before I’ll have a mental breakdown, I wanted to run an idea through this forum.
I want to use my Lowrider 3 for the occasional flattening of big tree cookies, since they are more than 10cm thick, I need to create some design that would be able to do that.
Specs:
Table size 2500mm x 1400mm
Lift would be made with linear guides and 12v linear actuators
I want to have a 1000mm x 1000mm removable rectangle in the middle of the table. For this occasion, I’d remove my spoilboard and then there would be a way to remove this rectangle under which there would be a constructed lift.
My main concern is flatness of the top with this adjustment. You can see what I have come up on the picture. The selected part would be removable (not sure what would be the mechanism yet) so when I am not using the lift, the whole area gets supported. I was also thinking that there would be some sort of a lip where the rectangle would sit, so I can fine adjust flatness if needed (with bolts or somethings similar).
Is this bs? Do you have in mind some hardware that I could buy for the removable beams?
I love asking the forum for this kind of help and I love the mental exercise of dissecting these kinds of problems.
It sounds like you want a plate that is totally flat when you’re doing full sized sheet goods and then you want to remove the blue section, and there will be a motorized table a bit below that bay. The table will be lifted by actuators to raise or lower the slab to get it to be flattened by the LR. Is that right?
My first impression is that a motorized table is overkill. How much are you realistically going to remove? You can make a deep bucket, and then add some plywood, 2x4s, 4x4s, etc to lift or lower the cookie to get it into the reach of the LR. The LR will manage making the last pass flat and precisely adjusted for the correct depth. Adding linear actuators is going to make it less rigid and more expensive for limited benefit.
For example, if you built a little 4x4 box (3.5" high (90mm)), a 2x4 box (1.5"/40mm), and a sheet of plywood (3/4"/20mm), you can stack them up to make heights of: 150, 130, 110, 90, 60, 40, 20. If you had another sheet of plywood, you could do even more precision, but the LR can manage inside of the largest 30mm gap.
I’m currently not worried about the lift per se. That I will figure as a second part of the build. But I am worried about the removable part of the plate on top of the table. So when I put it away and back, it won’t affect the precision of my cuts (e.g. the table stays flat).
I have made couple of quick drawings to show you what I mean. It’s not totally precise and in perfect ration but you’ll get the idea.
Part of the “base” will have the removable rectangle. So if I would want to use my lift, I remove the spoildboard, remove the rectangle in the base, remove the beams in the picture above and there is gonna be a lift table underneath where I can sit anything that is too tall.
How about, if instead of having the table adjustable, you mount the Y rail and belt on strips of ply screwed or bolted to your table? When you want to do a big cookie, you unbolt them and stand on some precut spacers 2x4’s sort or thing that locate in the right place to lift your whole lowrider above the table. You could even have them on pegs to locate and you could stack them to give you different levels of lift, say 100mm 50mm 20mm 10 mm options. Your spoilboard wouldn’t move or change and you would always be working off the same flat base.
This link might provide some ideas or inspiration (hopefully)…
But I agree with others - for changing the usable depth of the LR3, adding some boards under the Y rail and rollers would be easier, cheaper, and more likely to result in a flat cutting surface.
However easier and cheaper isn’t always the goal, so if you are thinking of a lift system, how about lifting the outside edges of the table that support the Y rail and rollers? That would provide an infinitely variable table depth along the entire table top. The devil would be making sure that all four actuators lifted or retracted the exact same amount. .
I think it would be easy to re square when it’s down on the table you could locate the y boards against a hard stop, and when lifted, you could square it again, but it might not be needed for surface leveling the tree cookies, I presume just accuracy in the z axis is needed.
I wish there was an easier way to square the table though because I have to climb on my table to get the tape over any marks I make and it’s not easy to measure accurately with a tape when you can’t hold both ends. I keep thinking about finding a better way but I don’t have to do it so often.
Perhaps this will help guide your thoughts. I used the removable middle to roll standing logs under, on a lift cart to machine surface just like you’re thinking.
I think somewhere between 10-50cm. In which the most used case would be 15-20cm.
I was thinking of something like this too. But I feel like the moving with the whole machine would be a pain in the bottom, as @Tokoloshe mentioned.
The best solution would be to have the Y rails lifting with some sort of system. But that’s certainly beyond my capacity right now. @Bartman Mentioned that. But to coordinate all 4 axis properly, since having no experience with that. Maybe for some next version?
If I were to do it ll over again I’d double up that 3/4" ply insert piece to ensure flatness, at the same time leaving a lip (as I had in this table) to make it easy to drop in. I’d also skip the nutserts next time around. I ended up mostly creating little “sleds” to hold the work piece or just screwing right down to the spoilboard.
I always had a little runout on the surface but also did not ever actually surface the machine. I just got to know the spoil board and where I’d need to maybe go deeper or not when laying the job out in ESTLCam. Cedar or plastic building shims are great for levelling things on the fly - you’ll find that if you surface cookies. Use shims to get it close for the first side and then you should need nothing for the flip side because one side should be perfectly flat now. I used one of these lift carts and removed the handle.
