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:

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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:

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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.

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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.

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9

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

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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.

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11

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

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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)?

13

hi cesar,
i want to build a v4 for ACM, were you ever able to get better than 0.5mm? thanks

Mikey

14

He never said he had 0.5mm difference, he said that 0.5mm difference ruins his workpieces… It’s pretty spot on.

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15

The lowrider is able to work with acm with a lot of success. If you are going to v-rout sheets to fold take my advice and place some kind of vacuum table, with a big pump or a big shopvac ("6hp"minimum)

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16

For your concern over Z, I’d recommend not the califlower print test, but rather the (for-purchase) one called calilantern.

Here are two links for where you can get it:

17

Yes i did that one. Thanks

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18

True, but he implied to me at least, that an Z error greater than 0.5mm could make a v-troove routed piece of ACM a piece of trash. I was wondering what Z accuracy he was getting with a flattened spoiler and vacuum hold down (which I am also intending to use also for a similar apoplication ).

19

Thanks for the replies Cesar and Phillip, yes I am going to be ACM folding. I am doing it by hand with a track and saws/trim routers at the moment but its tricky and a pain. Based on both your feedback I am going to start ordering parts for a 8x4 V4.

A 6hp vacuum is huge!! especially as I dont have 3phase. I guess thats mostly to keep the ACM pulled tight to the bed as the lateral forces from a 2.xxmm V-groove bit will be minimal.

I had a look at Califlower, I will invest $6 in that and look for some straight stainless tube.

Can anyone recommend any amendments/tweaks/buying decisions over the stock V4 design that are generally recognised as improvements.

20

6hp shopvac lol that aint that big.

I run my tables with 2.4kw 2stage pumps (220v)