Help with drill-Mill conversion

[Ross77]

You must be a mind reader I was just going to ask about the tables for speeds and feeds........ Is it not worth me knowing what it should be so I can work back? where can i finf these tables?

I'll have to check the flexing, The quill was hardly down and the bit was 10mm dia, 20mm long in a ER32 collect chuck so I hope it wasnt tool flex. And im not sure how i can slow the spindle down without a major redesign and a shorter belt. I was hoping to check it worked properly before I bought a 3 phase motor.

Certainly shallower cuts and plenty of cutting fluid improved the surface finnish, just how noisy should a rough cut be??? maybe I'm erring on the side of caution.

I'll have to refresh my memory on up hill and down hill milling. I always thought that learning how to use it would be harder than making it :oD

[Robin Hewitt]

Here are cutting speeds, milling is second table down, calculator below.

http://littlemachineshop.com/Referen...tingSpeeds.php

It suggests 1600 rpm for 10mm in aluminium. Personally I'd go for about half that. If the suds gets diverted for a moment by a fixing bolt, I prefer it if the tool doesn't go red hot :whistling:

My mill came with a 2hp motor but no way on God's green do I want to put anything like that down a small cutter, it's just too much. I replaced it with a 1hp on a digi phase inverter and I never work it hard.

How noisy should it be? Any loose fittings on a bench mill will rattle. The cutter should make cutting noises, if it becomes noisy that usually means you've lost the tool tip.

[Ross77]

Thanks once again for your advice, It definetly looks like I just need to learn how to use it..........The mini mill beginers guide was quite useful too, its suprising how much you read and then forget :heehee:

Ive ordered some 2 flute ali cutters 3,4 and 6mm so i can keep the speed up and find the right feed. Hopefully get there in the end.......

[Ross77]

Ok cutters arrived today, tryed the 6mm one and what a difference. 3mm deep cut in one pass with nice clean sides and no burrs on the edge. not sure on the cutting speed but the velocity is set at 400 mm/min. but the feed rate said 18mm/min I think . still need a bit more practice with mach.

You where definetly right Robin, I think I,m getting closer to the machines capabilities, althougth for what it is I'm more than happy with how it performed with the 6mm cutter. I'm sure that I can improve on the 3mm depth with a bit more tuning.

now its cutting clean edges It appears to be 0.3mm out, not sure if this is a step unit error ( had to round up to whole no.) or backlash. When I first tested it under no load I was getting 0.02 accuracy, is it possibly that the machine is still settling down? I dont think it can be machine flex as i was only typing the G-code line by line so it would have plenty of time to straighten up before the change in direction. I wont be to happy if the delrin nuts need constant attention tho...

[Robin Hewitt]

I'm sure that I can improve on the 3mm depth with a bit more tuning... now its cutting clean edges It appears to be 0.3mm out, not sure if this is a step unit error ( had to round up to whole no.) or backlash.

3mm deep sounds about right for a 6mm tool, so does 1420 rpm suggest you experiment with feed rates.

Measure the backlash, find out how much of the 0.3mm is accounted for. Perhaps a man has to ask himself, is Delrin better suited to free rolling gantry style machines?

I spent a lot of time and money removing the backlash from my machine, if I could have done the same with a plastic nut it would appear somewhat futile :whistling:

Robin