Please help with this build Albert

[bigal999]

Hi jazz here is a picture of my proposed layout for the gantry is this what you mean.
Also I am trying to work out the hight of travel for z axis I want a good range of possible but I am willing to sacrifice hight for acuarcey. I am thinking along the lines of the more travel for z axis the more strain on y axis when cutting am I right?
Please anyone give comments on my ideas I only need to build this once I hope.
Albert

[JAZZCNC]

Yes and no.!!
Yes, the profile layout is correct but my design doesn't use the plate on the front. The rails sit top and bottom of the profile and the ball screw goes at the rear out of the firing line of chips.
However, I don't use round type rails so it's a little more difficult for you to mount the rails. If I was using those rails I'd bolt 10mm flat plate to the top n bottom of the profile and then fasten the rails to that. The plate on the front doesn't add much more strength than the profile does but does add weight and expense so I'd get rid of that if using my design.!
Another advantage of the rails being top n bottom other than saving cutting area is they support the Z-axis rear plate better because of the wider separation.

But your design with a slight tweak would work ok, but with the rails on the front your wasting cutting area, plus the ball screw is exposed on the front.
The tweak would be centralizing the plate or even lifting up so the bottom is flush with the lower profile. As you have it now hanging down it could vibrate because most of the cutting forces will be at the bottom rather than at the top.

This is a cut away of my design if it helps.

[bigal999]

Hi I will change the profile to the bottom of the plate I already have the 15 mm plate so will use that.
Also will look at moving ball screws and rails to the back and have z axis like a box around y gantry. Would that work

[JAZZCNC]

Also will look at moving ball screws and rails to the back and have z axis like a box around y gantry. Would that work

Yes, it would work but again not needed and all your doing is adding weight. All you need is a drop-down bracket from the top bearing plate which extends backward.

But like I said your design will work and will be strong enough so if you are happy to use that then go with it.

[bigal999]

I don't understand how you about a drop down bracket from the top bearing plate could you do a little sketch to show me please

[JAZZCNC]

I don't understand how you about a drop down bracket from the top bearing plate could you do a little sketch to show me please

[bigal999]

I think I understand I will post a revised picture tomorrow thank for all the help
Albert

[bigal999]

Is something like this what you mean
Albert

[JAZZCNC]

Is something like this what you mean
Albert

Yes but in your case, it doesn't work very well because of the type of rails and the fact the rails are on the front so you have a long way to reach the back of the gantry.
I would either change the rails to top n bottom or drop the idea altogether and go back to your first plan.

Personally I'd be putting the rails top n Bot and dropping the plate because your wasting loads of cutting area and costing your self money in an expensive aluminium plate.

[bigal999]

Thank you jazz I did try a test piece on an off cut of profile but the rails are just too wide for the 40 mm side of the profile and do not line up on the 80mm side anywhere I could get a good fastening on both sides of the rail.
I will think about how I can do it.
Also what about the ideal hight for z axis from waste board to the bottom of the gantry. As I am looking for fine detail first and rigidity and height second.
Albert