it's place on the gantry.

Energy cable carriers and chains assembled.

It's time to turn this rusty machine into 'pearl'.

Manual steel brush and grinder steel brush did the work.
Nitro solvent used for wiping rust powder after mechanical treatment.

I decided for sponge roller painter, it gives very nice paint structure and it is not paint consumer ( like spraying process ). Furthermore, my workshop stayed without stains.:D

Priming first.