Lead-in problems

[szextreme]

Ok guys I have a Hypertherm 85 just doing some test cuts and have a simple shape of a rectangle with a complete radius at one end. Running .062 steel with 45 amp consumables. No matter what settings I have tried be it arc/tangent etc. I get a dimple into the part as shown in the attachment569
Help me out here

[jeepsr4ever]

It is the length of the lead it and lead out that will matter so try perpendicular .3 length, overcut .03 and arc .22.

[szextreme]

Lead in length was .5

[szextreme]

It is the length of the lead it and lead out that will matter so try perpendicular .3 length, overcut .03 and arc .22.

I see length and overcut but which arc are you talking about?
And is there a general rule of thumb for lead ins?

[szextreme]

Figured it out thanks, Still any advice on lead in/out would be great as I overlooked overcut as its not a prominent topic.

[jeepsr4ever]

It looks almost like your trying to cut steel and stainless. With steel or aluminum a strait lead in with a small overcut and an arc lead out give you near perfect hole quality. Overcut is a setting for the distance past the point of entry into the circle/hole path. This gets rid of the nub you will find without overcut. The lead out will ensure the torch is moved away from the hole/circle toolpath. With plasma the beam can turn off but the air is still moving out of the orifice. This can cause unwanted gouging.

With stainless steel the process is a little different. Stainless steel resists the exothermic reaction and can also act like a capacitor. You want a long arc lead in and a long over cut and a small arc lead out. This has yielded very good holes. One thing about stainless is that because it resists that reaction cutting it like steel will cause the cut not to cut all the way through the material and you have tabbing on every feature where the stainless is not cut on the bottom of the material. A couple of quick changes and you can have a very good part.

[szextreme]

Thanks Matt helps out a lot for a NewB. And yes I was using galvinized steel and stainless....the stainless was actual part and the galvinized was test material, but now I know my test material wasnt exactly helping my problem!