EstlCAM and 2 sides milling

Steuerungssoftware, CAM, 2D/3D CAD, G-Code Editoren
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jmf11
Beiträge: 7
Registriert: 03.05.2017, 12:37

EstlCAM and 2 sides milling

Beitrag von jmf11 » 03.05.2017, 12:55

Hello,

I'm thinking to building a composite RC glider with CNC milled foam core wings. The definition of the wing is in .stl format. A significantly big file. The wing core is 2500 mm x 200 mm x about 16mm XPS foam with foil shape. It shall be milled on the 2 sides,

estlCAM seems to be a very interesting option to generate the G-Code from the stl (which seems not proposed in F360 for example). And playing with the program, I saw that it can automatically generate CNC files for both sides.

I however don't perfectly understand how to use this EstlCAM "2 sides milling" feature. I have very limited access to the CNC, so I have to prepare everything on the computer before being able to run on the CNC. I have not seen a simulation function.

Help to clarify how it is intended to work would be very helpful:
- does it leaves a border around the piece that acts as a support for the second side ?
- Are there specific constraints on the piece to mill to be adequate for 2 sides milling ?
- For the second side, what is expected as of zeroing or stock placement to accurately mill the second face with the right reference ?
- should it work or not with quite thin wind trailing edge and no support below during the 2nd face ?
- Should be OK with XPS foam and few tabs (I played and placed some tabs, but don't exactly understand their placement).

Clarifications would be much appreciated.

Best regards,

JMF

Lars
Beiträge: 633
Registriert: 07.09.2016, 12:33

Re: EstlCAM and 2 sides milling

Beitrag von Lars » 03.05.2017, 14:24

The user "Marc P." has milled some 2 side foam core wings, but not with estlcam and not with the estlcam method. First he mills one side, then he puts the foam upside down in a negative and mills the second side. I think foam would be too soft to be milled hanging in the air only on some fixing points.
This is a link to some details: http://www.rc-network.de/forum/showthre ... rnen/page6

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Christian Knüll
Beiträge: 241
Registriert: 19.01.2016, 10:14

Re: EstlCAM and 2 sides milling

Beitrag von Christian Knüll » 03.05.2017, 14:38

Hi,
jmf11 hat geschrieben: I have very limited access to the CNC, so I have to prepare everything on the computer before being able to run on the CNC.
2-sided machining is one of the more advanced operations - it is something I wouldn't recommend as beginner project.
You should take some time, scrap material and just try it out.
  • Basically you just define the size of your stock material, define some holding tabs and Estlcam will do the rest.
  • After machining the first side you flip it like a book and machine the second side.
  • Zero is always left, front, top corner.
It is not hard - but there are so many little pitfalls to mess things up you just shouldn't expect it to work on first try.

Also as Lars suggested the wing may be too soft to be supported by tabs alone if it is large and thin - you may need to work with a negative to keep it in shape.

Christian

jmf11
Beiträge: 7
Registriert: 03.05.2017, 12:37

Re: EstlCAM and 2 sides milling

Beitrag von jmf11 » 03.05.2017, 15:03

The project from Marc P is really a nice one !

The fab lab (maker space) I use does not have the vacuum table for the CNC. I would have been happy to skip the Vacuum table build step in my project :-)

My idea (but I have no real hands on CNC experience) was that it could make sense for the wing milling, if doing it in one pass: the "weak" parts would be milled in a thick part of the stock.

JMF

Nota: I apologize for the English language posts. I'm French, my school level German is quite far, and it seems to be an active fortum about EstlCAM.

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Christian Knüll
Beiträge: 241
Registriert: 19.01.2016, 10:14

Re: EstlCAM and 2 sides milling

Beitrag von Christian Knüll » 03.05.2017, 16:55

Hi,

the vacuum table negativ is quite easy to create if you have the original CAD files.
Just create the negative with the CAD program and add a few air channels along the center and circumference.
This can also be done spearately after machining the negative - just machine some slots - their exact position does not really matter that much.

A vacuum cleaner can be used as vacuum pump - however a cheap rotaty vane pump for about 100€ may be a good idea - some vacuum cleaners tend to overheat if used for hours and the vane pump is also quiet.

Christian

jmf11
Beiträge: 7
Registriert: 03.05.2017, 12:37

Re: EstlCAM and 2 sides milling

Beitrag von jmf11 » 03.05.2017, 23:01

Thank you Christian for the advice.

Do you mean that the foam negative can be the vacuum table ?
- drill holes in the foam negative?
- carve air channels under the foam negative to connect the holes ?
- plug the vacuum cleaner to the foam negative (this one I don't see clearly)

But I may have misundertood, and this advice could be to use a conventional vacuum table like this one https://s-media-cache-ak0.pinimg.com/or ... 2eb067.jpg

Best regards,

JMF

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Christian Knüll
Beiträge: 241
Registriert: 19.01.2016, 10:14

Re: EstlCAM and 2 sides milling

Beitrag von Christian Knüll » 04.05.2017, 01:59

Hi,

the foam negative can be used as vacuum table.
You don't need to drill many holes - just one to connect the vacuum and from there a few channels running close to the wings border.
Actually you can just cut them with a knife - there is no need to be precise.

If I find some spare time during the next few days I'll make a video with a small example wing.

Christian

jmf11
Beiträge: 7
Registriert: 03.05.2017, 12:37

Re: EstlCAM and 2 sides milling

Beitrag von jmf11 » 04.05.2017, 20:27

OK, I think I now understand the principle.

I'm still interested by the video or a picture but don't want to abuse from your time.

Best regards,

JMF

jmf11
Beiträge: 7
Registriert: 03.05.2017, 12:37

Re: EstlCAM and 2 sides milling

Beitrag von jmf11 » 24.06.2017, 10:02

Hi Christian,

I come backto you in case you could provide a complementary explanation. I understand that you can carve the vacuum channels in the top surface of the foam negative. Is it correct ? This idea is new to me, but makes sense to avoid drilling many holes.

About the connection of the vacuum cleaner (cheap option for fist trials), is there a proven easy way to do it ?

I'm still balanced about the best option to get my foam cores between old fashion hot wire cutting of complete panels and CNC, especially because I don't have access to lot of CNC time "in a row".

Best regards and Thanks for the help and tips.

JMF

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