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View Full Version : has anyone tried to carve metal? (bronze specifically)



lawrence
09-07-2010, 05:48 PM
Yep, I know that carving metal is a no-no according to the LHR.... I'm curious if anyone has tried it though? (and would admit it)

Long story short... I am making a cast bronze infill plane (just like THIS one... it has flat and parallel sides)

http://showcase.netins.net/web/iabonsai/LaRue/SJBT.html
and would like to engrave the sides of the plane with a southwestern motif-- I am not looking to carve deeply, but would like to accomplish what is known as relief engraving... which requires going about 1/32 (or less) into the bronze

I am considering holding a shopvac wand (I use a festool vac so there is no static build up) close to the carbide bit while it carves which would minimize metal shavings getting into the works.

I'm thinking that I would make a sled out of wood that would house the plane but expose the surface to the bit... this way I could also practice on wood scraps first.

Any suggestions, real-world experiences, etc, would be greatly appreciated

Lawrence

TIMCOSBY
09-08-2010, 02:01 AM
i think it could be done on a real shallow cut but i dont want to be the first to try. any takers???? i think aluminum should be easier.

CarverJerry
09-08-2010, 10:27 AM
Lawrence, you might want to check and see what the cutting speeds and feeds are for the material you want to try and cut but 22 thousand RPM's is really smoke'n for cutting any kind of metal.......only my 2 cents worth from being a machinist for 33 years.

CJ

mtylerfl
09-08-2010, 03:38 PM
Hi Lawrence,

I just saw a post at the Vectric forum where a guy described carving/cutting a design out of aluminum. His project was pretty thick, so it's not necessarily what you would be doing. However, he shared some details about feed rates, etc. that I thought you might find interesting. Without the capability to make our own feed rate settings, I get the feeling it's not a good idea to try machining metal with our CarveWright machines (not to mention the issue of metal shavings and so on.) Perhaps doing your project in wood, foam or MDF and applying a faux bronze finishing technique would be possible as an alternative. Here is a copy of what he wrote...


I roughed the 3D out with a 10mm End Mill
2mm pass depth, 80% stepover
15 IPM feedrate, 12 IPM plunge rate
The chips were really flying off!
Cutting time approx 3 hours
I only have 4000 RPM available which is fine for this, but the smaller cutters could do with going faster

The 3D finish was done with a 3mm ball nose 2 flute carbide
again 4000 RPM
7 IPM feedrate
5 IPM plunge rate
8% stepover
Cutting time approx 24 hrs!!

The V carving for the lettering was done with a 90 degree V bit, also the chamfer round the outside edge.
4000 RPM
30 IPM feedrate
20 IPM plunge rate
0.5mm pass depth
Cutting time just over 1 hr

The cutout profile was also done with the 10mm end mill, same parameters as the roughing out.

I knew the 3D finish was going to take some time, so I set it real slow and left it running overnight, hence the 24hr cut, I could have brought that down, but it would have finished during the night, so it was no advantage.

JLT
09-08-2010, 08:08 PM
Lawrence,

I wonder if an indirect method might be better... Nothing I've done before, but something along the lines of the following: http://www.makersgallery.com/goss/etch.html. The idea being, that you put down some packing tape on a tight smooth surface (like PVC board), carve your pattern / text, and then lift the tape to then be used as your etching pattern on the plane. The wildcard is how tight will the pattern be reflected in the tape, or will some fraying occur?! Or will the tape simply wad up around the bit?! In a previous project, I used contact paper on PVC board (a concept courtesy of LittleRedWoodshop) and it worked well, although in my case, there was some inconsequental fraying via the carving bit, as the contact paper was simply used to protect the uncut portions for a subsequent paint job. (See http://forum.carvewright.com/showthread.php?14764-exacting-measurements/page3&highlight=slide+rule)...

Of course, it's not clear either how well the chemical etching will turn out after you cleared the aforementioned hurdles!

In any event, the basic concept might be worth some experimenting, as cutting packing tape will certainly put your machine at less risk than attempting bronze!

Jon

Fletcher
09-09-2010, 08:46 PM
Let me start by saying "this post is for entertainment purposes only and in no way reflects how a Carvewright should be used". Think that covers my ar$e?

Anyhow, I have been programing cnc machines to cut aluminum and copper for almost 20 years. I have run regular, or "low speed" machining centres as well as "high speed" machining centres. Based on the CW's rpms, I would use high speed machining strategy here. In other words, fast, but very light cuts. If you could break your 1/32 depth down into 3 separate passes of .010" depth or so, the CW should be able to do it - BUT.... 100% NO guarantees! I would also try to run it in "optimal" mode so that the feed rate is a little slower.

At 20000 rpm, with a feed rate of 80ipm, using a 2 flute cutter, the chip load per tooth is .002" which should be no problem if you only cut .010" deep per pass.

Again, this is just what I would try based on my past experience. If you break your CW, I had nuthin' to do with it! :)

Post your results here if you try it - i'd be interested to see how it goes.

bergerud
08-10-2011, 10:05 PM
I will try anything! My main worry with carving metal has been that the metal chips might foul up my machine. As a Dust Cap test, I thought I would give it a try. Besides, someone had to try metal!

I am happy to report that the dust cap collected all of the aluminum with no ill effects to the machine. The carving results, however, were not so good. I did a carve and a mill, both at a depth of 0.025. As predicted in this thread, the cut rate is too fast (at least for the 0.025).

The carving demonstrated that the Carvewright cannot hold the bit steady enough against the forces involved. The background of the engraving is lumpy. Under a microscope you can tell the bit was "out of control". The mill has more promise. The 0.025 was also too deep for the speed and there looked like some melting. In either case, shallower cuts are required.

(Note that the bits I used were not the standard Carvewright bits but stubby bits with a short LOC. The standard 1/8 bit would break just touching metal.)

A small diamond engraving tool might be fun to try.

I am not done with this yet. It was not a scary as I thought it was going to be.

lawrence
08-11-2011, 12:01 AM
Man- that is AWESOME-- thank you

My infill plane is at a friend's right now-- I misdrilled and he is brazing/welding on a patch. (here is a pic of it sofar....)
http://i171.photobucket.com/albums/u313/ldr_klr/infill%20plane/DSCF01231024x768.jpg

Thanks again - I will be giving things a try on a piece of scrap bronze at some point (after I make a dust cap)

'tips hat your way
Lawrence

bergerud
08-11-2011, 10:31 AM
Nice plane. I can see how engraving on the side would turn it into a masterpiece. I think it will work if the carving is shallow enough. A few passes and it would work for sure. I would buy a couple of 1/8 ballnose with 1/4 or less LOC (check eBay for example) for the job. Show us what kind of carve you plan and let us know when you start experimenting. Maybe we will find an even better method before you start.

Alan Malmstrom
08-11-2011, 11:06 PM
I bought a book on how to make a crucible furnace for use in your backyard as well as a how to cast metal in sand book from: http://www.backyardmetalcasting.com/ each book is only about $8.00

I figured if I ever wanted to make my own metal parts I could just make a replica or the part needed with the carvewright, and then mold it in sand, and melt the metal using the small homemade crucible.

Alan

Pratyeka
08-18-2011, 10:54 AM
That CNC router I bought from Redsail China a few months back for $3000 is working well for machining aluminium. Thickness is .400", aluminium.
Used a 1/4" "O" flute aluminium bit, 1 flute, at 18,000 rpm, feedrate 16IPM. The holes in the strainer are 1/8" dia. Each part took about 30min to make.

ktjwilliams
08-18-2011, 09:38 PM
Hey Dan,,, I was wondering how long it would take before U cut some metal and jump in here... As soon as I read this post, I tought of U.... I said, now someone gave Dan a new idea to try !!! LOL... Anyway I messed up my 1st attempt on the dust cap...

mtylerfl
08-19-2011, 08:53 PM
That CNC router I bought from Redsail China a few months back for $3000 is working well for machining aluminium. Thickness is .400", aluminium.
Used a 1/4" "O" flute aluminium bit, 1 flute, at 18,000 rpm, feedrate 16IPM. The holes in the strainer are 1/8" dia. Each part took about 30min to make.

Looks good. If desired, you can get a smoother finish on the piston by decreasing your toolpath stepover on your finish pass (I assume you are tooling both roughing and finish passes). For a finishing toolpath about 8 to 10 % stepover is usually a reasonable value. Did you tool the 1/8th holes, as well? If so, what bit did you use (brand and specs)? You mentioned you used a 1/4" O bit, so I am wondering how you got 1/8" holes with a 1/4" bit? <smile>

jiml
08-19-2011, 09:26 PM
Lawrence, Since you want to go so shallow couldn't you trace your pattern onto the plane with a Sharpie then warm the plane body enough to melt bees wax, then coat the plane surface with the wax about 1/64" thick forming a 1/8" ridge around the perimeter. Scrape through the bees wax along the pattern lines visible, fixture the surface horizontal and level, pour in acid and let it etch? Works on aluminium.

lawrence
08-19-2011, 10:41 PM
Lawrence, Since you want to go so shallow couldn't you trace your pattern onto the plane with a Sharpie then warm the plane body enough to melt bees wax, then coat the plane surface with the wax about 1/64" thick forming a 1/8" ridge around the perimeter. Scrape through the bees wax along the pattern lines visible, fixture the surface horizontal and level, pour in acid and let it etch? Works on aluminium.

It is certainly something I've considered--I hadn't thought about wax as a resist, but the idea intrigues me.

Holy cow, you live in Tucson-- PM coming your way

Lawrence

Pratyeka
08-22-2011, 06:30 AM
Looks good. If desired, you can get a smoother finish on the piston by decreasing your toolpath stepover on your finish pass (I assume you are tooling both roughing and finish passes). For a finishing toolpath about 8 to 10 % stepover is usually a reasonable value. Did you tool the 1/8th holes, as well? If so, what bit did you use (brand and specs)? You mentioned you used a 1/4" O bit, so I am wondering how you got 1/8" holes with a 1/4" bit? <smile>

Thanks Michael. The finish was not that important on this project, it feels pretty smooth to the touch. The 1/4 bit is 1 flute, and the bottom is not flat so cannot produce a fine finish.. The 1/8" holes are indeed done with a 1/8 drill bit by the same machine. The project is a solder dross separator for our wave slodering machines. It's just like a big potato press. I'll post pics when done.
http://www.toolstoday.com/p-5801-solid-carbide-spiral-o-flute-aluminum-cutting-up-cut-down-cut-router-bits.aspx