New Plasma and Template

[Heavy Hand]

Hi..usual noob question!

I'm looking to get a plasma cutter, mainly to cut thin mild steel (<3mm) dragged around an MDF templete to make up plates for old cars. - I can take care of the offset easily in a cad program!

Thought that I would probably go with the R-Tech P30C as I really like their quality control, they confirm it is good for dragging, and they were helpful when buying my Tig.......the downside is that it doesn't have a funky pilot arc. ....Good choice??

Would I be right in thinking that actually a pilot arc would just char the template quicker?

I will mostly use fresh steel, but on painted/rusty steel don't you have to get the grinder out anyway to make a good earth?.

Looking forward to the comments!
M

 

[ronan]

Once the plasma can get a start it will keep itself going. I have the r-tech you want and cut up about 15 sheets of 3mm over a week last year, it never missed a beat. So if you scrape rusty or painted steel with a stanley knife or an old screwdriver, you're good to go.

 

[Heavy Hand]

Thanks for the reply!. Another slightly odd question for you!......If i use a template how hot do you think it will get?.
I'm assuming that on fairly thin metal the heat is quite localised if people can use cardboard as a template, do you think a piece of plastic would survive one cut?....i'm wondering if a 3d printed guide would work?

M

 

[WorkshopChris]

9 mm MDF will occasionally char at the edge if sparks blow back, but normally just gets a little warm. Not so sure how plastic would survive.

 

[Wendelspanswick]

I've used offcuts of 3mm white plastic that they line commercial kitchens with as templates, they work fine apart from they tend to go floppy when warm, I was cutting out profiles from 10mm plate though.

 

[Heavy Hand]

Sounds like a good experiment when I buy a unit (end of month).... I like the idea of a quick 3d printed profile...It will automatically be accurate and I can add what ever offset I like, even if I just use it to make a decent metal template.

What about the machine?, should I cast my net further or just go with what seems a safe bet?

 

[skotl]

Welcome to the forum

I have a cheapie plasma cutter with no pilot arc and it's amazingly tolerant of crap-quality / rusted steel. Worst case is a quick buff with a flap disk or a file and you'll be away but I've maybe needed to do that twice in 18 months ownership.

I often use a bit of MDF as a template and it can char, but normally when I'm not paying attention. I think you'll get 15+ cuts out of a template, probably more with greater care.

 

[thinfourth]

Top tip

If you have a steady hand then try the following

Print out what you want on A4 paper

Get some spray mount glue and glue it to the steel

Then follow the lines

Works once and if you do a decent job of gluing the paper does not vanish

 

[Heavy Hand]

I got domestic purchase authority from the boss, so should have the cutter by Tue..... Bound to be lots of small bits of metal on the floor!!

I have a in line water separator, and there appears to be another on the regulator at the back of the plasma cutter...... Should this be dry enough??

 

[123hotchef]

Top tip

If you have a steady hand then try the following

Print out what you want on A4 paper

Get some spray mount glue and glue it to the steel

Then follow the lines

Works once and if you do a decent job of gluing the paper does not vanish

good idea thanks mate i need to borrow the works printer now!

 

[ronan]

 

[thinfourth]

good idea thanks mate i need to borrow the works printer now!

Not my idea

Copied from member on here

 

[123hotchef]

well a good memory then!

 

[henry Kadzielski]

good morning gentlemen.
Please note that when using the plasma the cut quality is a faction of arc gap, current and speed. A plasma cutter will and can cut with an accuracy of about 0.1mm. This being dependent on the arc gap (the distance from the nozzle to the material being cut), cut speed (keeping a consistant linear speed). As your speed reduces the kref (the amount of material that is removed) increases. Good plasma manufactures can and will give you the recommended speed verses the current setting, dependant on the thickness and type of material being cut. With the correct settings for the material being cut a plasma can give you almost laser like finish, however that is at best.

 

[Heavy Hand]

Just as a follow up..

Had a smashing time yesterday making big sheets of MS much smaller with my new rtech 30a plasma. Still playing with amps/speed vs thickness, but I did try a 3Dprinted ABS frame as a template... On 0.8mm steel worked really well with no melting (underside of frame was stepped back in profile away from hot area), on 4mm MS worked well as long as I didn't get blowback. It would certainly seem to work well enough for cutting out a metal template!