1200mmX900mmX170mm 4axis cnc

[Nr1madman]

The way I described has been done and tested many times. So why change?

Well the way I described was just the way that felt most logical to me.. read a few build logs but didn't grasp that everyone was going the way you described :)
This is perfect! Now I have something to think about tonight hehe

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[routercnc]

Hi Nick,

As per your pm:
Your requirements are to cut wood, guitar bodies, and occasional aluminium.

The L shaped gantry in a pair of 90x45 extrusions has been used many times on this forum and will cut your requirements as above. At 900 mm gantry width it is starting to get a bit wide, but I would say still OK.

The raised X axis can also use 90x45 extrusion so long as there are plenty of supporting uprights connecting it back to the main bed.

Would this be good enough or should you use steel? Well, I would say you are OK to use aluminium profile on the gantry and the X axis and still cut the requirements above. If however you want to do regular aluminium cutting then I would upgrade the raised X axis sides to steel.

Here are some aluminium gantry, steel sided machines:




You wanted to use profile to avoid using epoxy leveling - well I've not found the profile extrusion to be particularly level and flat. You can buy specially machined profile, but regular stuff is not likely to be flat. If you don't want to epoxy level you can always shim the rails manually, but need a master straight edge to compare to.

[hanermo2]

Your project is going well !
Congrats !

I have some positive news..
Mostly ... In most-all alu designs/builds I have seen, little to no serious alu cutting has been done.
BUT..
You can later upgrade the machine stiffness, pretty easily, imho.
If You do need to, that is.
It will be perfectly feasible to drill/ream a few dowel pins, through clamped flats into the alu, and fix steel flats onto the sides of any beams.
And You can even fix them mostly by gluing .. if You use industrial epoxy glues.
And yes, they are strong enough, and no, they wont reduce rigidity.

As-is, I would not give any advice.
You have a pretty good path, and it is likely to work out very well for wood.
And with suitable parameters it will likely do some alu, with hsm toolpaths and smallish cutters.

But rigidity-needed is related to machine work-envelope size, esp. free-length ie the working length of your beam.
900 mm is pretty big.
A mechmate at 1200 mm beam is pretty close, and they are a near-professional tool, in steel, heavy and expensive to build.

In a nutshell;
looks good.
Likely to give great results in wood.
Well done.
Keep going.
If You need to, *anything* can always be upgraded.

[Nickhofen]

Hmm I'm at this stage myself but I was thinking about drilling through the bottom extrusion and use tee nuts in the upper extrusion and cap head screws with washers to fill out the t slots. Then use the holes I drilled to tighten the screws. What do you all say about that?

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Maybe this way the conection between the two extrution is more rigid , because the bolts run all the leght of the upper extrution and not just hold it with the lower one only from the base,just a thought....

[Nickhofen]

I am thinking to make the base of X axe support plate 300mm, is it ok or too much?
I quess that to find the length of the ballscrew for x axis etc, I have to substract the legth of baseplate from the legth of the rail,right?

So 1200mm for Xaxis subtract 300 =900mm for balscrew plus f plus space for the end support bearings bk and bf.

[Nickhofen]

Small update.
I send an email to Fred, BST Automation, about the cost of the rails ballscrew and a VFD spindle asking for quote.
The price he offer is good but the shipping cost from China to Greece is very high ,324$

[Zeeflyboy]

I am thinking to make the base of X axe support plate 300mm, is it ok or too much?
I quess that to find the length of the ballscrew for x axis etc, I have to substract the legth of baseplate from the legth of the rail,right?

So 1200mm for Xaxis subtract 300 =900mm for balscrew plus f plus space for the end support bearings bk and bf.

300mm is more than enough.

Yes, although there is no real harm in having a slightly longer ball screw travel than the machine travel of course if it helps you in locating motors/bearing mounts. The only downside is possibly slightly more expense and a slightly lower critical speed if you get a screw longer than needed.

I was very happy with the TBI and HIWIN stuff I got from aliexpress, all machined to my own specs. Haven't used it in anger yet of course so can't fully comment but quality appears top notch, was most impressed with the ballscrew machining as it was done to an impeccable standard. The seller was this guy https://www.aliexpress.com/store/278...4b24ae2bMdgpHS although you just want to email them for a full quote rather than buy the individual parts from the store. I dealt with a guy called "John" (I doubt it lol) who was very helpful... his email was just john "at" topper-hz.com and you then pay through a special order on aliexpress so you benefit from the payment protections there.

Worth a quote perhaps. They do all the c3/c5 ground or c7 rolled.. just ask for what you need. They offer their own brand stuff too which is much cheaper but I can't comment on the quality too much... I got a couple of small c5 12mm ground ball screws and they seem ok. Not as smooth as the TBI stuff out of the box but I haven't really looked any closer at them yet as they are for a future project.

Shipping is always going to a be a bit expensive when you are shipping a lot of heavy and large items half way around the world, but if the price is good enough to begin with then that's the trade off! Shipping for me (4 x 16mm screws, 2 x 12mm screws, 2 big 25mm rails, some 20mm rails, lots of carriages and motor mounts, bearing mounts etc came to about $240 via fedex.