Nice! With so much machining space available, you should do a double-carriage Y version of the high-Z with A-frame extrusion, so that the extra leverage of the taller columns has opposing leverage on the actual rail holding it up. You'd lose an extra 6-10 inches of Y travel, but you'd have it in the X direction anyway.

Depends how much deflection is within the high-Z beams' torsional deflection and how much is actually transferred to the Y-axis carriage wheels, but larger carriage footprint always = better.

 

I just placed my order, now I need to figure out where to put it.

The lead 1010 has the option for nema 23 high torque motors but the 1515 doesn't. My caveman brain tells me bigger is better so why does the 1515 not have the option for the high torque motors? Also, the 1515 stays with 8mm screws. I know all of this has been rigorously tested but that doesn't seem very beefy for a near 5ft run.

 

I think it would benefit from using 40x40's for the front and back rail as well. It may be prudent to move the front and back rails inboard another 20mm so you can add cast corners on both sides of it, as well as a couple on the inside of the c-beams as well. IMHO, that is one of the major weak points of this design, there are only 2 little 8mm screws holding each end of the Y axis rail in place. The whole rest of the length is unsupported.

Also, I never understood why you only used 8 wheels per carriage on the Y gantry plates, they are holding a lot of weight and all the cutting forces as well. At least you went with 6 wheels on the Z axis this time.

Also, for the bed rails, it might be better to use 20x60's instead of 20x40's. This would make the bed a lot stiffer, and you could then put the spoil boards flush with the top of the rails. It seems to me that "hanging" the spoil boards from the 2 hole corner brackets would make it very difficult to get the bed level and flat.

MG

 

This is what I have been waiting for. Why is the material list unavailable?

 

I like this design very much! Two years ago I've built double C-Beam X axis CNC...it looked odd to me, so I never posted the build. Nevertheless here are some pics:



As you can see it's a bit different than your idea and I have to custom cut X and Y plates for two profiles screwed together, but those two C-Beams are really something; pretty sturdy and realiable.
Anyway, I like your idea better, it is easier to build with already available parts.

And PDF outlines of those plates, in case someone is interested

Double_C_beam_X_Plates.pdf

Double_CBeam_Y_Plate.pdf

Greetings from Croatia!

 

I watched almost 3-hour "movie" about building the LEAD 1515 router. If an user is expected to assemble two or more sub-assembles such as gantry carts, just tell the user to rewind the video and assemble all of the gantry carts before going to next step.

 

I think that the Z-Axis travel is too short. What if you want to cut 3/4" thick wood on 1/2" thick spoil board using 1/4" bit and then cut 1/8" thick wood using 1/8" bit?

 

Huh? Says it has 2.5" cut depth above the spoil board, don't see a problem with what you postulated...

In any case just make the side rails longer and you can get any height you want...

MG

 

The thing I'm interested in seeing is a table design for a beast this big. You're immediately looking at multiple sheets of for the top and for the bottom.

 

Can router be lowered enough to use regular bits? Or even lower the carriage assembly if needed?

 

Solved - Had the plate upside down. Leaving this here in case someone else does it too.

Am I doing something wrong on the z axis assembly? The lead screw will have to be bent on both ends to make the bearing go into the slot. It seems like I need an additional space on the anti backlash nut to push that section away from the z plate. That would align the rod better.

 

You also should have only one precision shim on each screw of the nut block, not two...

MG

 

I just have one shim...the other is a reflection. I had to go outside and double check.

 

Any thoughts on the gantry bowing out at the top?

 

It's never a good idea to force something to fit. The key to this whole thing is that if you have to force something into place using clamps, you have made a mistake somewhere and need to fix it, not cover it up by forcing the parts.

The front and rear members of the base need to be the right length. The base needs to be perfectly square as well. Pre measure and check all pieces for length. The front and back need to be exactly the same length, all rails running from the front to back in the base need to be exactly the same length, and all the c-beams need to be the same. You also need to check the ends of the beams to make sure the cuts are perfectly square in both directions. I have found that most kits have at least some of the cuts out of square. This is less critical on a machine like this than on a machine with plates, like the Workbee.

You have to check the length of the two X beams. They need to be EXACTLY the same length. Assemble the gantry first, making sure the verticals are exactly square (both directions) with the horizontal c-beams. Use a trusted framing square to check during assembly. Once you have it assembled and square, then insert the two c-beams (so it looks like a large "H" from above) into the Y carriages, space them evenly, and measure across each end of the Y beams. (make sure wheels are preset to have no play) The measurements on the front should be exactly the same as on the back of the "H" and in the center next to the carriages. You may need to adjust these until they are perfectly parallel by squeezing the wide side or adjusting some hardware. You also need to make sure the upright is perpendicular to the y axis c-beams, measure from the same points on the top corner to the end of the c-beam front and back.

Gantry
/|\
/ | \
/__ |_ _\
C-beam​

​

Once you have all this square, assemble and square up the base. Measure from corner to corner to establish square. Then set the Xaxis assembly with the Y c-beams on top of the base, and align the 4 corners to have the same offset, and tighten the angle brackets to hold them. There should be no "forcing" required.

Your front 20x40 beam may be bent, extrusions are sometimes bent or warped due to the extrusion process. Check it against a 5 foot framers level, or other known perfectly straight edge. If it is bent, have OB replace that beam. It may be that the ends of the front to back beams were not cut square or the same length, and are pulling it out of line.

It is imperative that you have a perfectly flat surface to assemble the base on, or you will have issues with flatness of the bed.

This is one of the down sides of this design, there are too many angles and corners that need to be perfectly aligned to get the machine to track properly, and the extremely long extrusions are more prone to being bent or twisted.

MG

 

I just finished assembling my 1515 with high Z mod and I've got the same "bow." I followed the instructions in the video like a madman but my machine seems to be functioning properly. I took a caliper to the two Y axis C beams (in between) and they are parallel. My X C beams meet at the extrusion like the instructional video, not the end plate but it looks like you moved that after the fact.

EDIT: I didn't use clamps to manipulate anything into place. I'd say the build almost built itself. The instructional videos were incredibly well done.