Topics

11

G-Code, CAD, and CAM discussions / Speeds & Feeds, in CAM Packages and calculators

« on: January 26, 2014, 06:10:09 AM »

I've found that the speeds & feeds in BobCad/Cam are, to say the least, a tad on the optimistic side for all materials and had been spending time with data tables & test cuts to get optimal conditions.
Last week I tried HSM Advisor and it took two minutes to deliver very close results to those yielded by hours of mucking about, so as it promises to make me considerably more productive I bought it.
Other things I particularly like about HSM Advisor are;
It takes into account machine RPM, Hp & Torque, warning of insifficient power or excess tool flex, adjusting cut parameters accordingly
Calculations take into account depth & width of cut when calculating tool flex and required torque.
It's programming allows it to locate a named active window in the CAM package and capture or insert data directly from selected fields.

What do you guys use and what do you particularly like about it?

 - Nick

12

General Mach Discussion / Help!

« on: November 09, 2013, 12:09:40 PM »

I feel left out!
Mach3 is working perfectly!
My mill and controller have had a variety of issues but even when I accidentally use the default BobCad 4 Axis Post I still get entirely useable code that makes nice parts, is there something I can do to remedy this lamentable situation?
TIA,
Nick 

13

Show"N"Tell ( What you have made with your CNC machine.) / Frame

« on: November 08, 2013, 04:58:28 AM »

I used to make this 102mm x 102mm x 270mm frame at the bench with a drill, drill bits, hole saws, an air saw, grinder and files. The results were functional but a lot of tidying up was required to make it look halfway pretty 
It struck me last week that although my CNC mill didn't have the envelope for all of it, with the right fixturing I could do half a face at a time, this is how the prototype came out -   



I wish I'd started learning with CNC years ago!

14

Show"N"Tell ( What you have made with your CNC machine.) / Pyrography Stamp With BobCad V-Carve Feature

« on: October 23, 2013, 08:21:23 AM »

I've just finished a pyrography stamp, I decided to do this one in stainless, possibly because I love a good steep learning curve 
The text is 11mm high and 40mm wide -



In this instance for the cost of return P&P I'll mill off the date, giving the couple a pyrography stamp they can use to mark a wide range of things. 

For hobby or low volume stuff an easier to machine material such as brass will be entirely suitable but I've had enquiries from furniture manufacturers and wanted to cover all the bases with the first job.

Things I've learned -
1. Use the option to rough out with a milling cutter, this will save huge amounts of time! It'll save engraving cutters too!
2. Make your stock big enough to allow the entire periphery of the job to be roughed with a milling cutter.
3. For fine detail work post the job twice, the second time with a smaller roughing milling cutter so that after roughing with a suitable milling cutter you can repeat the process with a smaller one and leave less work still for your engraving cutters.
4. Build or buy yourself a cutter grinder for sharpening your engraving cutters, you'll save yourself a mint in the long run 

ATB,
Nick

15

G-Code, CAD, and CAM discussions / BobCad/Cam 4-Axis Standard problem (V25 Build 996)

« on: October 13, 2013, 09:56:47 AM »

I've posted this on CNC Zone and BobCad/Cam Support Forum too in the hope of the best chance of finding someone who's encountered the problem before and might have found a solution -

I spent the best part of a day fiddling with my model assuming there was a problem with the it but then tried 3-Axis options on the problem surfaces and they all worked, potentially proving the model was OK so I started looking at the posibility that it was a software problem.
Has anyone else encountered a problem in 4- Axis Standard (and possibly found a solution) where BC works around any areas of a part below the centre line, leaving large chunks of stock untouched?
With some parts it's simply a case of using larger stock and moving the part to avoid any surfaces crossing the A-Axis centre of rotation and just making more chips. I'm currently working on something nominally S-shaped making it impossible to move both low sections above centre.

Paths generated -

I've experimented with moving the part around and verified that I can move it up or down far enough to get one or other face right. It's possible to vary the ignored areas slightly by choosing cutting around or along the A-Axis, but there are no feature settings that make any difference to the avoidance of any areas below the rotational axis.

Completed simulation -


Any help would be appreciated, even a confirmation that I need to get my cheque book out again ;-)
Regards,
Nick

16

General Mach Discussion / MPGs . . . Questions, Questions

« on: October 08, 2013, 02:30:34 PM »

I have searched and failed to find answers so I'm throwing myself on the mercy of the fine folks on this forum.

I'd like to add either an MPG pendant controller or individual MPG encoders on each axis.
The second option has significant attraction but to be honest I'd settle for anything that gives me a wheel and variable speed rather than a button with the selected jog speed.
If an encoder for each axis is a realistic option that would be fantastic as it would make CNC conversion of my Emco FB-2 based manual benchtop mill a practical project providing me with a comparatively huge envelope for CNC whilst maintaining manual capability and feel,
Any recommendations gratefully received,
Regards,
Nick

17

G-Code, CAD, and CAM discussions / A Simple BobCad V25 Job, or So I Thought!

« on: September 30, 2013, 07:19:35 AM »

I need to make a set of four of these hinge links for my heat treatment furnace -



and decided that rather than manually machining them it would be an ideal job with which to learn a little more of my way around V25 BobCad/Cam (Build 996).
I only made the model with one complete end as I'd be flipping the parts to machine the second side.
The model was constructed from a 90mm x 19mm x 3mm "Cube" with 19mm cylinders subtracted from the ends then a 19mm x 3mm cylinder added at one end and a 19mm x 6.2mm cylinder at the other end to give the projecting feature.
I'd started out by simply adding two cylinders to a cube and then in desperation when nothing seemed to be working resorted to first removing cylindrical sections from the "Cube" (in case there was some unseen complexity with hidden leftovers from the cube messing up the path generation) then adding the cylinders back in.

Pocketing the hole was a breeze, so was profiling the outside of the circular projection, then the wheels came off my cart!
Try as I might I couldn't get any of the available features to to generate a tool path to machine all of the large flat area without either missing some in the centre or ploughing through the projection, all with or without adding boundaries where possible.
Some features created paths inside the circle when the flat surface was selected to machine and the circle was selected as a boundary, where options were available it was possible to get them to flip to the outside but that just replicated the Profile feature and didn't address the flat surface.

I worked my way through all the 3-Axis features that offered a possibility of doing the job and was almost ready to give up and spit the dummy when I tried "Equidistant Offset". It works -



With the same model geometry Equidistant Offset works where all the other features fail, it doesn't need a boundary setting as it recognises the shape of the flat surface and deals with it, I feel sure there should be a feature available to 3-Axis Standard users which is capable of the job, but I can't fid it.  

Does anyone have an idea how this could be done by someone with 3-Axis Standard? It's only by chance that I ended up buying 3-Axis Pro and I feel sure this kind of job must be possible with the basic software and that I must have missed something somewhere,
Regards,
Nick

18

Show"N"Tell ( What you have made with your CNC machine.) / Steel Stamp

« on: September 22, 2013, 02:23:52 PM »

A friend asked if I could make him a stamp with his log to brand some parts he makes whilst hot, he provided the artwork and I made this -



This is what it does on hot steel plate -



I'm quite pleased with the results, I prototyped in aluminium then went straight to the finished item in one multi-pass operation starting with a .1mm cut then .2mm per pass to the finished depth of .9mm,

 - Nick

19

Show"N"Tell ( What you have made with your CNC machine.) / Airsoft Slide Engraving With V-Carve in BobCad/Cam

« on: September 08, 2013, 03:13:53 PM »

I was asked to engrave a couple of slides in Century Bold and Century Bold Italic, I used 30 degree V 1/8 inch engraving cutters running at around 16000 rpm with really slow feed to get clean smooth edges in the soft slide castings.
This was the first time I've used V-Carve in BobCad/Cam and I'm really impressed with the 3D cutter path generation and the sharp, bright look of the cut faces in the letters, I'm afraid my photography has failed to show the detail though





They've now gone for DuraCoat prior to return to the customer.
ATB,
Nick

20

Show"N"Tell ( Your Machines) / Improving a cheap 4th axis

« on: July 07, 2013, 10:12:02 AM »

I bought a cheap 4th axis and found that the backplate and stepper shaft can flex slightly under load.
By adding a couple of bearings on plugs with a bar bridging them the majority of load is now taken by the bar under compression -



The cap in the stepper end is an eccentric adjuster allowing precise adjustment of bearing spacing.

I'd welcome input as to whether a tensioner a good idea now that belt tension no longer applies significant bending moment to the stepper shaft or axis back plate?

 - Nick