Thread: Men's Shed Router

Originally Posted by electrosteam

Although we will be using Cambam in the shed,

I realise you are on your own path, but having used Cambam a couple of times (including once where its code suddenly sent the router nuts and crashed the tool through the side of the work), I'd strongly suggest you look at Fusion 360 - it's a production-grade tool that's free for hobbyists and is a much more refined piece of software with excellent simulation features.

John
The text progam I could not think of yesterday you can find at
NCPlot - Stick Font

It was a good day with power meltdowns, fire evacuations, and that is just in the 2 hours I was there. You do have a lively men's shed there....

Thanks for the hint about a possible UGS command string to clear the Arduino cache/buffer/RAM, if it is there we will find it.
We already tried the button 'Soft Reset'. but my memory is that it did not stop code execution.
We already have a 'big red button' to kill power to the steppers.

On Cambam, the Shapeoko Forum is currently running a 3D CAM poll.
Of 171 recorded responses:
- 28% Commercial other than Cambam,
- 25 % Cambam,
- 23% MakerCam,
- 8% Hand coded,
- 5% HeeksCNC,
- 4% PyCAM,
- others.

These results show that commercial products dominate the field.
Fusion 360 does not specifically list because the poll was apparently started before this option was significant.
We are using CamBam simply because that is what we were given, as we gain experience, we may change,

For the dxf2gcode and Camotics route, this is developing into an acceptable option.
But, advice on Fusion 360 has been provided on several occasions, and we will explore that route also.

Rusel, yes it was an interesting few hours.
Thanks for the link, it looks very attractive for special effects.
John.

Rusel joined us for another interesting few hours.

No apparent equipment malfunction.
Quite a few trial runs of hand and computer generated code clarifying various issues.
It is obvious that efficient hand coding requires a good editor with intelligent search and replace.

We downloaded and installed Camotics to provide a quick simulation of the code.
It worked fine and avoids the shed using up any of it 40 free usages of CamBam.

Final cut of the day was part of a proposed simple insect made from a few shapes into a desk ornament about 75 mm long.
The platen scored its first scars and the code will be revised to add some tabs.
With 3 mm MDF, we think two tabs 0.5 mm thick by 5 mm long should be adequate.
Hopefully, a complete insect will be demonstrated at an open day at the shed next week.

foobillious, I looked again for a clear buffer command, but not found.
I will try your %% command next week.

In UGS, there is another mystery, operating all the resets leaves the Z machine position displayed as 15.002 mm.
No available control will set it to 0.000 but, starting with the cutter hand manipulated until it touches the job surface for Z = 000, good code runs fine.

As a parallel issue, I am trialing dxf2gcode at home with success.
But, one of the configuration parameters set for a cutter is the 'Start Radius".
This parameter does not seem to do anything, and there is no documentation available (certainly in English).
Can anyone enlighten me ?

John

"But, one of the configuration parameters set for a cutter is the 'Start Radius".
This parameter does not seem to do anything, and there is no documentation available"

I am not familiar with the software that you are using but most CAD/CAM software create a circle with arcs so there are usually three numbers separated by commas ie 100,0,360. The first number is the radius, the second is the start point and the last is the end point. A circle has no start or end so most gcode is generated using three arcs.

I use Cambam because of all the CAM programs that I tried out it had the easiest learning curve and a very active forum that already had most of the answers to questions that I had. I gave up on Grbl as it was too complicated to get to work, was finicky and the Uno hasn't got enough ram to pause and backtrack the gcode to correct any errors and couldn't handle a long enough debounce to correct stuff like limit switchs and homing and I couldn't get it to work with more than one home position.

After spending nearly a year to build the machine without ever actually have seen one in real life I just didn't have enough hair left to pull out to limb the control processor mountain as well so opted for Mach3 and blew the dust of a old XP machine with a parallel port. It isn't exposed to the net so no firewall or antivirus and with only just the necessary files to run it she goes like the wind, can be controlled by a $25 wireless mouse and keyboard with the push wheel but also an estop.

The Cambam soft also has a very capable CAD package and I have even done 3D stuff with it but 2D and 2.5D is easy to learn. Solid Edge has made their 2D draughting program free now and has excellent tutorials on Youtube but I don't use it much now, the one in Cambam works for most that I have tried so far.

Camotics is a good soft as well but not as detailed as Cutviewer but at the price good enough although if I am not sure then air cuts are good to avoid bending shafts on spindles or breaking tools because those small DC spindle have a long shaft with the ER11 collet holder on the end and where the shaft goes through the lower bearing it drops down to 6 mm so bending them is easy and impossible to straighten without runout and vibration so I changed mine over to a Makita trimmer. That has enough power push a 6mm endmill through a 6 mm piece of perspex in one cut at 1200mm per minute.

Good luck with your project, I think that you will find that the spark that is ignited already will a rapid acquisition of skills as already noted by an earlier poster, there is nothing like the look on your grandkids faces when the see their name engraved in some flambouyant exotic script on a piece of edge lit perspex with blinky lights.

There is a Men's Shed just opened down the road from here and as today was my last day of working for a living I might wander down there and have a look.

Originally Posted by electrosteam

Quite a few trial runs of hand and computer generated code clarifying various issues.
It is obvious that efficient hand coding requires a good editor with intelligent search and replace.

what are you currently using?
I've found Microsoft word to be a very strong text editor -- there's ways to identify and edit paragraph and line breaks

Originally Posted by electrosteam

In UGS, there is another mystery, operating all the resets leaves the Z machine position displayed as 15.002 mm.
No available control will set it to 0.000 but, starting with the cutter hand manipulated until it touches the job surface for Z = 000, good code runs fine.

does the Z position always return to 15.002 mm?
if yes, then the "control" to set the cutter to an apparent Z = 000 would be to move the cutter to Z = -15.002

(by default I'm starting to learn something about machine control ...
your Z = 15.002 might be the default tool height used when moving the tool between cutting positions. In which case ALL cutting operations will need to include commands that plunge or ramp the tool into the work.

Originally Posted by electrosteam

As a parallel issue, I am trialing dxf2gcode at home with success.
But, one of the configuration parameters set for a cutter is the 'Start Radius".
This parameter does not seem to do anything, and there is no documentation available (certainly in English).

have you tried using google translate?

Found this https://wiki.nottinghack.org.uk/wiki/YooCNC

Tool correction:
Tool correction is set with Tool Diameter and Start Radius. By default, the CNC will treat each line in your drawing as the centre of the cut. Obviously, you're not using a cutter of zero-width, so that would be useless for making precise parts.
One way to compensate would be to redraw your DXF, painstakingly tweaking, scaling and repositioning everything to allow for the width of tool you'll be using. That though would be laborious, and each drawing you made would be useless for cutting with other tools.

GCode allows you to simply set the tool width and define whether or not the machine cuts to the right or left of the line.
In DXF to GCode, set the tool diameter in mm at the top left of the settings pane, then right click (Windows) or middle click (OS X) on the lines you want to set the tool compensation for. Select "Set Cutter Correction", then pick the corresponding GCode:
G40 - Acts as a cancel command for G41 or G42. No correction, the centre of the tool will travel down the centre of the line.
G41 - Left of the line.
G42 - Right of the line.
To visualise what G41 and G42 do, imagine you're driving a car around a giant version of your drawing. Left and right correspond to left and right relative to the cutter direction of travel, not the work area or your CAD drawing.

Each shape, when selected, will highlight red and show arrows indicating cutter direction of travel (Blue: start of cut, green: end of cut), tool compensation (If any, blue arrow tangential to the cut line).

Start radius:
Will influence the run in that the tool takes for the cut, shown on the mark by a curved blue line curling into the cut.
If you want to do passes of multiple depths for different lines, this may require multiple G-code files. You can use the same DXF file to export separate G-code files for each depth.
(If you learn to edit G-code or use a more advanced CAM program, you can put all of this in one file).
Start at X [mm]:
Start at Y [mm]:
These set the start point for the tool. LinuxCAD does not like minus values for X or Y moves, so I advise leaving them at 0,0 and planning accordingly in your CAD drawing.

inr700x,
Thanks for the comments and best wishes for your retirement - you will find the shed to be a wonderful environment.

ian,
Your descriptions of start radius match what I understood to be the case.
One particular application I discovered is with a plasma cutter cutting a large circular pocket in a steel plate.
The start/end radius allows the torch to enter the plate away from the design path and curve into the cut, while the end radius does the same at completion.
But, my observations with dxf2gcode is that there is no evidence of such in the generated code.

My description of the Z problem was lacking in clarity, and now I am a bit unsure of what we did.
Let me check it again next week.

John

Tracked it down, SourceForge has a Wiki on dxf2gcode.

Start Radius us only used when G40 is coded, the CNC machine then does cutter compensation on the fly.
My assumption is that dxf2gcode codes a Start Radius move first, then along the line in the dxf file.
The addition of the Start Radius code would presumably give the machine the opportunity to begin the compensation.

As our machine with Grbl does not do any cutter compensation, we code G41 or G42 as appropriate, and dxf2gcode codes the line with cutter compensation, and no Start Radius.

I will do some trial code generation later today.
John.

It was good to see the cnc come to life and cut a product out, admittedly only a test part, but it was correct. This gave all encouragement to go for it.
Hope you get it all together for your open day next wednesday.
At the moment I have another engagement on that day so I will not see the swarm of ants coming off the cnc.
Rusel

Originally Posted by electrosteam

Your descriptions of start radius match what I understood to be the case.
One particular application I discovered is with a plasma cutter cutting a large circular pocket in a steel plate.
The start/end radius allows the torch to enter the plate away from the design path and curve into the cut, while the end radius does the same at completion.
But, my observations with dxf2gcode is that there is no evidence of such in the generated code.

I would not expect any

as I understand the coding, gcode is the commands describing the tool path which are issued to the CNC's internal control software .
(dxf2gcode is a software suit that "reads" a CAD drawing file -- dxf file -- and converts the lines and arcs into commands the CNC's controller then interprets to move the cutter head. Note it's the cutter head which is moved, not the cutter itself which can be any size radius and length -- these parameters being set via G code parameters.)

I can see the start and end radii being useful for keeping any burning or blow out where the tool enters the material in the waste rather than on the cut line.

I note -- "It is common practice to bring the tool in rapidly to a "safe" point that is close to the part—maybe 0.1" away—and then start feeding the tool."

I have confirmed that dxf2gcode only codes a start move, short straight plus a short curve based on the nominated Start Radius, when the machine is nominated to do the cutter compensation with G41/G42 as appropriate included in the code.
If dxf2gcode is nominated to do cutter compensation, G40 is coded, cutter compensation is included in the code and no start move is coded. There are then no G41/G42 in the code.

We discovered we can get the machine to (0,0,0) on the Universal Gcode Sender control screen by turning Off the serial link (USB) between the laptop and the Arduino, selecting machine control on the UGS screen and turning the serial link On.

We tested the UGS macro facility and demonstrated that multiple commands separated by a ";" do process in turn.

We got one job done for a member, a short name on a decorative board but sorry we did not get a photo (next time).

The insect shape caused a bit of grief.
We lost X-axis steps on a couple of occasions, but no cause found and it did not repeat.
There was an excessive Z move into the platen at the start - traced down to the nominated clearance height of 15 mm driving the Z-axis into the physical stop, so that subsequent -Z moves were too deep.
Fixed by moving the spindle on the carriage.
The Z-axis limit switches have not been fixed yet.

The final cut of the day was part of our insect, very successful with tabs (added by hand ) included.
We are making progress.

John

Oh man I'm so glad I don't have to work in G-code...

Another software tool you may wish to look at is G-Wizard. This is a speeds and feeds calculator that helps you work out acceptable depth of cut, stepover, and feed for a large variety of cutters and stock materials.

Initially I was doing these calculations by hand for my little Taig CNC mill but when I found the program gave me results that I could rely on pretty much first time every time (which is a useful attribute for CNC work) I decided to stump up the cash. Originally aimed at commercial high end heavy metal, the program has been enhanced in recent years to provide sophisticated calculations for low powered machines and setups lacking rigidity which is a huge advantage for us users of gantry routers and desktop mills.

There is a one month full featured trial available.

At first I thought I was doing the right thing by toughing it out and doing feed calculations from first principles but since I have started using G-Wizard I have have been much more confident in approaching new (for me) materials and cutter types and broken cutters and excessive cutter wear due to rubbing have become a thing of the past (well, I still get fat finger breakages when manually positioning at the MDI window but thats another thing). The site also has a wealth of useful information to explain the mechanisms of capricious cutter breakages and premature cutter blunting.

No financial connection, just a satisfied user.

Even if you decide not to buy, you will learn a heap during the trial period.

PS In your surfacing programs (hand written) I would tend to use a much lower feed for the plunge operation (ie don't make it the same as the feed for the surfacing) - wood router bits may plunge better than end mills but I suspect plunging is still a stressful operation (just my intuition - I haven't confirmed this).

McDuff,
Thanks for your comments, we will follow up the link for feeds and speeds.

We have eventually achieved our first real job, see attached photo of an insect about 180 mm long made from 3 mm MDF with a 3 mm single flute cutter.
Much celebration and joy, members are now actively seeking other similar jobs.

I am pleased to report that we got to this point with only a failed stepper power supply.
No broken cutters or damage to machine.
But, much work to do before we could claim the machine is commissioned.

We can control our machine, but we do have to occasionally power down, disconnect the USB comms link, move the machine manually to our desired start position and power up again to get all work coordinates and machine coordinates to 0,0,0.
UGS (Universal Gcode Sender) and Grbl have reset features, but not sure yet if they are complementary.

Ant1 Prototype 22Jun16.JPG

The spindle motor is 24-52 Vdc, 2000-12000 RPM, 400 W with an ER11 chuck.
John.