View Full Version : Machining odd shapes on a denford starmill

29-11-2010, 12:20 PM
Hi all 3416This is a trigger from a woodwork clamp.
It is not so clear but the noes or top right hand bit has broken off.
It is made of a cast type plastic good smooth outer but honeycombe on the inside.
So I have been asked if I can make new handles. Yes I can make them but new to cnc so not sure how to get this shape into the Gcode as is needed.

can anyone offer some good advice please.
this is a bigger pic well it was ment to be lol can not seem to get it to the right size.


29-11-2010, 12:42 PM
Yes I can make them but new to cnc so not sure how to get this shape into the Gcode as is needed.

You need 3d cad/cam to draw/scan and generate the Gcode. This type of software does not come cheap.

How many do you want to make ?


29-11-2010, 12:52 PM
around 6 intotal I have the ally sheet to do it with lol its just the chair keyboard interface that is a bit dodgy. I have solid works and solid Cam but dont know how to use them really yet they are so complicated.

29-11-2010, 12:59 PM
From the photo it looks like it's basically flat with pockets cut out, if so, I'd do it this way...

Photograph it next to a ruler (make sure you use a longish lens and are square to the object to minimise distortion) or scan it.

Load the image it into inkscape and trace round it manually - also create a box 1cm long by tracing the ruler.

Export from inkscape in DXF format and load that into Cambam.

Clean it up in Cambam (may need to resize using 1cm box as reference), define machining operations and generate the gcode.

Inkscape is free, Cambam is reasonably priced and you can use it quite a few times before you have to pay for it - should be plenty for this project.


29-11-2010, 01:12 PM

FatFreddies suggestion involves two more software packages, he didn't look closely enough to see that the inner edges have a radii

And you will not be able to reproduce those shapes using his method as a rounding over cutter will not go into the sharp corners.

So the only true way is 3D, it seems you already have the software so you must learn to use it, if you have a funny version it is hard to ask questions without being asked questions if you know what i mean.


29-11-2010, 01:20 PM
No Its a Student version I am doing CNC operator at college waiting to get on the CAD CAM course. To make it easy I was a blacksmith untill an accident in 200 this left me disabled I retrained to computer networks and have done that for a few years but really miss making stuff and fixing things. So I have just been made redundent and with money bought two machines lathe an mill both denfords from I2I on here he is a great bloke and the support is out of this world with what he has done for me. Oh and no he is not paying me to say this I belive is say good where it is not just slagging people off too many complain but never enough praise where it's due these days.
The molded shape is not needed just the nose top right and the hole ir the main datum bits the rest as long as it works and is near this shape great.

29-11-2010, 01:40 PM
Kai if that is the case you could do it the way FatFreddie mentions, but you really need to learn to use what what you already have as that would be best for you in the long run.

It may be better to ask if there are any solid works users on here that could help you to get the part under-way

Some software just doesn't work for some people yet others find it easy and vice versa. I dont use solidworks so cant offer any assistance in that respect.


29-11-2010, 02:27 PM
PM Sent


29-11-2010, 02:42 PM
You could use solidworks to trace the part if it can import an image to trace or use inkscape as I described and then import the DXF into solidworks. I've used solidworks in the past and it's a great program but it does take a bit of getting used to. No experience of solidcam I'm afraid.

Alternatively you could measure it carefully and create the sketch in solidworks from the measurements.

If I remember correctly, you'll need to create a sketch of the outline and then extrude that to the thickness of the plate. You then create sketches on the face of that part to define the holes / pockets / counterbores and create extruded cuts from those sketches. I'm not sure how solidcam works but in cambam you would then use the outline to create a profile machining operation (MOP) and then the other shapes to create pocket or drill MOPs.

29-11-2010, 03:44 PM
Got the PM thanks M250cnc I will call you as soon as my parents leave lol I'm nearly 40 and they still think I'm there little blue eyed boy (monster)
In my case lol if its too late I will try to make it wednesday as I have to take the car for new brake lines oh joy and exspense.

29-11-2010, 06:02 PM
Got the PM thanks M250cnc I will call you as soon as my parents leave lol I'm nearly 40 and they still think I'm there little blue eyed boy (monster)

It will be difficult as i did not give my number.

Sending another PM

30-11-2010, 12:45 PM
is it possible to export a drawing from sketchup ?

30-11-2010, 09:12 PM
There is a free plugin that lets you export an .stl file

The pro version of sketchup has lots of export options

01-12-2010, 01:09 AM
Thanks Pavlo I have got an iffy copy to see if it will do what I want if it does then I will buy it.
M250 I will PM you tomorrow been a bad day here in Hull with the weather and the wife getting stuck at work lol.
Had another quick look at it tonight I got the immage into a polly line from inkscan and looked at a trial version of CamBam it took the image and it works just to flaming big and no real easy way to resize it.
I know I am new to all this but bloody hell there has to be a better way to do this or we as a comunity need to look at putting a knowlage base together for people of all skill leavels.
I know this is an old topic but we need to start saving the how to's of skills that are being lost on the whole I worked in thin plate welding and a little forge stuff and even now the basics are being lost just my rant sorry.
Just a quick one does anyone know of a how to site for engineering etc to avoid the loss if these skills?

Also anyone know of some idiot tutorials lol for me? I really want to learn this due to me having two machines sat there waiting to earn me money lol so I hate giving in call me stubbern but I'm sure with a little gental to moderate prodding I can do it. Famous last words hehehe.

01-12-2010, 11:26 AM
Resizing in CamBam was a bit of a pain but that's been fixed in the latest beta release - what version are you using?

If you want to post your CamBam file here I'll have a look at it.

The CamBam site has some tutorial stuff...



There are also some very helpful people on the forum...


You might find it useful to go through the process of building this with CamBam since it looks like SolidCam uses the same principles (pockets / profiles etc) but I think CamBam is one of the easier CAM programs to use. I know it took me a while to get my head round SolidWorks so I suspect the combination of SolidWorks and SolidCam will be quite daunting.

01-12-2010, 03:14 PM
Ok the first is the dxf the next is a .nc so you will need to rename it(I can not seem to get the add files to see the .cb extentions)
The names of the files is as so
these are for the next two files from camba
sorry its so stuffed up new to all this :redface:

P.S thanks for all the help on this I know it would be easy to ask someone else to do it but then I would not learn anything or where I am getting it wrong.

01-12-2010, 03:59 PM
trigger.cb (the .b1 file is just a backup) looks pretty good - have you tried machining it?

You could replace the two circles (imported as polylines) with CamBam ones but it should work ok as is.

The drill MOP needs to be deeper than the material by a couple of mm.

You might want to put some holding tabs in the profile.

The triangular pocket won't be too accurate with a 6mm cutter but it's probably only there to save plastic so I wouldn't worry about it.

The feed rates are very low - 25 for plunge is ok but 200 - 300 (or more depending on your machine) would be better for cutting otherwise the tool will rub and wear quickly. What are you using as a controller? It should allow you to alter the feed rate as you cut so you can start off slowly. It should also show you the tool path so you can check that it's sensible.

For test runs I often use MDF and a router cutter or an old slot mill. For the very first runs you can just cut in air with your finger on the emergency stop button if you're not too sure about it :)

You can get a better picture of the part by rotating the view in CamBam (alt + left mouse button by default)

I've attached a copy of the file that I've had a quick go at to demonstrate some of the above.


01-12-2010, 09:33 PM
Thank you so much. I have just got half a dozen bars of soap that will go in the vice I have they are bigger than the job so there should be quiet a big outline left round the side. This is the very first thing I have made comp wise to send to the machine.
I have a denford starmill the small ones that schools used to have. The controler is mach3 I have done a few dry runs with it and so far the code looks good so fingers crossed

02-12-2010, 12:15 AM
Well I started off well then I put the job in the wrong way round lol so used to the machine at college thats huge hehe not my little one at home.
In the end I did triumph and got some shapes cut is a bar of soap I was so chuffed it was untrue.
Too late to get pics sorted but will get some tomorrow and post them for you to have a look at I am even starting to understand the gcode lol never thought I would.
Thanks to all that helped me start.

02-12-2010, 05:52 PM
Well this this is my bar of soap lol.
I did not do the outer profile last night just the inner ones.
I had a little trouble with the set up of the machine and set the Z too low.
When done it should look like the black bit of plastic lol I wish