My Build - I blame you lot for this....!

[Robin Hewitt]

Come on, don't be shy, 'fess up, what's the tolerance and finish like? :naughty:

Tell me I haven't been wrong all these years about the need for lots of cast iron

I'll even go first with a pic, iron cut .001" deeper than intended, biro tip for scale.

[HiltonSteve]

Come on, don't be shy, 'fess up, what's the tolerance and finish like? :naughty:

Tell me I haven't been wrong all these years about the need for lots of cast iron

I'll even go first with a pic, iron cut .001" deeper than intended, biro tip for scale.

Robin, I don't think your wrong about the need for lots of cast iron for a solid machine, I did my apprenticeship at British Rail (a few years back!) and spent a good chunk of my time in the heavy machine shop operating a Noble & Lund plano mill. Bed was about 10m long x 4m wide and the whole machine must have weighed about 100-130 tonnes, 5mm depth of cut with a 15" face mill no problem at all and a nice finish, but you could still find the limits of the machine when you pushed it.

As for my mini plano mill!, I did not expect it to turn out as good as it did if I'm honest and I am not expecting miracles from it. Accuracy on the 30mm holes that I put in the plate was fairly good, measured them on the X and Y plane and they are 29.94 and 29.97 so slightly oval but not too bad. Finish could be a bit better but I just roughed them out, will have a go tonight with a 0.5mm finish cut climb milling to see how it performs and post up some pics.

[Robin Hewitt]

Accuracy on the 30mm holes that I put in the plate was fairly good, measured them on the X and Y plane and they are 29.94 and 29.97 so slightly oval but not too bad.

Fairly good?

One or two thousandths of an inch out and he's complaining :whistling:

PS: Climb milling sounds like a terrible idea

[Jonathan]

Wow, that's a sharp corner! Have to try that on my mill ...

[HiltonSteve]

I have been profiling a couple of 20mm aluminium router sideplates at the weekend and been playing with different speeds and feeds to see find out what works best and gives the best finish.

Ended up at around 4000rpm with a feedrate of 600mm/min with a 2 fulte HSS slot drill, roughed the profile first stepping down 2mm at a time and leaving 0.5mm on all round, then did 2 finish pass's at 10mm deep with the same cutter but dropped the feedrate to 350mm/min, cutting time around 45 mins.

Finish is OK but still room for improvement, i have a couple of ali-master 10mm cutters which have completely different geometry to a standard slot drill so may give that a go to see if it improves the finish.

But overall still quite happy with the results!!

[Jonathan]

I don't fancy cleaning up the machine after that!

I was also experimenting a bit on friday with feedrates on 20mm aluminium plate. I'm using a nearly new 20mm 4 flute HSS cutter. With a maximum cut width of roughly 5mm (plate was allmost to size, just machining the edges), stepdown of 2mm and 2150 RPM I found 720mm/min to be good. It would go faster, but I'm only putting the cutting fluid on with a brush and I didn't want to push it...

For finishing I tried various speeds still at 2150rpm. I left 0.5mm for the finishing pass and did one 20mm deep climb milling pass. I couldn't really see any improvement in finish below 300mm/min, so I stuck with that.

On the first of the attached photos you can see the difference between accidently running the finish pass at 600 compared to <300.

[HiltonSteve]

Been doing a bit more testing tonight and decided to see the results on aluminium with 5 different type's of cutters.

1 - Alimaster 2 flute 8mm
2 - HSS 2 flute 6mm
3 - HSS 6mm ripper
4 - Solid carbide 2 flute 6mm
5 - K2 coated 3 flute 6mm

Ran them all at the same speed and feeds to see which gave the best surface finish results, spindle speeds 4000rpm and 6000rpm, feedrate 300mmpm, side cutting taking 0.5mm off which is what i would normally leave for finishing, depth of cut dependent on cutter length. Tried both climb and conventional milling with each cutter.

Results -

1 - Alimaster - Certainly removes material easily but not the best surface finish.

2 - HSS 2 flute 6mm - Cuts nice but still get the chatter lines, surface finish similar to alimaster.

3 - HSS 6mm Ripper - Does what it says on the tin, rips the material off very easily without producing loads of swarf. Finish not good but definitely my choice for roughing.

4 - Solid carbide 6mm 2 flute - This gave a poor finish, carbide is very hard and sounded like it when it was cutting. Kept leaving lots of very small but even ridges. May need to be pushed harder to get best results.

5 - K2 coated 3 flute 6mm - Cheapest cutter of the lot and gave the best results, i put it mainly down to it having more flutes than the others which helps with the intermittent cutting. I have not got any 4 flute cutters but i will be getting some to try.

A few photo's attached, did not take photo's of all the results as some started to look similar to others so did not see much point!

Conclusion - More flutes give a better finish but a ripper is best for roughing out, also need a more sturdy machine to give a better surface finish, but now at least I know what surface finish the machine is capable of and what to expect from it.

[AdCNC]

Interesting Steve, i use the alu-power alot also, ive noticed that when i use them to mill say a pocket the bottom face is never super clean, it alway leave swirl marks but when do a finishing pass of a profile on some 12mm alloy DOC 0.1mm spindle at 12000 rpm feed at 600mm/min i get a mirror finish. im also going to try some k2's seeing as they are on offer at the mo.

On your video have you limited you coolant flow or is that what the pump flows normally?

[HiltonSteve]

On your video have you limited you coolant flow or is that what the pump flows normally?

Aydee,

There is a tap on the stayput nozzle to adjust the flow and usually I have it about half way open. The biggest problem is getting the coolant back to the tank through the 16mm bore return pipe, machine turns into a paddling pool fairly quickly!

[AdCNC]

I see, i have concocted my own coolant system from a parts washer, and what i have done is position it under where i am cutting, at the moment tho i have used some polythene sheet as a catch to funnel the coolant back into the parts washer and i have made a removable screen that goes around the spindle from some clear plastic that is used for doorway screens.

When i get five ill pop some pictures up on my thread