Hi Wes;
This looks very interesting. I would extend the sideways stiffeners on the gantry sides all the way to the top of the sides, and keep them thick (ie as high along the Y direction) as possible. Why do you have an open gap facing forward on the gantry sides between the two 3" extrusions? If it is to accommodate the drives etc, I would have a hole for the shaft and bolt holes for mounts, but close in the gap if possible. Leaving the opening this way allows the two rails to flex almost independently at the ends. Another vertical stiffener nearer the 3" extrusions would be a plus too.
Cheers!

Hi Paul,
Thanks for the input on the gantry. I had at one time planned on using ballscrews for the motion on the gantry but have since been thinking more on the line of rack and pinion. I did a quick revision and did not pay attention to the side view much, so thanks for pointing out the un-needed gap between the rail cross supports. I have some 1.5" x 3" extruded tube that will be placed vertically at the ends of the 3" square cross supports so I don't think there will be much flexing between the supports, but it would not take much to extend the vertical ribs along the gantry uprights full length and I am working on changing the drawing right now. I believe I can run the front edge of the gantry uprights flush with the front of the cross supports and the rack could be placed between them. I will take a closer look when I get that far but for now I think this will work. I also shortened the width of the uprights some so I can use smaller width material or cast smaller parts.

Hello,
I have made some changes to the design of the gantry parts and updated the drawing in an attempt to correctly show the things that I have changes and thought it might be good to post this as my last snip posted was not completely correct. I think this is a better representation of how I plan to construct the gantry now and should show the changes better if I have drawn them right. I have also begun to break the assembly down into individual parts.

Hello,
I have seen a lot of 4x4 machines with horizontal CRS slide ways and am know questioning my previous plan to use the slide ways in a vertical orientation. I figured this was the easy way to mount to the side of my machine, had 3" width of material to support weight rather than the thickness of say .25" or .375", and the carriage would allow easy mounting of the gantry uprights with this orientation. Upon seeing multiple machines with horizontal ways I have been re-thinking the design and maybe this horizontal orientation will allow 4 bearings with full contact as opposed to only 2 bearings as in the vertical orientation? Any other pros and cons to the two orientations that you can think of? I can change/revise things now but would rather not begin construction of the gantry without thinking this through some more. Any advice or comments on this? Thanks in advance!

Hello,
I have assembled the gantry cross beams to a couple 1.5" x 3" end pieces and this is basically the way I plan to use the 3" square slotted tube on the gantry. It is already gaining weight fast (approx. 35lbs so far) and it will gain more weight fairly fast when I get the uprights made and assembled. I am also contemplating and alternate construction that would use only one of the square slotted tubes as a central member with the rest of the cross members attached to it, and I might try a design along this line to see what I can do and how much weight can be trimmed. I want this to be a rigid machine so maybe I will just go with the 2ea 3" tubes as cross beams. Not much to show but these pictures should fit with the sketches I have posted somewhat.

Regarding your vertical/horizontal bearing orientation question:

Vertically oriented bearings efficiently transfer the weight to the bearing axle, and is the designed orientation for many of the bearings commonly used in these machines. Horizontal orientation might result in increased friction, plus possible early failure, if the bearings are not designed for that particular usage. (Check the bearing specs for allowable side loading.)

That said, I do have a very old Xenetech cnc machine that successfully uses V-bearings in a horizontal orientation on the edges of a flat crossbeam, supporting a fairly lightweight spindle assembly. Xenetech later changed their rail & bearing design to a vertical orientation.

Hello again,
Thanks for the reply with the info on the vertical rails Rick.
I have acquired some used machinery parts and will be making some efforts to implement whatever I can from these used machine parts into my build. I have some 14" lengths of hardened steel rack that I need to find mating pinions for and then I will see if I can use them for the drive on my X axis. I have something like 16 pieces of these at 14" so it should be plenty for my X travels. I also got 2 hardened linear rectangular bars(about 78" long) with the mating flat rollers and carriages(4 of them) that I think will work well for the X axis slides and the pre-drilled holes in them look to be very close to the same as the spacing on my threaded rod that runs through the concrete form for the worktable. They are actually just a bit further spaced than my threaded rods but the holes are large enough to probably allow them to fit. I have not poured the concrete yet so I can change the spacing but I'd rather not go through that extra work if it is not needed. I have some very large cable carrier in a couple of lengths that I feel will probably be overkill for this machine and a small length of a smaller 2" width carrier that looks like it will be possibly a good fit for the Z axis. There is also some more extruded aluminum that will most likely be used where it fits well in the design and I also got an 8' length of 1.5" x 5" 8020 extruded aluminum bar from another source. I have not had much time to try and figure out where it will all fit yet, but I will definitely be taking advantage of these newly acquired machine parts and adding them to my design accordingly. I will attach some pictures I got of some of this stuff today while I was going through the inventory. Just for an idea of the size of the cable carrier the width is 8.375".

Hello my friends,
I am sorry for the lack of progress with this build thread, and have refrained from posting 'off topic' information here but I feel maybe I owe the people following this thread an explanation.(at least it might help them understand) My wife and I were hit with some alarming news about a month ago, and she now has stage 4 cancer and limited time here with us.
Without going into further detail on this subject I would just like to thank everyone for their patience and support and I have all intentions to complete the build when the time is right.
I just want to wish you and yours the best of holiday seasons and remind you to treasure the ones close to you, because one really never knows when things can change for the worse. All the kings men and all the kings horses...

My best to your wife, you and your family. I look foward to seeing you finish this build. When your ready I'll be here to follow.....

Hi Wes,

We are all very upset to hear of your wife's illness. We are all thinking of you and your family at this difficult time.

Take care

Brian and the Vectric Team.

Hi, Wes,

My family and I are all thinking of you and your wife as well as your family through this very difficult time.

Enjoy every single day, my friend,
Dave

Hi Wes,

I am so sorry to hear about your wife and challenges. Thanks for letting us know and be assured you are both in our thoughts.

Tim

Wes,

My wife and I are praying for your family.

Scott

Hi Wes.

I'm am so sorry to learn of your troubles. My family's thoughts and prayers go out to yours.

Sincerely,

Lynn

Hi Wes,

Our prayers are with you and your family.

Angie