New Build Log ... 2440 X 1220 X 300

**Wobblybootie** · 15-10-2014

Well I posted in General as an introduction but didn't even get a 'Forget It' comment. So I will try again.

I have need of a machine to cut Ply and MDF from 8X4 Sheets. I am thinking an Extrusion based build using a Kress spindle. 20mm Aluminium Plate for Gantry Sides, Rack and Pinion for the long (X?) axis and Lead Screws for the Y(?) and Z. Or possibly one Lead screw positioned centrally under the bed (prefered option)

One end open to facilitate loading would be necessary. Here comes the Interesting (but not original idea) I would like to build in a 4th Axis across the machine for spindle work. If it's not feasible then I will find a Lathe instead.

Suggestions for Min/Max Extrusion sizes and appropriate linear bearings eg Hewin or supported Rail (I am concerned there may be too much dust/debris for Hewin type Bearings) would be much appreciated.

Questions about motors etc can wait but I will again be looking for any help I can get.

A Workshop (read Shed) is being built to house the beast as we speak and will be ready by the time I have collected all the bits and pieces needed (I hope).

**EddyCurrent** · 15-10-2014

'Forget it' is not a bad start but I'll stick my neck out and give it a go.

First it's a big machine for a first build, not impossible but just saying.
For spindles most use the 2.2kW or 3kW water cooled ones, make 2.2kW your minimum size.
20mm plate sounds good for a lot of the parts.
Not sure about using extrusion as I've no experience with it but a lot of people use it. Steel would be cheaper, for the frame at least, but you'd need to weld it.
Rack and Pinion is not the first choice but it might be okay for your size machine and application.
Ball screws are what you need for Y and Z. If you use these for X also, then one centrally mounted is a definite NO NO, you need two, one each side.
4th axis integration is fine, it just means the machine will be longer to accommodate it.
Hiwin or similar rails are much preferred over round supported rails but are more expensive.

Wait for more people to chip in then using that information knock up a drawing. Unless you already have some CAD software, 'Sketchup' is commonly used because it's free and easy to use
Look through the build logs and get ideas there. http://www.mycncuk.com/forums/253-DI...ter-Build-Logs

**Wobblybootie** · 15-10-2014

Okay thanks for that ... I'll look into spindles. I can weld (in a fashion) so I'll look at steel pricing. I've just had a lightbulb moment (don't laugh) If the bed was correctly stressed I could mount the ways for the 4 th axis into the bed. Just remove a section of bed to reveal the space. The centreline of the 4th axis does not need to be higher than the bed. I have an unused Wood lathe I can use for the ways and tailstock, a Stepper/belt to drive the Headstock assembly.

**EddyCurrent** · 15-10-2014

The links I posted here might be of interest ?

http://www.mycncuk.com/threads/7960-...2243#post62243

**Wobblybootie** · 15-10-2014

Is Mild Steel box 100 X 50 X 3mm okay for frames or would I be better using 5mm

**EddyCurrent** · 15-10-2014

Well I used 50x50x3 and 100x50x3 albeit on a smaller machine. These sizes were ideal and provided the design is right there should be no flexing of the structure. You do though have to consider that the 3mm thickness is not much if you intend making threaded holes in it, and you will for the X rails at least. In my case I glued a piece of 30x6 flat strap inside to beef the threaded thickness to 9mm.
I think you should go with the 5mm thickness

**Wobblybootie** · 16-10-2014

Thanks everyone. BUT all change!! (for the better I think, read cheaper and Easier!!) I have spent the day on the floor with paper templates that I will be using. I have discovered that I can fit the the templates onto 2 half sheets IE 1220 X 1220 with very little waste.
So Ball screws all round and Hiwin 20mm blocks and rails.
I have sketched a frame for your perusal and comments that I will post shortly (when the kids have finished homework). Is there a preferred format?

**EddyCurrent** · 16-10-2014

Just upload jpeg snapshots of the drawings from whatever software you use.

**Wobblybootie** · 16-10-2014

First Draft.

Gantry to fit on 20mm rails atop the frame. Z travel needed 350mm

**EddyCurrent** · 16-10-2014

I think you would be better with something on these lines.
http://www.mycncuk.com/threads/6565-...4294#post54294

You don't need a back in it and your top beams are not suitable for carrying the X rails due to the legs coming up through.
If you notice, my top beams are bolted to the frame, this allows for shimming to get it within a gnats knacks, ready for the epoxy.