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My cnc mill
#11
My interest has been peaked in cnc milling at the moment. I've been looking at 3040 mills on the bay. How has this project been progressing Vern? Any thoughts on an out of the box solution or is this an easier/cheaper/better route?
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#12
the item I bought has a fixed head, and the xy table moves around. Means its a bit stable and strogn in the head area.

but, you aint half-limited in the size of things you can make. I spent an awful lot of time going over the 3040 specs and youtube videos etc. Its a better idea than one with a fixed head...BUT, because the head isnt fixed you end up sacrificng stability a bit (not talking about plastics and wood...light metal milling)

I bought my mill for a song to be honest, while saving up for a 3040.
some of the 3040's also comes with a rotary axis (4th axis) so you can theoretically make tubes like the V3-flip mod from a year or so ago.
Box, check...juice, check...new battery, check.....SQUONK! Big Grin
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#13
I'm thinking of cutting aluminium plates for RC monster truck chassis and shock towers amongst other stuff. The 4th axis is a real draw too.
I looked at the Proxxon and it does have a small build area which was a bit of a turnoff when I'm wanting to do 400mm x 250mm plates but it looks to be great quality.

Since I know your an accomplished deal finder, are there any 3040 deals your aware of? (With or without the 4th axis) I've got up to about 800 kicking about in the savings account, not sure what mileage that'll get me though(don't necessarily have to spend it all either, lol!)
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#14
you'll never do 400mm x 250mm on the proxxon. biggest is going to be about 110mm x 60mm (and thats with a mod the the Y axis) (the table can move a small bit further but you need to clamp the piece down etc, so these things take space and prevent you cutting in that area). You may think you can clamp and reclamp and move the workpiece around and so on but in reality this ends up a crapshoot and just doesnt work out nice. You need to be able to put the piece in place and then do your cuts and call it a day.
I know I'm talking the proxxon down, but it has its place..and cutting big things is not its forte.

the ones (3040) I was looking at on ebay were around £400-£600 depending on accessories. budget about half that for accessories and upgrades.

How thick are these plates...2mm?

If you are going up to the $2000 route Ive got an interesting item to show you
https://www.youtube.com/watch?v=9JAMzARLiNw
Box, check...juice, check...new battery, check.....SQUONK! Big Grin
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#15
That thing is smart but 800 is my absolute stretch. It's my left over savings from my account after we put airsoure heating in the house. The Mrs doesn't know about it so CNC mill is the only logical option for the money to be used on.

The plates are 3mm aluminium and likely no harder than 6061 if memory serves.
I'm thoroughly taken by the 4th axis on the 3040 as it'll allow me to do flat notches in a round bar.

Have you got any suggested auctions that would be reasonable out of the box or without a fortune of upgrades?

Edit:- this is one that had my attention as it looked fairly complete
https://www.ebay.co.uk/itm/152157783961
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#16
not really, so had a look (the brexit exchange rate seems to have pushed the pricing up since I last looked)

ok, this one
http://www.ebay.co.uk/itm/4-Axis-Cnc-Router-Engraver-Engraving-Machine-3040T-3d-Cutter-PCBS-Milling-/121721693622?hash=item1c572da5b6:g:kSQAAOSwFe5XxpHK
technically, 3040T is the ballscrew model. I picked this auction because it is 3040T, includes 4th axis and has a "best offer" part, and its in the UK already
So offer them £450 and see how they like it

so thats for the 3040T cnc machine...but please please check if it will be suitable for what you want it to cut. 3mm aluminium isnt on the list of things these hobby machines should be cutting, and you may well have to make multiple passes at e.g. 0.3mm cut depth to get it to work nicely. check on youtube how the folks are getting on and see if its suitable...bearing mind *most* of the videos are sped up and have music overlays because it does sound horrendous at times:-)

here's one doing 4mm



he's doing 100mm feedrate, i.e. 10cm/minute, and multiple passes...so that piece is likely going to take about an hour to cut
Box, check...juice, check...new battery, check.....SQUONK! Big Grin
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#17
Yeah, I'm all for slow and steady vs fast and broken. It's amazing what things will do with patience.

That video was the exact one that gave me the confidence to have a shot at it, I think a combination of some coolant, time and a quality bit will probably be the best route. I've seen a few vids cutting alloy plate at varying feedrates.
Is the spindle motor a day one upgrade do you think?
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#18
no...personally I would just use it as it and adjust my speeds and feeds to compensate until such time as it wound me up enough to change.

I dont know if I've mentioned this, but I bought a mini-lathe a few years back and that taught me an awful lot about metal, and especially cutting metal. What I thought was an abrasive process is actually meant to be a controlled melting process. You're putting so much stress into the metal that it heats up at the leading edge and becomes "butter" for the cutter to remove.

Kinda what I am saying is that you will be scared and run it too slow initially, thinking you're doing the right thing. When actually it needs to go as fast as the metal requires.
Thats the "speeds and feeds" part...you figure out what the metal needs, figure out how many flutes your cutter has (a lathe has one...a milling but is probably 2 or even 4) and then you do some math. When the math is right, then the cutter is under the least amount of strain and will last longer, ans the metal will be removed cleaner.

Most of what I see on youtube is spindles running way too fast and cutting speeds way too slow, so theyre rubbing bits of metal off, instead of literally shearing it like butter.

Find a bloke called "abom79" on youtube and watch his milling/lathe videos. While he uses manual stuff, you'll need to tell your machine to emulate that. So its good homework to understand what the cutting bit is doing at the point of contact
https://www.youtube.com/watch?v=Bs-CRzXEnM4
Box, check...juice, check...new battery, check.....SQUONK! Big Grin
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#19
I did know I'd best not clamp some alloy down and "have at it" but that's probably the best pointer I could get for beginning with.
I'll put on an offer like ya said and look at cooling solutions as alloy loves to heat up.

I'm quite looking forward to carving something into a mod too.

Any tips on accessories?

Edit :- 450 offered, now the waiting..............
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#20
e.g
http://zero-divide.net/?page=fswizard
at 10000rpm, 6061 aluminium, cut with a 3mm, 2-flute cutter cuts best at 601.59mm/min. So you're aiming for a machine that wont flex too much under those strains, and a spindle that wont strain too much either. This is your perfect world scenario for that metal....as you go slower (due to spindle power problems, rigidity problems etc), you deviate more form "milling" and enter" I'm grinding with a fancy dremel"
Box, check...juice, check...new battery, check.....SQUONK! Big Grin
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