Suggestion on STEEL capable Benchtop CNC

Hello all its wonderful to see all the fun projects and get all the takes on various aspects. I liked cruising through trying to find answers for similar situations, what a great community.
I myself have a mechanical and industrial Electrical design/maintenance background and have built from scratch a couple wood capable machines. I am looking though now as we all do progress to delve into tinkering with Steel projects.

I WANT TO STAY AROUND 2K... which I know several of you would say I have an 8k machine that I love, ect... but I am not really into production level. So while my initial thought was a LMS (little machine shop) 3990 as those seem to be best suited at that level for milling and upgrading from there to CNC that puts me over 3k... and I really do like CNC from the 6040 wood working level I have.

Ok so the couple options ... ok possibly really only 1 that I am really trying to get you-alls backing on is the Steel Desktop CNC 3040 3axis Router Engraving Cutting Machine Mach3 USB Machine (yep that's a steel frame construction not the typical aluminum ones and its about 2k)

https://www.ebay.com/itm/17410247417...MAAOSwclhd1gzq

3040A.jpg

Any reason this would not work for mild steel (possibly some stainless and aluminum)
unlike wood I am really taxing myself why I would need anything that would require any more than 6" height when it comes to metal

someone on the boards had gotten the 6040 version, but never completed there experience posting

unless of course which is intriguing 5th axis capability, but even though its a column type as compared to gantry it says it handles only up to aluminum? any reason it shouldn't with the 3hp motor it can't handle steel as its column type? - CNC Router 5 Axis Cnc Milling Machine 3040 6040 Engraving Machine VFD 2.2KW Spindle

https://www.aliexpress.com/item/1005...f6625350f61-39

6401A.jpg

and of course the LMS shop 3990 that it would be nice if someone would offer up their pre-owned one for sale but at over 3k all in for CNC its too steep for me to take serious right now.... it that really going to be that much stronger from all of you that might have experience with the steel frame 3040s?

https://littlemachineshop.com/produc...ory=1387807683

Lms1A.jpg


My Metal work right now may be simple pockets cut out, but as I also have an art background and was quite ornate in my woodwork, I can see me being intricate at some point. --- Ok you guys I'm counting on ya!

Nobody has experience with the Steel 3040 slag tank versions?... someone has to, I know I see manufacture demos with 1/8" bits, but I want to know about practical 1/4, 1/2" size (on Steel) and peoples experience.

sorry just looking for x2 and adding kits alternative

You could get a CNC-ready Taig mill and add your own motors and control box. The Taig, while rather small as mills go, will cut steel with no problem. The 2019 CR mill lists for $1211, and we sell it for a little less, which leaves you enough left in your budget for a decent controller, like the Geckodrives G540, some low-inductance NEMA 23 frame motors, a 50v power supply and an enclosure to put it in.

Can you give numbers for the accuracy and size of work you intend to do?
Will it be made from flat sheets or blocks of raw material?

1/2" end mill in steel on those machines - you are dreaming.

A G0704 (DIY conversion) can't run a 1/2" end mill in steel properly. They are bigger and costs add up to a lot more than your budget. That's without any labour cost.

That 3040 on eBay lists "Chrome plate shafts" as linear bearings. Not clear if they are supported or unsupported.

Supported = uncooked spaghetti, a little bit stiff
Unsupported = cooked spaghetti

Not suitable for steel apart from surface scratching (light engraving)

thank you all for your inputs... thought that I saw somewhere that the STEEL frame 3040 was linear guides, but maybe that was for the 6040 size... a G0704 can't handle 1/2" interesting, not that I really need beyond 1/4"... think a LMS 3990 would be in the same class but wind up being almost 1k less after conversion, taig seems a bit limited at 1/8" in comparison at around the same price.. looking mostly at this point up to 3/16" steel tubing and a few 1" square pocket cuts...
still would like to know from anyone who has one of those Slag tank CNC's from china what their experience has been with steel.

Quote:

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Originally Posted by pippin88

1/2" end mill in steel on those machines - you are dreaming.

A G0704 (DIY conversion) can't run a 1/2" end mill in steel properly. They are bigger and costs add up to a lot more than your budget. That's without any labour cost.

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I am looking at similar capability for steel but 1/2" tool in steel is a big want. There is a reason they run smaller tools. There are two basic limits I think you will run into - machine stiffness and spindle power. The nice thing about CNC is you can take lots of smaller passes with smaller tools.

You need: lowish rpm, plenty of torque, rigidity for steel afaic
Router= no torque
LMS= no rigidity

In terms of milling:
I have similar to LMS machine, hated it. Twists all over the place. Too light.
Now have similar to G0704, miles better with alum, steel will be a push unless small tool, slow, several passes, especially if slotting.

A small router: I wouldn't even try metal with one unless shallow engraving only.

Unless you're prepared for gruelling hours of mundane shallow slowness, anything short of a RF45 size machine, your living in the clouds.
https://www.penntoolco.com/rong-fu-m...ed-head-rf-45/
My 0.02.

dazp1976 thank you for your suggestion... while I am sure nice 5k with CNC is pretty far out of the parameters (and size really)... I know there is people that have success out there up to 1/4" capacity and cnc that have accomplished it... need the most cost effective/painless easy to find and setup route to get there...

There are videos of people scratching away at steel with small and floppy machines.

Are they actually then making decent parts and continuing to do so? Doubt it.

You could cut 150mm solid steel bar with a hacksaw by hand. Maybe you would do it once in desperation...
Doing it multiple times? You would buy and use the correct tool (a bandsaw).

Quote:

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Originally Posted by pippin88

There are videos of people scratching away at steel with small and floppy machines.
Are they actually then making decent parts and continuing to do so? Doubt it.

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Which is basically both the machines in the original question.

I'll give you a +1 for the taig. It was my first mill and quite capable for the size. It was VERY capable after epoxy bedding the columns and upgrading the spindle motor!

...with the price of machinery these days you might get a real milling machine vs a router for 2K price range. Knee mill type are good Prototype/Tool Room machines for the price. Here is one example of an older brand.
https://www.ebay.com/itm/22466910614...sAAOSwOndhOSGk

happy hunting

Taig has recently come out with an upgraded spindle motor which is more powerful than the original and allows the speed to be controlled via software. https://computersculpture.com/taig-m...l-cnc-equipped

Wow Andrew that's some really nice artwork there... thank for the suggestion of the Taig.. although that seems a bit small compared to a 3990 and not as robust...
and please lets stay away from knee mill class, as would be ok for a bigger more industrial space and more funds than willing to invest by the time you add everything and trying to find just the right things to work together for CNC... another though... what about this machine from aliexpress

https://www.aliexpress.com/item/1005...rch-mainSearch

or

https://www.aliexpress.com/item/1005...rch-mainSearch