Countor vrs Pocket

[Sai]

Hi Guys New to the forum. I have a basic question. if I have to mill out a triangular hole in a 1 inch thich Al sheet. Would it be better to use the CONTOUR option or POCKET option. What is the basic diference between these options w.r.t my case.

[Guest]

Welcome Sai,

 

Well in answer to your question it depends on a few things. The size of the area you are going to remove stock from for one. If it is a fairly large area in comparison to you tool size and corner requirements, pocketing seem sto provide more robust material removal. If you are providing a start hole and just going in to contour the shape in one or 2 passes then contour may be easier to use at that point.

 

Contour will follow the shape of the defined geometry, taking into account step overs if defined.

 

Pocketing will use one of the chosen pre-defined cutting schemes to get the material out of your pocket.

 

HTH

[Jim at Gentex]

Welcome to the forum Sai!

 

I agree w/ jmparis. It depends on a few factors. If the cutter overlap from the contour cut will remove all of the material from the center of the pocket, then it's virtually the same as a pocketing routine. I personally will use a pocketing program whenever possible b/c I think it is more efficient and the finished pocket usually looks nicer. All you need to do is verify your toolpath to see if all material is removed with the contour program. If not, pocket is the way to go.

[Sai]

Thanks for your responses guys!! I would be machining a 102" X 60" , 1 inch thick AL plate. The holes are all of different shapes ,some like Sector of a circle , rectangle, traiangle . The largest being the rectangle about 50 " X 10".

 

I programmed both ways and what I see is that for pocketing the cycle time is way more than contouring. Guess I need to be patient to get better quality. What are your thoughts?

 

Sai

[Jim at Gentex]

quote:

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Guess I need to be patient to get better quality.

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Good observation!

 

However, if it's aluminum and your machine can take it, I say crank that mutha up and watch the chips fly! WOOHOO!! It's really kewl!

 

Jim teh crank that feed rate override knob!!

[Müřlıń®]

Do a 3-d ramped contour and drop the slug.

 

my .02

[Lumpnut]

quote:

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I say crank that mutha up and watch the chips fly!

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+1000 Jim , Wurd to Yo Mutha Brutha!

 

And WELCOME Sai !

[Jim at Gentex]

DUH!! My bad.

I just realized you mean THRU holes!!

I thought at first you meant traditional pockets with floor surfaces.

 

If they're thru holes, then Murlin is 100% correct! 3D ramp contour and drop the slug is the quickest way.

[Dan_AKA_ROY]

You could contour the "holes" with a larger bit and remachine with a smaller bit if you have small inside radii. Pocketing would work but would be ineffecient if machining a large area. Contouring them would go much faster BUT... you gotta be careful contouring pocketed thru cuts. The material will shift when cut thru which can mark the part or possibly break the bit [not likely but it can happen]. Maybe good strong tape can hold it in place?...so that's a concern.

 

If the thru cut areas are smaller, just pocket them! If their larger areas, you have enough 'room' to hold down the part manually during the last depth cut. Maybe create offset contours around holed areas by a small amount and hold down during the last depth cut. Program ends. Then remove the larger piece(s) and start program again to contour to the exact extents.

[Hardmill]

I say ramp w/ multi pass. Best of both worlds.

 

PEACE

[Dan_AKA_ROY]

Your right hardmill [and murlin]

 

My advice was IF someone didn't have a vise to hold down part. The part can drop down if vised. Gotcha!

 

Wish I had a vise! ...long story, I'll have one sooner or later - probably later. I clamp my parts down, I use wood or renwood underneath the part. So there's no where for the thru cut to drop. So, contouring inside thru cuts can have it's problems.

[LaszloK]

Also, with a job like that (countouring the perimiter creating a center slug)we would use a sub plate to avoid machining into the table. We would also add screw holes to secure the slugs to the sub plate in order to avoid a slug shift which could break the cutter.

[Dan_AKA_ROY]

Laszlok,

 

Excellent advice! That technique of securing the slug will come in handy when needed!

[jeff]

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We would also add screw holes to secure the slugs to the sub plate in order to avoid a slug shift which could break the cutter.

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I've odne that alot of times.

works great and you dont have to worry about breaking the endmill.

[Aaron AKA. Zippy]

Im with the above, if you want to get it done fast, contor and deal with the sulgs. On the other hand I find that I have more importent things to do, you know... BS on the forum, chat with the sexatery yada yada, so alot of times I pocket just so I dont have to babysit slugs.

 

 

Hit the big green one and walk away!!