Thread: Game on!

  1. #1
    After some lurking, quite a few questions, a lot of sums and some FEA I've just started building my first machine. It's not as big as I really need (I want to cut out large loudspeaker cabinets amongst other things), but I'm having a lot more difficulty finding larger premises than I thought I would. So having kind of got the bug and wanting to get on and do something I thought I'd make a small (but capable) one anyway, the experience will do me good, it will be useful for machining up metal parts and a lot of it will be transferable to the big machine design when I get the space.
    Sorry I've not shared any of the initial drawings, but I don't really do 3D CAD and without being able to turn layers on and off and have the thing in your head, the 2D drawings are a bit of a nightmare to interpret. The design ethos is:
    1) To try to keep all individual deflections of the gantry extrusion/side beams/bed to less than 1um for a 50N cutting force - this has been determined by calculation (thanks @routercnc for the spreadsheet) + FEA
    2) Minimise twisting moments by keeping all assemblies as compact as possible - no massive spindle overhang please!
    3) Keep the number of bolted joints to a minimum.
    4) Try to get a good price performance compromise
    It's being made out of aluminium extrusions/plate simply because I'm able to machine that better and more accurately - and you can anodise it to a nice finish

    Not having any CNC machining capability until it's made, I'm having to "bootstrap" the process, apart from one or two pieces that I need to get laser cut, it will all be done using the trusty Elektra Beckum chop saw, a drill press (Axminster ED16B2) and my little lathe. First job was to fettle up the saw and make a decent clamp for it:
    Click image for larger version. 

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    With a new blade fitted and a few minutes true-ing it up it goes through 15mm plate like a knife through butter. Squareness is about 0.25mm across a 125mm cut, and with a wee drop of WD40 to help the cutting, the cut ends are smooth as a b******s bottom.
    First parts to make were the carriage plates for the Y axis (please note I denote X & Y from the point of view looking down at the front of the machine i.e. the X-Axis runs L to R along the gantry):
    here's marking them out using the trusty optical centre punch:
    Click image for larger version. 

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    Last edited by Voicecoil; 3 Weeks Ago at 09:51 PM.

  2. #2
    I've found time to do a bit more on this in the last few days, firstly got the gantry extrusion fully end drilled and tapped..... it just fitted under the pillar drill with 15mm to spare
    Click image for larger version. 

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    talking of tapping I soon realised that there were going to be A LOT of holes to tap and if I wanted to save a lot of time (and avoid w*****s cramp!) machine tapping was the way to go. Tapping machines looked a tad expensive for the moment, thought about changing the motor of the pillar drill to give a quick reverse function, but some bits were on a couple of weeks lead time.... then I tried one of the Europa tool interrupted-thread spiral point taps:
    Click image for larger version. 

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    These seem to require a lot less tapping force than anything I've tried before and seemed hence offer up the option of tapping with a cordless drill (which convieniently has a torque limter to stop breaking taps, and a reverse to extract them). In order to keep things straight I added a circular level to the back of an old drill, using the pillar drill and a length of tool steel rod to get it properly level whilst the glue dried.
    Click image for larger version. 

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    With this and a known flat surface I seem to be able to tap holes pretty straight and all for the outlay of a 1.80 level off the Bay of fleas; and you can do it in large pieces that wouldn't fit under a normal pillar drill.
    Last edited by Voicecoil; 3 Weeks Ago at 09:49 PM.

  3. #3
    Quote Originally Posted by Voicecoil View Post
    In order to keep things straight I added a circular level to the back of an old drill
    Nice bit of customisation! I've taken to using a guide for my taps to pass through; find a block of something (wood, aluminium) that is about as thick as your tap is long, minus 1cm and the length of the square drive section. Using the pillar drill, put a guide hole through the block - diameter to be as close fitting as to your tap as possible. Now you can place this block up against the surface you're going to tap, passing the tap through for the first bit of the hole - hey presto, nice and straight tapping every time.

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