cutting tapered thickness material

[exapprentice]

Is it any at all possible to cut tapered material? I have a PM45 with CandCNC DTHC 1V ethercut set up.
I have been asked if I can cut a piece of material that tapers in thickness from 2mm upto 8mm over a length of 350mm
basically its like a long thin wedge, O/A dims of the cut out area are 350 x 350mm square
material is steel, the cut out details are quite intricate.
Has any one tried this or have any suggestions, positive would be good
thanks and regards

[mike 1948]

Just a thought, what if you put a shim under the thin end and made the top surface level?
Or just maybe the DTHC will take care of it once it starts cutting.

Mike

[exapprentice]

Hi Mike
sorry I didnt explain well enough, its not that the material face is tapering / sloping
the actual thickness of the steel plate is tapered from 2mm thick at one end to 8mm thick at the other
this is the bit I am trying get guidance on, I dont think its a case of setting say for 5mm thick material.
I think it will probably (if possible) be something with cut rules or speeds

[tcaudle]

The Preset voltage won't be a lot different so you should be able to pick a value in between. As for feedrates you could use the Cut rules in SheetCAM to increase the feedrate as the material gets thinner . It also possible to change the preset voltage on the fly with Cut rules as well but that will takes some treaking and testing. You can set trigger points in the Cut Pules and change any parameter you have software control over. interesting rpoblem. Do you have a lot of this to cut and goes it include shapes cut out of the tapered material?

[rdj357]

Hmmm, with the PlasmaCam I'd just let the DTHC take care of the cut height and set the speed (and amperage) for the thicker end. Then could use the jog knob to adjust the cut speed on the fly when cutting thinner. I've no idea how it could be easily controlled on other systems.

[tnbndr]

If it were me I would set everything up for the thicker material and have a go.
I am curious though as to why they need to use this material, tapered thickness for the product?

[steel 35]

I never liked the stopping and starting on non connected lines but it may be another easy option to restart before and after intricate spots and change settings accordingly?
How was the material made to have a taper?

[exapprentice]

Hi all

just thought I could answer some of the questions regarding the material.
the area to be worked on is approx 350mm square but the whole peice is probaly nearer 400 x 800mm.
Its part of a bespoke machine for a customer, my original intentions were to try and mill the details through the thickness
BUT
Then had the brain wave wondering if I could do this on my plasma table hence the original question
basically milling would ba a RPITA to do and take ages as my mill isnt cnc'd (yet )

thanks for the suggestions & best regards

[jimcolt]

We have run into this application many times over the years....often cutting from about 6mm up through 32 mm on things like grousers for track shoes (Caterpillar, Deere, etc.). With the high end industrial plasma systems everything is programmable and has been for about 30 years.....so we would do some test cutting and simply vary the cutting current (within the safe operating range of the torch consumables) as well as varying the speed while the cut progressed. On high production applications such as this one you have time to spend fine tuning the process so that when it is placed in a production cell it works for years.

In a "one off" application such as this I suggest setting the cut speed and height to be ideal for the thickest section....then cut the whole part with those specs. The thin section will have low speed dross, easily removed.

Jim Colt Hypertherm

[exapprentice]

Hi all

Thanks you all for your comments and suggestions all very much apprieciated.
But
I whimped out and did the job on the Bridgeport and yes it was a real PITA

I am going to follow up the techniques at a later date and when the pressure is off a bit and the customer isnt sat there waiting
I will post the results, but dont hold your breath

Thanks again to everyone who contributed to the post
exapprentice