[philba]

How rigid is the CNC Router Parts PRO48xx design?

I've got a small aluminum extrusion "desktop" CNC machine (OpenBuilds CBeam) that I bought to learn on, And while it has been a great way to learn without breaking the bank, I'm finding a lot of limitations. Probably the biggest one is the issue of machine flex. It's a fixed gantry machine and Y axis beam shows a lot of flex that makes pocketing and surfacing pretty ugly even with light cuts. This forces slow speeds and shallow DOC and thus means long run times for even small jobs. And cutting aluminum, while it is possible, seems like a real push. For my next machine, I want to not only increase the work envelope size but also increase speed and be able to cut aluminum (though I don't expect super speed on that!). It will mostly be a wood and plastic cutting machine..

So, I'm looking at the CRP4848. It seems like it has potential with a lot stronger construction. But the Y axis beam has the same basic design of my smaller CBeam machine and is more than twice as long. How much flex will this impart to the Z assembly? I can get 0.025" (0.6mm) of vertical deflection in the X direction at the tip on an endmill in my CBeam machine (measured with a dial indicator when pushing by hand on the top of the Z assembly). Some of that is due to overall structure flex but a fair amount is from gantry flex. How rigid is the gantry in the CRP48xx pro design? I know that moving gantries have more flex potential but am hoping the CRP4848 design overcomes a lot of that. What do you think?

[nlancaster]

Any router of course will have some flex. I have an older CNCRouterparts Standard machine which is the same basic construction as the PRO machines with the 8020 Aluminume extrusion gantry.

Here is a sample pocketing 6061 aluminum with a 3/8 single flute HSS cutter at 16,000RPM .050 stepover, and .250 DOC.

While I have never measured the flex on my gantry, I can tell you that the pocket in the below video was smooth to the touch.


https://youtu.be/lOFGVhtwr1w

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And this picture shows the finished pocket.

[ger21]

How rigid is the CNC Router Parts PRO48xx design?

About as rigid as you can get without spending at least 2x more.

Cutting aluminum on any router is always going to be a compromise, as even industrial $100K routers are not as rigid as mills. But the CNCRP (Avid CNC) machine should be much better than your current machine. All of those "Open Builds" machines are very lightweight machines.

[philba]

Thanks, guys. I know it's all about compromises. Even my shaky little CBeam can cut aluminum but with such a shallow doc that I'd rather not. But then it only cost me $700 and I have made a lot of things on it so no regrets.

I'm impressed with the speed in the video. Seems like the CRP stuff is worth considering.

[dgage]

I haven’t cut much aluminum yet but I cut commercial HT subwoofers with my 5x10 CNCRP Pro machine with linear rails and CNCRP spindle. I would have had to spend over $40,000 for a better machine, which is twice as much. The machine would have been beefier with an auto tool changer but I’ve been very productive with the CNCRP machine. I still don’t keep my machine busy enough and I’m building my business with the CNCRP machine. It would have been nice to have the beefier machine but I didn’t have the extra money at the time. And the machine is working well enough that I feel no need to spend $40,000 for an entry-level professional machine, industrial CNCs are closer to and over $100,000.

[Richmaple]

If you haven't already, look up Robert Cowan's YouTube videos on the matter. His latest one is all aluminum machining and is a pretty good capabilities demo (he also has a tormach, FYI)

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