Will steel angle work for a decent machine?

[amd7000]

No. You guys have been a massive help. Saving me loads of time money and a lot of disappointment in the end. Think i will try and build a aluminium extrusion cnc slightly smaller instead with less expectations of accuracy. Thanks for the brilliant detailed answers. Time to trawl the internet for some designs that are possible on my budget. Cheers

[routercnc]

Don't want to scare you away! Have a look at the build logs on this forum > machine building > gantry style

In general the general DIY builds on the 'internet' leave a lot to be desired in my view. The builds on this forum, plus some of the cnczone ones, are much better having benefited from the collective wisdom and continuous feedback over a number of years.

For ideas about a deceptively simple but solid machine (using some extrustions) have a look at this recent build:
http://www.mycncuk.com/threads/8701-...ght=Jazz+build

Finally, if CAD is not your thing then you could post links to a couple of other people's ideas you like and get feedback on those. But the CAD trip is well worth it in the end so I do encourage you to try.

[amd7000]

No, you haven't scared me away, just given me a lot to think about. hehe

Gunna have a long look at the builds, cheers.

Yea, I think I will get into CAD before I lift a single tool, but first, I definitely need to do far more research.

On a side note. I've taken a nema 23 stepper out of one of the photocopiers, its 2.8v and 3A and weighs about 1.12kg. The length without the shaft is 78mm and I think it has around 270 ounce-inch holding torque. Does this sound about right?


Will this stepper be O.K for an Ali gantry?

[routercnc]

I wouldn't like to say for sure on electrical bits but comparing what you have with popular steppers for general CNC work:
.
Yours.....vs...Typical (e.g. SY60STH86-3008BF)
1.9 Nm..........3 Nm
2.8 V............5.46 V
78 mm..........88 mm
?.................3.2 mH (inductance - important value to get right)
3 A..............4.2 A
.
I have a stepper close to your spec on the Z and it works OK but I wouldn't use it on the X or Y (gantry) as it's a bit low on torque etc. M60STH88-3008DF is another popular choice with a similar spec. I'm giving you this info so you can build up your library of knowledge and have a look around - don't buy these sorts of bits yet until the design is ready!

[amd7000]

No. Not thinking of purchasing anything yet. Just thought I'd have a look at one of the steppers I have from the old photocopiers. Looks like I'll need to buy some then. Oh well. Thanks for the great information.

[Boyan Silyavski]

Steppers are one of the smallest expenses you are to deal with. Plus these steppers are possibly much more modern than the one in the photocopier. Plus the shaft may be is bigger and so on. Another thing worth noting is that most people drive them at 70V.

Here you will find them / the 3nm motors/ fairly priced.

[amd7000]

Thanks for the link. Are they a decent company/reasonably priced?

Yea, its only a 7mm shaft on the stepper I have. What voltage could my stepper be run at?

[amd7000]

Thanks jess. I wouldn't trust myself with chemicals, played around with them too much when I was younger!!

Think I'm just gunna make one for wood and ali now. I just wanted to see if steel work was viable at my price point, it wasn't essential. It would have been handy to make a few bits for work, but it's no big deal.

[Jess]

and later modify the cnc to cut thin plate steel by getting a spindle etc later on

'Thin' makes me wonder if the requirement is for cutting out 2D/flat shapes, which might make a plasma cutter a viable option. It's often attractive because the lack of contact with the work piece means that the machine doesn't have to be nearly as rigid.

If there's a need for 'engraved' features on plasma cut work, then one option is to etch it with acid. If you've seen a brass and enamel sign, chances are it was produced this way. With very thin materials it's even possible to cut out shapes by etching from both sides. Etching is faster (specifically, it's great for area, but rubbish for depth) and cheaper than CNC but does involve some fairly nasty chemicals.

Yea, I think I will get into CAD before I lift a single tool, but first, I definitely need to do far more research

That CAD experience will pay off when you've got a CNC machine, and you need to prepare jobs for it.

If plasma cutting sounds like it might meet your requirements, BTW, then I think there's a few machine designs in the plasma table forum.