Solid vs. serrated table slats for DIGITAL thc?

[Deezl Smoke]

So after fighting with my torch height control for so long, and now having it operate like it did when new, learning a lot in the process, I got to wondering when the plate is setting directly onto the table slats, if they are solid like mine vs. serrated like i see so many other brands, when the torch crosses one, or,....the cut runs right over the top of one for a distance, can the added cutting depth cause voltage changes in the digital sensing system?

Cutting some .375" A36 this morning, 85amp, 70ipm, I did watch the voltage reading and though it was very quick and brief, when cutting "Y" crossing the .125" slats, it was more erratic than cutting "X".

[adbuch]

I'm not sure what "solid vs. serrated" exactly means with respect to plasma table grates. Perhaps show us a photo or two of your cutting grates.
Thanks,
David

[Deezl Smoke]

My slats are .125"x2.5" flat bar. Nothing more, just flat bar.
Here is a picture from Eastwood Certiflat? Showing what I consider a serrated slat.

[adbuch]

OK - I understand. There are many table owners using the "solid slats" with no problems with their height control. Also, many I have seen run the solid slats and an angle to make it less likely that a long straight vertical or horizontal cut will coincide directly with the slat orientation. My Plasmacam DHC2 table uses slats with "grate points", so a similar idea to the serrated slats you show in the photo.

David

[SegoMan DeSigns]

My slats are .125"x2.5" flat bar. Nothing more, just flat bar.
Here is a picture from Eastwood Certiflat? Showing what I consider a serrated slat.

I call that a "Sharks tooth design" I run it on my 6x12 table and a flatter version on the 2x2 table. The sharks tooth design lasts longer as less dross builds up on it, this is attributed to the metal cooling with the water prior to hitting the dirty slat. I am going to re-design the slats for the 2x2 table to prolong their life as well. You did not mention if your slats have a bow to them or not, a bow in the slat will help prevent it from being split. I also run arc voltage THC and have not noticed a problem with my design.

Here is a picture of my school of white tip sharks:

White Tip Sharks.jpg

I also designed the slats to be reversible to cut my material cost in half :

Reversible Slats.jpg

[Deezl Smoke]

My slats are .125"x2.5" flat bar. Nothing more, just flat bar.
Here is a picture from Eastwood Certiflat? Showing what I consider a serrated slat.

I call that a "Sharks tooth design" I run it on my 6x12 table and a flatter version on the 2x2 table. The sharks tooth design lasts longer as less dross builds up on it, this is attributed to the metal cooling with the water prior to hitting the dirty slat. I am going to re-design the slats for the 2x2 table to prolong their life as well. You did not mention if your slats have a bow to them or not, a bow in the slat will help prevent it from being split. I also run arc voltage THC and have not noticed a problem with my design.

Here is a picture of my school of white tip sharks:


White Tip Sharks.jpg


I also designed the slats to be reversible to cut my material cost in half :


Reversible Slats.jpg

Very nice, and I like the shark tooth description better than serrated.

Yes, my slats are bowed. I too run a 6x12. I put 6.5' into the 6' width, making a pretty nice curvature. And they are as you know already, reversible. I agree fully the flat bar slat builds way too much dross too quickly. That's why I was having so much concern about my thc, once the plate no longer sits flat, the torch height control gets a workout.

My table has a tubular spine along the "Y" in the middle. I'd have to include that notch when cutting the shark tooth design.

How do you deal with moving the plate on the table to square up? Now and then I get a job that the plate needs to be kept gouge free. I have a roll up door right over the table so a crane with magnets wont work. I'm thinking I may have to design something for the forklift, but curious what others have come up with. I load the plate with the forklift, but the barn I use has a low ceiling, then the roll up door,.....makes even using the forklift a challenge at times because of the backrest.

[tcaudle]

Its good you have the center bracket to hold the slats in three places. I have seen curved (and straight) salts) that act like springs so when the table moves and changes direction rapidly the table flexes and the material tries to move in the opposite direction. It it sets on springs it DOES move and you get waffle cuts . Its usually evident on direction changes so shows up on circles and slated lines rather than the straight stuff. The bigger the table the more important that the slats do not have any flex in them . it does not take a LOT or flex to setup a vibration and get the small waffle cuts. Since the weight of material (steel sheet) is involved it it may not sow up with a pen and paper test. Also torch wobble in the holder . The more you have sticking up above the sprog loaded "collision detector" the more likely a sudden direction change can cause an irregular cut. It POSSIBLE by attaching the hand torch under the torch you added stability to the torch holder ring. While the air oscillation theory is interesting I would have to wonder why its as intermittent unless it has to do with pressure and CFM that changes the longer you cut with some air systems.

You might try instead of the hand torch lowering the torch some more into he bracket and maybe look at securing the upper hose if its not already to stop any motion from causing it to jerk. These types of things being intermittent are REALLY tough to nail down.

[tcaudle]

I have seen slats done several ways. The sharks tooth approach is good and an inner locking grid is better BUT if you DO cut inot a tooth its damaged and can effect a much wider span. it having only one tooth every 4 to 6 inches. Lose a couple of teeth close to each other any you have to start thinking about replacing the entire slat or several. The flat slats do accumulate slag and get cutup but the slag chips off pretty easy and you have the back side to get a fresh edge . Using arched slats reduces the possibility that a cut will end up directly along the slat for any distance but it increases the "spring effect" so they need to be secured at least in the center as well-as the ends.. I have seen Z axis that are sloppy and wobble. I have seen torch holder brackets that are not rigid enough and flex. I have seen gantries that are held down mostly by gravity so they tend to flex (lean back or forward) as they accelerate/decelerate and cause the torch to cut a wobbly line. While slowing down the table helps with the flex it plays heck with the THC .

[rick_b]

I have to say, going to the "shark tooth" patterned slats fixed many of the problems we were having with our machine.

[SegoMan DeSigns]

Follow up to the above responses:

You will find you get less gouging on your material with the sharks tooth design as there is less dross above the slats, doss is harder than the metal.

If you look at my table you will see 3 sections, the center section with slats can be removed by unbolting. This allows for a section of 12"x12" square tubing to be cut. Another benefit to the 3 sections is I only have to replace 2' vs 6' slats.

I use a fork lift to load unload my table as well, however the future Jib Boom is under construction. Is that an option for you?

This would be an ideal setup with some improvement to rollers on the drawers and an electric hoist: