anybody got a cnc machine

[scott0031]

Name one thing.



If a manual operator can't clamp down and cut out a rectangle in a flat piece of stock faster than you can programme, set up for and complete the same job they have no claim to the title 'machinist'.

PDG I am very careful what i write and for the reason of people coming out with comments exactly like this.

The Key word here is:

because it {CNC} can do things a manual machine simply can not do.

I did not make reference to this particular simple slot if indeed that is all it is. (and often its not) It was a general reference to the fact you said this

CNC isn't really a good prototyping structure.

Total rubbish for the reasons i raised.


Please go and mill me a radial slot lets say 150mm rad covering covering lets say 180 deg to keep it simple, 25mm deep and 25mm deep. How long will that take you? I will have the thing, drawn, programmed, and done before you have even clocked in a rotary table and that goes for any other guy out there with cnc. And i am a manual machinist.

 

[MrFluffy]

To ignore the which method is quicker bickering, just to ask the obvious questions that need asking if you take this to a proper job shop for a pitch, how sharp do you need the corners?
If you don't allow a little curvature in the corner, it will have to cut by another process rather than milled out. If you don't absolutely need square corners and can tolerate a little radius as most cosmetic windows have, make sure you communicate this to the person pitching for the job.
The old ancedotal story is a company sending a aluminium box out for a square window at a shop, and specifying absolutely square. Then getting the bill for having it wire edm'd to spec...

 

[PhillipM]

Name one thing.

If a manual operator can't clamp down and cut out a rectangle in a flat piece of stock faster than you can programme, set up for and complete the same job they have no claim to the title 'machinist'.

For a rectangle? I'd have the program done probably before I'd finished sticking the stock down,It's literally seconds with anything conversational. Even producing a cad file first would be a minute of work at most including sending it to the machine. Then I can set the machine to go flat chat with 15m/s rapids...whilst I don't think there'd be much in it I'd be amazed if someone on a manual mill was faster.

 

[Hood]

Then I can set the machine to go flat chat with 15m/s rapids...

What machine have you got that does 900m/min? or was it a typo and 15m/min?

 

[MattH]

Guys, OP was asking for help.

Not for everyone to argue about what help would be the best/faster/easiest blah blah blah.

 

[MattH]

But he would like it CNC cut, rightly or wrongly.
Those are his wishes, what's the point in arguing about it?

 

[WorkshopChris]

I was going to off help but was trying to get some more info. As have had a nightmare job one running a batch of plastic enclosures for a outside garden lighting manufacture. The boxes looked flat but were slightly convex with some sprue or flashing in the centre.
Often once a few holes were cut we would lose suction as they would pop back up. we ended up having a jig to hold then down to the table.
The people doing them before us were doing them clamped down on a conventional milling table they would start to chatter part way through and the edge of the tool would catch causing the plastic to split. From memory the material was ABS.

 

[Jonwhite]

Hi, i can sort out a cad file

 

[awemawson]

IF the plastic is suitable it's a piece of cake with a small laser. DXF of lid outline and DXF of the rectangle. Lay thin plywood on the laser bed, and mark the lid outline as a reference. Then place lid in the reference mark and cut the hole. Before this though you need to experiment with the plastic to select correct parameters.

Don't even need to hold the lid down as there are no cutting forces.

 

[agrimog]

some folk dont understand cnc's very well, with a modern machine, a retagular slot is less than a dozen lines of code, setup, half the time of conventional, and run time for a simple hole in a plastic lid, less than a minute.

and to answer the question, what can a cnc do that a manual cant.........5th and 6th axis programs, you cant physically turn the handles, and its nearly impossible to gear train a 6th axis with conventional machine tool

 

[MrFluffy]

I know pdg is being a pedant, but cam controlled hydraulic tracer machines were doing 5th axis long before servos started to turn those handles.

http://frankieflood.blogspot.fr/2010/07/nasa-tracer-mills.html

I'd just 3d print them for a one off proto personally

 

[MattH]

Do that by hand. Have fun.

 

[MattH]

I don't think you are getting the OP's point. He wants a one off CNC cut to see the results to then decide if he want's to get lots CNC cut.
What's the point hand cutting it in that instance?

I've never said CNC products can't be made manually. It's a stupid pointless argument.

I.e. What's better PC's or Mac's? Who cares!

 

[ukracer]

PC stands for Personal Computer, which is what a Mac is (a computer, for personal use).

Argument invalid.

Expensive personal computer though. Lol

 

[Wozzaaah]

The OP has asked if someone can do him a job so I'd suggest if you can help him then do it, if you can't then leave the thread.
No need to drag it down with off-topic arguments.

 

[scott0031]

Could this be merged into a new thread Wozzah? To Cnc or not or some such similar title I stopped posting for the reasons you have said above. I would like to add images to add weight to the argument of a incorrectly claimed statement.

Thank you

 

[Screwdriver]

700 off? Well if I can find the right size tool, my flypress is going to be quicker than the lot of you.

What is the plastic? ABS, PP? A brittle plastic might be problematic.

For that number of runs, would be worth making up some tooling. I'll have a look tomorrow.

A.

 

[Maxakarudy]

Do that by hand. Have fun.

View attachment 96500

What's the benefit of a "lead in" on mdf?, never used them myself, except on a laser and then only on a corner

 

[wookie]

I know pdg is being a pedant, but cam controlled hydraulic tracer machines were doing 5th axis long before servos started to turn those handles.

http://frankieflood.blogspot.fr/2010/07/nasa-tracer-mills.html

Those pictures on that link are a wonderful example of what we used to be able to do, at some point some very smart people sat down and worked out how to build/modify a machine to make the parts they needed. I'm more impressed with what clever people can produce with simpler machines and some ingenuity than what can be made on a sophisticated machine just by pressing buttons.

Many years ago I was given a CAD drawing of a part to be made by the drawing office, took a look at and in under a minute I said that can't be done, the guy in the office (on way more money than me) insisted it could. So I stood there while he told me how to make it, then I said it I build it that way I can't get access to do those welds... A bit of a pause and then he says Oh okay, then do it this way then, so I reply but I then can't get access to do those welds instead...

After nearly an hour of this back-and-fro he finally accepted that it couldn't be made and went away to redesign it.

 

[Jonwhite]

I have got someone to help me with this now
Thank you very much everybody