Another First Router

[ger21]

It seems to be very solid. And the gantry moves really smooth, although it's quite heavy. The only thing is that the 2 sides can move quite a bit independantly, but the 2 screws will take care of that. And I'm not sure you can build a 40" wide gantry out of wood that wouldn't do that.

[anoel]

I'm thinking about building a 24"x36" cutting area version of similar construction... My current machine has been serving me well, but it's shortcomings are starting to limit what I can do with it. So a rigid machine with a full size router is high on my list to build. Just can't afford to go to an aluminum frame machine right now.

[ger21]

Originally Posted by anoel I'm thinking about building a 24"x36" cutting area version of similar construction...

For the most part, I'm pretty happy with it. The torsion box table is perfectly flat, and can support a LOT of weight. There's no flex or movement at all with the ~75lb gantry roilling it.

What would I change?

One issue is the EMT conduit. The galvanized coating wore off very quickly, and flat spots developed very quickly. Only time will tell how well it holds up, but I have a feeling that after the initial wear in, it will be fine.

If you followed this entire thread, the Z-Axis you see hear was basically a patch on my original design, which needed some help. The original design is in there, but needed to be boxed in. I'd recommend something like either Lionclaw's or Joe's Z-axis, with the Y-axis screw in the middle, as opposed to on top like mine.

One other thing would be to figure out how to make really, really stiff gantry sides, and a really soilid way to attach them to the gantry beam. That's the only place I have any flex. But if you can't eliminate it, dual screws will do it for you.

The only other issues were caused by building it without finishing the design. Overall, it's pretty much what I had planned, only a lot heavier.

[spalm]

Gerry, did you notice a problem with the Y screw drive on top instead of in the middle back? This does not seem like a big difference to me. Did your side plates on the Y carriage work as planned?

The two problems I found with my mini version of your machine were the twist of the gantry (as you said it should be solved by dual X axis leadscrews) and “lift flex” caused by I think poorly designed (my fault) linear bearing holders on the Z that were not strong enough to hold the Z plate steady. Have you tried driving your Z (without the router turned on) into the table to see if it flexes? Maybe this is a illegal test, but it looked pretty bad on my machine. I was never able to determine if it was the carriage tilting back or the Z axis flexing.

Steve

[ger21]

Did the sideplates work? Yes. If I really push on it, I can get it to flex a little, but very little. This is because it's screwed together, rather than dadoed and glued. It's acceptable for being a fix.

As for the screw on top, I haven't made it yet, so I don't know. I'm sure it would have been better in the middle back, but I didn't think it would be a problem when I designed it.

I haven't hooked up the drives to see how the Z-axis works, but there is no play or flex at all. I'll check again tonight, but I'm pretty sure it's rock solid. It's 3/4" SS shafts with Thompson bearings (2 per shaft). By wrapping the bearings with a layer of tape, I can actually add a little preload to the bearings, but I can already feel a very slight binding at the bottom of the travel, so it's not needed right now. They're very tight. I thought the shafts were perfectly aligned, but apparently they're not . But they're as close as I could get with a drill press.

I don't plan on running the motors until it's done, unless I can borrow a laptop for a quick test. I don't want to drag everything in the garage and then have to move it back in the house. I'll have a new PC in about 2 months, and the current one will be running the machine. I'm going to build a box to house the motherboard, power supply and Xylotex.

[randyf1965]

Have you thought of using a torsion box for the side panels? I am building them on my router from 1/4" plywood for the ribs and skins, all glued and nailed. From memory they are 25" long x 10" wide , fairly light and I can't detect any twisting or flexing.

[ger21]

If you mean for the gantry sides, that's not really the problem. What happens is that the gantry beam itself acts like a 40" long lever. It doesn't take much force to move one side with the other side held in place. With dual drive screws, there will be absolutely no flex at all. With a single screw, I'm not sure you could avoid it.

[ger21]

Originally Posted by spalm Have you tried driving your Z (without the router turned on) into the table to see if it flexes? Maybe this is a illegal test, but it looked pretty bad on my machine. I was never able to determine if it was the carriage tilting back or the Z axis flexing. Steve

According to Nook, it takes .625 oz to lift 1 lb with 1/2-10 acme (My Z leadscrew). So, in theory, my 250oz stepper should be able to drive the router into the table with 400 lbs of force. I'm sure that would cause some flexing. I went with 1/2-10 because I wasn't sure I'd have enough torque to lift my heavy Z. But I can turn the screw so easily with my fingers, I'll probably be switching to 1/2-8 2 start to double my speed if I find it's too slow.

I just went out and pushed on it pretty good. No movement. The only place I can flex it is moving the Z-axis side to side along the Y axis. Just a little bit. If I have to, I'll make a new panel to fit behind the leadscrew to eliminate this. The one I made got rid of almost all of it, but I can still move it a little bit. I'll wait until I run it for a bit, because I think I'll need to remove the threaded rods on the front side to get enough room.

[phantomcow2]

So how is your skate bearing setup working? Ridgid enough?
I was going to go a very similar route as you, with the mounted pipe. BUt I am also considering adding an extra pipe so i have 2 per side for the extra strength

[ger21]

Originally Posted by phantomcow2 So how is your skate bearing setup working? Ridgid enough?

It's plenty ridgid, with 1 minor issue, which I'm sure affects all similar designs. As you tighten the bearings (preload?) to the pipes, there's a fine line as you go from a nice smooth tight rolling setup, to a slightly cogging type motion. This is when you put too much axial load on the bearings. I think that the heavier the rolling components, the more apparent it becomes. It doesn't appear to really be a problem, though.

[zachjowi]

I am pretty new here but I really like your design do you have a link to it? Also are you done with this machine?

thanks

[ger21]

Sorry, no plans, I never finished them, and it keeps changing. And no, it's not finished, I've been too busy. But I plan on finishing it up this winter.