[JoeyJoe]

We've put around £1000 into this CNC in total. Some of the parts were given to us by another hobbyist (no doubt a member of this forum) who were moving house and didn't have space for his CNC equipment anymore.

The frame is made from box steel welded together, it's very rigid. The MDF parts were made just to be able to CNC the parts again in aluminium later. The MDF isn't pretty but it will do for now! The router is fixed using a metal band and a rubber mat... for now anyway, the plan is to CNC that part too.

For now the only bit we have is a 1/8th end mill which apparently is supposed to be used for drilling, although we have been using it for everything until we can get some more collets and ball mill bits etc. (Still haven't figured out exactly what type of bit is used for what yet, some advice would be appreciated).

The router is a Kress FME 1050 which is a pretty powerful router and good enough for what we need. The plan is to wire that up to the relay on the controller.

With the testing we done, it seemed to be accurate to within 0.5mm on the X and Y, but the Z seems to be slightly out. the MDF parts dont help and there is some springyness to it.

We're using MACH3, and CAMBAM trial to do some test cutting. My brother is good with solidworks and autoCAD, so when we figure out how to setup CAMBAM to cut models from those programs, we will have a test with those too.

[awerby]

It looks like you're off to a good start! That bridge looks pretty stout. I think that once you replace that MDF and rubber Z axis with something stiffer you'll see a marked improvement in cut quality.

End mills are typically fairly poor at drilling; they're made to cut sideways. You should be able to use a larger tool, like 1/4" or 6mm. If you just want to drill, and not move sideways, then a drill bit will work better. If you want to do both, then you can get a drill-point endmill. Ball-end tools are used for 3D work, such as sculptural carvings, since using a flat-ended tool would give the work a "stairstepped" appearance.

[JoeyJoe]

Thanks Werby!

Trouble is that the collets for the Kress FME's are not cheap! I think we will get some 10mm for clearance for now, possible some 20mm too.

We're now also looking at buying an injection moulding machine and a 3D printer. Would be good to be able to make the moulds for the injection moulding using our CNC, but we would need a good finish, especially on the surface plane where both parts of the mould would join together. Do you know what sort of bit I would need to get this smooth finish?

[awerby]

If the mold has a simple flat parting line, that's not too hard; you can use the largest flat-end cutter that fits in your spindle, or a face mill if the Kress will slow down enough. Any surface marks can be stoned off using fine sandpaper adhered to a thick glass plate. If it's an undulating curved surface that gets a lot more difficult; you'd start out with ball-end cutters but you might have to polish and fit the mating surfaces by hand to get a good fit. There's a lot to making molds for plastic injection; you can find some good information (even "for dummies") here: Proto Labs: Molding and Machining Resources

[wizard]

A

Thanks Werby!

I have to agree that you are off to a good start there.

Trouble is that the collets for the Kress FME's are not cheap! I think we will get some 10mm for clearance for now, possible some 20mm too.

20 mm might be on the big size for that spindle. That depends of course what you are machining.

We're now also looking at buying an injection moulding machine and a 3D printer. Would be good to be able to make the moulds for the injection moulding using our CNC, but we would need a good finish, especially on the surface plane where both parts of the mould would join together. Do you know what sort of bit I would need to get this smooth finish?

Mold making is high art for a machinist as you need both the skill and the right equipment. I'd suggest that you may never get the results you want with this machine. Of course that depends upon what you want. It also depends upon how well you finish off the machine. Top notch finish though requires a stiff and highly repeatable machine. Your current design may need improvements for you to realize your finish goals. This might include profile rails, a reinforced vertical structure and a higher quality spindle.

Again the suitability of your machine for mold making depends to a great extent on what your goals are. You have a very good start with the basic design though.