Newbie: Stepcraft for carving a plastic box?

Hi Julius!

POM an PVC is everydays business for our steppis.

So, I'd say the limit is whatever you can do in 2.5D and with milling cutters with a cutting depth of 10mm.

Maybe you should post some CAD images of the boxes you plan to build. When saying "Vergussgehäuse", do you mean that you want to mill the casting mold with the steppi?

Hello MagIO2,
so maybe I'm just dreaming in doing something like that?

Obviously all internal corners will be rounded, they depends on the size of the bit.

I don't want to produce a casting mold, just a limited number (maybe 50) of the same carved box. The cube is small, so I have calculated around 40 minutes per box...
Furthermore, the metal-bit of the spindle should have no problems in milling for long time on plastic material. I mean, it should be not get "consumed" after long milling... or not?

It's just a dream? :blush:

First of all it is a waste. You have a block of material and want to turn >90% (guess) into waste.

I have to say, fortunately you won't find a tool long enough to do this.

Does it have to be POM or PVC? Or would ABS or PLA do as well?
This is a good job for 3D printing. If you really want to buy a machine yourself, then the steppi with 3D printhead would be an option.

But I guess it would be cheaper to order the parts at a 3D printing company. There you also have better quality and more choice of material.

PS: would it be an option to divide the box into separate walls and assemble the box by fixing the walls with screws?

Still did not get the Verguss-part. Is the plan to put the PCBs inside and then flood the box with epoxy?

PS: would it be an option to divide the box into separate walls and assemble the box by fixing the walls with screws?

I think this idea makes much more sense ....
Maybe he could build a little jig to keep the parts in place and use an adequate adhesive instead of screws.

MagIO2 you make my heart bleeding... 🙁

So in your opinion I cannot carve more than 10mm with the Stepcraft machine? So why the documentation states 80mm of travel distance on Z-axis? If nobody can exploit this possibility then it has no sense...

I don't care about the waste of material, in any case there is no company that will produce for me the box-case for a so small amount of pieces. You need to make orders for 1000 or more pieces to get a reasonable price, otherwise you're going to pay even 9,- Euro per piece for that small ridiculous box.
ON the other hand here at Gemmel Metalle I can buy flat pieces of PVC at good price. By cutting and carving blocks I can get a reasonable price of 1,8 Eur per unit.
Furthermore, when I pay somebody else than nothing remains in my pocket. Using the Stepcraft machine I have almost the machine itself, it that stays mine.
Where I'm wrong? :dry:

Maybe he could build a little jig to keep the parts in place and use an adequate adhesive instead of screws.

Well... that is a possibility, but I'm not sure if it will be enough robust and water cannot get in... :unsure:

About the choice between POM and PVC I still haven't decided what material is more stable outside at open air.
Also, I have excluded 3 printers 'cause the quality of the flat surfaces is honestly horrible, seems like a sandwich prepared by a drunk man on a drunk horse 🙂
Yes, milling machines are not perfect too in that sense, but surfaces quality has no comparison with 3d printers.

Still did not get the Verguss-part. Is the plan to put the PCBs inside and then flood the box with epoxy?

In my plan, the box will be closed by a little plexiglass window, screwed and sealed with a little amount of silicon around borders.
Maybe I should make a drawing of that too so you can give me your opinion.

Here the final idea: the same box together with the plexiglass window. The little transparent window should go down inside the box to be screwed at the four corners.

As I understand the main limitation, in my case, is that there is no tool of 43mm length (cutter length + shank length). So carving 43mm deep inside the box is impossible, or have I misunderstood?

The longest tool I know so far is 30mm with 3mm diameter. But it is only good for milling foam. Anything harder and it will bend, which means you won't get straight inner walls. Maybe there are better/longer tools available for the stepcraft spindle with ER11 tool support?

If you go for separate walls and glue, POM is out of scope, because it is hard to glue.

Can't you cut the box in 2 pieces? If I understand you correct, only the bottom part will be housing the PCB/display. You can add some mounting holes to the upper ring and mount it with the same screws which hold the plexiglass.

Can't you cut the box in 2 pieces? If I understand you correct, only the bottom part will be housing the PCB/display. You can add some mounting holes to the upper ring and mount it with the same screws which hold the plexiglass.

Nice suggestion MagIO2, I have to admit that I didn't think about this :blush:
I could mill the bottom part (around 23mm depth) and then the top part (25mm). As you can imagine, the top part it's just a sun-coverage useful at open air.

There is a little bit more work (more screws, more holes, etc.) but maybe that is the only way :unsure:

The longest tool I know so far is 30mm with 3mm diameter. But it is only good for milling foam. Anything harder and it will bend, which means you won't get straight inner walls. Maybe there are better/longer tools available for the stepcraft spindle with ER11 tool support?

I have to investigate about longer milling cutter...

Anyway, as I understand (remember: I'm a newbie) the collect is a piece of hardware clamping the spindle to the axis (shank) of the milling cutter. So an ER11 collect should allow to clamp a shank with a max diameter of 11mmm (!!!)
That would be enough rigid and stiff, yes?
(mmmmh.... but by using a "fat" shank I will be not able to carve the detailed internal corners... mmmmh...)

As I see, the Stepcraft HF 350/500 spindle allows a standard max shaft diameter of 8mm. If equipped with the ER11 nut it can be augmented to 11mm (I suppose).
But even an 8mm shaft seems quite rigid to my eyes :woohoo:

(but the HF 350 costs a lot! wow! And maybe it makes a lot of noise too? :unsure: )

Cutting deep is difficult. Even on our professional routers up to 7-8,000 euro cutting 50mm deep is a challenge. We did this recently for a guy cutting stock timber for furniture. 50mm tool at 10mm diam cost 80£. As you increase the cutting diameter you increase the material removal rate. Which requires more power.

Anything up to 6mm IMO is max cutter for STEPCRAFT - and even at that thats a large cutter.

With extra cutter stick out - comes more leverage. The point of contact between the bottom of the cutter and the spindle is then large - 50mm and this is a large lever. Its almost too much for out larger routers - and then ask to mill with SC? No way... if the machine can do it - you will not get clean lines on the passes as the machine moves down.

Only in foam maybe.

The travel of the machine is completely different to the cutting envelope. Just because the machine can move 80mm does not mean the machine can "machine 80mm"... our larger routers travel up to 125mm but the max cutting thickness is 40-50mm and even this is a challenge.

Travel of Z axis is for access to the cutting surface. The cutting depth is dependant on the cutter, machine setup, machine stiffness, material and machine parameters..

You have too much waste from your process. The way you wish to manufacture requires special tooling - and lots of machining and a heavy machine - therefore the cost of your process - because of the way you have chosen to make it - is too high.

you need to approach this differently - 3D print. Or build up in 2 edges. limit the X axis cutting height to the thickness of the edges.

Or - find someone with a router that can do this for you. We can cut this for you.

With extra cutter stick out - comes more leverage. The point of contact between the bottom of the cutter and the spindle is then large - 50mm and this is a large lever. Its almost too much for out larger routers - and then ask to mill with SC? No way... if the machine can do it - you will not get clean lines on the passes as the machine moves down.

Ok, I understand this. Bigger is the length bigger is the lever, so the radial force on the end mill increases when cutting the material.
But what happens if you decrease the DOC (Depth Of Cut) as the total length of the tool increases? I mean, you need more power if you want to carve/cut the same material as you do with a shorter tool. If you decrease the DOC then the force on the milling bit should not decrease too? So, even if the tool is more long than before by applying a reduced force it should not bend excessively.
(Please remember that I'm a rookie and I don't know what I say :blush: )

On the other hand how could this french guy cut for 9,6mm depth on an Alu 7075T aluminum plate???
:blink:

He uses just a poor 100W Proxxon IBS spindel (!!!). So I could think that by buying a plutonium-cobaltium-titanium cutting mill (produced by the Kryptonit company) I could mill a PVC plate. I don't know the proportion between the hardness of aluminium and PVC (or ABS or POM), but plastic seems a lot softer...

The travel of the machine is completely different to the cutting envelope. Just because the machine can move 80mm does not mean the machine can "machine 80mm"... our larger routers travel up to 125mm but the max cutting thickness is 40-50mm and even this is a challenge.

Travel of Z axis is for access to the cutting surface. The cutting depth is dependant on the cutter, machine setup, machine stiffness, material and machine parameters..

Yes, I understand this. Anyway, I could carve an upside-down pyramid (with large large steps) for, let's say, 70mm depth with a short-short-supershort cutting tool, yes?
The problem is the rigidity of all the machine plus the cutting tool.

you need to approach this differently - 3D print.

I still cannot find data about the robustness of 3D printing artifacts... I'm quite skeptic on this, maybe I'm wrong.

Or build up in 2 edges. limit the X axis cutting height to the thickness of the edges.

Edges? Do you mean in 2 dimensions and to assembly every part with glue or screws? :dry:

Or - find someone with a router that can do this for you. We can cut this for you.

This is interesting :side: