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Computer Aided Manufature?

Discussion in 'Luthier's Corner' started by Techmonkey, Sep 4, 2005.


  1. Techmonkey

    Techmonkey

    Sep 4, 2004
    Wales, UK
    I'm building a 5er for a GCSE exam, which I'm doing all at school in the D and T labs... They've got thousands of pounds worth of equipment there, including a couple of CAM (Computer Aided Manufcature) machines... One of them is basically like a large triangle which pulls the material forwards and moves a knife type blade left and right through it, like a printer, for cutting things like vinyl and card, and that's about A5 size... The other is about A4 sized or smaller, but it uses a drill bit to cut through materials (I guess it would be possible to put a router bit in it too) as strong as steel or aluminium.

    If I used AutoCad to make the body shape to scale could I cut a template out of aluminium in 2 parts and bolt them together, and just stick that down to my body blank and use that as a router template?
     
  2. The capability of the machines in your shop there should be well understood by the instructors. I would check with them when considering the possibilites. Have all of your material specs (thickness, temper, finished size, etc.) in hand for this chat because that's the whole ball of wax right there. Even if the machine appears to be a heavy duty device, it may still not be up to the side loads exerted when cutting plate aluminum or even hardwoods with plunge mill bits. The drilling you mentioned is a relatively light duty task that doesn't take much beef to accomplish. There is also the need for a coolant to be applied to the contact area when cutting metal and that will cost a little money if there isn't a system in place already. Then there's the need for vacuum clearing of the waste material. If your machines are only cutting films and doing light drilling and don't have this system, you'll have several hours of cleanup from the chips and slivers generated by the cutting process. Of course these little tidbits will be extra sticky from the coolant they've all got on them!

    I've done quite a bit of this type of work and can tell you that it isn't an easy thing to convert a machine to do this task without some large expenditure and permanent alteration of the existing systems. Of course if you can get your instructors to go along with it then full steam ahead my man! :bassist: You'll have some great fun - there's nothing like watching aluminum get milled out in shapes before your eyes. But I sort of have my doubts that the school is going to spring for the extra's if they don't intend to use the capability in the future.
     
  3. Techmonkey

    Techmonkey

    Sep 4, 2004
    Wales, UK
    [​IMG]

    I'm fairly sure that's one of the machines in the lab, the one that cuts vinyl and card... As for the other one, I'm not sure of the model or anything, but it looks something along the lines of this:

    [​IMG]

    As for width of the aluminium? Well I'm not entire sure about that actually - I've only ever used a drill press before, I've never used a router, and definitely not with a template... So how thick should it be for using as a router template? I'm not entirely sure about the school's routers, I've never seen them before, but I'm going back to school on Tuesday ( :bawl: ) so I can pop down and ask about them then.

    As for the body dimensions, Larry cut me the blank extra thick incase the glue creeps, so after gluing the body blank I'm gonna use the thickness planer to bring it down to about 1.75 "
    It's 22" long, and 16" wide. I have a few different body designs, which I made to scale as much as I could on the graph paper I was using, I'll try and scan them in and post them on TB soon - They're all about an inch thinner than the body blank, and half an inch shorter... So it would be fair to say the body could be about 21" by 15" in the largest possible places.

    As for the machines themselves, I'm fairly sure they both have extraction, as there's a huge extraction unit in one of the DT rooms that connects to all of the equipment through air ducts. However I'm not sure about a cooling system - I've seen one of the DT technicians cutting a sheet of metal with the machine in question, and so far as I could tell he didn't need to do anything special to the machine, so I assume they've already modified it... But I can't be sure till I go back to school. Soon as I do, I'll post some more accurate information.

    Edit: Whoops, just realised I've spelt "Manufacture" wrong in two different ways, once in the title and once in the first paragraph of my first post. Sorry! :p
     
  4. You won't have to ask about either of the two machines illustrated - neiither are of the type that will do the work you are looking for. The one on top is a vinyl plotter - I have one here at the house - it's a light duty machine designed for just what you've noted - cutting vinyl film. The second machine is an engraving machine for etching and engraving most any material. It's not big enough for cutting materials thicker than about .050" in a single pass and isn't suited for much in bass building other than making pickguards.

    The machines you'll be looking for are going to weigh in the neighborhood of 4000-10000 lbs and take up a room in most cases. You won't miss them. Our router at work can hold a sheet of material 5' x 10' and is better than 6' tall but the machine is closer to 7' x 12'. The 5 hp router motor alone costs over $20k! It can cut 1 1/2" hard maple with a 1/4" bit in a single pass at about 2"/second or better. That's the kind of power we're talking about needing here. There are smaller tables and they will do a fine job too but they will require smaller bites and multiple passes.
     
  5. Techmonkey

    Techmonkey

    Sep 4, 2004
    Wales, UK
    Ouch! So much for that idea! I guess I could just use the vinyl plotter, stick some vinyl to a spare piece of 0.5" thick hardwood, bandsaw the rough shape around the vinyl, then clean it up with a file or drum sander or something, then use that as a template for a plunge router?
     
  6. That's one way to do it but it's a little wasteful and doesn't give you the best results. Here's how I do it here at Hovel de'Hambone - Do a really complete 2D drawing of your bass in your software with all dimensions and details drawn in full scale. Make all of your production notes on and around the outline of the instrument with callouts to the important parts. Then plot this drawing on white plotting paper for adhering to your work pieces. I would even plot several to be able to cut up and put the different pieces on the seperate neck and body blanks you'll be using. Then you can cut them on the bandsaw. With the paper plot as your pattern, you'll have an inside and outside line visible AND you'll have hole patterns with drill points and the various measurements already printed on your workpieces. I keep these patterns glued to my pieces for as long as I need while I work on them. Only when all of the details have been attended to will I remove the pattern and move on to another aspect of the build.