Tuesday, September 28, 2010

How to Tell Me What You Wanna Cut

CNC Cutting Service is new to local customer. In almost all cases, guiding the customers to provide information to fulfil his/her needs is a must.

Obviously, saying "YOU DESIGN, I CUT" is not even close to enough information...

Similarly, "I want a cabinet", "I want a chassis", "I want a box" are not specific enough too...

In this article, I will go through what I find helpful to a meaningful transaction.

All I really need is a clear idea of what you are after.

These tips may seem pretty basic but they can save you time, and money.

  • Send something in writing:  Email, or Letter is fine, or just Email an image.
  • Don't spend to much time on plans to start with, a quick sketch or photo of what you are really after plus if needed a chat on the phone will cover most thing.
  • It's better to get a rough sketch to us sooner than a fine drawing later.
  • If you want simple shapes like circles, rectangles, triangles or quadrants, a simple list with radius or diameter and the thickness plus quantities.
  • In a perfect world we like longer lists on an excel sheet with each dimension in a separate cell. If you don't know what I'm on about ignore this.
  • prefer sizes in millimeters but if you happier with inches or centimeters please state which. We just need to understand what you want. 
  • If you can send a CAD drawings or vectored files please do.
  • If possible put all parts, and instructions on a single file.
  • If your not a CAD person don't worry we can still read Bits of paper,  Word Doc's, PDF's, JPGS, Spreadsheets, etc. 

    Tips to sending CAD files for CNC routing machining

    • Importing from Apple Mac vectorworks can still cause problems but it is very rare
    • It's always a good idea to also send a PDF file so we can check against the CAD file, which can sometimes be corrupted when converting to our CAD/CAM software.
    • Intersecting curves, and lines need to connect.
    • Lines on top of each other can cause problems.
    • We can sort these things out but if their are a lot of curves or shapes it can be very time consuming.
    • Scale should be 1 - 1 full size. Not vital but a good idea.
    • We machine from files in millimetres so millimetres are preferred.
    • Polylines with thicknesses should be set to thickness zero.

    2D Files

    • All the parts on a single of CAD file grouped in material, and thicknesses.
    • If we have 20 or 30 individual files to handle it's harder to get an over view for quoting, and key file can be missed.
    • Notes, and details on the file are very useful. Files can be loaded on different computers stations, and emails, and note become separated.
    • Using layers for groove depths board thicknesses different hole sizes an be very useful.
    • Early version of DXF, and DWG are can be more reliable than the latest version.
    • When we transfer data via DXF we will use version 13 or 2000 if possible.
    • We find DWG slightly more stable than DXF.
    • If you have a 3D model it is always useful for getting an over view.
    • It can take time to convert a 3D file into a 2D file so send the 2D file as well.

    3D Files

    • We Machine with V-Carve Pro & AutoCad for preparation
    • We can take most 3D Solid and Surface files.
    • Mesh files like STL can loose definition when the parts are large.
    • An indication of the block size is always useful.

    Tips for Adobe Illistrator users sending files for CNC Routing.

    • If you can send the file as PDF as well it can be a great help.
    • Files can sometimes change when tranfered to other programs. PDF's give us a visual double check.
    • It's a good idea to put scale reference like a 500mm square with a dimension on the file with free flowing shapes. Some time's the scale will change when changing from Illustrator to CAD.
    • We can import Adode Illustrator so machining directly from your files is possible.
    • If you want text machined explode the fonts to turn them in to graphics. If you send text as fonts, and we don't have your font a different one will be substituted, and your elegant font can come out as Helvetica. Again a PDF can give us a quick double check.
    • Send the your file as an Adobe Illustrator file not as a DXF.
    If you use Illustrator to convert to DXF curves can be broken into small steps that take up a lot of space, and lose accuracy.

    Examples of files for CNC routing

    • We like all the information on a single file.
    • Some times the file becomes separated from the Email.
    • From starting to writing the CNC machining program takes just a few minutes.
    • This saves time, helps prevent error's, and keeps setup cost to a minimum.

    This example shows material, holes numbers with detail, and a couple of dimensions.

    This job was more complex but the principle is the same.

    CAD drawing of parts for a 10 metre boardroom table

    We grouped the different thicknesses of MDF in to boxes.
    The 12mm MDF (bottom left) was used a templates for the veneer.
    The narrow strips are templates for the Hardwood edging. (top centre 25mm box)
    25mm parts are machined upside down with work top key hole cut outs.
    This may seem a bit chaotic

    I sincerely hope that the above information is helpful to you like they are useful to me.

    Any comments are welcome. Please feel free to comment. Need your comment to horn my communication skill.

    Pleas Please Please!


    Friday, September 24, 2010

    How to Vectorised Artwork from Photo & Scanned Images

    CNC work with vector files, eg. file extension such as .svg, .dxf, .dwg, stl, ai....etc etc

    Normal digital photo or scanned images are in raster format, eg. file extension such as .jpg, .png, .bmp

    There is an easy way to do it using free open source Graphic Editing software call InkScape.

    I wanted to produce a video tutorial but I quickly realised there are plenty smarter people with sexier voice & production skill... hence this wonderful video tutorial...

    The first 7min 30secs is what I use exactly for my CNC work... Then save the result in .svg or export as .pdf.
    *ps, some times, "edge Detection" yield a better result... but there are no fix solution, its really all about trial & error.

    This is for color pix

    So now you know how to capture vector graphics using Digital camera, Scanner & robbing pix from the net...

    Relief Carving

    Tuesday, September 21, 2010

    Put em Togetter

    This is one of the easiest combination of joinery I use.

    My vocab is not good enough to describe

    Hopefully the pix can say it better.

    Do you get it?

    Digital Wood Joinery Lesson No.3

    Finger join is another of my favourite. Practical & aesthetically pleasing to my eye.

    Picture tells a thousand word... let the pix talk...

    I would love to post phot of this but I have yet figure out the way to make onject float in mid air...

    Friday, September 17, 2010

    Digital Wood Joinery Lesson No.2

    The 3D illustration isn't as clear to some readers as I wish they are so here is a 2D figure with a few more varieties of tong & grooves which I like to employ in my designs.
    The Magenta vertical blocks are the various varieties of Tong (male) & the bottom horizontal Cyan are the Grooves (female).
    the 1st & 2nd on the left is the simplest form which are my favourite.
    the the 3rd requires turning the job to cut  both sides of the tong hence I rarely use it.
    The 4th, 5th & 6th  are great when I want to show off how my stuff snaps on perfectly... :D
    The grooves are usually half the wood thickness & the narrower tong of the 5th, 6th & 7th are normally half the plank thickness too.
    With CNC precision & cut quality, I usually design the tong to fit the grooves exactly, no need for small clearance/allowance for adjustment during assembly like traditional carpenters do.

    These Tong & Groove Joints are self-reference, holding themself up when assembled & you don't need set sqare to square them up or clamps to hold them on. A few tander knock will persuase them to mate up nicely.

    Wednesday, September 15, 2010

    Digital Wood Joinery Lesson No.1

    Wood joinery is a priced craft.

    Traditionally, any carpenter will feel insulted if you say he nail up his work...

     Deep inside, I too feel humiliated without implementing some sort of wood joints in my personal projects.

    The RED & Blue are simple butt joints... I don't feel proud when I use them....

    The Magenta & Cyan are tong & groove some call it tenon & mortise... this is the least I'll have in my personal projects.

    Another modern woodworker's must have is PVA glue, commonly called wood glue or white glue. It is a water based glue that will not break before the wood fiber tears... great for indoor use.

    A properly glued  joint will take all the abuse you can throw at it before the wood itself give way...


    Thursday, September 9, 2010

    CNC-ed Stools

    Kenneth & Gabriel threaten to boycott me if they don't get a chair to seat on their next visit to my shop... :(

    Buying chair for my shop use just isn't me... Too lazy to hand build some chairs... Procrastination sets in when it is a non-paying design job....

    There must be plenty of free chair plans available in the net... so started strolling mindlessly across the WWW....

    One will find when one seeks.
    A nice stool design in the project page of 100kgarages. I like what I saw here and downloaded the free cad files immediately.

    Unfortunately, I can't cut it as it was designed for 3/4 in thick Plywood but I only has 18mm thk MDF. Some customisation is require... but hey, having a free download already save me from loosing gallons of brain juice... can't complain over that...

    Without further a do, open up the CAD file, changed the slot & finger joint size to suit the 18mm thk MDF I have, It is always a goof practice to double check the actual thickness for both plywood & MDF before working with it as they can very as much as 3mm... A good a verneer caliper reads 17.4mm averageof 5 readings...
    To prevent any possible infringment of trademark of the Makers & the Shopbot, I  removeg their logo from the stool panels just in case & pop in some simple graphic pattern? The added bonus is reduction in weight :)

    Then pop the modified CAD file into my CAM program, do some careful tool bit selection, tool feed rate, put in some tabs & G-code is ready for my Mighty Blue Beast.
    Load up the MDF sheet, calibrate the positions, turn on the dust collector & I'm off for an extended coffee break.
    The stool parts are completed & ready for assembly when I return...
    As usual, everything snap-on perfectly.... ;)

    This should make Kenneth & Gabriel happy on their next visit ;)...