Author Topic: Little CNC mill  (Read 1459 times)

Stonemull

  • Hero Member
  • *****
  • Posts: 847
    • View Profile
Re: Little CNC mill
« Reply #30 on: July 23, 2017, 01:20:21 AM »
Mate you're a legend, that one is visiting distance, about a 40 minute drive and just up the road from my nearest ikea which I was due to visit soon.

I might have to plan a visit.
A3 Eleksmaker 2500mW
Solidoodle V2 Pro
Wanhao I3+ touch
Hacked Roland DXY-880
CNC3018 engraver
CNC Plasma (work in progress)

Stonemull

  • Hero Member
  • *****
  • Posts: 847
    • View Profile
Re: Little CNC mill
« Reply #31 on: July 24, 2017, 11:09:40 PM »
Managed to mill my first pcb using FlatCam, double sided, drilled and took 4 attempts. I started with a 0.5mm track width design is pretty much my regular.
The first one I used my surface probe to set the zero but forgot to readd the 1.56mm pcb thickness offset that is removed by the software, I heard the tip of the engraving bit snap off in a split second.
The next one I had set too deep in software, also snapped a tiny part off a new hit.
Next one I realised that 0.5mm tracks were never going to work and that I shoukd use 0.21mm as the bit width setting.
Redesigned the board quickly with 1mm tracks and larger pads and board 4 was acceptable.
Drilled 0.7mm holes and 5mm deep alignment holes for a pin, then used board cutout with 5mm buffer, which I realised in hindsight is better done after the reverse is milled..

Side 2 I thought would be horrible but I dropped the mill depth to 0.05mm from 0.1. and the tracks came out really clean.
Clean up with steel wool, bench grind the final shape, assemble and it works !

A3 Eleksmaker 2500mW
Solidoodle V2 Pro
Wanhao I3+ touch
Hacked Roland DXY-880
CNC3018 engraver
CNC Plasma (work in progress)

Stonemull

  • Hero Member
  • *****
  • Posts: 847
    • View Profile
Re: Little CNC mill
« Reply #32 on: August 02, 2017, 08:40:52 PM »

An Australian supplier may be http://www.northernsmelters.com.au/. They may call it Casting Alloy or White Metal. Have to ask them. The alloy we use has about 18% aluminum in the Zinc.


Wow, just phoned these people as they had no pricing on the website, because it changes monthly .. don't dare suggest it dan possibly still be priced, 'i'm a 75yo woman and don't have time for that sh**'  .. just ask us what you want and we can help .. I want to cast mechanical parts from 3d printed components .. nobody has done that before, usually people make tin soldiers ..

So after she yelled at me for a while for daring to suggest pricing would help me decide, or just an idea of it, yelled at me some more for not knowing exactly what i want, yelled at me some more for not having a clue what is required, probably not helped cause i was laughing at her as I only answered the exact question she asked, I think I just have to go up there and buy some stuff, about the crankiest woman I have ever spoken too, funny tho. I think she has been inhaling metal fumes for too long.

She suggested linotype metal perhaps, lead free pewters etc, eutectic bismuth for low MP, more research needed.


A3 Eleksmaker 2500mW
Solidoodle V2 Pro
Wanhao I3+ touch
Hacked Roland DXY-880
CNC3018 engraver
CNC Plasma (work in progress)

Stonemull

  • Hero Member
  • *****
  • Posts: 847
    • View Profile
Re: Little CNC mill
« Reply #33 on: August 03, 2017, 07:37:40 AM »
Posted up the bolt head despinner ..

http://www.thingiverse.com/thing:2466416


A3 Eleksmaker 2500mW
Solidoodle V2 Pro
Wanhao I3+ touch
Hacked Roland DXY-880
CNC3018 engraver
CNC Plasma (work in progress)

mrehmus

  • Sr. Member
  • ****
  • Posts: 347
  • Pilot, submariner, model engineer, etc., etc.
    • View Profile
    • Model Engine Builder
Re: Little CNC mill
« Reply #34 on: August 03, 2017, 09:00:38 AM »
Plastic has some give and using it as part of a clamp for milling could turn out to be a disaster or at least contribute to a poor finish. Use the mill to make yourself some aluminum t-nuts.
mrehmus
editor, Model Engine Builder magazine
Elekslaser A3 2.5 watt via Banggood
BCL
Qidi X-one 3D printer
Machine Shop with manual and CNC machines

Stonemull

  • Hero Member
  • *****
  • Posts: 847
    • View Profile
Re: Little CNC mill
« Reply #35 on: August 03, 2017, 09:10:00 AM »
I'm not that silly :) , the bolt is in direct contact with the extrusion, the plastic just stops it spinning.
A3 Eleksmaker 2500mW
Solidoodle V2 Pro
Wanhao I3+ touch
Hacked Roland DXY-880
CNC3018 engraver
CNC Plasma (work in progress)

ggallant571

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1724
    • View Profile
Re: Little CNC mill
« Reply #36 on: August 03, 2017, 09:14:46 AM »
Your photo shows that they have further cheapened the supplied hold down clamp mechanism. Mine is a simple 4mm bar of steel with threaded hole and slot.
SARCASM - Just one more service we offer here.

mrehmus

  • Sr. Member
  • ****
  • Posts: 347
  • Pilot, submariner, model engineer, etc., etc.
    • View Profile
    • Model Engine Builder
Re: Little CNC mill
« Reply #37 on: August 03, 2017, 11:53:05 AM »
I'm not that silly :) , the bolt is in direct contact with the extrusion, the plastic just stops it spinning.

If you mean the bolt is pushing against the bottom of the T-slot, it is not supposed to do that. The T-nut is supposed to be staked on the bottom of the thread so the bolt cannot go beyond that level and contact the bottom of the T-slot.
mrehmus
editor, Model Engine Builder magazine
Elekslaser A3 2.5 watt via Banggood
BCL
Qidi X-one 3D printer
Machine Shop with manual and CNC machines

Stonemull

  • Hero Member
  • *****
  • Posts: 847
    • View Profile
Re: Little CNC mill
« Reply #38 on: August 03, 2017, 05:55:25 PM »
ok, now I am confused, the clamp has 2 bolts, one is the regular hex head bolt which clamps to the undeeside, the other is a countersunk bolt which I am using to push on the T slot bottom. See the ohoto on thingiverse.

The 2 act like the old toolmakers clamps we used to make as apprentices, it needs one in tension and the other compressed. I believe I have it configured as intended, if I added a hammer nut to that second bolt it's not going to work. They did supply these clamps assembled with the wingnuts, I dant think of any other way to use them.

There were no hammer nuts provided in the kit for this size extrusion though I do agree it would be preferable though.

I have currently given up on the idea of milling alumnium with this thing anyway, there is simply not enough stiffness in the Z mounting to deal with it. At least the stuff I have tried so far which was from a chunk of billet stock, may have been a harder magnesium alloy like Duralloy (which I have since found is dangerous to recast, can ignite an unstoppable magnesium fire)

Your photo shows that they have further cheapened the supplied hold down clamp mechanism. Mine is a simple 4mm bar of steel with threaded hole and slot.
A3 Eleksmaker 2500mW
Solidoodle V2 Pro
Wanhao I3+ touch
Hacked Roland DXY-880
CNC3018 engraver
CNC Plasma (work in progress)

mrehmus

  • Sr. Member
  • ****
  • Posts: 347
  • Pilot, submariner, model engineer, etc., etc.
    • View Profile
    • Model Engine Builder
Re: Little CNC mill
« Reply #39 on: August 03, 2017, 06:59:36 PM »
Reviewing the design again, I see that the bolt with the wingnut is pulled up against the bottom of the T-slot wings. The other pivot bolt, at least in the machine too world pushes against the top of the table, not the bottom of the slot.
mrehmus
editor, Model Engine Builder magazine
Elekslaser A3 2.5 watt via Banggood
BCL
Qidi X-one 3D printer
Machine Shop with manual and CNC machines

Stonemull

  • Hero Member
  • *****
  • Posts: 847
    • View Profile
Re: Little CNC mill
« Reply #40 on: August 03, 2017, 07:14:34 PM »
Your photo shows that they have further cheapened the supplied hold down clamp mechanism. Mine is a simple 4mm bar of steel with threaded hole and slot.

So they have, just checked the item page and can see the new ones supplied though the last photo on the page still shows the aluminium blocks in the kit.
Never know, it might even be an improvement as the profile on the aluminium blocks is pretty tall and working close to the clamp means with a short too, the spindle cannot clear the clamp and reach the work as well.

Just working on my sales pitch :)

Reviewing the design again, I see that the bolt with the wingnut is pulled up against the bottom of the T-slot wings. The other pivot bolt, at least in the machine too world pushes against the top of the table, not the bottom of the slot.

Yeh I have used it like that too with a circular piece, prefer to not mar the top surface if I can though so been using it in the slot 99% of the time.
Even doing that I still cant see how I would use a hammer nut in the slot, you would have to reverse the bolt or the head would be in the way meaning both the bolt head and wing nut are now up top. Unless the hammer nut looked pretty much like my plastic one to take the bolt head that is.

I have been careful to not wrench it up too tight as you can feel it biting into the alloy.


A3 Eleksmaker 2500mW
Solidoodle V2 Pro
Wanhao I3+ touch
Hacked Roland DXY-880
CNC3018 engraver
CNC Plasma (work in progress)

Stonemull

  • Hero Member
  • *****
  • Posts: 847
    • View Profile
Re: Little CNC mill
« Reply #41 on: August 06, 2017, 10:00:11 PM »
Reviewing the design again, I see that the bolt with the wingnut is pulled up against the bottom of the T-slot wings. The other pivot bolt, at least in the machine too world pushes against the top of the table, not the bottom of the slot.

Clamps are better to use this way, thanks for the comment.


These arrived today, I figured more cutting edges the better at the fairly low spindle speed, these work great on mdf and useable on aluminium, not much good as end mills but if you can use lift milling on the edges it has reasonable cutting speed. Only doing 0.25mm cut depth and around 100mm/min feed it was cutting a 4mm vertical surface. So slow and needs thinking to get the cutting direction, feed rates etc correct but doable on aluminium.
Not something I want to do much, just good to know it is possible.

http://s.aliexpress.com/3iAruuI3


Edit just a note: these will not clamp up in the standard 3.125mm collet, you need a 3mm one, luckily I have the 1mm to 7mm in 0.5mm set now.



« Last Edit: August 06, 2017, 10:02:45 PM by Stonemull »
A3 Eleksmaker 2500mW
Solidoodle V2 Pro
Wanhao I3+ touch
Hacked Roland DXY-880
CNC3018 engraver
CNC Plasma (work in progress)