Thread: What I woud REALLY REALLY like to get

Wolfie I am sure I have seen CNC for Dummies still its about the machines.

try CNCcookbook site

Or CNCzone

Thanks Wheels
I looked up the cookbook site, lots of reading to do now.
Cheers
Wolffie

The CNC portion is just the computer control. I f you are familiar with the use of a hand router feeds and speeds things don't change. The same tooling is used for the same purpose.
if you are going for production work there are chip load calculations for the feed rate based on the speed of the bit.

Originally Posted by oreos40

The CNC portion is just the computer control. I f you are familiar with the use of a hand router feeds and speeds things don't change. The same tooling is used for the same purpose.
if you are going for production work there are chip load calculations for the feed rate based on the speed of the bit.

Not quite right.
With a handheld router you are in control at all times as well as using other tools to get where you want to go.
I could not imagine cutting a lithophane or a picture with a handheld router nor cutting non ferrous metals.
Neither have I ever used 1 mm v-bits, ballnose nor tapered bits in my handheld/table router.
I could not do this


Nor this

with a handheld router
Cheers
Wolffie

A lot of the CNC stuff is vague and nebulous, as at the low end of the market (that's us folks) the CNC routers tend to be very individual, so a fair amount of time (and material) is going to be spent working out the individual kinks of the machine, let alone getting used to the control software and the drawing package(s) that you want to use.

Things such as speeds and feeds will have to be tweaked; an MDF framed CNC router won't have the same rigidity as an aluminium framed one, and a steel and epoxy-granite frame will be different yet again. Each requires an amount of fiddling to get the best result for a particular machine.

Then the control devices have their own quirks to work out - is it better to let the software power-down an axis that won't be used for (however many) milliseconds, or is it better to let the control circuits do this?

As for the physical part of using a CNC...not counting the loading/unloading of the job, there isn't one. All that has been worked out by the machining package, and you've hopefully simulated it to make sure it makes sense. The closest really is deciding on tool type/size, and if you will make roughing passes with one tool, then switch to another for a finishing pass. Often, this will come down to tool availability and your knowledge of your machine ("Oooh, I could cut this with a 10mm bit, but I don't have one, so three 6mm passes it is") or machine rigidity ('Oooh, I could cut this with the 10mm bit, and put up with a bit of chatter on the surface as the machine is a bit flexible under that load, or triple the cutting time by using the 6mm bit but get a really good finish).

The best place to be when using one is in the next room to get out of the dust. Generally, by the time you notice something is wrong the bit or the part have already been broken and the positioning motors may well be trying to push the spindle through some other part of the machine (which is why soft and hard limits are useful...) and you'll be slapping your head realising that you forgot to re-zero the axis after offsetting it for some (now silly) reason.

Originally Posted by wheelinround

Wolfie I am sure I have seen CNC for Dummies still its about the machines.

try CNCcookbook site

I finished reading through the cookbook and that is the kind of information I am looking for.
Pity it is all about metalwork

It was not the working of my machine I was after, that is simple enough, it was the mathematics of bits/depths/spindle speed and how they work together for the finished product.
I still can't work out why one project looks great then, when I use the same tool setting for a similar one, it goes all haywire.
Gimme time, gimme time
Sadly, that is not what I have most of these days
If I can't be in the workshop because of my bung leg, then, at least I can read up on the subject.
Cheers
Wolffie

Wolfie try here

Originally Posted by Wolffie

mathematics of bits/depths/spindle speed and how they work together for the finished product.
I still can't work out why one project looks great then, when I use the same tool setting for a similar one, it goes all haywire.

Hi Wolffie,

I'm currently working in a small factory, driving CNC machining centres (unloading, loading, pushing the green button). When a job has a 2-3 minute cycle, I grab a manual, and read a page or two. Last week I read through the Sumitomo tool tip catalogue, and realised I was forever out of my depth!

However, there are very detailed guides about what tooling to use, based on material, operation(s) being performed on it, surface finish required, tool life required etc. etc.

One thing I've learned is that the *material* is not always the same, and this would be even more obvious in wood, than in metal, and this can cause different outcomes.

On Friday, a milling cutter broke after doing it's first slot, and as we were rotating the tools around to replace it, noticed that 3 of the milling cutters had a small cap of metal adhered to their tips, and would have broken when they next tried to plunge into the workpiece.
So, the previous bit of steel, for some reason, stuck to the tip of the bits, where the previous several hundred had not. Hmmm

Cheers,
Andrew