Here you go. I based all this on your picture. Bear in mind it is a work in progress, so between scratching your head and laughing, enjoy
1. Clamp 2 frame rails together at 6" starting width. The back rail most be as straight as possible. It is the guide. Before using square stock, run a file along all faces or sand on flat plate to check for any rolled up edges. Not all metal is the same.
2. Clamp some 1" wide blocks on bottom plate along long side. They will space plate out for horizontal bearings. Lay some small 3/8-1/2" wood wedges at places where you think vertical bearings will go and press on plate to check for flex. Add as many vertical bearings as needed.
3. Make up some temporary supports for the tubes and set in proper locations. The back set of supports must be as inline with the edge and bearings as possible. The front set needs to be parallel to the back set.
4. Just keep messing with the damn thing until it all looks good. If the frame rails work better at 4" or 5-1/2", move them and try again. Same with the plate. Same with stands. The skate bearings are 22mm OD so 1" overhang should be good. Maybe the stands will work best inset 2 " from edge. You want to leave a few inches in between tubes for benders if needed. 4-5" should be good.
5. Mark all locations and disassemble. Put away until tomorrow. Reassemble on your marks and see if you still like it.
6. Assemble the frame with countersink bolts. Make straight, flat and parallel. No wiggle or flexing allowed.
7. Layout the three precision bearings and make perfect. Then start mounting all the rest of the bearings. The horizontal bearings will need spacers to run 1/4" or so down from top of frame after verticals are installed. Not critical. Other then the three outside bearings, all the rest of horizontal are slotted for adjustment. Use as many as you want. They prevent twisting or torquing the top plate as it moves.
8. You now have a flat plate that should slide easily back and forth. The 3/8" thick plate should not bend or torque at all. This platform will do what ever you want to do. You can attach extra plates on top for specialty items.
9. Back plate. You need around a foot or so of 1/2" ID seamless tube and the same as 1/2" smooth rod. Space out the back plate from frame. I would use some 3/4" thick bar or plate bolted to bottom frame rail. You may have to face it a tad thinner so it doesn't touch the drill press table. Attach with countersink bolts.
The first piece of pipe sticks out from back plate at a height you like. Tack it or somehow hold in place. Cut a piece of rod to slide in it. Then attach a piece of pipe 2 to 2-1/2" to the end of that rod. Make sure rods will slide in both pipes without play. The position pins will slide up and down to engage the holes. You slot the pipe on the back plate for back and forth give. Then with rod installed mark location for slide pin. Line everything up dead perfect and weld and slot and drill holes for pins. No sideways twist for slide rod. The pin must slide smoothley in groove. Your last adjustment when all else fails is the slotted holes at bottom of back plate. You can get a little sideways tilt adjustment.
10. Stands. I would make dedicated stands that slide left and right to accommodate the different brands. That's me. However you do it the stands must be in line with the plate and parallel with each other. You mount the pieces in the stand. Locate fixture so position pin is in line with drill left to right. This is critical. Adjust the fixture so drill is in center of rod. Slide plate and watch. The drill should track in the center. If there is a little warp between supports, make the rod benders. Place up against the piece and push/pull until straight. Mark location for mounting hole, drill and tap.
I went with 12' lengths of 1" square because it is a common length. The 3/8" plate is stiffer then 1/4" and I don't think you need 1/2". I went with 608ZB skate bearings. 8mm bolts to mount. I really don't think you will ever wear them out. Sorry for the book, but this is how I would approach this. Again, it is a work in progress. You now have the fun of adapting and setting real dimensions. Good luck!!!
1. Clamp 2 frame rails together at 6" starting width. The back rail most be as straight as possible. It is the guide. Before using square stock, run a file along all faces or sand on flat plate to check for any rolled up edges. Not all metal is the same.
2. Clamp some 1" wide blocks on bottom plate along long side. They will space plate out for horizontal bearings. Lay some small 3/8-1/2" wood wedges at places where you think vertical bearings will go and press on plate to check for flex. Add as many vertical bearings as needed.
3. Make up some temporary supports for the tubes and set in proper locations. The back set of supports must be as inline with the edge and bearings as possible. The front set needs to be parallel to the back set.
4. Just keep messing with the damn thing until it all looks good. If the frame rails work better at 4" or 5-1/2", move them and try again. Same with the plate. Same with stands. The skate bearings are 22mm OD so 1" overhang should be good. Maybe the stands will work best inset 2 " from edge. You want to leave a few inches in between tubes for benders if needed. 4-5" should be good.
5. Mark all locations and disassemble. Put away until tomorrow. Reassemble on your marks and see if you still like it.
6. Assemble the frame with countersink bolts. Make straight, flat and parallel. No wiggle or flexing allowed.
7. Layout the three precision bearings and make perfect. Then start mounting all the rest of the bearings. The horizontal bearings will need spacers to run 1/4" or so down from top of frame after verticals are installed. Not critical. Other then the three outside bearings, all the rest of horizontal are slotted for adjustment. Use as many as you want. They prevent twisting or torquing the top plate as it moves.
8. You now have a flat plate that should slide easily back and forth. The 3/8" thick plate should not bend or torque at all. This platform will do what ever you want to do. You can attach extra plates on top for specialty items.
9. Back plate. You need around a foot or so of 1/2" ID seamless tube and the same as 1/2" smooth rod. Space out the back plate from frame. I would use some 3/4" thick bar or plate bolted to bottom frame rail. You may have to face it a tad thinner so it doesn't touch the drill press table. Attach with countersink bolts.
The first piece of pipe sticks out from back plate at a height you like. Tack it or somehow hold in place. Cut a piece of rod to slide in it. Then attach a piece of pipe 2 to 2-1/2" to the end of that rod. Make sure rods will slide in both pipes without play. The position pins will slide up and down to engage the holes. You slot the pipe on the back plate for back and forth give. Then with rod installed mark location for slide pin. Line everything up dead perfect and weld and slot and drill holes for pins. No sideways twist for slide rod. The pin must slide smoothley in groove. Your last adjustment when all else fails is the slotted holes at bottom of back plate. You can get a little sideways tilt adjustment.
10. Stands. I would make dedicated stands that slide left and right to accommodate the different brands. That's me. However you do it the stands must be in line with the plate and parallel with each other. You mount the pieces in the stand. Locate fixture so position pin is in line with drill left to right. This is critical. Adjust the fixture so drill is in center of rod. Slide plate and watch. The drill should track in the center. If there is a little warp between supports, make the rod benders. Place up against the piece and push/pull until straight. Mark location for mounting hole, drill and tap.
I went with 12' lengths of 1" square because it is a common length. The 3/8" plate is stiffer then 1/4" and I don't think you need 1/2". I went with 608ZB skate bearings. 8mm bolts to mount. I really don't think you will ever wear them out. Sorry for the book, but this is how I would approach this. Again, it is a work in progress. You now have the fun of adapting and setting real dimensions. Good luck!!!