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View Full Version : Using a ShopBot for cutting aluminum?



Terry Teadtke
02-06-2009, 1:03 AM
Iím just curious if it is at all an option to use a PRS standard to cut aluminum with coolant, a dedicated router, and fabricated coolant collecting tray? The reason I ask is while the majority of my ShopBot use would be for wood, it would be convenient if I were able to cut aluminum once in a blue moon if I needed to.

Thanks

Terry

Guy Mathews
02-06-2009, 6:51 AM
Yes, coolant and the proper bits are the only issues. You will have to play with feed speeds to get optimum performance. I just cut brass yesterday for the first time and I used a carbide 1/4 inch down cut bit. WD-40 was my coolant. Bit got hot as did the substrate. It was one of those "we need to try this or cut it with a hacksaw situations!
We had to make three small parts out of brass. I am going to cut one more today and take photos. From what I have read so far, aluminum cuts a hell of a lot easier then machinable brass. Call Brian at ShopBot. I am sure he can fill you in on proper bits and feedspeeds.

james mcgrew
02-06-2009, 8:56 AM
i cut aluminum with a "o" flute up spiral bit, you could go to youtube and enter -cnc router cutting aluminum- for many examples of this, onsrud provides a chart for feed speeds and bit parameters,

http://www.amanatool.com/cncroutingdetails/aluminum-cnc-spiral-bit-51402.html

jim

Terry Teadtke
02-06-2009, 4:10 PM
Thatís good to know. There would be occasions I would need to cut 1Ē aluminum stock up to 8í long and thought it might work on a ShopBot with coolant, proper cutter speed, and conservative feed rates. There would have to be proper modifications to the ShopBot such as a coolant tray, splash guards, and a dedicated surface but I donít see why it wouldnít work. I worked in a CNC machine shop years ago while in college and could probably figure out the proper modifications.

Thanks

Terry

james mcgrew
02-06-2009, 4:15 PM
it really isn't that messy, i did muck up a good spoil board the first time i did it, learned that lesson!! the big deal is all of the metal chips.

jim

Terry Teadtke
02-06-2009, 11:32 PM
The metal chip issue is a good point. Thatís why Iím planning on using a dedicated surface for metal machining and changing it out for regular wood machining. I just wanted to know I wasnít completely out of my mind considering the ShopBot for occasional metal work rather than having to purchase a 2nd machine just for metal work.

Terry

Guy Mathews
02-06-2009, 11:51 PM
The metal chip issue is a good point. Thatís why Iím planning on using a dedicated surface for metal machining and changing it out for regular wood machining. I just wanted to know I wasnít completely out of my mind considering the ShopBot for occasional metal work rather than having to purchase a 2nd machine just for metal work.

Terry

The only time you will be completely out of your mind is when you sit around many, many years from now wondering if you coulda, shoulda, woulda.

Until then, keep thinking of new and wonderful things to do with your CNC. If you are unsure, come to the forums and ask a question. I just read a post about a guy wanting to engrave leather with a CNC machine and he was not sure if it was possible. One fellow suggested he put it in the freezer so it would be harder. He suggested it would possibly engrave better because he does that with rubber. It makes sense. The fellow with the leather can sit around and coulda, shoulda, woulda the rest of his life... or he can freeze 5 bucks worth of leather and give it a try! Hell, I'll try it for him if he sends me a small piece of leather.

I tried milling brass yesterday with good results. We got the job done and learned a few things along the way.

Keep your CNC imagination exciting by thinking, dreaming, guessing and doing. If you make a mistake with your CNC, make sure the bit you break belonged to your buddy! When in doubt, come to the forums. Chances are, someone has already done it and they are happy to share.

I wonder if I can remove a tattoo from my wife's backside with my CAMaster? Probably drive myself nuts thinking about that one! :D

Angus Hines
02-07-2009, 1:12 AM
First great post Guy couldnt have said it better myself.

But I will add along the same vein that from what I have seen here at the ShopBot Camp in FL.

If you want to make a Mod for your CNC Be it a SHopBot or any other quality CNC it can be done.

You should see Gary Cambell's machine I think in has everything but a seatbelt.

It even has an air actuated dust foot....LOL *Scratchs head ??? *

I'll let ya'll know more tommorow.

Eric Mims
02-07-2009, 11:43 AM
You could always just buy a cold air gun system to cool with.. I think they run about 300 bucks and would save you from making a dedicated tray for liquid coolant.

Terry Teadtke
02-08-2009, 3:58 AM
I'll have to look into air cooling. When I was working in a CNC shop during college in the late 1970's, we used some kind of pink coolant. All I know is if for some reason the coolant flow was interrupted at anytime, whatever we were machining usually turned into junk real quickÖvery expensive junk. To this day I still marvel at some of the complexity and close tolerances of the kidney dialysis pump housings and parts we did. Amazing stuff.

Terry

Scott Shepherd
02-10-2009, 10:14 AM
Coming from a machinist background, a couple of issues you might consider- a lot of metal is cut using High Speed Steel. In the metal world, the difference between high speed steel and carbide do exist. The two materials use two difference principles in cutting and those differences can be seen at the cutting point when viewed under a microscope. High Speed Steel shears the material off, where as carbide tends to rip it off. Carbide, being so brittle, does not like to be thermal shocked. It likes to be hot or cold, but not hot/cold/hot/cold. If you use a spray mist system on carbide, you will likely have problems with your cutters chipping out or shattering. The heat from making the chip and then being sprayed with cool air is not good for carbide. High speed steel is very good with that. You can air cool or spray mist that, no problem. You'll also get a nicer finish with the high speed steel on most metals because of the mechanics of how it does actually cut versus carbide. Also, carbide needs to be dead perfect in runout. You can't have a carbide endmill running out .015". If so, you'll shock it and it will break. Not "might break", but "will break". Again, that's only on metal, nothing to do with wood at all.

If you plan to cut metal, HSS works very well, it's very forgiving, and it can handle air cool, spray mist (works great and would be prefect for the Shop Bot- probably can get a spray mist system for less than $100), and you'll spend less in cutters, especially if you are learning.

Cutting speeds/feeds are easy, just plan out the chip load per tooth and calculate it all out and you should be fine. You will be talking about inches per MINUTE not inches per SECOND as you do with wood, so don't try and kill it!

I know nothing about cutting wood, so the things I said above are only for metal.

Terry Teadtke
02-10-2009, 11:56 AM
Thanks Scott, it sounds like a mister is the way to go for cooling and lubrication. It's been many years since I worked in a CNC shop and I'm sure things have changed. From what I remember, the only time we used carbide was in machining cast iron, everything else was with HSS cutters.

Terry

Scott Shepherd
02-10-2009, 12:40 PM
Terry, go to somewhere like mscdirect.com and enter "Spray Mist" and you'll get a load of options. I would think it would be an excellent addition to a shop bot cutting metal, since it's not flooding and you don't have to deal with a massive amount of fluid, plus a good spray mist system will help keep the chips out as well.

Leo Voisine
02-10-2009, 9:28 PM
Terry - I just got done doing some cutting of aluminum on my Larken. No it's not a ShopBot but its the same thing really.

I made a branding iron test piece out of aluminum cause I can get aluminum free. It was 6061-T6

I will do the brass one in the next week or so.

I was running a 1mm solid carbide 2 flute right hand spiral end mill. RPM's at about 20,000 and feed rate at about 15 IPM - dry - no mist no air blast. It cut fine.

After the end mill - I used a solid carbide V-Groove bit to get into the detail and get the inside corners sharp.

After I was all done - I heated the aluminum and did a test burn - it all worked out just fine

Scott Shepherd
02-10-2009, 9:44 PM
A 1mm diameter cutter? That's .040", less than 1/16". That's little bitty for cutting metal :)

Leo Voisine
02-10-2009, 11:58 PM
Sure is small

I received the 1/64 end mills but have not tried those yet. So the 1mm seems BIG.