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My latest plasma CNC cut.



Gadget
05-30-2009, 01:27 PM
This was cut out of .080 aluminum for a friend. I made one previously out of thin sheet metal but this one is better.

Dan

HerbD
05-30-2009, 03:36 PM
Gadget,

Neat job on the Jeep plate :-D We don't use front license plates here in Arizona, so there would be a lot of possibilities. My Rover is black and I could see a plate like that on the front bumper (Rover of course, not Jeep).

Now you make me want to get those stepper motors out of the box and finish my CNC conversion on the mill, or maybe even fab a plasma table . . . so much fun to do, so little time . . .

HerbD 8)

Gadget
05-30-2009, 03:59 PM
Herb,
I couldn't agree with you more on the line so much fun to do, so little time . . .
I can't wait to retire so I have more time to play.
Dan

HerbD
05-30-2009, 05:23 PM
Gadget,

The plate looks great and you've probably read my ongoing battle with slag when I try to clean cut stainless. How clean is the cut you get from your setup on aluminum? Did it take much finishing or is it pretty much what you see is what you got? I haven't tried plasma cutting on aluminum yet.

Thanks,

HerbD 8-)

Gadget
05-30-2009, 06:31 PM
Aluminum is sloppy but soft enough to clean the back with a belt sander. The actual cut surface looks good enough but the back has hairy slag that doesn't chip off easily.
Stainless is the worst for slag and it is extremely hard to clean up. I use an angle grinder on stainless but it warps the metal pretty badly. I wonder if a water table would make a difference.
I am about to put the router table back on my unit to make some foam cores for aluminum patterns. Mostly parts for the table such as a better torch mount and router mount.
Dan

HerbD
05-30-2009, 08:49 PM
Ah, I see. So there is no free ride - LOL. I have some aluminum sheet and after seeing your Jeep plate I was tempted to give it a try.

In an earlier thread I mentioned that I had been researching how to get a clean cut on stainless and found that the welders in the food equipment industry use a back gas apparatus when cutting to minimize discoloration, slag and distortion when welding and cutting, but I figured it was too complex to try to emulate at home.

This afternoon, while researching types of welding rod online, I came across just such a back gas fixture made by an individual. I emailed him asking permission to link to his pictures and credit him with the idea, hopefully he will OK it. The fixture looks like something that could be made with minimal tooling. If he OK's I'll share what he has done.

HerbD 8)

Gadget
05-30-2009, 09:00 PM
Sounds interesting Herb. I hope he approves the sharing of his post and info.
Dan

jbman45
05-31-2009, 04:14 AM
Youse guys have been talking about clean cuts on stainless and a post on trying back gas to keep down the slag, but not sure back gas would do any good unless you're talking about shielding with argon or nitrogen. Just occured to me that I think original plasma cutters used nitrogen rather than air for cutting. Have any of you tried either nitrogen or argon for the plasma cutting gas?? Iknow it sounds expensive but wonder if it would be worth a test. With our rigs it would be easy to give it a shot, I would but don't have any stainless handy.

Gadget
05-31-2009, 06:11 AM
I've only used compressed air for cutting. The volume of gas needed for the cutting operation makes using anything but compressed air too expensive for hobby use. I'm not making any commercial cuts with my unit and probably won't so it just isn't practical for me.
I still wonder if a water table would cut down on the slag, that's something I might try. I could use a tub of water as a testing unit. It would probably cut down on warpage when cutting too.
Dan

woofer456
05-31-2009, 09:53 PM
Just occured to me that I think original plasma cutters used nitrogen rather than air for cutting. Have any of you tried either nitrogen or argon for the plasma cutting gas??

Hi
I got an e-mail form Simon a while back about using nitrogen as an alternate gas for the plasma,
Here is what he sent:
Bob,
We cannot be responsible for the nitrogen as our manufacturer advises against it. Please do not use anything other than compressed air.
Simon

jbman45
06-03-2009, 01:24 PM
I checked with some ole 'experts' in the plasma business and they said stainless cutting can be quite a bit cleaner if nitrogen is used but you can not use the same torch electrodes, they must be tungsten electrodes. So, probably not worth all the trouble and risk of messing up your torch to try it, especially since you can't just switch to nitrogen with normal torch parts. He also said they cut stainless underwater with nitrogen as well to minimize slag formation but did not know if air plasma would work the same way. Just fyi...

HerbD
06-03-2009, 02:56 PM
Thanks for the info on cutting stainless. This is the type of information that isn't easy to come by without knowing someone who has first hand knowledge or someone who has a friend who has done it. :)

I've just about given up on getting a super clean cut on 20 ga stainless sheet with a standard plasma torch. For what it is worth, my current project, fabing panel doors for a BBQ cabinet, is all straight cuts. I've found that a 4" right angle grinder, equipped with a diamond wheel, makes clean cuts at a reasonable IPM rate.

I picked up about 30' of 1" x 2" aluminum tubing and 1" x 2" aluminum angle for scrap prices and am working on a design for a clamp and tracking system to facilitate cutting large sheets. Not quite as large as a vertical panel saw cutter, but similar in function. I'll share pics when it is all together.

HerbD 8)

clearchris
06-03-2009, 05:19 PM
I've found that a 4" right angle grinder, equipped with a diamond wheel, makes clean cuts at a reasonable IPM rate.


Does the diamond wheel cut faster than a regular abrasive metal cutting wheel? My cheap HF wheels seem to work pretty well on stainless.

HerbD
06-03-2009, 09:38 PM
Hi Clearchris,

I'm not sure if the diamond wheel cuts any faster than an abrasive wheel. My main goal was to have a thin kerf (cut) in the metal with a straight line and the diamond wheel is a consistent thickness that doesn't change through the whole life of the wheel. Even after more than a year of use it is still the same size and width. In a way the 4.5" diamond blades are a good buy for how long they last at around $9.00.

I have a couple of the 4" right angles and I do keep a metal abrasive wheel on one of them, but I use it for grinding welds and wire brushing metal so the wheel becomes worn to different thicknesses from outer rim towards the center of the wheel. At its best or in some ways worst the abrasive wheel would leave a wide or varying width cut as the wheel went deeper or shallower since I use it hand held along a straight bar of metal. In other words the edge would not be a straight line most of the time.

I also have a 14" cutoff saw and yes, it does cut like a banshee through metal, but the length of its cutting area is too short for the size sheets I am cutting. I mostly use it for cutting rebar and other tubing type materials.

HerbD 8)

KHK
06-03-2009, 10:11 PM
HerbD, after some thought from 25 years ago, I seamed to remember that I cleaned some stainless steal with an electrolis process.

FROM MEMORY!!
24 Vdc power supply
Negative wire to part to be cleaned
Positive wire to the wand, wand head covered with auto body fiberglass
Dip wand head in viniger
with power on wipe area of discolored stainless.
Check out this web site, It is a little hokey, but the idea is there

http://www.screenpro.net/weld.htm (http://www.screenpro.net/weld.htm)

If i get the time I will test tomorrow.

HerbD
06-04-2009, 12:03 AM
Hi Keith,
Thanks much for another good lead. I've got the hardware to try it too and will see how it works.

I've been anodizing and colorizing aluminum with pretty good success and find it amazing what can be done with moving those electrons around on metal. Same goes for putting black oxide finishes on machined/welded steel parts.

Today's project was building a larger oven for powder coating. Have you looked into powder coating for that great wheel weight and snow blower project you welded up?

HerbD 8-)

KHK
06-04-2009, 05:08 AM
I have looked into powder coating. There are a lot of advantages to this process.
I am waiting for HF to have a sale on the setup.

I have painted the wheel weight project with some poly-urthane grey paint.

HerbD
06-04-2009, 08:31 AM
Yep, HF tools are great, especially when you get a good sale plus 15 - 20 percent off coupon. As I recall I paid around $49.00 for the applicator. I got the base of my larger oven built yesterday. It will take 4' pieces when it is completed.

I followed the URL you posted yesterday regarding cleaning stainless weld discoloration. Looks neat. Did a search and found several manufacturers of this type of equipment. I like your idea of perhaps making such a device and using vinegar. Can't justify purchasing a $700 machine and can live with a slower (perhaps) homemade version. Thanks again for the suggestion.

HerbD 8)

matteh99
06-04-2009, 05:00 PM
My dad has one of these:

http://www.milwaukeetool.com/ProductDetail.aspx?ProductId=6370-21&CategoryName=SC%3a++Circular+Saws

It is basically a metal cutting skill saw. For straight cuts it is awesome. It says it can cut up to 3/4 if you are careful but it will cutt 1/4 inch stuff all day. My dad has used his to rip metal roofing if the pieces don't quite line up with the width of the roof. It doesn't work well on expanded metal or interrupted cuts because if you start the cut to quickly at the edge of the metal you can chip the blade.

HerbD
06-04-2009, 08:54 PM
Hi Matte99,

The Milwaukee saw looks great. I'm going to look into the cermet blades more deeply. From what i read on the link you provided the description is pretty close to what I'm doing, i.e. straight cuts, clean edge, etc.

Found one on eBay for $279 which is in line with other Milwaukee tools. I'm still going to go forward with a guide system for the 4 1/2" right angle with diamond blade that I've been using, but the saw you show looks interesting too.

Maybe I better buy an extra lottery ticket this weekend. How much is the jackpot? LOL

HerbD 8-)

matteh99
06-05-2009, 07:03 AM
I wonder what would happen if you put a cermet blade in a table saw or regular skill saw. The only two problems I can see are getting the right RPM and keeping metal chips out of the motor. :)

I am having trouble winning the lottery also. Darn it.

arandall
06-05-2009, 08:54 PM
My dad has one of these:

http://www.milwaukeetool.com/ProductDetail.aspx?ProductId=6370-21&CategoryName=SC%3a++Circular+Saws (http://www.milwaukeetool.com/ProductDetail.aspx?ProductId=6370-21&CategoryName=SC%3a++Circular+Saws)

It is basically a metal cutting skill saw. For straight cuts it is awesome. It says it can cut up to 3/4 if you are careful but it will cutt 1/4 inch stuff all day. My dad has used his to rip metal roofing if the pieces don't quite line up with the width of the roof. It doesn't work well on expanded metal or interrupted cuts because if you start the cut to quickly at the edge of the metal you can chip the blade.

Matteh:

Wish you hadn't showed me this!!

Cheers,
Art R.

clearchris
06-07-2009, 11:25 PM
True, the diamond blades hold up much better. How are they on heating the metal?

BTW, sounds like your alternative is cutting with a grinding wheel. It's always worth it to me to switch wheels to a thin cutting wheel (has a thinner kerf than most diamond blades). They can wear pretty fast, but I don't think the thickness would change much if any. Put any lateral pressure on those wheels and you'll be glad you are wearing eye protection. 8O

Sometimes I can get this to work for maintaining a consistent height. Sometimes it ends up being a serious pain instead.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=45921


Hi Clearchris,

I'm not sure if the diamond wheel cuts any faster than an abrasive wheel. My main goal was to have a thin kerf (cut) in the metal with a straight line and the diamond wheel is a consistent thickness that doesn't change through the whole life of the wheel. Even after more than a year of use it is still the same size and width. In a way the 4.5" diamond blades are a good buy for how long they last at around $9.00.

I have a couple of the 4" right angles and I do keep a metal abrasive wheel on one of them, but I use it for grinding welds and wire brushing metal so the wheel becomes worn to different thicknesses from outer rim towards the center of the wheel. At its best or in some ways worst the abrasive wheel would leave a wide or varying width cut as the wheel went deeper or shallower since I use it hand held along a straight bar of metal. In other words the edge would not be a straight line most of the time.
HerbD 8)

HerbD
06-08-2009, 10:26 AM
Hi ClearChris,

I hadn't really given much thought to heat buildup with the diamond blade because there is no discoloration and it seems like I can pick up the cut pieces without a glove. I looked at the thin abrasive blades too, but dismissed them because of how fragile they seemed.

Once I get my track/guide device built I may try them. When I cut freehand along a guide I still have to be careful about steering the wheel along the guide and with a thin abrasive I don't think it would take much to have a piece snap off.

Won't be back on the cutting project for a bit. One hundred and six degrees in Arizona has sent us to San Diego and the beach for a few days :p Sunny and seventy this morning!

HerbD 8)

clearchris
06-08-2009, 05:23 PM
No discoloration, no problem! I'll have to try it out.

Thanks!


Hi ClearChris,

I hadn't really given much thought to heat buildup with the diamond blade because there is no discoloration and it seems like I can pick up the cut pieces without a glove. I looked at the thin abrasive blades too, but dismissed them because of how fragile they seemed.

Once I get my track/guide device built I may try them. When I cut freehand along a guide I still have to be careful about steering the wheel along the guide and with a thin abrasive I don't think it would take much to have a piece snap off.

Won't be back on the cutting project for a bit. One hundred and six degrees in Arizona has sent us to San Diego and the beach for a few days :p Sunny and seventy this morning!

HerbD 8)