Hello everyone, I am new to this forum, and I am seeking some advice and a push in the right direction. I am a photographer and I need to move a tabletop with a motorized XY system. I am doing very high resolution, art reproduction photography. I have built a vacuum table prototype where I can place a piece of art and the vacuum can vacuum the art down perfectly flat onto the table. A camera is independently hovering over the table and I want to be able to create something with motorized XY movement to support the table and move the vacuum table under the camera. currency I am using a prototype platform which is a 900 x 1300 x 15 mm sheet of plywood. in the center, I cut out a 500 x 500 mm opening with a rabbet ledge. in that opening I slotted in homemade 500 x 500 x 10 mm plywood vacuum box. what I want to do now is motorize the entire stage. it seems like I can use some sort of XYCNC style structure, but as opposed to CNC machines, there’s no tool on top being moved around. Instead, the entire table top is going to be moved around. my idea is to build some sort of a wooden ladder base to hold the initial two rails of the system. And then finally on top will be the large table top that gets moved around. For distance of travel I need about 500 mm in one axis and 750 mm and the other axis. These amounts of travel will be doubled because it should go 500 on one way and 500 on the other way. Basically when the table is in its center position the center of the table underneath the camera. Now I need the table to move so that the camera can see the edges when necessary. I have never ventured anywhere with these XY systems before this is completely new to me. Could someone help me out with a basic understanding of how to begin or take me under their wing and give me some advice? Thank you very much! I have added some pictures of the prototype that I built in my studio. I was thinking to get the motorized equipment next and even apply the motorized equipment to my current prototype vacuum table platform. The next step will be to get a much larger vacuum table not just a little 50 x 50 cm insert. my idea is to build a box that is 1000 x 1500 x 100 mm which will be one large, continuous, vacuum table, supported by the XY rail system thank you! - Mark
What you seek to do is fairly simple but you lack a bit of clarity in your dimensional requirements. What is the exact field size you wish to cover? What is the exact size of the moveable tabletop?
Thank you! tabletop (vacuum box) 1000x1500x120 mm Camera fixed above center Table movement 500mm in both directions short side; 750mm in both directions long side
It is your use of the phrase "in both directions" that I am unsure of. 500mm in both directions is 1000mm of movement. Are you wanting a scan area of 500 x 750 or a scan area of 1000 x 1500? The difference between the two is significant in the structural requirements.
yes, sorry for my non-engineering language! OK here’s what I mean. The table is 1000 x 1500 mm. The camera is centered over the center of the table via separate structure, the visible area of the lens over the table has the potential to be quite small ( as a small as 100 x 250 mm). so, I need to be able to move the table enough so that virtually all of it at some point is visible to the camera. That means that if it’s centered, and I want to see the edge, the short dimension of the table needs to move 500 mm to be able to bring the edge to the camera field of view. so for my amateur way of saying this, from the Central point, it needs to move 500 mm in One Direction along the short axis and 500 mm in the other direction from center along the same axis. In the long axis, it will need to move 750 mm in one direction and then when it comes back to center, 750 mm in the other direction. There is some flexibility to this, I can deal with not going quite exactly so far. I can certainly deal with 10% less movement. but that’s more or less what I’m trying to do.
Okay, got it. 1000x1500 viewable area. Let me think on it a bit as this is a fairly substantial build.
Thank you very much. I have been searching online for inspiration and I found these two systems that I thought looked like possibilities. Both are quite different. Of course, I am also looking for relative simplicity. I certainly do not want to over engineer anything for the obvious reason that I have never done this before and also for budget reasons. I don’t mind a manual system at all, but if cost and complexity are similar, I may prefer a motorized version.
Have you considered moving the camera instead of the table? At that size it might mean moving less mass. Alex.
Attached is my best suggestion. Right now, motion is limited to around 850 mm x 1350 mm due to the limitations of 1500 mm extrusions. The two long rails on the upper section and the drive rail on the lower section will need to be increased to about 1650 mm in length to achieve the full 1000 x 1500 mm range of motion requested. Increasing the drive rail to 1650 mm in length does present some issues with the lead screw whipping but as this is a low-speed endeavor, it hopefully won't be a problem. There are solutions however if it is. You will need to verify if you can get 1650 mm C-Beam extrusions and 1690 mm lead screws in your market. Sketchup files attached below. Note: there is a minor conflict at the non-motorized end of the lower lead screw. The end plate sticks up a bit too far to clear the upper framing even with the 15mm plywood shims shown on the gantry plates. You will either need thicker shim plates to provide clearance or trim off the top of the end plate.
Rick, you are a champion! Thank you so much for this! I really appreciate your time and effort. let me get your opinion on something. I did an exceptionally rudimentary and low quality test of concept using an XY motion rig for my small 50 cm² prototype vacuum table. as I am a photographer I have some photographic sliders used for camera motion in video. I connected them together perpendicularly, clamped the base one to a table , and connected my vacuum box to the top. Essentially, I had manual tracking XY motion. Now this set up is wrong for 1 million reasons, and it did have a fair amount of flex, particularly in the aluminum rails of the lower slider. I centered the rig and centered the camera over the top. I used my typical mirror technique in order to ensure that the cameras sensor plane is perfectly parallel to the shooting surface. This is where the problems began. As soon as I move either axis of the slider rig or both, the accuracy of the parallel alignment between the camera and the shooting surface suffered quickly. in order for my photography of the flat art in stitched tiles to be successful, I have to ensure perfect parallelism between the camera’s shooting sensor and the flat art. Because my test, albeit a very low quality one, showed me so quickly how I can lose parallel, it raised some doubts about this entire endeavor! so, my question to you is, given that you have put some thought into this design, and you have a very good understanding of these components, and you can now see the failure of my admittedly poor test, do you think it will be possible to maintain perfect parallelism with a system like you have sketched up and a camera floating overhead? One more detail, the floating camera is on a very heavy duty 100KG Cambo UST studio camera stand with geared tripod head. This allows me to really lock in its position and dial in the angles to get to parallel. finally, my studio is in a 120 year-old European building. The floor, old oak boards, is not level at all. Of course that’s what leveling feet are for. so now, with all this extra information and knowledge of your build design, do you think once I adjust for perfect parallelism, this motion XY platform will be able to maintain perfect parallelism? When I first started this research, I took it for granted that this would be totally achievable, but after my crappy test, doubts have entered my mind… I would love to hear your opinion. Thank you very much!
The reality is, there is no such thing as perfection in the built environment. The best anyone can hope for is acceptable tolerances. And only you can determine what the acceptable tolerances are with your system. So let's go over where errors may happen and how to best mitigate them. The framing is designed such the center of mass will always be between the two base rails so you don't have to worry about uplift at one end of the upper gantry causing rotation when the table is moved to the far opposite end. That solves one problem but doesn't resolve how to deal with system deflection and imperfect rails. Deflection of the upper rails shouldn't be an issue based with the way the gantry plates are spaced out but ultimately will be dependent of the weight of the vacuum box. The heavier the box, the more the potential for deflection. If it becomes an issue, the best solution would be to spread the base rails out even farther and add another support rail down the center. As to the issue of imperfect rails, it's pretty much a given that extruded aluminum rails are not perfect. It is important that you check them when you receive them to verify that they are within your acceptable tolerances. On the lower rails, some slight bow may be eliminated when the rails are fastened to the table but the upper rails will need to be pretty much dead-on perfect. Straightening there can be aided by adding a center rail on the lower level but this should only be done as a last resort. One final thought on the framing involves the splice in the bottom rails. The bottom rails are shown at 2400 mm which exceeds the available length of C-Beam. Arbitrarily, I have shown the splice in the center but that may or may not be a good location depending on how smooth the transition across it is. You will want to set up test fits when you receive the rail and run a properly fitted gantry plate assembly across the joint to verify smoothness. (I would suggest inserting a tight-fitting 20x40 mm piece of wood blocking or aluminum tubing in the channel of the rails to help achieve proper alignment.) If you can get 2000 mm lengths of the extrusion, you may also want to consider setting the lower rails up with a 2000 mm section in the center and 200 mm pieces spliced on to both ends. While this would create the potential of having to cross two spices, it would mean that for the majority of work that is not using the full table width, you would not have to cross a splice at all. The final part of the necessary precision is up to you. You cannot expect laser level precision without doing a laser level precision build. Make sure your table is stout enough there is no deflection. Framing members should span the short direction, not lengthwise. Using slotted hold down clips for the base rail may help with tuning the framework. You might also want to consider mounting dial indicators on your camera mount, pressed against the surface of the vacuum table and moving the vacuum table around to verify flatness. So good luck with this, keep us informed. We love to see successful builds. Be sure to source quality OpenBuilds parts to the greatest extent possible. There is nothing more expensive than cheap parts so avoid the direct from China mystery vendors. They don't demand the same level of tolerances in their products. The OpenBuilds parts store can give you a list of authorized resellers in your part of the world. And finally, please remember that as I am a volunteer moderator on this forum and not an employee of OpenBuilds, OpenBuilds itself offers no warranties as to the suitability of the outcome. I do however have many, many years as a structural engineer so the probability of success here is extremely high. But no matter how good a design is, ultimately the success or failure of a project often comes down to the care and precision used while constructing it. And that part is on you.
