Cnc wiring!

[Cobey3289]

Thanks guys, the wealth of knowledge on here is great.
My cnc is going to be 100cm x 75cm c beam construction. I intend to cut wood, acrylic and some aluminium with it. At this stage, the aluminium cutting will be to cut bulking blocks for the stickmaking world. Anything else will be ideas that come into my head at a later date.
As stated it will be run by nema 23's 425 oz 3amp motors x4 with8mm threaded rod. I can't say it's going to have a hard life, but that's just my thoughts at the moment. Once built and working, my thoughts and practices may change.
I plan to use a MacBook as my computer for the cnc. This I think will necessitate using a USB breakout board. Are there any particular boards suited to the USB side of things and as I'm heading for USB, was looking at chilli pepper as opposed to Mach 3/4.

Thanks
Mick

[Clive S]

As stated it will be run by nema 23's 425 oz 3amp motors x4 with8mm threaded rod.

Threaded rod and cutting ally don't go together very well

[Cobey3289]

What would you suggest, as that's what come with the mechanical build. I thought at least that's a step up from the belt system!
Mick

[Cobey3289]

Hi Clive,
That's tr8 lead screws not threaded rod, my mistake.
Mick

[Desertboy]

Hi Clive,
That's tr8 lead screws not threaded rod, my mistake.
Mick

still lead screws are only 50% efficient ballscrews 95%

That means 50% of energy is lost to friction! It just doesn't make sense anymore to use them for our application.

Where they work well is using really big ones for lathes, etc. Where ballscrew prices are prohibitive.

[JAZZCNC]

Hi Clive,
That's tr8 lead screws not threaded rod, my mistake.
Mick

Mick starting to appear you are a classic case of the internet searching leading you up the wrong path.
In the early days of DIY CNC components like ball screws and good off the shelf drives etc cost lot of money. Things have changed massively and now the cost is down to sensible figures we can afford.

Now it's very easy and we see it all the time that new builders find old build's which used components like Tr8 and even threaded rod and all sorts of DIY methods and follow this route. Unfortunatly often they are sadly dissapointed and waste lot of money.

So my advice is to take a step back do little more research and ask any questions you may have no matter how stupid you think it may be.
UNDER NO CIRCUMSTANCES BUY ANYTHING Until your sure it's correct for your build.

For instance, all the previous info regards Voltages drives etc to achieve best speeds is mostly irrelevant because the limiting factor to speed will most likely be the Tr8 and everything that comes with it not the voltage. So you would have wasted money building PSU etc that's much more than needed.
Said this many times that machine is only as good as it's the weakest link and for a great machine you need components which are well matched to give balanced machine.
Trying to save money only costs you money when comes to CNC, so don't try cutting corners because will only regret it.

Suggest you start build thread if you haven't already which shows your design. Then ask any questions there. If we can see what you have in mind it's easier to advise the correct components or approach.

[Cobey3289]

Hi jazz,
Seems like a total re-think is in order.
Just off the bat then, having already purchased the nemas and drivers (already en route)! What would you recommend for the rest of the kit to complete my 750x1000mm . I have c beams already, may need to add to this to adapt to ball screws etc.
Thanks
Mick

[JAZZCNC]

Hi jazz,
Seems like a total re-think is in order.
Just off the bat then, having already purchased the nemas and drivers (already en route)! What would you recommend for the rest of the kit to complete my 750x1000mm . I have c beams already, may need to add to this to adapt to ball screws etc.
Thanks
Mick

Mick Neil says it all really but straight off the bat I can tell your design is probably working along the wrong lines for good machine because you mention C beams. This type of beam isn't often used because of it's weak flexy nature.

This is why we ask new builders to start a thread and give some idea of the design. Even if it's just picture of fag packet sketch.
Like any structure you start at the foundations and if these are flawed then the whole structure fails. The Machine design then leads you to what components are required.

Building a good CNC machine is done in orderly stages and nearly all those that shoot off buying components before the design is finalized waste money.

Start a Build thread mate.

[Cobey3289]

Where do you guys get your kit from, as it seems like ooznest is the most popular place for purchases?
Mick

[Neale]

Definitely a rethink needed! I doubt if many people on this forum buy anything from Ooznest, for example. I don't want to sound as if I'm knocking anyone, and I'm sure that the Ooznest machines will do most of what is claimed for them (i.e. allowing for all advertising hype!). However, whether they will do it particularly accurately, fast, with a decent surface finish, or for very long without frequent adjustment, is more open to question.

A couple of UK suppliers of the more specialised kit for CNC building are CNC4YOU and Zapp Automation, both of which sell decent quality kit with a decent level of service as well. People like KJN will sell aluminium extrusion for frame building, and you can use rather better quality guide rails and drive systems from the first two I mention. However, a lot of people go direct to China, e.g. via AliExpress, but you do have to know a bit more about what you are looking for. That's where help from folks on this forum can help immmensely, so you buy the right stuff first time.

As suggested, post a proposed design as a build log, and wait for comments. Don't be too upset if you are told to start again - it will be advice based on past experience, and will help avoid disappointment. For a bit of background, read Desertboy's build log as he has significantly changed direction since he started based on advice from here, and will have a much better machine as a result.

Good luck - people genuinely want you to succeed, and we all had to start somewhere.