PhotoSgt85 published a new build:

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So I have mechanically completed the build (this is at work so I can work on it in spurts). Just have to complete the wiring of the stepper drivers, power supply and work on setting up the smoothie board. I have the spoiler boards (not shown) but am considering pursuing a different type of spoiler board because there are some tools that can induce moisture in the area and I really don't want to be replacing MDF constantly.

 

My thoughts are to have a permanent aluminum base (either V-slot or just a plate of 1/4 or so inch plate. On this would be mounted a HDPE spoiler board. I have to look into it more but there is an Open Source recycling system called Precious Plastics that I would really like to utilize in general, and this would allow me to reuse spoiler boards as they are cut into. Recycling used 3D printer filament would also be optimal since we print a lot here for experiments. Basically I want to build an ecosystem in which I am capable of extremely efficient with materials and reusing what I can. This may not be for everyone, but I just keep looking at all the milk jugs and cat litter containers I am trowing in a recycling bin that I could be using productively. My XL will be almost exclusively used for aluminum and will be tried to be used for some sheet steel (front of 19" rack mounts), so I wanted a dimensionally stable spoiler with minimum moisture sensitivity as I will eventually add coolant flow.

 

I love the look of an aluminum bed on these machines. Awesome jamesdjadams!

 

I have plans for a HDPE spoiler board on my aluminum (vslot) bed. The best part is that after you cut into it a few times you can recycle it into another spoiler board. The recycling part will be a whole other projects though.

 

for the forces that the CBeam XL should see in the z axis I cant imagine 1/2" HDPE flexing any discernible amount.

 

Has anyone else had any issues with their X axis carriage loosening during cuts? I have been cutting plates that take about an hour each and when im done there is a lot of slop in the x carriage. When I punch through a material into the spoil board i get this bouncing that ruins my surface finish and in a few cases my whole part. Anyone else have this issue and what are your solutions?

 

My problem is the eccentrics loosening. I've been working on a full redesign of the z but the issue is really those ecentrics. I hesitate to locktire the nuts as if it doesn't solve the issue I don't want to have to mess with getting it off.

 

So in looking at the mechanics involved I have an idea for how to possible minimize this issue: flip the X axis carriage. If you take into account what is loosening and its location (the front bottom eccentrics) and look at it through the lens of a statics problem with the reactionary force from the work piece you will see that the front bottom wheels see the most force on them due to the direction of the torque and the distance to the line of action for the force. While most may not be familiar in academic terms the length of a moment arm (think of a breaker bar vs a normal sized ratchet) changed the force needed to generate the same torque, or in this case resist it. The upper rear wheels see a lower force for two reasons: the front lower wheels become the pivot point around which the carriage wants to rotate and their relative distance to the force. The relative distance part is easy to see, they are farther away from the line of action of the force and therefore resist the force with less stress being developed. The other part is that when the carriage tries to rotate some of the force is exerted along the tangent line formed by the circle with a radius from the pivot point through the point of contact of the upper wheel. This means that the force that could turn the eccentric nut could be resolved into two forces , a thrust load which the threads of the bolt will resist and a downward force equal to F * Sin(Θ) where Θ is the angle of incidence of the force. Conversely the thrust load would be F* Cos(Θ). So this makes sense but the proof is in the pudding, therefore I will have to wait and see how it works after I change the carriage around. I haven't looked at the plates yet to ensure that doing so wont mess something else up but I think it should be OK.
-PhotoSgt85

 

Figured since I took a swag at some signage I should post them up. These were cut on my CBeam XL. Not bad for a first go.