Engraving slate for an art project

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Xaracen
Posts: 122
Joined: Sat Apr 20, 2013 7:41 am

Engraving slate for an art project

Post by Xaracen » Tue Apr 08, 2014 12:46 pm

For about a month I have been learning to engrave small pieces of slate for an art project my son came up with for an assignment at university.

I had no idea if the shapeoko was rigid enough for slate but it turned out that slate is actually quite soft, and milling it was no real problem. More of an issue was keeping the small irregular pieces in place firmly enough and correctly oriented to keep a natural nearly-flat surface level with the shapeoko's x-y plane to let me engrave some short bits of text on them.

Early in the project a powerpoint project proposal would be presented to the class for comment, so some sample engravings were made to create a front page for this.
Art Project Presentation.jpg
Art Project Presentation.jpg (71.31 KiB) Viewed 6384 times
Now all I had to do was deliver!

Several early pices were marred by uneven depths of engraving due to the slate surface not being sufficiently level with the shapeoko's own x- plane. After some experimenting I ended up using a simple bulls-eye spirit level, first on the top of the spindle, and making sure the spindle was accurately vertical, then on the slate itself, held in a small modelling vice screwed to the mill bed.
Levelling the slate chip.jpg
Levelling the slate chip.jpg (74.31 KiB) Viewed 6384 times
The spirit level is one that came in a camera hot-shoe cover, and only cost about £2 from Amazon. I'll be buying a couple more. It is small enough to sit on the slate chip. We bought a whole bag of "Blue Slate Decorative Chippings" from B&Q for under £7. The blue slate is better than the graphite slate alternative because it tends to cleave in flat planes while the graphite slate only rarely does this. A good 30-40% of the blue slate provided large enough flat surfaces. But even when you have a good flat surface, it may be unusable because the rest of the chip itself is so irregular it cannot be gripped properly in the vice at the correct angle to present the flat surface at the needed angle.

However, you can mill a flat level surface into the chip with a flat end mill, but my son and I agreed that, while it worked, the naturally flat surfaces looked better, so we would level our own surface only as a last resort. We found more than enough usable chips not to need to do this.
Came out nicely.jpg
Came out nicely.jpg (67.13 KiB) Viewed 6384 times
In the end, all the engravings came out pretty well, and we engraved all 14 chips over the course of a day with no hiccups. My son went out with his selection of mini cairns and placed them in the park as planned, taking lots of photos. Then he left them for the public to come across, no doubt to wonder what on earth was this all about.

I'll add a few more photos in the next post.
Shapeoko v1 #????
500mm Y-slides with dual Y-steppers
375mm dual X-axis gantry
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conductive probe via spindle shaft/toolbit (can probe while spinning!)
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Xaracen
Posts: 122
Joined: Sat Apr 20, 2013 7:41 am

Re: Engraving slate for an art project

Post by Xaracen » Tue Apr 08, 2014 1:03 pm

This is a photo of one of the cairns in its park setting, with our engraved chip sitting on top.
1ft 10.jpg
1ft 10.jpg (89.04 KiB) Viewed 6380 times
I post the next photo as a tribute to Scorch's F-engrave utility. This is the only piece we milled flat, to see how it turned out.
Cut by F-Engrave.jpg
Cut by F-Engrave.jpg (115.55 KiB) Viewed 6380 times
And the last one is of course another well-deserved tribute. This was actually the first piece of slate I engraved, and it was a piece found in the garden.
shapeoko engraving.jpg
shapeoko engraving.jpg (75.41 KiB) Viewed 6380 times
I've had my shapeoko for just under a year, and it has given me endless enjoyment, it is just such a useful tool, and it's possibilities are so vast.
Shapeoko v1 #????
500mm Y-slides with dual Y-steppers
375mm dual X-axis gantry
150W DC ER11 Sable2015 spindle
conductive probe via spindle shaft/toolbit (can probe while spinning!)
Arduino Uno running grbl v0.9i with grblShield v4.

WillAdams
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Re: Engraving slate for an art project

Post by WillAdams » Tue Apr 08, 2014 1:07 pm

Very cool!

I especially liked that you properly used prime and double primes for foot and inch marks.
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Schruminator
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Re: Engraving slate for an art project

Post by Schruminator » Tue Apr 08, 2014 3:45 pm

Out of curiosity, what sort of endmill did you use for milling the slate?
1.8m x 1.0m SO2 #3638 / Vectric Aspire / ACME Z-axis / View my photography at http://www.mschrum.com

halfnormal
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Re: Engraving slate for an art project

Post by halfnormal » Tue Apr 08, 2014 4:01 pm

I too have had this idea to mill on stone. I am glad to see someone else is doing it. Please share the milling bits used and any hints for a good cut.

ALuomala
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Re: Engraving slate for an art project

Post by ALuomala » Tue Apr 08, 2014 4:07 pm

Very nice!! I was hoping someone would do something like this (I just recently ordered my SO2). I read somewhere (ref carving slate and/or other rock surfaces) that the dust can do a number on the bearings of your spindle, so keep that in mind.

I am most impressed that you were able to mill the slate flat: I thought it would be an achievement to simply carve letters/numbers into it.

In a similar vein, has anyone had experience with carving into stone tiles (of the floor/wall) variety?? Due to their size, consistency (i.e perfect dimensions and manufacture) and relative cheapness (any big box store carries these by the pallet-load), I thought that they would be perfect for creating plaques and the like. Combine these with a nice frame (whether created on the SO2 or just pre-made) and you have a nice gift (especially for things like house-warmings, anniversaries ("Our anniversary is tomorrow?!? Of course I bought you a present!!! Now excuse me for an hour or so while I go the garage/basement/shed......").

Allan
ShapeOko2, serial ??
DW660 spindle;
Upgrades: 900mm X axis and 1000mm Y axis; ACME Z Axis; modified MDF wasteboard with t-slot
Primary usage: wood crafting (signs, plaques, and ultimately a CNC-made electric guitar)

CalebPeters
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Re: Engraving slate for an art project

Post by CalebPeters » Tue Apr 08, 2014 4:39 pm

That is really cool. I had no idea you could do that with a ShapeOko. Thanks for sharing.
Shapeoko 2 #3164 : GRBL, NEMA 23 motors, 350W Spindle, Limit/home switches, Drag chain, X-Carve Upgrade.
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Xaracen
Posts: 122
Joined: Sat Apr 20, 2013 7:41 am

Re: Engraving slate for an art project

Post by Xaracen » Tue Apr 08, 2014 5:13 pm

Wow! Right, let's see...

My son was the one insisting on the use of primes and double primes, partly because he likes the ambiguity between feet and inches, and minutes and seconds. He's arty and sometimes has a different slant on things. They worked out well because they kept the text lengths small, as did the use of the 1/2 symbol. Given the dependency on naturally flat surfaces, the longer the text string, the more likely the engraving would encounter a significant deviation, thus spoiling the evenness of the engraving.

For the engraving I used one of the 1/8″ 60° V bits supplied by Inventables as part of the Premium Kit when I bought my Shapeoko last year. In using F-engrave, one part of the configuration is to tell F-engrave what bit you are using. It can also engrave with a ball-nose bit, but I haven't tried that yet.

One feature not well documented was that F-engrave can engrave a ring or box around the text, but with the v-carving option, doesn't specify how deep the bit will go, and I found nice boxed text had a very deep/wide groove around it, because F-engrave assumes the box groove thickness will be the full diameter of the bit. You can just tell the v-carve config that you are using a thinner bit, which limits the depth v-carve will cut. I set the feed rate at 5″ per minute, and the max depth per cut at 0.005″. I think this was probably conservative but it worked well.

For the piece I milled flat, a piece of graphite slate, I used a 1/8″ 2-flute flat endmill, also supplied as part of the Premium kit. I used the same feed rate and plunge as for engraving. This is the one above with Cut by F-engrave on it.

You can buy slate tiles from various places, these are flat(tish) on both surfaces, flat enough to stick down on the mill bed with double-sided tape. The shapeoko slate in my second post was engraved that way.

I have some small bamboo boards I am going to try out with some slate embedded in them, and engraving across both surfaces. I also bought some silver-plated chain and some loops and pins, and will attempt some necklaces etc.

F-engrave will also let you import dxf images, and I transferred a couple of celtic knots from my drawing app (XaraXtreme) via svg to Inkscape to dxf that way.
Two chips two knots.jpg
Two chips two knots.jpg (132.98 KiB) Viewed 6322 times
The smaller knot is ¼″ across.
Shapeoko v1 #????
500mm Y-slides with dual Y-steppers
375mm dual X-axis gantry
150W DC ER11 Sable2015 spindle
conductive probe via spindle shaft/toolbit (can probe while spinning!)
Arduino Uno running grbl v0.9i with grblShield v4.

edwardrford
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Re: Engraving slate for an art project

Post by edwardrford » Tue Apr 08, 2014 5:44 pm

Great work!

#tweeted.

-Edward
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RobCee
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Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Engraving slate for an art project

Post by RobCee » Tue Apr 08, 2014 5:46 pm

Superb idea!
I have a load of tiles and stone samples that I may have a play around with. Another real project!
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

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