[MajorTendonitis]

Epic build! I'm really impressed with the build quality and design , and just don't know how it could get any better than this . Can't wait to see some video of the Beast in action

[pippin88]

Nice.

I think the pieces of angle where the uprights mount to the long axis bearings is the weakest point of your design. Some gussets / bracing like you have elsewhere would improve this.

[1Jumper10]

Pippin88 - I would have to agree with you but what may not be obvious from the pics is that angle iron is 5/16" (8mm) thick. Its almost impossible to put in a gusset without distorting the metal and I wanted that angle to be as true to 90 as possible. Thats why I used the thicker angle iron so I wouldnt have to gusset it. I think it will work fine but I'll keep an eye on it. I'm a little concerned that my motor mounts may be too flimsy. I wanted them to be cut from steel instead of AL but that was cost and time prohibitive. That might be one of the first parts I re-make when its operational. Either out of thicker AL or steel. Another thing to evaluate later on...

[mikechandley]

Great job!
Thanks for sharing your build I learned a lot.

[1Jumper10]

Thank you. I'm watching your 5 axis build. Its pretty fascinating and I hope it turns out well.

[1Jumper10]

More progress today.
On the electronics box I got the sides put on and it mounted on the machine. Still need to make front cover. I'm leaning toward acrylic and magnets so I can see the inside and get easy access.

I leveled up the gantry and got the joints somewhat ready. You can see in the pic the gap that will get filled with epoxy. Still working on that process. Never done it before and it's a critical joint.

In the process of doing that I measured the level variation across the X axis from the epoxy. Got out the feeler guages, 1-2-3 blocks and the calipers. As near as I could measure, the left side I beam was .004" lower than the right. This assumes the X axis bearing rail is straight. It very well could be that I'm wrong but I was pretty happy that I had to measure very carefully to discern a difference.

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[NIC 77]

I have a little mini mill that I bought from busy bee tools years ago. It's not the greatest thing, but it serves it's purpose, so I am grateful to have it, not sure what I would do without it. No CNC conversion, it's just a little manual mill.

So I was cutting some aluminum some years ago, and I was using curved router bits, and cutting curved shapes in the aluminum. This was giving me a bit of vibration in the machine. That vibration damaged the electrical box that was mounted to the machine. I had to look through the box to see what was broken, I got it working again, but the digital RPM readout is still broken. I took that stupid electrical box off, and rewired the connections to the motor with longer wires, now the box is mounted to the wall, and not the machine. I'd recommend this as a first step to anyone who bought one of those.

Ever since that experience I would never mount electrical components to a vibrating machine. Of course, your machine has far more mass, etc to dull out any vibrations, and should be fine, but IMO, I'd put the box on the floor instead of mounted to the frame. Or perhaps I'm over reacting after my one bad experience.

Good to see your progress. Nice work as always.

[1Jumper10]

Thanks NIC. I considered vibration and I've taken steps to mitigate it; sand filled frame, and eventually anchored to the concrete floor. I can also suspend the electronics enclosure from hooks to really isolate it from the machine if I want. Right now it's bolted on.

Appreciate your suggestions so post them when you have one. Your calcs for weight estimation were very close and your motor graphs were very helpful.

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[matth]

On my commercial Tekcel router the electronics enclosure is in the same position but it is mounted with rubber vibration dampers.

[1Jumper10]

I've started getting ready to epoxy bed the upright/gantry joint. It's definitely the most critical part of the whole build. The relationship between the X,Y and Z axis are all affected by this joint. It joins the weld distorted upright to the machined pad on the gantry. If I do it right, when it's all done the joint will be strong and stress free.
I decided to use Devcon Steel putty instead of the liquid version. It has a 45 minute working time which should give me enough time to verify the gantry is in the correct position.


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[1Jumper10]

The first thing I did was to set the gantry square with the left side Y axis. I set a 3-4-5 triangle off the machined edge of the Y axis. 4ft down the Y, 3 ft across the X. I scribed lines in the I beam and set the Z at the corner of the triangle. Where the 5ft hypotenuse intersects the 3ft mark became the second point of the line that is perpendicular to the Y axis.

Without precision measuring equipment, I used a large triangle so the error would be easier to see since it would increase over a larger distance.

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[1Jumper10]

With the X (gantry) set square to the Y, I clamped stops against the back of the uprights so I wouldn't lose the position. Then I started on setting the Z perpendicular to the bed and level across the X. I clamped a 4ft level to the bottom of the spindle mount and adjusted the Z height so the bottom of the level was close to the top of a couple of 1-2-3 blocks set on the I beams. I futzed around for quite a while but using the jack bolts in the uprights, feeler guages and 1-2-3 blocks I was able to get it adjusted pretty darn close.

All this assumes the ruler and level I used are accurate. It's all I have available and it should be close enough.

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[1Jumper10]

With these good reference marks I should be able to take apart the joint, prep it with release agent, apply the epoxy and put it back in place accurately. Epoxy arrives in the next couple days.

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[1Jumper10]

Set the riser/gantry joint today. It was harder than I thought it would be and I ended up not getting it as perfect as I had it in the dry run. In the pics you can see the jack bolts on the riser pad and the bottom pad of the gantry. I used release agent on the gantry and in the bolt holes and on the bolts and eased the 2 parts together while screwing in the bolts in an effort to expose as little of the threads to the epoxy as possible. So hopefully I can get the bolts out if I need to. I'll definitely need to tighten them up. I used Devcon steel putty with a 45 min working time. Its a little thinner than peanut butter and I was aiming for about an 1/8" thick application. And 45 minutes goes by fast! The gantry is definitely on there square but there is a greater level deviation across the X axis than what I had in the dry run. But the deviation is only ~ .020" and will be easily corrected when I surface the cutting bed. Squareness was most important and that came out perfect. Now I wait. I'll be busy the next few days so it will get a chance to totally cure before I can do any more with it.

[1Jumper10]

I popped open one joint to inspect it and later on I have to break it again to do the motor tuning with a dummy load. I used the jack bolts to lift it and I should have used a floor jack. The jack bolts lifted the epoxy along with the gantry. It's not a big deal. The pieces went right back in place and the joint went back together solid.

I moved on to working on the tensioning mechanism for the gear boxes. I pondered on this for about 2 days. There's a dozen different ways I could do it; snail cam and a screw wedge arrangement were good options but I wanted some way to tension it. Either with a spring or a flexible material. Eventually I decided on a lever with a screw adjuster with the drive plate shoulder bolt as the fulcrum. The lever would impinge on a piece of high durometer rubber to provide some tension. I've got some refinement to do but it's taking shape.
I broke a tap today to. It was the last hole. Got it out and finished it up without much trouble.

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[mactec54]

1jumper10

I thought you where using helical racks

[1Jumper10]

I am. Why?

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[mactec54]

I am. Why?

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Then you can't use any kind of spring to control the loading of the pinion, in one direction the pinion will pull into the rack, in the other direction the pinion will try to push away, they don't work like a straight cut rack where you can have a constant loading of the pinion to the rack

The pinion has to be fixed for a helical rack, and you would set the Rack Parallel to the linear rail, or within .001", you then adjust the pinion to have the correct clearance

[MajorTendonitis]

Then you can't use any kind of spring to control the loading of the pinion, in one direction the pinion will pull into the rack, in the other direction the pinion will try to push away, they don't work like a straight cut rack where you can have a constant loading of the pinion to the rack

The pinion has to be fixed for a helical rack, and you would set the Rack Parallel to the linear rail, or within .001", you then adjust the pinion to have the correct clearance

That's interesting, I would never have thought of that

[1Jumper10]

The pinion in and out movement relative to the rack is constrained by the mount plate. Also, the high durometer rubber isn't much of a spring. It's just a little insurance in case things aren't perfectly parallel it can give a little. The rack and the bearing rail shoulders were machined together in one fixturing on the horizontal boring mill so theoretically they should be exactly parallel.

I've looked carefully at my mounting method for the gearboxes. Especially for the disengagement forces in play that you mention. I think the weakest point of my design is the aluminum mount plate as it might be prone to flexing. But fully half of its surface area is bolted to steel plate. I wanted to make it out of steel but it was too expensive. It might be one of the first parts I make on this machine when I get it running.

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