Tips, tricks, guides and templates....

[plantlife]

Thought it might be handy to have a thread on tips, guides etc. If anyone wants to share.

I've been mainly looking to see if it's possible to have a template to help cutting the lines.


This info is linked to the orignal source at the bottom, just incase there is any copyright issues.


Ten Tips for Improving Plasma Cutting Quality

Plasma cutters are so easy to use that it's tempting to take your new plasma cutter out of the box and go to work. However, there are a few practices that can increase your efficiency, improve your cut quality and prolong the life of your equipment.
Plasma cutters are so easy to use that it’s tempting to take your new plasma cutter out of the box and go to work. However, there are a few practices that can increase your efficiency, improve your cut quality and prolong the life of your equipment.

• 
  
  
  
  Fig. 1–A drag shield allows you to rest the torch on the work surface and helps maintain the proper standoff distance.
  
• Thoroughly read the owner’s manual to familiarize yourself with the safe and correct operation of your particular plasma cutter. This will help you optimize your plasma cutter’s capabilities.

• Make a sample cut on the same type of material with which you’ll be working to ensure you’re using the right settings and travel speed.

• On long cuts, it is difficult to stop cleanly and continue. Practice your movements before pulling the trigger to make sure you have adequate freedom of movement to make one continuous cut.

• Use a drag shield if your plasma cutter is equipped with one. (Fig. 1) A drag shield allows you to rest the torch on the workpiece while maintaining an optimal 1/8-in standoff without touching the tip to the metal. (Touching the tip to the work surface will adversely affect your cut quality and consumable life.)

• To maintain the optimal 1/16- to 1/8-in. distance between the tip and the workpiece without a drag shield, use your non-cutting hand as a support for your other hand. This provides freedom of movement in all directions while helping to maintain a constant standoff and steady your cutting hand. (Figs. 2a-2b)

• Use the right tip for your amperage setting. A lower-amperage tip has a smaller orifice to maintain a narrower plasma stream at lower settings. Using a 40-amp tip at an 80-amp setting will distort the tip orifice and significantly reduce consumable life. Using an 80-amp tip on the lower settings will not focus the plasma stream as well and lead to a wider kerf. Use extended tips to reach out further for cutting in corners, using patterns or in tight areas.

Fig. 2a– Maintain a 1/16- to 1/8-in. standoff to increase the longevity of your consumables, produce a cleaner cut and maximize your machine’s cutting capacity.

Fig. 2b– Using your non-cutting hand as a brace helps to maintain standoff and provide a cleaner cut.

• When piercing thin material to start a cut, the arc may be able to punch through with little or no backsplash. However, on thicker material, start with the torch on a 45-degree angle so the first blast of metal has somewhere to go. Otherwise, the metal will splash back and quickly wear your consumables

Fig. 3–If you’re maintaining the proper travel speed, the sparks will exit the workpiece at a 15- to 20-degree angle.

• The faster your travel speed (especially on aluminum), the cleaner your cut will be. When cutting thicker material, set the machine to full output and vary your travel speed. On thinner material, turn down the amperage and change to a lower-amperage tip to maintain a narrow kerf.

• The arc should exit the material at a 15- to 20-degree angle opposite the direction of travel. If it’s going straight down, it means you’re moving too slowly. If it sprays back, it means you’re moving too fast. (See fig. 3.)

• For precise cuts use a straight edge clamped to the workpiece to guide the torch. (Fig 4.) If you’ll be making multiple cuts of the same shape, create a template. Straight and circle guides are available to help guide the torch and ensure precise cutting. (Fig. 5)

Fig. 4–A straight guide used with a straight edge.

Fig. 5–A circle-cutting guide helps with clean, repeatable circular cuts.
- See more at: https://www.millerwelds.com/resourc...g-plasma-cutting-quality#sthash.xviRu10e.dpuf


Link to text,

https://www.millerwelds.com/resources/article-library/ten-tips-for-improving-plasma-cutting-quality

 

[Badger1bear]

Use flat magnetic strip from eBay, various lengths/widths/sizes are available. You can cut a perfect straight line on flat steel and you can cut a perfect straight line on round gas cylinders

 

[gaz1]

i use an 1 ,1/2" angle iron as a straight edge works great i can hold it with one hand though thinking of sticking a handle on it but my speed is something else

 

[plantlife]

DIY
TOOL SCHOOL: A QUICKER WAY TO CUT STEEL
http://www.popsci.com/diy/article/2009-11/tool-school-plasma-cutting

Vin Marshall

Plasma Torch

Building things from metal can seem intimidating—metal just feels so much more permanent than, say, wood, and with the all the sparks and pressurized cylinders, it seems like just a matter of time before you blow up your shop. But once you know your way around a few key tools, you'll be amazed at how simple metalwork can be. Case in point: the plasma cutter. This small, relatively inexpensive machine has one dial, no cumbersome gas tanks, and can zip through any conductive material faster than a jigsaw through pine. It's also basically a sci-fi machine made real (c'mon, it slices through steel with hafnium and air!). And since they're for sale in most big-box home stores, you can even put one on your X-mas list. Master this, and your metal creations can take on just about any shape you want.

In a previous Tool School post, we looked at oxy-acetylene cutting. Oxy-fuel cutting is great for thicker materials. But when it comes to thin materials, especially 0.25-inch and thinner, the plasma cutter shines. For the record, plasma cutting shines on thicker materials as well, but requires a bigger, more expensive machine. For the shop on a budget (and who isn't?), stick with oxy-fuel for the thick stuff and keep a small plasma cutter for thin materials. Also, while oxy-fuel cutting is limited to steel, plasma cutting can cut through any conductive material.

The plasma cutter works by using sophisticated electronics and a bit of hafnium, which releases electrons into the air very easily, to create a superhot plasma (ionized gas) at the tip and compressed air to blow that plasma through the material being cut. (Here's a good video on how plasma cutting works from machine-maker Thermal Dynamics.) Because of that, the heat applied to the part being cut remains far more localized than with oxy-fuel cutting. In practical terms, this means that thin metal is less likely to warp when plasma cut than when cut with oxy-fuel methods.

Safety:

As with the oxy-acetylene Tool School post, we need to address safety first. Plasma cutting generates hot sparks and slag (hot bits of melted metal), which means that all of the apparel guidelines that apply to welding and gas cutting apply here as well.

1. Apparel: Wear a protective jacket designed for welding. Wear pants made of a natural fiber without cuffs. Wear gloves. Protect any part of your body you don't want to touch hot bits of melted metal.

2. Eye Protection: Plasma cutting generates intense light. Wear shaded eye protection in the range of #7 to #9. Thicker materials call for a shade on the darker end of the range.

3. Environment: Hot sparks and slag will rain down from the cutting area. Make sure they can't fall onto anything they can ignite.

4. Ventilation: Plasma cutting produces gasses and airborne dust; have a way to evacuate them from the work area in short order.

5. Remember that no quick post online can convey all of the safety points needed to operate complex and dangerous tools. It is your responsibility to do your own research and to educate yourself as to the safety best practices. What is provided above is only a primer. Always make use of the best tool that you have available: common sense.

Cutting:

Plasma cutters are far easier to setup and use than oxy-fuel setups. There are really only two variables and they are related: The power level (the single dial on the machine) and how fast you move the torch. Given the same thickness of material, you can cut at a lower power level if you move the torch slower. Conversely, the torch can move faster at a higher power level. Unless the situation calls for a very narrow kerf (the width of the actual cut), it's generally easier to lean toward higher power settings, especially while still getting a feel for the equipment and the process.

I made a few sample cuts on 1/8-inch mild steel plate to show some common beginner problems. Comparing these cuts to yours should help to dial in your power settings and cutting speeds.

Vin Marshall

Plasma Cuts (Top)

1. The power level was set way too low for the material, especially at the cutting speed used. The cut did not even penetrate all the way through the material. Remedy: Turn up the power and/or move the torch more slowly (probably both).

2. The power level used here was the same as that in cut #1, but the torch was moved very slowly. This is still not a good cut. The power level is just too low for the thickness of the material, as indicated by the buildup of slag on top of the piece next to the cut. I didn't put enough energy into the cut to blow the slag out the bottom. And slag on top of the cut is much harder to chip off than the slag on the bottom. Often it has to be ground off. Remedy: Turn up the juice.

3. The power level used here was higher. Technically speaking, it was too high for the material and cutting speed used. It works fine, but leaves a very wide kerf. The great thing about plasma cutting is that you don't really need to be that precise with the dial—just vary the torch speed accordingly. Remedy: Either do nothing, or turn down the power slightly.

4. This is the cut you want. The power was set higher than on cut #1 and lower than on cut #3. Approximately the same cutting speed was used in cuts 1, 3, and 4. The kerf is a reasonable size and there is no slag on top of the cut. Once you have dialed in the amount of power and the cutting speed to this point, all that is left to do is practice your hand eye coordination and learn some of the finer details. (Experts may want to share some of the tricks they've picked up over the years in the comments below.)

5. This cut was made with worn out consumables—torch tips, electrodes, cups—in the torch head. The cut is a bit rougher and, although it is hard to see in this picture, is angled rather than straight through the metal. The plasma jet has a tendency to go wherever it wants as the torch tip begins to wear. Remedy: Replacing the worn out parts will bring the cut back to the point of cut #4.

Cleanup:

After cutting, there will be slag on the back side of the cut, as in the picture below.

Vin Marshall

Plasma Cuts (Bottom)

Resist the temptation to grind this off! If the cut was well executed, with the proper power settings and cutting speed, this slag should easily chip off with a cold chisel and hammer. Using the cold chisel will leave a far cleaner edge than grinding ever would and will also take far less time.

Cuts # 1-4 have been left untouched. The slag has been chipped from the back side of cut #5 to show the result. It took about 10 seconds.

While this may seem oversimplified, plasma cutting, like wire-feed welding, really is something you can pick up in an afternoon and start building your first project. Of course, like any DIY skill, there's almost no limit to how good you can get with enough practice and, if you're lucky enough to know some, tips from old pros. In the meantime, check out Miller's extensive plasma-cutting resources to learn more.

 

[gaz1]

the cut 50s are ok for what they are designed for it van do plenty of cuts however its consumables arnt like the expensive types

our cuts are different to say the least ive played with mine already and had it cutting 10mm and other 3mm and 5mm however it finaly chewed through the tip

most mistakes are at the earthing side of it as has to be a clean surface to clamp too

 

[plantlife]

Info about the cheap cutters
http://www.machinistblog.com/id-like-to-buy-a-plasma-cutter/

Cut manual
http://www.winnerwelding.com/product/CUT manual .doc
Another manual, not sure if it's the same model
http://www.plasmapart.com/pdfs/PlasmaPart CUT 50 Pilot Pro S-45 Euro Connector Torch.pdf



How to fix a cut 40

http://www.electro-tech-online.com/threads/compatable-mosfets-for-a-chinese-plasma-cutter.103029/

 

[plantlife]

http://cut40.blogspot.co.uk/

How to fix a plasma cutter. How to fix a 40 amp plasma cutter, 50 amp plasma cutter, 60 amp plasma cutter.

How to repair a plasma cutter.

This page could potentially help out someone who owns any of the following plasma cutters:

Lotos CUT40 plasma cutter
Lotos CUT40A plasma cutter
Lotos CUT40D plasma cutter
Lotos CUT50 plasma cutter
Lotos CUT50A plasma cutter
Lotos CUT50D plasma cutter

Volt Silverline CUT40 plasma cutter
Volt Silverline CUT40A plasma cutter
Volt Silverline CUT40D plasma cutter
Volt Silverline CUT50 plasma cutter
Volt Silverline CUT50A plasma cutter
Volt Silverline CUT50D plasma cutter

Simadre CUT40 plasma cutter
Simadre CUT40A plasma cutter
Simadre CUT40D plasma cutter
Simadre CUT50 plasma cutter
Simadre CUT50A plasma cutter
Simadre CUT50D plasma cutter

Riland CUT40 plasma cutter
Riland CUT40A plasma cutter
Riland CUT40D plasma cutter
Riland CUT50 plasma cutter
Riland CUT50A plasma cutter
Riland CUT50D plasma cutter


Chicago Electric CUT40 plasma cutter
Chicago Electric CUT40A plasma cutter
Chicago Electric CUT40D plasma cutter
Chicago Electric CUT50 plasma cutter
Chicago Electric CUT50A plasma cutter
Chicago Electric CUT50D plasma cutter

Why? Because when trying to fix my Lotos CUT40 plasma cutter, people sent me resistor values for their plasma cutter's high voltage rectifier circuit and the values were all the same even though the plasma cutters were made by different manufacturers and the models were different.

Continue reading this blog to find out if your defective plasma cutter has the same problem as mine: burned out diode, leading to a burned our resistor.

There are extremely high voltages and currents inside a plasma cutter. I take no responsibility for anyone doing any repair work on their plasma cutter. Before working on any internal components, unplug the power, hold the trigger switch so the capacitors discharge (you will hear them), then hold a screwdriver or other insulated device across one of the four large capacitors on the bottom power board so you see a spark. Good luck!

 

[plantlife]

http://cut40.blogspot.co.uk/


Today I spent a little more time trying to figure out why the plasma cutter still isn't working, and more specifically why the new resistor gets so hot.

Well, I found the problem!!!!!! With the multimeter on the diode setting, one of the diodes in the rectifier bridge was reading 0.284V in both directions which isn't correct. The other diodes have a reading of 0.84V in one direction and 0V in the other direction.

The bad diode is a 2000V RU1H fast recovery diode. I couldn't find one in stock anywhere, so I just put three 1000V 1N4007 general purpose diodes in series. I also added a 470,000 ohm shunt resistor across each diode to help protect against transients. There are already disc capacitors across each diode in the bridge, so I didn't worry about adding any more.

As an aside, I noticed that there are two diodes in series in one position of the rectifier bridge, so the designers must have figured their diode choice wasn't big enough. They should have doubled up all four diodes right off the bat.

Original RU1H diode that burned out:




New replacement "diode". Three in series = 3000V:



New diodes installed where burned out diode was.





Thanks again to everyone who helped me find the resistor value!

POSTED BY LUKE AT 9:11 PM 1 COMMENT:

 

[plantlife]

Making Progress

I'd like to thank eBay's motorcycleman561 for opening up his plasma cutter and sending me his resistor values. My plasma cutter is a CUT40 and his is a CUT40D, but the resistors seem to be the same!

I ordered a 10W 1kohm resistor (colors Brown, Black, Red, precision Gold). The plasma cutter initially had a resistor of 5W 1kohm, but since it burned out, I'm replacing it with one that can handle double the power...

The results:

The plasma cutter still doesn't work... The resistor gets very hot (270F) when the trigger is held down.

Here's the new resistor:



Installed:

http://4.bp.blogspot.com/_Q-FTUFOo3yY/SiyOi48GhYI/AAAAAAAAALs/WoOuMZc5VVw/s1600-h/part.jpg

POSTED BY LUKE AT 7:45 AM 1 COMMENT:

WEDNESDAY, MAY 27, 2009
CUT40 Plasma Cutter[/paste:font]

I'm creating this blog for two reasons:

1. To hopefully repair my plasma cutter.
2. To help others repair their plasma cutter if it has the same problem as mine.

I have a LOTOS CUT40 plasma cutter, but I'm sure that many other models are very similar, if not identical. Other similar units may include CUT40D, CUT50, CUT50D or Simadre CUT40, etc.

I opened up the plasma cutter and found a burned out resistor on the bottom transformer/rectifier circuit board. The circuit board consists of four large capacitors, a transformer, some rectifier diodes, some resistors and connectors.

I wouldn't be writing this except that before the resistor burned out, it appears to have gotten extremely hot and the resistor color bands burned off, so I can't see what value I need to order. I could make a guess or calculate the value, but I thought that I would ask you if anyone would consider opening up their unit and tell me the color band colors?

I have attached some pictures to show exactly which resistor it is. The resistor is about 1" long, 1/4" thick, gray in color, and it appears that the second band from the left is black.


If anyone has the time to open up their unit and let me know what the colors are on the resistor, I would be extremely grateful.

Thank you for your time, and if anyone needs help repairing their plasma cutter, let me know!

 

[plantlife]

http://cut40.blogspot.co.uk/


Pictures

The plasma cutter:


A top view with the case removed:



A side view to show the orientation of the next pictures:



Zoomed in on the location of the rectifier circuit and three resistors including the bottom burned out one:



The burned out resistor:

The color band goes from left to right in the photo below. In-case another unit's resistor is oriented opposite, the color band ends with the color that is slightly separated, ie. gold for the top resistor. The gold band is often silver and shows the precision of the resistor.
Eg: The top resistor has the colors: Brown, Green, Black, Orange, and precision Gold.




The burned out resistor removed:



POSTED BY LUKE AT 6:52 PM 2 COMMENTS:

What's this part for?[/paste:font]

If anyone has any idea what the circled electrical part is, I'd love to know. There are two metal bars sticking up, separated by about 1/16", and each bar has a circular copper piece near the end. It appears to be some sort of contact, but I've never seen one before...



POSTED BY LUKE AT 5:53 PM 10 COMMENTS:

 

[plantlife]

I thought these might be handy, I know people have fixed their own on this site but I figured it might be helpful to some one.

 

[gaz1]

your pics dont help being upside down

@skotl has boards similar to yours on site here as well

i presume thats the firing trigger on the cut 50

this one is the newer type cut 50 with brass firing pins and looks like bushes

 

[gaz1]

im adding these here as a reference

 

[plantlife]

A few questions answered on my thread has opened my eyes, thought I'd add this on too.

A pantograph for a plasma cutter
https://woodgears.ca/pantograph/plasma.html
http://www.plasma-cutter.org/plasma-cutting-tips/how-to-make-a-metal-pantograph-for-plasma-cutting/
https://en.m.wikipedia.org/wiki/Pantograph

 

[plantlife]

Again, added info. As it didn't occur to me to make an item in a different way. I thought an external outline was the only way :/

Either use the internal or external Side of your line to use as a template to cut your shape out. You'll have to adjust sizes accordingly.

http://www.clker.com/cliparts/e/h/h/Y/H/K/seagull-outline-line-drawing.svg

 

[skotl]

http://cut40.blogspot.co.uk/


Today I spent a little more time trying to figure out why the plasma cutter still isn't working, and more specifically why the new resistor gets so hot.

Well, I found the problem!!!!!! With the multimeter on the diode setting, one of the diodes in the rectifier bridge was reading 0.284V in both directions which isn't correct. The other diodes have a reading of 0.84V in one direction and 0V in the other direction.

The bad diode is a 2000V RU1H fast recovery diode. I couldn't find one in stock anywhere, so I just put three 1000V 1N4007 general purpose diodes in series. I also added a 470,000 ohm shunt resistor across each diode to help protect against transients. There are already disc capacitors across each diode in the bridge, so I didn't worry about adding any more.

As an aside, I noticed that there are two diodes in series in one position of the rectifier bridge, so the designers must have figured their diode choice wasn't big enough. They should have doubled up all four diodes right off the bat.

Original RU1H diode that burned out:




New replacement "diode". Three in series = 3000V:



New diodes installed where burned out diode was.





Thanks again to everyone who helped me find the resistor value!

POSTED BY LUKE AT 9:11 PM 1 COMMENT:

As both you and Gaz have pointed out, most of the boards in these cutters seem to be pretty generic.

Your diode in this pic;

Is also what failed in mine (it went completely short circuit so took a couple of other components out, too). This is my board for comparison;

(180 degrees oriented compared to yours).
You'll note that my board was marked with the component spec, RP1H, which made it easier to find a replacement. That said, you'll see that on mine, the original manufacturer also put two diodes in series for each connection, as you've done!

FYI; my it's broken thread, the think-I-know-what's-wrong thread and my it's working thread. Happy for you to link to either from your site.

 

[Wendelspanswick]

Here a link to the repair job I did on my Cut50:
http://www.mig-welding.co.uk/forum/threads/my-plasma-died-but-i-managed-to-fix-it.61108/#post-762091
A simple fix which involved replacing the electrolytic capacitor.