[NegativeNines]

So the setup you are seeing is for me to cut several 2D parts out of the 2.5" 1018 steel bar stock that is secured. I am working with a Taig CNC mill. I am wondering if this setup (roughly) is the proper way to secure something with strap clamps. Both the top and bottom pieces being used to secure the bar stock are 6061 aluminum.








Would it be better to get rid of the top piece, putting the strap clamp directly on to the bar stock?

Would it be better to use steel instead of aluminum on the top, bottom, or both?

Is this entire setup rubbish, and there is a much better way for me to go about getting the material off the table so I can do through cuts?


I should also mention that the bottom pieces, although you can't see it, are secured to the tooling plate by 2 recessed screws, and there is a .03" deep pocket across the length for the 2.5" stock to fit in to for alignment, but it is not snug inside that pocket.

Any advice and help is much appreciated. Also, if this is in the wrong forum, please feel free to move it some place more appropriate!

[Eurisko]

Clamping onto the aluminum blocks shouldn't be a problem.

That long stretch of unsupported steel worries me. You really need some support under it. If you don't have any sacrificial material that you can rest on, consider placing some rest buttons at various points under the steel. This will help keep the steel from flexing from the tool pressure.

[christinandavid]

Agreed. Sacrificial plate under the stock is best way. That setup may vibrate and knacker your cutter.

If the parts have holes in them you hold with clamps, drill holes, screw through holes, remove clamps and mill contours to finish.

DP

[Shane1234]

also be careful with cutting multiple parts out of a sheet like that, because the cutter will try to treat it like chips when it breaks free, and can break your cutter easily.

[Shane1234]

another tip.... pennies will work just as good as your aluminum blocks if you are placing those just to not mark the steel

[Boots]

I agree with the others, you will need support to keep down vibration and flex in that "Cold Rolled steel". Although it is mild and easy to cut it will also flex and vibrate and you might not get the finish you are seeking. Your clamping looks fine.

[ImanCarrot]

Agreed, sacrificial plate and clampswith double sided tape to stop the cut out parts moving and chipping your cutter.

Your placement of the clamps is perfect.

[NegativeNines]

Ok, so after your collective comments and consulting with a friend who has a little experience with a mill, I think I am going to just have a piece of 4" wide sacrificial aluminum under the piece for support.



Would you all expect any problems with clamping force from only having those 2 relatively small strap clamps securing the work with a setup like this?

[Boots]

Perfect.... you have the rear of the clamp slightly elevated and the clamping force is directly on the end of your clamp and the underside of your part is now supported.
Happy machining ! ! !

[Shane1234]

i agree with boots, looks good, ready to roll. just be careful when you get close to done with each part's full profile cutout.

[rowbare]

I often use 1/8" hardboard as a sacrificial support. It is dirt cheap and does the job nicely.

bob

[Fastest1]

Use mdf under it for support instead of aluminum or steel. Much cheaper than aluminum and easier on the end mills. Since you are cutting thru the depth shouldnt be critical. Personally I would leave it elevated with no support in the middle so the part would drop thru when cut free.

[Fastest1]

just saw rowbare's post. Sorry

[UUU]

Your left hand clamp looks better than the right hand one - the stud is closer to the nose of the clamp so you get more clamping force for the same tension in the stud.

[NegativeNines]

Ok guys, 3rd and hopefully less costly configuration!



I will make sure and get those strap clamp studs as close to the work piece side as possible.

[Boots]

Push the button.....Let's see some parts..LOL

[universalfab]

For 1 I wouldn't be using that mill to cut steel even mild steel. 2nd you need something under your stock material to support it. By leaving all that gap between the table and material is going to result in very poor finish and alot of chatter/vibration which is bad on your mill. Also if the reason you left a space between your table and material is so that you can cut your parts all the way through it's a bad idea. Your going to get your parts wadded up and chucked out all over the place, maybe even destroy your cutter which is really the least of your concerns. You should make tabs on your drawing so that your part is still being held by your stock material, then when your parts are done just pop them right out of your stock and file or belt sand them down. For you being that tolerances aren't important, you could just use a piece of wood to clamp your material over. Good luck

[UUU]

The Taig should be fine. It won't be the quickest piece of work, but it will handle it.

I've just set up a very similar job in my mill. Slightly thinner bit of steel, sightly beefier mill and I'm aiming for a good finish - it's a precision cut-out. Very similar clamping arrangement - sacrificial board underneath.

Here goes...

[UUU]

Well I said my steel was a little thinner - about 2.5mm..

So it flexed in the middle and started to vibrate - cutting forces pulling up on it - then the cutter broke.

So I've added extra clamps in the middle, larger 4mm slot drill (UK term for two-flute centre-cutting mill - no spare of 3mm size) - reprogram g-code for new cutter offset - and reduced the feed.

Then cut proceeded OK, and no difficulty on final pass when breaking through into MDF. Lubricant required - applied by brush, I've no auto system - cutter sounded much happier, no vibration.

Perfect result, just what I wanted.

Let's see how NegativeNines gets on.

[NegativeNines]

Broke the cutter (4 flute carbide 3/32" flat) on a .03" deep slotting pass (3 of 5 in the operation). There was heat in the spindle nut when I turned it off and I had been smoking up the cutting fluid on 50% stepover .03" deep slotting passes before that, but I was hoping keeping it nice and wet with cutting fluid would alleviate the heat problems; it didn't. Keeping it wet with cutting fluid then also lead to a buildup of oily chip slurry in the channels being cut by the slotting operations.

I was running at 6500rpm and 10ipm. The guy at UltraTool (manufacturer of the bit) that I spoke with said my next RPM option, 10500, would be ok, but only so long as I had a "stable spindle" whatever he meant by that, and anything up to 12000 would be ok. I also got the advice from a friend to crank the speed up and the feed down, however I don't really understand why my 6500/10ipm was a problem since this puts me just under .0004" FPT