Now....the Z-Axis Design ?

[RakmUp]

Well....I have the biggest part done and all looks great to me. I have saved the design for my Z-Axis and the A-Axis until I had the main framework done so I can have a better perspective of how to proceed.
My main question here is does it make any difference strength and rigidity-wise which way I mount my Z-Axis linear bearing blocks? By "which way", I mean, bolted to the X-Axis blocks or moving on the Z while the shafting is rigid? (ex. attached)
The design is for 6" of Z and the brg blocks are 6" long. I would like to have full engagement of shafting in the bearings when extended to the max. Originally, I had it so the blocks were rigid on the X and my Z shafting moved. I felt having the extra bulk of material behind the spindle plate would be more rigid at extension giving me less vibration on the tool.
(the red machine, I was trying to show what material I have already and will use in some configuration...red-I have)

Any other criteria in the Z-design I need to watch out for?

Thanks for any consideration......

Chuck

[wcarrothers1]

Well your frame looks like it's welded nice. Over kill there to even (if you ever looked at my 4x8 mine is a lot more sparce with the steel.) I'd bet yours weighs almost as much as mine does..

what ya going to use for your Y drive? Guessing X and Z will be ball screw.. Since I see linear shafting on Y just wondering where the drives will be..

I think either option on Z looks like it will be good enough. Good argument to me having the shafting on the moving pannel.

[widgitmaster]

So far that looks like its really ridgid, and I like the compact design of the Y-Z Axis slides! That will enable you to do some serious cutting!

Have you thought about a counterweight on the Z-axis, a balanced slide will not kill your stepper/servo motors, and make for faster z+ movement!

Eric

[RakmUp]

Thanks guys......

Yeah...overkill is an understatement. The guy who did the fab for me had all the tubing in stock and actually used heavier wall than I spec'd. The delivered crate weighed 1050 lbs. Probably 350 in the crate alone though.
It can't hurt anything other than my back though and may prove valuable as I stretch the capabilities of the machine.

The reason for my question is based on having as compact of a head design as I can. Just to be more rigid and thus accurate. I'll count your vote for the moving shafts then. Thanks.

Just ordered a gas spring from McMaster today for the counterbalance on the Z. I don't have it in the drawing yet as you noticed.

The Y actually is from the front to the back in the picture. The X is the width as you look at it (The rail). The front part of the base is for a lathe (A-axis).
The Y will be driven by 2 ball screws and drives and slaved in Mach 2. The motors will hang below the screws on either side and slightly inside.

Interesting, my big fear with this wider than deep of a design was racking from side to side. But right now sitting there, a pull on one side and the other side responds immediately with "0" racking. I can maybe force some racking if I push really hard. I am impressed with how rigid these 6" brg blocks are.

If interested, some previous design questions and drawings.
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