Another Newbie

[Chris J]

Hiya

I wanted to get a CNC mill/router and thought here would be a good place to start.

My wife makes brooches out of 1mm thick copper sheets.
At the moment she cuts the shape out with a hand fret saw, this takes ages and costs an absolute fortune in blades.

So I'm thinking that there must be a better solution to this, I'm thinking that a CNC machine would allow me to knock a sheet of these out easilly and earn me much needed brownie points.

Any suggestions gratefully received.

I have looked at something like this (http://www.worldofcnc.com/unassembled-cnc-machines/ballscrew-un-assembled/ballscrew-un-assembled-a3-size-cnc-router-kit-p-1273.html), any good ?

[John S]

Copper is an absolute bitch to machine, dead gummy and just wants to weld itself to the tool. Have you given any thought to a plasma cutter?
All depends on the amount of detail needed.

[mocha]

Hi Chris,

You don't mention if the designs are simple or complex, but have you tried the band saw / jigsaw or sander type route? If they are all the same design, a Flypress? It might work out cheaper? (more brownie points too! :-)

[Chris J]

Copper is an absolute bitch to machine, dead gummy and just wants to weld itself to the tool. Have you given any thought to a plasma cutter?
All depends on the amount of detail needed.

I did think about a plasma cutter but wondered if I'd need to have a water flow ?
Would it cut neater.


Hi Chris,

You don't mention if the designs are simple or complex, but have you tried the band saw / jigsaw or sander type route? If they are all the same design, a Flypress? It might work out cheaper? (more brownie points too! :-)

If you imagined a flower shape cut on a 2" square or something like this.
Terrible picture sorry, it's about 3" wide.

Too fiddly for a bandsaw I think and too varied for a press.

5830

[Jonathan]

You don't mention if the designs are simple or complex, but have you tried the band saw / jigsaw or sander type route?

The issue with a bandsaw and difficult to cut materials is new blades will cost about £6-£8 and may not last longer than much cheaper blades for fret saws.

I didn't have problems when cutting 5mm thick copper on my CNC router, but maybe I just got lucky.

Roughly many of these broaches is your wife making? If they're all different shapes then a fly-press wont be cost effective, but getting them laser/plasma cut might be? If you do cut them on a router you're in danger of making her redundant as the router can of course do all the engraving...

[Chris J]

The issue with a bandsaw and difficult to cut materials is new blades will cost about £6-£8 and may not last longer than much cheaper blades for fret saws.

I didn't have problems when cutting 5mm thick copper on my CNC router, but maybe I just got lucky.

Roughly many of these broaches is your wife making? If they're all different shapes then a fly-press wont be cost effective, but getting them laser/plasma cut might be? If you do cut them on a router you're in danger of making her redundant as the router can of course do all the engraving...

She doesn't make a huge amount more to do with the time it takes to cut them out.
Engraving Mmm at the moment she enamels them.

[Chris J]

The issue with a bandsaw and difficult to cut materials is new blades will cost about £6-£8 and may not last longer than much cheaper blades for fret saws.

I didn't have problems when cutting 5mm thick copper on my CNC router, but maybe I just got lucky.

Roughly many of these broaches is your wife making? If they're all different shapes then a fly-press wont be cost effective, but getting them laser/plasma cut might be? If you do cut them on a router you're in danger of making her redundant as the router can of course do all the engraving...

What was the power and speed of the router motor when you cut the 5mm ?
Was it on a CNC machine ?
Thanks

[Web Goblin]

Chris,
If you go for laser cutting you would need someone with an anti reflection/ polarising kit fitted to their laser. Materials like copper, brass and aluminium can cause problems with lasers, especially older types like the one we have at work. Are all of the broaches different designs? If so getting them laser cut would prove expensive I think given the continual changing of programs.
As for plasma cutting some of the smaller hand held machines are air cooled torches so no water cooling required. The big problem with plasma is the fumes it creates when cutting. You will need an extraction and filtration system for a plasma cutter. Also the kerf size on plasma might be an issue for you. Even at a low current cut you would probably still have a kerf value of around 3mm to 4mm and this might be too wide for the slots in your designs.

Ian

[Chris J]

Chris,
If you go for laser cutting you would need someone with an anti reflection/ polarising kit fitted to their laser. Materials like copper, brass and aluminium can cause problems with lasers, especially older types like the one we have at work. Are all of the broaches different designs? If so getting them laser cut would prove expensive I think given the continual changing of programs.
As for plasma cutting some of the smaller hand held machines are air cooled torches so no water cooling required. The big problem with plasma is the fumes it creates when cutting. You will need an extraction and filtration system for a plasma cutter. Also the kerf size on plasma might be an issue for you. Even at a low current cut you would probably still have a kerf value of around 3mm to 4mm and this might be too wide for the slots in your designs.

Ian

Yes they vary as the whim takes her.
I was looking at some videos on U tube and was worried about the kerf, not such a problem as long as the edge that is left as the job is sharp and crisp but they sometimes have slots in (as per my bad photo) and that would need a narrow precision cut.

I do have a fairly good extractor in the workshop so I guess that could be adapted for plasma.

I'm begining to think that a high speed router might be the way to go.

Thanks

[m_c]

There are precision nozzles available for the better brands of plasma cutters, however it all depends on how much you want to spend.
Hypertherm is one of the top end brands that I can think of right now that I think does them.

[Chris J]

There are precision nozzles available for the better brands of plasma cutters, however it all depends on how much you want to spend.
Hypertherm is one of the top end brands that I can think of right now that I think does them.

The minute someone says it depends on how much you want to spend my blood chills a bit :dispirited:

I guess I was hoping to spend £1k maybe a bit more, not including a pc, so not a huge budget.

[russell]

You mean brooches. Broaches are used for making holes in metals :-)

Russell.

[Web Goblin]

A Hypertherm Hydefinition plasma system will set you back way over £1K. I think all Hypertherm Hydef systems are all mechanized systems and not available as portable units which means they would all need three phase supplies.

Ian

[Chris J]

Russell, That's what I wrote :whistle:

[Chris J]

A Hypertherm Hydefinition plasma system will set you back way over £1K. I think all Hypertherm Hydef systems are all mechanized systems and not available as portable units which means they would all need three phase supplies.

Ian

So it would seem, nice gear though.

[Chris J]

.....I didn't have problems when cutting 5mm thick copper on my CNC router, but maybe I just got lucky......



Jonathan, what machine / cutter did you use to cut the 5mm sheet please ?

Chris

[Jonathan]

Jonathan, what machine / cutter did you use to cut the 5mm sheet please ?

Chris

See here:

http://www.mycncuk.com/forums/showthread.php/3623-i7-Water-cooling-system/

The outer profile and 2mm wide slot were on my CNC router and the 0.5mm slots were cut with a slitting saw on the milling machine. To be honest I can't remember which cutters I used. Probably these:

http://www.ebay.co.uk/itm/5x-6mm-Carbide-CNC-Router-Bits-Single-Flute-Tools-25mm-/140548881261?pt=UK_Home_Garden_PowerTools_SM&hash=item20b95dbb6d

The same seller has plenty of smaller ones too...

[Chris J]

See here:

http://www.mycncuk.com/forums/showthread.php/3623-i7-Water-cooling-system/

The outer profile and 2mm wide slot were on my CNC router and the 0.5mm slots were cut with a slitting saw on the milling machine. To be honest I can't remember which cutters I used. Probably these:

http://www.ebay.co.uk/itm/5x-6mm-Carbide-CNC-Router-Bits-Single-Flute-Tools-25mm-/140548881261?pt=UK_Home_Garden_PowerTools_SM&hash=item20b95dbb6d

The same seller has plenty of smaller ones too...


Brilliant, thanks

[m_c]

The minute someone says it depends on how much you want to spend my blood chills a bit :dispirited:

I think it has that effect on most people!
If only I could match those 6 numbers...


I guess I was hoping to spend £1k maybe a bit more, not including a pc, so not a huge budget.

As Ian's highlighted HiDef plasma is out of the budget.
I know normal plasma has a cut width of 2-3mm, and would be fine for doing the main outline cutting, so it may be worth considering a router/plasma hybrid. The two processes do have opposing requirements for cnc, but given your requirements, and with some careful design, should be doable.
Under typical use, a plasma table requires lots of speed with little torque and not very tight tolerances (when you've got something cutting +-0.5mm/trailing behind the torch position, tolerances/backlash requirements aren't that high), whereas a router table needs more torque with less speed but tighter tolerances.
However, given the size of cutters you need, torque won't have to be much for the router, and with the reasonable price of ballscrews, a good compromise of torque, speed, and tolerances should be doable, and combined with a lower power plasma cutter you shouldn't need crazy high cutting speeds.

[Jonathan]

I think you'd be best to design a CNC router than can incorporate a plasma cutter, but don't get the plasma cutter until you've tried cutting with the CNC router. I'm fairly confident that with plenty of coolant you'll be able to cut the copper without problems. When I cut that part from 5mm copper the part got exceptionally hot, but with flood coolant that wont be a problem.

[Chris J]

Ah coolant, I hadn't thought of that.

I guess that means I could't have any board involved.
I had thought I might clamp the working sheet to a sacrificial piece of board.

Mmmm, there is always something

[JAZZCNC]

Ah coolant, I hadn't thought of that.

I guess that means I could't have any board involved.
I had thought I might clamp the working sheet to a sacrificial piece of board.

Mmmm, there is always something

Not a problem just use plastic sacrifical board, hdpe is what I use very flat and stable? . . .BUT a far bigger problem you will have with small items like this is the actual clamping and holding.? Unless they have holes for screwing or clamping thru then it's a night mare holding small items for profiling.!
The thinner the material the worse the problem, I often spend more time making holding fixtures, jigs or repositioning clamps etc than the actual parts take to machine. IE: Recently machined some small Brass items and the total Job time was 30 minutes per 4 buckles the machining time was 17mins the rest was made up having to swap clamp positions without disturbing position and 1 tool change(2mins max).

[mocha]

I can see myself trying this sort of job... Would tabs solve the problem Jazz??

[Chris J]

I wonder if some kind of picture frame might work.
Slide the sheet in, make the cuts.

[JAZZCNC]

I can see myself trying this sort of job... Would tabs solve the problem Jazz??

Yes they work for some jobs but not all and with really thin material or small parts then there's not much left for the tab and they break or let the part lift.

On small parts I often leave a thin skin 0.1-0.2mm and don't actually cut right thru so it's kind of like a one big tab then just clean up with de-burr tool or quick blast across the sander and the skins gone, tabs on small parts don't really work very well.!


I wonder if some kind of picture frame might work.
Slide the sheet in, make the cuts.

Chris the problem comes from when you do the profile or outside cut thru the material, if not held down it will get grabbed or flung by the cutting tool. No sicker feeling than seeing a beautiful part which took 2 hours machine time come to life only to get chewed up and spit out in 2secs.!!:sorrow:

Clamping is probably one of the most un-thought about and time consuming things in DIY CNC.!! Unfortunatly the smaller the parts or thinner the material the worse the issue the more the need to get a good system in place.
If you have any thoughts to make multple identical parts then it's often worth taking the time to make a dedicated Jigs.!

[mocha]

Yes they work for some jobs but not all and with really thin material or small parts then there's not much left for the tab and they break or let the part lift.

On small parts I often leave a thin skin 0.1-0.2mm and don't actually cut right thru so it's kind of like a one big tab then just clean up with de-burr tool or quick blast across the sander and the skins gone, tabs on small parts don't really work very well.!



Thanks Jazz, I was thinking, using the OP question as the example, leaving 4 tabs of completely uncut material... then cutting through them with a fret saw, but yes, take your point.

[Chris J]

Anyone got a comment on this machine. (http://www.ebay.co.uk/itm/Black-Cat-CNC-Machine-600x400mm-cut-area-EU-Support-Warranty-/270962335071?pt=LH_DefaultDomain_3&hash=item3f169d1d5f#ht_9644wt_1026)

Seems to tick a lot of boxes for me.

[mocha]

There's a similar thread running here (http://www.mycncuk.com/forums/showthread.php/4131-Ebay-Chinese-Routers-%28CNC3040%29-anyone-purchased-one-of-these-machines-recently)that you might find useful;

[Chris J]

There's a similar thread running here (http://www.mycncuk.com/forums/showthread.php/4131-Ebay-Chinese-Routers-%28CNC3040%29-anyone-purchased-one-of-these-machines-recently)that you might find useful;

You forgot to mention depressing :-)

Seems too many folks have electrical problems Grrr

[mocha]

You forgot to mention depressing :-)

Seems too many folks have electrical problems Grrr

lol, What's that axiom? "If you want something doing properly..."?

[Chris J]

lol, What's that axiom? "If you want something doing properly..."?

All good if you know what is needed to do it properly.

[mocha]

well, you're in the best place to find out :-)

[Chris J]

Ok then, your task, should you choose to accept it is to find me a suitable machine for say £1500 (not inc pc)

[JAZZCNC]

Ok then, your task, should you choose to accept it is to find me a suitable machine for say £1500 (not inc pc)

What cutting area do you require in X,Y & Z. .?

[Jonathan]

I can see myself trying this sort of job... Would tabs solve the problem Jazz??

Tabs will clearly hold it, but they wont stop it flexing in the middle which is the main problem with a thin soft material like copper. It doesn't have to bend much for the engraving to be ruined, however you might get away with it, could always try double sided tape and tabs. The tape wont last long with flood coolant, but it may last long enough so long as your bed is impervious.

One way to get round the bending is the probing compensation method, though clearly it's preferable to get it flat to start with:

http://www.youtube.com/watch?v=fwgT9sCL8fs

I should think with some combination of the methods mentioned so far you'll find something that will work. Designing in a couple of strategically placed screw holes is a lot easier. On this keyring (1.6mm brass) I had one hole and double sided tape. That held it easily, but no coolant...

5861


What cutting area do you require in X,Y & Z. .?

Next question will be what's the biggest you can do for £1500!

[JAZZCNC]

Next question will be what's the biggest you can do for £1500!

Yes but that doesn't mean It will get answer'd. . Lol

( Oh forgot to say those screws arrived at my warehouse eventually (Wed), They said couldn't find it because I only put unit number not company name.!! IT's 10,000Sqr feet building with 18" tall unit numbers above main 10ft wide door, when pointed out to Dickhead driver he said " Awww ye dint fink tu luk up thier"

Oh ye and why didn't ya polish that key ring it's scratched to buggery. . :thumbdown:

[Jonathan]

( Oh forgot to say those screws arrived at my warehouse eventually (Wed), They said couldn't find it because I only put unit number not company name.!! IT's 10,000Sqr feet building with 18" tall unit numbers above main 10ft wide door, when pointed out to Dickhead driver he said " Awww ye dint fink tu luk up thier"

Snigger


Oh ye and why didn't ya polish that key ring it's scratched to buggery. . :thumbdown:

That photo was before de-burring and polishing. Didn't have chance to take a picture after that as it was already 25/12!

[Chris J]

What cutting area do you require in X,Y & Z. .?

Hard for me to say but as I understand it I need certain things whatever the overall size, spindle, motors & controller, pc etc (I'm sure you know).
So as long as I am not shooting myself in the wallet something of the A3 size with a height cutter to bed surface (Z?) of say 4"

Chris

[Chris J]

On small parts I often leave a thin skin 0.1-0.2mm and don't actually cut right thru so it's kind of like a one big tab then just clean up with de-burr tool or quick blast across the sander and the skins gone, tabs on small parts don't really work very well.!



I've been trying to get my head around this tab/skin business.

Are you saying that after cutting out I would use something like an orbital sander to remove the skin ad drop each piece out of the sheet.

Would a deburring tool go through a tab of say 0.2mm skin or tab?


Chris

[Chris J]

If anyone is replying specifically to me I have now started a build thread here (http://www.mycncuk.com/forums/showthread.php/4493-The-Dark-Satanic-Mill?p=30256#post30256), so maybe you could reply there - cheers

[JAZZCNC]

I've been trying to get my head around this tab/skin business.

Are you saying that after cutting out I would use something like an orbital sander to remove the skin ad drop each piece out of the sheet.

Would a deburring tool go through a tab of say 0.2mm skin or tab?


Chris

Yes you can usually press them out by hand or whip round with sharp stanley blade.
Usually quick blast across sander, I have a flat bed sander but orbital would work just as good, and then deburr edges followed by a thrash across buffing wheel.

This pic should give an idea, unfortunatly I'd snapped them out but you can just see the thin skin which just peels away with a quick bend and when first buckle is removed others just snap off easily with a slight burr left on the edge which you can just see if you look close. These are so tiny the deburr tool won't work but with a quick rub across sander these are gone in seconds and after quick buff on polisher they are silky smooth, all in all these take me 10mins each to deburr and polish and 30mins per 4 to machine.
5869

[Chris J]

Perfect, thanks.