Thread 2950082

Thinking about building a small cnc mill for small steel and aluminum parts. I’d like to make the thing mainly out of aluminum extrusions.
I was thinking that a fixed gantry design like picrel would be the most rigid, except I’d like to mirror it so there are diagonal braces on both sides and to increase the depth of my work area.

Is this the most rigidity possible given the size and format constraints?

>>2950082 (OP)
I'd be concerned about the rigidity if you're trying to cut steel.

>>2950082 (OP)
dont most edamamebois that build 80/20 routers get disgusted with the lack of rigidity pretty quick and move on to something else? and theyre just trying to cut interwoven cellulose

>>2950082 (OP)
Those things don't even have enough rigidity for cutting aluminum.

>>2950082 (OP)
this thing might cut plastic, maybe some soft wood.
you will spend more on end mills trying to cut steel on that than just buying a grizzly g0704 or something and converting it to cnc
actually is that a taig headstock on that thing in your model?
just buy a taig or sherline imo.
one of those will be infinitely better than this

/emt/ retards begone

>>2950082 (OP)
>Thinking about building a small cnc mill for small steel and aluminum parts. I’d like to make the thing mainly out of aluminum extrusions.
You'll need to replace that with plate aluminum parts for steel or aluminum. you can start off with aluminum extrusions to cut / drill aluminum plate.

or just buy a chink cnc machine and modify it with a chink 110V 1.5KW ER11 spindle.

>>2950082 (OP)
>steel
lol

Milling steel on a router like this is going to be unbelievably slow. Like you can get a tiny feature into a tiny part over 20 minutes, while holding the spindle by hand the entire time to reduce vibrations and add preload. And it's still going to break at least one endmill per operation.
Aluminium is much more forgiving but still painful. If you do not particularly NEED large parts, it's a very good idea to build the CNC around a machine vise, since it immediately resolves all your workholding woes. And then you should adjust the Z axis so it's the smallest reasonable distance away from the vise. Make sure to use beefy linear rails. The open bottom SBR12/SBR16-UU round slides have tension adjustment, the MGN types don't, but larger MGN rails are very solid.

>>2950082 (OP)
Your design looks like it is 8 times as stiff as my cheap wood-aluminium thing, but the table looks like it’s exactly the same as mine so that would be a weak point unless those two rails are some super tight tolerance hard steel kind of slides I don’t know about. And don’t you need some plates on the diagonal braces as well

>>2950082 (OP)
I’ve mostly just roughed out steel with these table top things then finished with one of those belt sander kits you can buy a hand file and a countersink to deburr

i've seen some mexicans make diy sliding tables out of slabs bolted together. do you guys think this would be rigid enough for machining on it?

if i bought two of these alibaba sliding tables and bolted them on an L shaped steel frame, wouldn't I technically have a milling machine? the top slide would have a router with a spindle under it. the spindle strapped in place by two bolted flange bearings. the bearings bolted on plates secured to the vertical sliding table. voila

>>2950584
You would technically have a milling machine and practically have a big pile of junk metal.

>>2950584
like so

>>2950592
do they have ball screws or do they have threaded rod?
if they have threaded rod, they are junk and not worth your time.
What you should do is source 3 linear stages with rails and ball screws and build your own.

>>2950082 (OP)
Diagonal braces do surprisingly little. First of all, the base isn't perfectly rigid and, unless ridiculously overbuilt, twists under its own load by about the same amount. Second, by the time the gantry legs are beefy enough to not twist into a pretzel (a major weak point in many designs), they're also beefy enough to transfer the forces into the base without much need for additional bracing. For pic related the difference is less than 7% which is not worth the trouble imo.

>>2950082 (OP)
I was watching a weird chinese guy build a 4 axis like this in his 1 bedroom apartment, he had to keep it small so it would fit in soundproof cupboard (lol)

Realistically i think the Not An Engineer / Kris Temmerman design is the only one that would work but what would i know, fucking nothing

Get a DMC2 mini.

anybody in the 1st world try out one of the chinkshit ddcs controllers? i see them on lots of ruskie builds but it seems like they have no look ahead so they slam on the brakes and creep around every g02/03 circular move. that seems like it would completely defeat any high speed roughing programming

>>2950898
Need to make it out of steel if you want it to be good the stiffness of steel is around 2-3x stiffer than aluminum. Your best bet would to design it out of an epoxy granite base and 1/2" -1" thick plate weldments to hold the table and spindle assemblies. It needs to be super duper stiff if you want to be machining steel with any kind of efficiency, look at how much mass people add to their Bridgeport and things to adjust the vibrational frequent of the machine. Look at how much mass and stiffness there is on a modern consumer mill, and that is the weakest you should go

>>2953374
>look at how much mass people add to their Bridgeport
wtf are you talking about? poast proof
ive been in and around west coast job shops for 40 years and never once seen mass added to a bp mill. with the exception of insurance mandated bolt downs otherwise all of them were simply plopped on the floor and plugged in without complaint. and anybody that claims a bp will chew away with a 3/4 endmill buried 2" deep in steel is full of shit. theyre not a #5 k&t

>>2953374
>Need to make it out of steel
>Your best bet would to design it out of an epoxy granite
So which one is it? FYI elastic modulus of EG is about 15% of steel, and while it's a useful material, it's quite a bit more of a meme than a lot of people love to imagine.

>>2950082 (OP)
There's videos of people shitting together 200usd builds capable of roughly cutting steel so shouldn't be impossible.

Use rectangular steel sections, bolt it together, and fill with either cement or sand.
Aluminum extrusions are not rigid and are not vibration dampening, they're also too light.

>>2950898
>Diagonal braces do surprisingly little.
Not trying to be a jerk anon, but if you put diagonal braces where there is the least of distortion then you shouldn't expect much. Can you run another sim with braces protruding away from the bed?

>>2954728
>with braces protruding away from the bed
I don't get it

>>2954969
Well the pillars show a ton of distortion to a side so maybe a brace there will to better than where there is less distortion