Prety much finished...

[wcarrothers1]

Well except for limit switches and the actual install of the table top.. Those will be in tomorrow.. But figured most would be better off seeing pics of the structure with that out of the way.

Also have 2 sections of c channel left over that I will probably make triangles with between the 3 side legs..


Can't wait to post come cuting pics..

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[wcarrothers1]

And 2 more..

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[wcarrothers1]

Also one side benifit of doing rack and pinion on X... That you would not notice till you built/played with your machine.. You can move X up and down the axis under human power by just pushing the thing. Don't think you would be able to do that as easy if it were screw drive..

Don't know if that is a show stoper feature.. But as you can see from the pics my mill computer is currently not around (connected to the other machine).. Would have been a pain to have to power up the motor to move it down when painting if it were screw drive..

heeh..

I sure hope it cuts as good as it looks

Anyone want to make a prediction?

Also if anyone has any 500cpq incoders I need 1...

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[widgitmaster]

Way to go wcarrothers1!

Were you able to add a pre-load pressure on the pinion so there wasn't any backlash on the gear mesh?

Eric

[Madclicker]

Are your Y rails unsupported?

[wcarrothers1]

Well the shaft for the pinion is half inch. And I do have screws to bring them tight then lock the mesh in place. I don't really believe in the "Spring" method because then your supports for the shaft are not locked to the frame. My racks are plenty accurate enough down the distance not to need a spring loaded mesh.. I have a washer welded to threaded rod from one of the pillow blocks going up to a plate with a hole and a nut to tighten the mesh.

The Z rails are not connected to eachother..

But the Y railes are 1" and 60" long. on eithe end there are thompson supports linking them togehter and bolted to the side plates as well as the shafts for 9" from eithee plate. The center link plate is 24" so there is about 9" between the tubes on either side of that which is unsupported. Although on the back I have some T slot aluminum..

If I end up having flex I will back it with more or something but far as I've felt it should be plenty ridgid.

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[wcarrothers1]

In picture http://www.cnczone.com/forums/attach...9&d=1161740030

You can see the 2 larger hex bolts and the 2 smaller ones around the square ball screw shaft bearing support.

Those are both 2.5" long screws. The smaller ones are 1/4 20's and the larger ones I think are 3/8" and anchor the 9" length of thompson rod support to the end plate..

So needless to say that took care of a LOT or all the flex the shafts orignaly had when they were freestanding. It would not have worked with out them..

Also since the design (in theory) pushes = from both ends (because of the rack drive rather then a center screw) torquing isn't a huge issue far as having huge angled plates supporting 90 deg from the rollers..


But on the flip side the supports and such only cost me 125 bucks..

I also threaded a screw into the end of each shaft. Not sure if it helps or not but they will not be moving much (becides they are also clamped into the end plates..)


Measured this morning.. I have ~10" clearence to the table top with 1 = 3/4" piece of MFD in. I will be stacking 2..

Set the top in place this morning and it sure looked nice..

I'm happy with just about all aspects of the design so far with the exception of the larger foot print. Although the extra few feet it requires isn't really an issue for me at the moment.. Becides in theory.. If I need to take it appart I could remove the gantry in 1 piece then each side would be it's own piece and the table support would be another piece. Don't know if I could have designed an under supported gantry to do that..
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[MrGilly]

That is a pretty big gantry, I think I would stick to 1" plate at that size.
I would use alot of boxing, to try and pull the aluminium straight and true, I know my gantry, at a 1m wide, there was bow in the plates that straightened out when assembled.