Adventures In Aluminum

[Brady Watson]

I had a few hours today to mess around with some aluminum experiments that I have been putting off for a while. One of them was engine turning, also known as jeweling and damascening...I didn't find a ton of info on it on the web as far as technique went..but I always liked the prismatic look of engine turned aluminum.

I found a mandrel-mounted brown felt cylinder among the Dremel tools I had stashed away...and pulled some AL sheet out of the scrap bin. This piece had some serious oxidation on it!...I mean white! So after a few minutes of sanding...wet sanding and polishing (quick & dirty) I screwed the piece down to the spoilboard. With a gloved finger, I spread a thin layer of valve grinding compound onto the AL. I set the zero height and created a drilling file to run at .05 IPS in the Z. I started at 3000 RPM and moved up to 5000 RPM. I thought that the slow Z speed would be long enough dwell time...apparently not. I wound up creating a routine in VB that inserted a PAUSE 5 statement in the SBP drilling file after each plunge and ran it again...Not too shabby except that PartWizard is weird when it drills multiple rows...it skips the 1st hole in the 2nd (and subsequent rows) and goes back...it messes up the design..so I'll have to make my own array of holes programaticaly so this doesn't happen...anyway, the dwell time of 5 seconds seemed to do the trick! Here's how I did:


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After I did the engine turning I decided to try my hand at engraving the same piece. From my stash of 'rainy Saturday don't feel like working so I'll play in software' folder I grabbed something to engrave. I used a Machine Along Vector strategy with a 1/16" ballnose endmill. I ran it a .2,.2 IPS at 10k RPM and at a depth of .01". I just squirted a puddle of WD40 from time to time in the engraved area (4" square)...When I cleaned everything off I was pretty suprised! It turned out better than I thought! The vectors weren't the cleanest in the world and you can see some jaggedness on some of the arcs...but the SB handled the cut with no problem...and no bit breakage.
Here's how this piece came out:


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If I painted the AL black gloss and then engraved it, I bet it would look really great!

Anyway...just wanted to share today's experiment...more AL stuff to come in the future


-Brady

[waltie]

Brady,

Real cool stuff

[fleinbach]

Looks great Brady.

I'm sure there are many things like this that can be done aside from general parts most of use cut with the Shopbot. If only there where more hours in the day.

[bleeth]

techno-rad Brady. Go for it.

[stevem]

Nice

[elcruisr]

Bray, another engine turning trick I learned from an old gunsmith. He used a pencil eraser chucked up in a mill. Swore it was better than anything else he could buy. His work was sure beautiful. Maybe we need a special CNC eraser tool?

Engine turning was actually meant to have a purpose. It was a beautiful way to insure oil stayed on a surface evenly.

Eric

[Brady Watson]

Thanks guys!

Yeah...I've hard that others have used a simple wooden dowel...although I am not keen on running a wooden dowel in the spindle. Pencil eraser sounds interesting....pink or gray?

Suppliers sell abrasive impregnated rubber cylinders...I may give that a go.

-Brady

[propellers]

We have used a 3M lock on adapter that has the scotchbrite pad that work well for the swirl pattern.

[joe]

Brady,

Great post.

You've sparked my interest with these techniques. Noel Weber, a master sign artist is using turnings as part of his stunning and colorfull sign work. He creates border designs and patterns using old world classic decorative patterns. Once turned he has found a way of apply colored anodize soluction made perminent with a tourch. There seems to be a masking process, by which colors can be combined, making a jewel like surface.

Your post of samples are really appreciated. Do you have you any further information on tools and techniques or where to look?

J
www.normansignco.com (http://www.normansignco.com)

[Brady Watson]

Part Deaux.......


I actually engraved some prime material today after a little visit to my local tooling supply. I bought 2 dbl ended 1/32 ball end mills and a 1/32" (or there abouts) engraving cutter. I also got some 'Majic Elixir" there for cutting/tapping AL:


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I probably used more than I should have, but it seemed to do the trick. I went thru 3 1/32" ballnose bits with about 2/3 of the pattern done...I then decided to switch to the engraving cutter, which allowed me to run at a blistering .4 IPS....I was previously running between .1 and .3 IPS. I made sure to set my Z Jog AND move speed to .05 IPS before zeroing out the bit...it didn't break on impact. Here's a few shots of the design during and after:


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The engraving bit definately lasts a lot longer than the carbide end mill...but it doesn't produce the same effect as the ball end mill did. I was going to paint it black before I machined it...but laziness and expediency got the best of me. Between prep, cutting and changing out bits it took about 3.5hrs. If run with just the engraving bit, I bet it could be as low as 2hrs now. I used plenty of the cutting fluid on there to help keep the bit cool. I used the same machine along vector strategy as the last one I did. All designs were done in Corel and then piped into PartWizard. It was cut at .005" deep. I did a profile pass with a 1/4" bit to cut out the sheet (.100 AL) but you aren't seeing that part! I was definately running too fast and it welded the chips to the edge...had some grinding and sanding to do which took some time...

All in all I think it went pretty well! I might try some brass in the future and see what I can do with it. Who knows...maybe we'll be making watch cases in the future...yeah right!


-Brady

[paco]

Brady,
IMPRESSIVE effect!!! Thanks for sharing your experiences!

Curious:
I had thought that engraving that little deep could make some part of the design "unengraved"; I guess you used vaccum hold down to flaten the AL sheet on your spoilboard?

How your engraving tool look like (description)?

Do you feel you could have done it dry?

[Brady Watson]

Thanks Paco.

Like I said...I was feeling lazy today...so 1 screw (I actually had to get the drill out!!!) in the bottom left corner of the sheet and clamps on the X & Y extents. Actually, just clamping worked fine. Screws have a tendency to buckle the sheet (3 X 6')....so no vacuum on this one, but if doing it in the future I would use vaccum on a pre-cut blank. Fedex just delivered the last piece I need for my vac pump project...so I should have that running soon.

The engraving tool is a 1/8" shank with 45 deg V with the tip knocked off of it at about 1/32". It's a standard engraving bit. I think it was about $12 from my supplier...and is double ended.

I probably could have done it dry...but the fluid didn't hurt anything.

-Brady

[robert_starkes]

Not quite the detail of Brady's work but still in keeping with the aluminum theme. I was recently asked to create a master mold out of aluminum to be used to make multiply plastic (thermoformed) molds for concrete patio slabs 24" x 24" x 2"t.

Details on the cut: feedrate 5mm/s,0.66mm stepdown, depth of cut 2mm, 5/52" HSS end mill,50% stepover, cut dry.

I changed the bit half way through but think I could have cut the entire job on one bit. I had a challenge to match the exact Z-height of the first bit and still did not get it quite perfect (but close enough for concrete forms). Here is the finished product:

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The design for this mold was pretty simple but I hope to get a number of additional jobs for other custom designs.

Robert

[Brady Watson]

Pretty cool, Robert!

I like seeing alternate ways of using the ShopBot outside the normal woodworking envelope.

This is a great example and shows one more way to set yourself apart from your typical CNC shop. Interesting choice of mold material ~ thermoformed plastic I mean...We use a high durometer (about 95 Shore) polyurethane rubber material to create concrete molds from masters. By using this material, you can stamp or mass cast concrete. The PU material has the advantage, in lower durometer, of being able to cast patterns with undercuts...but thermoforming is great too if used for a stamp.

I will be doing a small presentation on moldmaking with the ShopBot at the Jamboree. Are you going?

Thanks for posting pics!
-Brady

[paco]

Thanks for sharing Roberts! Very interesting work!... (please, don't be so modest!!)

Curious; how long it took to machine this (24" x 24" x 2"t; 2mm deep) part?

What about RPM of the router/spindle?

PS: The little guy at your WWW site must have a painful back?!... shoveling hard and FAST on the site... 8-D

[robert_starkes]

Brady/Paco,

I have been able to do a number of machining projects in aluminum but this was the first mold job I have had. The buyer was pleased with this mold and has plans to buy several others. I hope this is an idea other shopbotters can use.

Brady, to be honest I am not familar with molding techniques but this company is definately thermoforming thier molds and using the aluminum blank as the master. Unfortunatley I will not be attending the Jamboree to get more info.

I used the PC router at 10,000rpm. The machining took about 20 hours in total. I secured the aluminum to the table with adhesive spray and a few screws pinched around the perimeter. I found that this kept the aluminum flat and solid on the table and I got better results than I had in the past. I was able to pull the aluminum off with no problem. The edges were deburred using a drill-mounted wire steel brush.

Given the slow cutting rate, I will admit that I was not able to charge my full hourly amount to the customer. The job cost was low ($10 for tooling) and I did not have to monitor the job so it was still attractive.

The worker at my www. site is something like the Shopbot, he just keeps going and going. I do have plans to complete but not the top priority. Too busy working, see below another aluminum job:


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Robert

[drodda]

Here is my first attempt at Engine Turning. I am trying some different ways to make it look better. Has anyone tried this on their shopbot lately?
By the way how do you get a picture large enough to see yet small enough in size to allow it to post? The 25k limit had me pulling out my hair.

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[drodda]

?

[gerald_d]

You can put a big photo here (http://www.frappr.com/shopbot/photos).

[drodda]

How do you delete a post?
Here is another try at the picture?

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[gerald_d]

You can't delete a post by yourself. You could mail ShopBot and ask them to do it for you. You can edit(empty) posts within 30 minutes of posting if you click on the edit button at the top right of your post.

[drodda]

Gerald,
Thanks for your help.

Dave