[jvalencia]

Some time ago I found this cnc model and I liked how simple and rigid it looked.



Now, I'm buying parts to make my own cnc based on this design.

I'll be using ballscrews instead of rack and pinion though.

I really like that I'll skip making custom Y-axis lateral plates, only aluminum profiles.

My plan is for a CNC build that requires no custom parts at all.

[fretman_2]

Designs like those are notoriously prone to flexing because of the aluminum extrusion. I had a Shapeoko 2 which was very inflexible...Although your design has larger extrusions.

[jvalencia]

Designs like those are notoriously prone to flexing because of the aluminum extrusion. I had a Shapeoko 2 which was very inflexible...Although your design has larger extrusions.

These are 8080 extrusions, I think they are fine (cncrouterparts use 4080 IIRC). X axis will be several extrusions tied together.

[awerby]

That design provides very little headroom. If all you're using it for is cutting shapes out of plywood, it could work, but it doesn't seem suitable for much else. You'd still have to provide a solid table for the extrusions to mount to, and a way of holding them down securely. If you use ball screws, you'll have to figure out a place to mount them; that design doesn't provide any that I could see.

[A_Camera]

Designs like those are notoriously prone to flexing because of the aluminum extrusion. I had a Shapeoko 2 which was very inflexible...Although your design has larger extrusions.

It's not the extrusions which causes the flexing, it is the way it is designed and the size. Mine is also built of extrusions but it is not flexing. Of course, it is not a match for a 2 tonnes machine, but definitely not flexing.

[A_Camera]

Some time ago I found this cnc model and I liked how simple and rigid it looked.



Now, I'm buying parts to make my own cnc based on this design.

I'll be using ballscrews instead of rack and pinion though.

I really like that I'll skip making custom Y-axis lateral plates, only aluminum profiles.

My plan is for a CNC build that requires no custom parts at all.

I think that design is far too weak, even if it is built out of 80x80. ...but it depends on what you are planning to use it for.

[florins]

I think that design is far too weak, even if it is built out of 80x80. ...but it depends on what you are planning to use it for.

Please see my router at

https://www.youtube.com/watch?v=wj4N-etTauM

- it uses Bosch profiles 90x90 mm, it is working 12 hours per day, 5 days a week, from 2010, I am cutting on it aluminium, acetal and wood, it never slipped. I changed three bearings and one belt from then. I would re-design it very much the same today , probably using linear rails instead of supported round rails. I can even explain why this design flexes much less than the usual machines made of profiles, and why the design offers as much headroom as needed. No time now, but please let me know if you need details.

[wizard]

I woukd say the design is rather incomplete. You are probably missing half the machine.

Some time ago I found this cnc model and I liked how simple and rigid it looked.



Now, I'm buying parts to make my own cnc based on this design.

I'll be using ballscrews instead of rack and pinion though.

That means designing and fabricatng new parts to mount the leadscrews

I really like that I'll skip making custom Y-axis lateral plates, only aluminum profiles.

My plan is for a CNC build that requires no custom parts at all.

Not to discourage you but the minute you cut materials to length you have custom parts. Even if you order the parts from an extrudion jobber they are cut and machined to your spec and thus are custom.

As to mounting a gantry beam on extrusions that can wirk but to be reliable you will need gussets and tie plates. 90 degree intersections like shown are not extremely reliable if you rely upon just the T slots. Beyond that you still need a way to mount the linear bearings. The linear bearings may require an adapter plate thus another custom part.

[A_Camera]

Please see my router at

https://www.youtube.com/watch?v=wj4N-etTauM

- it uses Bosch profiles 90x90 mm, it is working 12 hours per day, 5 days a week, from 2010, I am cutting on it aluminium, acetal and wood, it never slipped. I changed three bearings and one belt from then. I would re-design it very much the same today , probably using linear rails instead of supported round rails. I can even explain why this design flexes much less than the usual machines made of profiles, and why the design offers as much headroom as needed. No time now, but please let me know if you need details.

It looks nice, but I am not saying that profiles are generally bad, so you don't need to convince me. Some side notes though... you are milling pretty slow in that example, I think if you'd increase the speed you'd be in trouble. The main reason is the Z beam design, not the round rods. I am also using extrusions and fully supported round rods. In my next machine, or if I ever upgrade this one, I will also use linear rails. Another point is that the design which I call weak, is not completely similar to your machine, and in fact, the differences are very large, especially in terms of the Z and the beam. Of course, none of this excludes the possibility of using the machine, as long as it is used within it's limitations and is used slow enough.

[wizard]

These are 8080 extrusions, I think they are fine (cncrouterparts use 4080 IIRC). X axis will be several extrusions tied together.

The problem when referring generically to extrusions is that they vary widely strength wise. Even extrusions from the same vendor can vary in weight and design. Most of these extrusions are not as stiff as can be accomplished with other construction methods.

The nice thing about the X (table) axis is that no matter what material you use you can reinforce it in various ways. You can do this after the fact too if needed. The real challenge is building a proper gantry and supports the first time through.

When it comes to sheet sized goods i just don't have a lot of confidence in T -Slot extrusions. The good thing here is that you don't have a lot of Z height which should mean less twisting forces on the beam. Speaking of Z height make sure your design has enough clearance for your intended usage. Remember with the Z, the saddle must clear the work as well as the cutter and router combo.

Just to qualify, im on my cell phone at the moment thus haven't looked closely at the detail. In any event it might help to detail intended usage. Is this hobby focused only on sheet goods or something else?

[jvalencia]

Sorry guys, the first photo is just the "top" of the machine, it will require a table.

The machine is suppose to be raised from the bed, as in this photo:



As you can see in the next photo, the X axis is composed of 3 extrusions tied together, and no custom plate was used.



Almost all the machine is made of extrusions with very few custom parts (by custom I mean cnc machined for example).

[jvalencia]

That design provides very little headroom. If all you're using it for is cutting shapes out of plywood, it could work, but it doesn't seem suitable for much else. You'd still have to provide a solid table for the extrusions to mount to, and a way of holding them down securely. If you use ball screws, you'll have to figure out a place to mount them; that design doesn't provide any that I could see.

That cnc uses rack and pinion with geared steppers. My modification will be to use ballscrews. I've yet to figure how to attach them. I'm waiting for some parts to arrive yet.