Basic CNC

Hi Raymond,

when I was being trained on CNC milling we used foam to test our programmes, that allows you to see the tool path and note if you've run the tool into the work piece by mistake. Oasis foam from a florist supplier should work well. You might want to post onto a model engineering forum as there could be someone who could help there.

See:

The home of Model Engineer and Model Engineers' Workshop Magazines

and

Home | Model Engineering Clearing House

Good luck with your search.

Andy

The worst thing with a CNC mill is to crash the cutter into the table.  You can use a piece of wooden dowel rod to simulate an end mill and 'cut air' the first time you run your program.  You didn't say your device was a lathe or a grinder or a wire EDM, lotsa stuff can be CNC.

This is not a trivial topic.  I live in the states and one of the local JuCos (Harper) is putting a program together.  I don't know the hierarchical divisions of secondary education where MK got his certs.  But however you do it over there I would try to get trained in school.  Failing that, manufacturers of CNC equipment do a lot of educating as well.

Are you acquainted with conventional machining?

IIRC Chicago is the machining capital of the planet, because O'Hare, as an aside.  Around here they use machinable wax as a practice material.  They superglue parts together when they want to make a part so complex that it would be impractical to mill, then sandcast it.  It is a mix of paraffin and polypropylene, AFIK.  They typically dye it blue.  You can melt and re-cast it, but no one ever seems to.

MachinableWax.com

Does your machine have a toolchanger? 

There is a process to cast foam as well, it is called 'lost foam.'  They spray the foam with a ceramic coating before casting it.  That is how Saturn auto engines are fabbed.  Now that I recall.

Hello Raymond,

To be honest I am attracted by your offer, but unfortunately I can't stay outside here where I temporary live for at least until the next end of september. But I am reasonably sure that I can help you by remote avoiding you destroy your machine and giving good results. It is at least the worth to try. I think that we can organise a sort of step by step helpful discussions. I can transform them in articles and you can follow me experimenting. Take in account that my personal experience with CNC machines is focused on a self-teaching path so there are lot of errors I can avoid. And probably give you good suggestions on hardware settings and the principles.

When I started (my very first step was to make one CNC from scratch) I tried to follow and interact with a lot of specialised CNC forums but frankly I have just found a great confusion. If the idea sounds good, you can contact me privately just to discuss the boring parts related to the steps then we can start. Making public a path to reach results I think this may be also useful for a lot of other users.

Enrico

Like Enrico, I too could help you by remote. I have built a CNC from scratch as well, I also program G-code (CNC language) and run a CNC (for woodworking) almost every day. If I can do anything to help, PM me. Between Enrico and I as well as any other help, I'm sure you will get through this!!

Dale

Can you post a picture and spec of your machine.

If you want some trial material to cut that's a step up from Oasis flower stuff then buy some ModelBoard- here's a note I sent to someone a while ago:

It was made from this stuff (probably M540):

http://www.alchemie.com/category/products/modelboard/polyurethane-modelboard/ 

but only because that was convenient for prototyping - for production it should be molded and there are a host of suitable plastics you might use - you would need to get advice from the tool designer/plastic molder.

You can make functional things from the right grade of modelboard - one day I mean to make some loudspeaker cabinets from it.

MK

Many thanks for the foam idea. I know someone who knows where to get t

he foam. I will post my result.

RayMort

Hi, just looked at the site url that you sent me. I will look at the options that are sold.

I will look now and see if I can find the machine I have. Due to illness I have not been able to use, and

its been on my bench for 2 years.

regards RayMort

I don't have a pic at the moment but here is the spec.

Ballscrew Machine Assembled

A3 size Machining Area - 500mm x 300mm, Z Axis 155mm

Footprint: 950mm x 750mm

Accuracy/Repeatability: 0.01mm

Translation: Ballscrew

Linear: Hiwin profile rails and carriages

MDL NOTE: CUSTOMER TO SUPPLY: Desktop PC, Monitor, Keyboard and Mouse

Machine Control Software - Mach3 Full License

Design Software - VCarve Pro 7

Electronic Jogging Handwheel

Controller: 3 Axis Controller and x3 NEMA23 3.1Nm Stepper Motors (X, Y and Z)

Proximity Home Switch (X, Y and Z) and additional external emergency stop

Kress Spindle 1050FME, Kress Motor Mount, Brushed dust hood with connection for 38/63mm out

3 x Kress Collets: 3mm, 6mm and 8mm

Sample Milling Cutters, 4 x T-Nuts, Grease

Single phase - standard socket 240V

One socket required - extension lead supplied

Code: [VCARVEMACH3]

CONTROLLER: FEATURES AND SPECIFICATIONS:

USB (V2.x) from PC/Laptop running Windows XP, Vista or Windows 7 (32 bit or 64bit)

motor driver connector pin-out is compatible with 10 pin open source interface (Linistepper, PICStep)

controller works with most step/dir stepper and servo motor drivers available on the market

buffered IO for maximum performance

advanced interpolation algorithms

start, stop, pause and resume execution of program on your machine

standard RS274/NGC G-code (EMC2 compatible)

advanced G-codes - G40, G41, G42 (Cutter Radius Compensation) supported

advanced G-codes - G43, G49 (Tool Length Offsets) supported

advanced G-codes - G54, G59.3 (Coordinate System Origins) supported

tested with SolidCAM, MasterCAM, ArtCAM, Vectric, CamBam, MeshCAM ... generated G-code

Profili 4-axes and 3-axes G-code supported

import toolpath from DXF files

import toolpath from PLT/HPGL files

import toolpath from image files

import toolpath from NC-Drill (Excellon) files

import toolpath from Gerber (RS-274X) files

toolpath simulation

automatic homing procedure

advanced toolchange procedures

automatic tool length measuring

export toolpath to G-code

export toolpath to DXF

SDK (software developers kit) is available

works on MacOS X (Snow Leopard 10.6.3) with virtual machine emulating Windows XP SP39 axes USB CNC controller Mk2:

100 kHz maximum step frequency

7 digital outputs

12 us minimum pulse width

manual jog inputs for all axes

limit inputs for all axes

5 general inputs

8 control inputs for pendant or similar device

SD card support for running g-code without computer

control external devices with I2C protocol