Luthier CNC

[A_Camera]

Thanks, it would certainly make things easier to go with air-cooled. I have a small room set aside for the CNC to go in anyway, so that will probably be the best way to deal with overall noise.

You mention that you have a brushless spindle? The one I'm looking at has brushes as far as I know:
https://www.aliexpress.com/store/pro...56c041d6TtIpdJ

I can't find brushless spindles above 1kw. Where did you get yours?

The link is not working.
Anyway, all three phase spindles are brushless, for example this one:

https://www.ebay.com/itm/From-EU-3-P...8AAOSwBydbh178

Note that this is just one I picked from ebay, though I bought mine from a different seller. Anyway, the only thing I'd do differently today is that I'd probably by a spindle with square housing today, and if possible, I'd buy one with active cooling fan, which is driven with a separate 24V, so the fan has a constant speed. I think those are better than the round ones with the fan mounted on the motor axis.

[bluesking]

The link is not working.

Here is a link to an eBay listing of the spindle I'm looking at:
https://www.ebay.co.uk/itm/EU-3KW-Ai...g/254196400436

I quite like the mounting plates on these square ones - seems easier to relocate the spindle up and down. Obviously still not as easy as a round spindle!

Note that this is just one I picked from ebay, though I bought mine from a different seller. Anyway, the only thing I'd do differently today is that I'd probably by a spindle with square housing today, and if possible, I'd buy one with active cooling fan, which is driven with a separate 24V, so the fan has a constant speed. I think those are better than the round ones with the fan mounted on the motor axis.

I have read that a constant speed fan is quieter as you suggest, but I don't think I have actually seen that mentioned on any of the listings I've seen on eBay/Aliexpress. I haven't planned a 24V supply either, so maybe it will be easiest if the fan is spindle driven, but I'm obviously still concerned about the noise.

[cropwell]

you'll be surprised how quiet an air cooled brushless spindle is compared to the Kress or a router....

I wouldn't. I've got a Kress, they are just as noisy as any other brushed motor router.

[bluesking]

Made a few minor updates based on the useful comments to date:

Upped the side plates from 15mm to 20mm (I've changed my mind about using reinforcement ribs here - seems like these might increase the risk of snagging on something or someone whilst the CNC is doing its thing)

Changed the front and back from extrusions to solid 20mm plates. Added 3 foot-like features to these so the base of the machine is basically a tripod to prevent it wobbling on the workbench.



Added some heavy duty steel brackets to the centre of the bed - I can't afford the cost or weight of a solid aluminium bed so this is my compromise. It'll all be connected to an MDF sheet lying on top of the bed structure with a 2nd MDF sheet on top of that as a spoil board.



Most everything else will be achieved using long screws into the extrusion cores, attaching them to the various plates.

Won't be able to machine my big plates on any CNC I can get access to but I am hoping to get access to a Bridgeport mill so I can at least drill all of the holes in precise locations (assuming I can figure out how to use a Bridgeport!)

[cropwell]

Hi Bluesking,

I don't know if you are aware of Nottingham Hackspace, but there is a Bridgeport there. I am a member, but haven't been there for a long time as they were located principally up stairs and I can't negotiate stairs and carry anything. They were in the process of opening up a downstairs workshop for the heavy machines.

https://hms.nottinghack.org.uk

Cheers,

Rob-T

[bluesking]

Hi Bluesking,

I don't know if you are aware of Nottingham Hackspace, but there is a Bridgeport there. I am a member, but haven't been there for a long time as they were located principally up stairs and I can't negotiate stairs and carry anything. They were in the process of opening up a downstairs workshop for the heavy machines.

https://hms.nottinghack.org.uk

Cheers,

Rob-T

Thanks Rob,
Yes, that is the very Bridgeport I'm referring to. Still waiting for an induction on it - I've never used a mill before!

I was there a few days ago and the metalworking stuff is still upstairs. Theres lots of setup work going on in the downstairs area but its far from complete by the looks.

[Voicecoil]

Won't be able to machine my big plates on any CNC I can get access to but I am hoping to get access to a Bridgeport mill so I can at least drill all of the holes in precise locations (assuming I can figure out how to use a Bridgeport!)

If you can't get access don't worry. You'd be suprised at how accurately you can place holes "the old fashioned way" using a surface plate, height gauge and optical centre punch.

[bluesking]

If you can't get access don't worry. You'd be suprised at how accurately you can place holes "the old fashioned way" using a surface plate, height gauge and optical centre punch.

Interesting, I don't understand what method you are referring to - can you describe a little more or point to a vid? What are the surface plate and height gauge used for?

If I can't use the mill I was just going to print some templates - stick them on the stock - punch the hole centres - and drill them out on my drill press. This is basically the same as what I do for making guitar templates - a job I thoroughly hate, mainly because I can only print A4 and have to tile my printouts.

[bluesking]

So a short update on my build. Things are going slower than I would like. I have gathered almost all of the components I need but am still waiting on a few key things.

Last few days I have been working on the various end plates and spacers for the machine.

I produced a technical drawing containing all the plates from my fusion 360 model. Using the fine-line-style setting when exporting to PDF was important to produce the most accurate output. All fits on a single sheet of A0, cost about £3 to print at a local printing shop:


Cut everything out and used spray contact adhesive to glue to the plates. Every time I use this stuff with paper I regret it. Horrible to clean up and unnecessarily strong.

The design of the my CNC means the actual plate dimensions are not critical. You can see all my plates are cut about 2mm too big from the supplier but this doesn't matter - the key thing is that all the holes are precisely located relative to each other. There are only 2 critical plate dimensions - and these only on one edge, corresponding to the 2 butt joints in the design. Paying attention and gluing the corresponding templates right up to the butting edge should be good enough.

Heres all the plates with their templates applied:


Thanks to reading Voicecoil's posts, I bought myself an optical centre punch and had a bit of fun using it. Its fun playing with the scope, pretending you're a CNC sniper, hahaha.


Silliness aside, the end results look well worth it - best punching accuracy I've ever had, should have got one ages ago:

[A_Camera]

I wouldn't. I've got a Kress, they are just as noisy as any other brushed motor router.

The Kress is MUCH noisier than any brushless motor of the same (or even higher) power. My 1.5kW brushless spindle is definitely much quieter than the 1kW Kress. Perhaps you misunderstood my post... ;)