Messages

901

Show"N"Tell ( Your Machines) / Re: Success! Mini Machining Center under Mach3 control - Video link

« on: April 29, 2010, 11:24:04 AM »

I thought you had three modes:

1. Full A axis mode
2. Indexing mode
3. Spindle mode

Now you're saying you will need the locking only in the "indexing" mode. Can't see how the program "knows" whether you're in "indexer" mode or in "Full A axis mode"? Looks like a macro is needed...?

Dan

902

Show"N"Tell ( Your Machines) / Re: 4th Axis Round-up...

« on: April 29, 2010, 06:28:20 AM »

That's a much more reasonable price But again it looks like a worm driven so I'd ask them what is the backlash and whether it's adjustable.

Dan

903

Show"N"Tell ( Your Machines) / Re: 4th Axis Round-up...

« on: April 28, 2010, 02:11:05 PM »

Yes, designing your own one would be best. Your best bet in terms of backlash and simplicity of design would be using a direct timing belt drive from a stepper to the 4th axis spindle.

You will need to establish the holding torque required. For this you need to know the most far point away from the 4th axis centre line that you will ever cut. And you'll need to consider the tool load at this point - tool diameter and material you'll be cutting. then we'll need to estimate the plunge down force produced by that tool. I can figure how to claculate longitudinal cutting forces and moments at the spindle, but have never calculated a plunging force. Best thing to do is to experiment, but I don't know how could you possibly arrange to put a weight scale under a workpiece and see how much force does the tool produce when you plunge...  If you find a way to do it safely it will be the most invaluable and important information you will need for this project... or at least I think so

Dan

904

Show"N"Tell ( Your Machines) / Re: 4th Axis Round-up...

« on: April 28, 2010, 01:38:52 PM »

Barry, can you possibly consider not CNCing the 4th axis?

Dan

905

General Mach Discussion / Re: spindle does not rotate

« on: April 28, 2010, 08:50:38 AM »

Can you test pin17 on the PP and see if voltage gets through to it when you turn on the spindle in Mach?

Dan

906

General Mach Discussion / Re: THIS IS DEDICATED TO "HOOD"

« on: April 28, 2010, 08:46:33 AM »

Thanks again, Hood!

Dan

907

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: April 28, 2010, 08:33:56 AM »

Hi Tweakie,

A friend recently bought a plasma table which was claimed to cut 30mm steel with no draft angle at all. Don't know how it's achieved there and haven't seen the machine yet.

You might be better using a lens with a longer focal length and further away from the workpiece, so that the beam travels more distance to the workpiece surface. May be that's what you meant...(?) But then you already have your design constraints. Also, can you play with the point where the beam is focused? Do you focus it on the surface of the material? Can you focus it in the middle of the material thickness?

The picture does have a nice effect indeed

Dan

908

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: April 28, 2010, 07:03:41 AM »

Very nice Tweakie!

6mm acrylic, now that's something! Could you take a better photo to show the cut edge? Just curious what kind of finish does it leave. Does it cut 90 degrees, or does it have a draft angle like with plasma?

Interesting photo, BTW, looks like a photo of a moving object with that blurred background.

Dan

909

Show"N"Tell ( Your Machines) / Re: 4th Axis Round-up...

« on: April 27, 2010, 03:10:05 PM »

Don't think it should get complicated. You will have to remove the manual handle and see how you can fit a stepper instead. You will use a shaft coupler to connect the motor's shaft to the table's one and you will need to do some machining to make the mounting plate for the motor. Easy said ha... Never disassembled these rotaries myself neither.

I think if you could find one to play with and figure what can be done there before you buy it, it would be best.

Dan

910

Show"N"Tell ( Your Machines) / Re: 4th Axis Round-up...

« on: April 27, 2010, 02:59:05 PM »

Hi Barry,

The one in the first link looks very small for your need...? It doesn't mention the size, but judging by the chuck, looks like it's something like 3 or 4 inch in diameter at most.

In the second link there are the 8" rotaries that might do. You have to consider that with the part sizes you're going to cut there will be significant moments generated by the tool cutting a foot away from the axis centre line. Looks like the tables in the above link have a worm gear drive so should be no problem with holding torque, but you will still have to work out the way you're going to fix the workpiece to the rotary.

I would make my own rotary table. Those in the second link, are nothing more than a standard rotary table that is fitted with a stepper motor. You can get a Phase II (or the like) rotary table for less than $400 and fit a stepper to it for another $50 and you have a CNC rotary table and save $400! Since you only need the rotary to flip over a work, you don't need to worry about backlash and these manual rotary tables have locks, so you should be fine. Besides there should be an adjustment for the backlash.

Here are the manual rotary tables I am speaking about:

http://www.emachinetool.com/accessories/catalog/large.cfm?OptionFamilyID=244

You can probably find a place with better prices too.

Dan