My 3/8 improving but still needs more

[alleykat]

Yesterday was my 1st time cutting 3/8 on my table.Im running a TD A60 torch. http://www.weldfabulous.com/p-22383-the ... torch.aspx

I already have a preloaded tool in sheet cam for 3/8 but it was way too fast at 50ipm.I went back and cut it down to 25 and it did way better.Figured I would kick it down to even lower and see the results.Also changed the lead in from .25 to .3 -BUT- the thermal dynamics book does have a suggestion of 1.2 lead in.

The media blasted one is
17ipm
.3 lead in
clockwise run

Raw metal one is
15ipm
.3 lead in
counter clockwise







Things I noticed -
-On 15ipm way more underside slag and some on top
-counter clockwise made the 1inch hole on right slightly better
-Also on 15ipm the metal underside looked too burned "browned"

For sure I should stick with the 17ipm but not sure how I can improve the hole quality or just give in and drill them out.The only holes that matter are the one to the far left and the far right,other weird shape 1 is cosmetic.

On both setups there is some slight angling of the cut towards the bottom of it.Going outward but its hardly noticeable to the eye but when i put the pieces in next to each other there is the gap from the lower part being further out.

[pertneer]

if you are familiar with machining you always want to run the torch on the climb side of the cut. If you are not familiar with machining that in a hole you will move counter clock wise the outside of the part will be clock wise travel. It has to do with the rotation of the plasma arc and the better quality cut in on that side of the arc. Someone posted a link to some help videos on this site, but I cannot find them at the moments. One of them goes into the specifics. If I find them I will post refer you to the post.

Hope this helps, it did me.

[pertneer]

I found it now
viewtopic.php?p=31362#p31362

[JJsCustomDesigns]

You could use the "Drill" feature (sheetcam) to mark the hole center and then use a drill bit to make it proper size.

[Diverdude]

How does that work JJ, I just tried it in sheetcam and when I ran the simulation it did not do the holes I set for drill. I used the drill operation and selected the plasma tool. Is that the way or what?

[I Lean]

You're right, drill operation with plasma tool. Also, you need to make sure the min/max hole size selected is smaller/larger than your holes. Then it'll pierce the center of each hole.

[alleykat]

I'll have to try out that drill function.Let me see if I find a youtube tutorial on it.

[JJsCustomDesigns]

If i remember right theres a section in the "help" tab (in sheetcam) that talks about using your plasma cutter as a drill to center mark the holes. Shows you how to set it up.

I tried to do a quick google search for the help section, but ive run outta time.

[bwshop]

Have a look at that http://tech.groups.yahoo.com/group/shee ... sage/13576

[alleykat]

Have a look at that http://tech.groups.yahoo.com/group/shee ... sage/13576

Haven't finished signing up but will look at it soon.

Found another thread talking about same thing.
http://www.cnczone.com/forums/sheetcam/ ... holes.html