Vertical accuracy?

LowRider CNC Advice
1

Hello,
LR4 looks perfect with it’s size and simplicity, but i’m not sure about vertical (Z) axis accuracy.
I see that most users are just doing “flat cuts” (full cut through entire material). My needs are slightly different - i want to cut forms (moulds) - and they require good Z accuracy.

Can someone using LR4 comment about actual Z accuracy? For example 1m x 0.5m work surface, MDF board - is 0.5mm achievable (if depth is important - 4cm out of 5cm board at maximum)? I used full-size industrial CNC before and i believe that for Z accuracy i need stiffness on both ends of axis (while LR4 is fixed on one end only), but i may be wrong.

2

I use my cncs to cut and v-route acm sheets were 0.5mm is the difference between a sheet/work you can use or trash, that said: i only do it with a table with a vacuum bed, perfectly sealed mdf spoilboard so that humidity doesn’t do its thing

3

I do a lot of inlays where Z is critical, it’s not a problem at all. Mine is full width.

There are also a lot of examples of 3D carving in the gallery. That shows how accurate it is.

4

Thanks!
I understand, that this depends on toolpaths, on material itself but if ~0.5mm is doable then this should be OK for my needs.
Going to build one, brb :smiley:

2 Likes
5

0.1 or better is doable. But only if you are able to set the 0 exactly. That’s the far bigger problem for my inlays that I am sloppy. :smiley:

6

So, no vertical backslash (due to one-sided rail or bearings-on-tube type mount)?
Setting dimensions and checking if axis can move commanded amount is one thing, having tool at set height over table is different thing.
But i already ordered 1/3 parts from ali and will get others soon, will see how it works :wink:

2 Likes
7

You have the weight of the X axis and the core/router pressing down on the leadscrews all the time. That’s a pretty effective anti-backlash measure.

8

Your build is going to be as accurate as how well you can build it. This isn’t a 15k cnc, remember this. Check your conduit when you buy it, try to make your 3d printer to be more accurate (califlower), follow the build instructions and don’t cut corners.

1 Like
9

one thing, with that, YOU HAVE to surface your spoilboard. That way you will get great results!

10

I would argue it is more dependent on how well you use it.

Surfacing the spoil board for large pieces and using a finishing pass are both needed for high Z accuracy.

The machine can do it though. The gantry is plenty big enough to handle the backlash on a finishing pass, even with a downcut bit.

11

Of course good cam and regular maintenance (that includes surfacing the spoilboard regularly) are a must also.

12

I will build CNC on 22mm plywood board, which itself will sit on 18mm desk top so i hope it will be stiff enough. Spoilboard - 6mm wood dust place, not sure if 6mm will be enough (maybe - i plan to do only moulds without cuts through surface).

One more question - “how low” i can build entire system - minimum vertical height of entire CNC? I have space under desk, but it’s only 29cm height, probably won’t be enough for proper operation (even limiting working Z depth to 3cm or so)?