I look forward to following along. I currently have a Shapoko 5 pro 2'x4' version and am looking to get a larger machine, and plan on going with the rack version.

I have going through the frame and cable calculator and had a question.  I want to max my X -axis, and keep with nice round lengths for rack parts.  so putting the max 1500 in tells me I need X-rack of 1490 mm. rack lengths come in increments of 100 mm, do you cut those?  or can I just round everything up 10 mm? or can you modify the calculator to allow me to put 1510 in?

thanks,

Dan

Hi Dan,

Great to hear that you are planning to build the rack version.

Yes, it is normally very easy to cut the rack to the correct length. The rack can be cut with a metal saw, angle grinder, bandsaw or similar, and then the end can be cleaned up with a file or grinder. It does not need to be complicated.

In your example, if the calculator says 1490 mm rack, I would simply use a 1500 mm rack and cut it down if needed.

You can also use a slightly shorter rack, for example 1400 mm, because the X-axis will never use the full outer length of the frame anyway. The gantry and carriage have their own offset, so the machine does not physically reach all the way out to the very end of the X frame.

So you do not need to change the calculator to 1510 mm. I would keep the calculator values as the real design reference, and then adapt the rack length practically when you build.

So in short:

Use 1500 mm rack and cut it if needed, or use 1400 mm if you want to keep it simple and the available travel still fits your needs.

I'm looking forward to this build as well.  I'm looking to be able to process 1220 x 2480 sheet materials. Here in the US, 4 ft by 8 ft sheet panels are the common size.

I'm very impressed with RawCNC's attention to all the detail of craftsmanship as well as all the various ideas and methods to achieve the end result. Grattis och lycka till.

Same boat as Davin Tormanen. Unless it complicates the design or come with other drawbacks I'll be aiming for a rack version in "full sheet size".

Thank you for running this project!

Tack! Yes the rack version is a tested machine and it has very good cutting results and perfect for larger machines.

Posted by: Olav Nymoen

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Same boat as Davin Tormanen. Unless it complicates the design or come with other drawbacks I'll be aiming for a rack version in "full sheet size".

Thank you for running this project!

If you think the belt version looks manageable, than the rack version is as easy, i can take the belt version as it is now and convert it to racks in an hour, it is that easy.

I'm planning on building the 2.5 very soon.  I am looking to use it to make steel parts.  Would you recommend rack over other options for this use?

For steel cutting, I want to be a little careful with my recommendation.

The Raw Creative 2.5 is an aluminium profile based machine, and I would not personally choose an aluminium frame machine as my first option if the main goal is to cut steel parts. Steel cutting requires a lot of stiffness, mass, correct feeds and speeds, good tooling, and usually a more industrial type of machine if you want to do it reliably.

That said, if you want the strongest drive options for the Raw Creative platform, I would look at either rack and pinion or ball screws.

Ball screws are a very good option for smaller, more precision-focused machines. They are stiff, smooth and give good repeatability when installed correctly.

Rack and pinion is the better option if you want a larger machine or longer travel distances. It is strong and practical for bigger builds, but it still does not change the fact that the machine frame itself is aluminium.

So my honest answer is:

If your main goal is steel cutting, I would probably not build an aluminium CNC router for that purpose.

If you mainly want to cut wood, plastics and aluminium, with maybe very light steel engraving or very careful light passes sometimes, then the machine can still be useful.

For the strongest Raw Creative versions:

• smaller precision machine: ball screw

• larger machine: rack and pinion

But for regular steel part production, I would recommend a much heavier steel-frame machine.

RawCNC,

Thanks for your honest reply.  It is truly appreciated.  I might abandon my plans for steel cutting and plan on only aluminium for the machine which is still the majority of my needs anyway.  If I was planning on a 650x650 cutting surface, what maximum thickness of aluminium material do you think I'd be capable of cutting with good precision?  I'm looking at using ball screws

Hi Dave,

Yes, aluminium is a much better match for this type of machine than steel.

With the correct settings, you can cut a lot of aluminium on a machine like this. We have cut hundreds of meters of aluminium on our own machines over the years without any major problems. The important thing is to use the correct cutter, correct feed rate, correct depth of cut, and not try to force the machine like a heavy industrial mill. We have a guide for this on the site.

Regarding thickness, there is not really a fixed maximum aluminium thickness in the same way people often think. If you take it slow and use multiple passes, the practical limit is usually more about the clearance under the gantry/Z-axis than the material thickness itself.

So if the aluminium plate fits under the machine and you have enough Z travel and tool length, you can cut thicker material by taking several shallow passes.

For a 650 x 650 mm cutting area with ball screws, I think aluminium work makes a lot of sense. A smaller machine with ball screws should be quite stiff and precise compared to a larger lightweight machine. A rack version of this machine will do the jobb as good as with ballscrew, but it's your choice. 

Material choice also matters a lot. Some aluminium grades are much nicer to machine than others. I would look for machining-friendly grades such as 6082-T6, 6061-T6 or 7075-T6 if available. These usually cut much better than very soft aluminium, which can be gummy and stick to the cutter.

So in short: I would not worry too much about the thickness itself. Focus more on using a good aluminium grade, sharp tools, proper chip clearing, and conservative cutting settings.