Applying foil to bookcloth?

[carb (Carlo B)]

Everything is unbound still! Doing a couple test builds and am trying to formulate a basic plan before i do anything that isn’t reversible. And definitely expect to have some sacrifices.

I didn’t think about milling an aluminum plate on the mini cnc. I haven’t done anything but wood in the mini but it would be fun to try that. Thanks for the idea! iirc aluminum doesn’t have coolant needs but I’ll do the research.

The nipping press sounds useful though in general. How big is it? The books I’m binding are going to be A5.

[scday94 (Sam Day)]

The press should be up to a4 if memory serves though I wouldn’t consider it a heavy weight press, more of a cheap one we bought of eBay.

There is a small amount of metals we can mill on the small cnc but best talk to a cnc tech for spec. I’ve done brass myself and have bought aluminium for it but never did the cutting.

[Kyle (Kyle Barker)]

Aluminium is happiest with WD40 but can be cut dry on the mini cnc @CNCtechs

[sarab.sethi]

I’ve done a little bit of aluminium on the mini CNC recently.

For a 6mm end mill, I used 120-150 feed rate, 0.7mm depth of cut, ~20% step over, and got my own bits from Shop APT. Also spray tool and stock with WD40 as often as you can (ie would recommend stopping in between operations).

Got pretty nice surfaces but it is still a little bit hairy…! Especially with ramps/helixes down etc.

Good luck if you go that route and happy to chat more if helpful!

[Federico]

This is NOT how the mini cnc should be used. No coolant / liquid must be used on that machine. If you metal stock gets warm let it cool down or double check the settings.
Are you sure you are following the manufacture spec for the tool?

[sarab.sethi]

Oops, sorry I was following guidance from a few experienced people in the space/SMEE. Did a thorough cleandown of course afterwards, but will avoid any WD-40 if that’s the rules.

The tool can handle way faster feeds and speeds than those settings - but we’re limited by the machine itself (both from me searching around and from in-person advice)

[carb (Carlo B)]

Thanks all. I saw the mini-writeup here too: Aluminum on the mini-CNC

The recommended bits, and everything on that site, look like flat end mills. Does anyone have any experience with using engraving bits / v-bits on aluminum or brass? (Was watching this video: https://m.youtube.com/watch?v=2cIHCPI27bo though they use a tiny bit of coolant which is out of scope for us) I’m not sure if it’s the DLC coating on the other tips that allow for dry cutting or if it’s due to the other recommendations we’ve gathered from experience.

I grabbed some bits from the recommended site, I’ll find some aluminum to test with before switching to brass.

[Federico]

Hi @carb,

I did use engraving bits on brass and aluminium quite successfully. Some are already set in vcarve database under brass material.
I’ll be in Saturday and i can show you

[carb (Carlo B)]

Thanks! Do we already have the required engraving bits in the space (shared) or should I purchase my own? (I’m assuming the former given that you said they were in the vcarve database)

Additionally to everyone, is there a preferred source for brass and aluminum?

[scday94 (Sam Day)]

I know the engraving bits are pretty fragile so if you need a specific one, might be good to get a set. I think they are pretty cheap as far as bits go.

[carb (Carlo B)]

Good point. The video I watched above discussed that a little and he recommended some bits that had a slightly flatted tip with rounded edges to avoid breakages that seem prone to the sharp tipped engraving bits.

I’ll probably get my own but might not have time for delivery by Saturday.

[Federico]

What do you need in terms of engraving bit?

[KB98 (Karl B)]

I’ve got some spare gold bookbinding foil if needed. Definitely interested in how it goes as I’m also looking at making some bookbinding tools at some point out of brass.

[carb (Carlo B)]

You’re a bit ahead of me I’m still finalizing the design.

But imagine a simplified version of a monogram like the following. Cleaned up so that it’s only two black and white, no greyscale, and also simplified to make it feasible on our CNC’s resolution and whatever bits I’m using.

Centered on the cover of an A5 page, maybe 100mm x 100mm. Like the following “A”

I want to do those corner bits as well, but those are much simpler and I could get away without needing sharp corners / the need for an engraving bit on those.

[KB98 (Karl B)]

Looks really good, I’ve got absolutely no idea about the CNC machine but all of the bookbinding tool companies seem to use CNC.

Heating the plate up on a stove hob and then putting that in the nipping press could work. Just not too sure how accurate it would be.

[carb (Carlo B)]

Ended up snagging a design from “An Encyclopaedia of monograms” by James O’Kane (1884)

I followed @Archie’s general instructions and everything went really well (Except for accidentally setting the feed rate to 0% between runs once and getting very confused that the machine would start perfectly but then halt just as it started the first plunge. Thanks to @dannz who spotted this after 30 minutes of me trying to figure out if the issue was in my design, my bit settings, vcarve, or the machine. As usual: it was user error.)

For future discourse reference, these are the amateur numbers used. Better described here: Aluminum on the mini-CNC

Stock

• 6082 Aluminum from metals4u
• 101.6mm x 12.7mm x 101.6mm

Bits

Bit	shop-apt link	Flutes	Pass Depth	Stepover	Spindle Speed	Feed Rate	Plunge Rate
4mm End Mill	shop-apt link	1	2mm	40%	11000 rpm	950 mm/min	160 mm/min
1mm End Mill	shop-apt link	1	0.5mm	40%	13000 rpm	450 mm/min	160 mm/min
3.175mm Engraving Bit	shop-apt link	1	0.2mm	40%	22000 rpm	400 mm/min	125 mm/min

VCarve Process

• I first did a large 0.5mm depth pocket carve that covered the whole face to level it off.
• Then used the vcarve/engraving toolpath with the above bits as “Clearing Bits” with a starting depth of 0.5mm and a cutting depth of 1mm.

[carb (Carlo B)]

Note for any future readers:

Using these settings today I immediately broke my two 1mm end mill bits, literally as soon as they touched the aluminum they shattered. So clearly there might be some dialing in to do still. (Though I think I was using the wrong collet size)

The 4mm and engraving bit settings worked perfectly still, no breaks.

[mbg (Max G)]

An Encyclopaedia of monograms

Would you happen to have a copy of this book? And would you mind if I borrow?

[carb (Carlo B)]

Available online for free! https://archive.org/details/encyclopaediaofm00okan/page/n5/mode/2up?ref=ol

[carb (Carlo B)]

Note for any future readers:

Another iteration today saw me successully switch the pass depth of the 45/90 degree 3.175mm Engraving Bit from 0.2mm to 0.7mm which is a pretty massive speed-up.

I’ve yet to figure out how to get vcarve to properly skip engraving passes that don’t cut anything (already cleared by the Clearing Bits), but the full runtime for this pass was two hours, down from maybe four hours before where I ended it early.