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Author Topic: 3D problems  (Read 1697 times)
m.marino
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« on: February 14, 2012, 08:41:09 am »

Okay,

First LOVE the new user interface. Only still have a problem, I cut custom pieces that either have sloped sides, ramped bottom surfaces or on the odd occasion both. Now to add the kicker, there is always more then one of the in a project and have to meet rather tight tolerances (.2mm and less in most places). What I make are custom pieces for chromatic harmonicas, concertina parts, and other free reed musical instrument parts. So I am dealing with the absolute requirement of being able to make the mating surfaces an air tight seal (often without gaskets as that brings in a whole new level of problems).

I have been looking for a tutorial on this and have not found one. If some one needs a file for this please let me know and will send a .stl file.

Thanks for any and all help in advance.

Michael
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atwooddon
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« Reply #1 on: February 14, 2012, 14:29:14 pm »

Michael,  a file of something you need to cut might be a good idea to give us a better idea of your issue.  However, I think there is a thread hear on CamBam forum dealing with a very similar requirement of needing to cut a sloped piece and have it be 'flat', a reed valve for an engine I believe but don't hold me to that.

The problem is to get a flat surface (or very nearly flat) and cut at an angle you have to use a ball nose bit and very very small stepover to minimize any grooves that might be left.

Is there any possibility to make a part holder that will hold the piece such that the slope(s) you are cutting are being held flat during the milling process?  If you could do that, then an endmill would leave you with a flat surface.

Don

PS  here is a link to the CamBam thread on the reed valve machining
http://www.cambam.co.uk/forum/index.php?topic=1827.0
« Last Edit: February 14, 2012, 14:46:29 pm by atwooddon » Logged
m.marino
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« Reply #2 on: February 14, 2012, 21:03:06 pm »

Don,

Here is an image of two of the pieces that I am working with, I hope this helps.

Michael



* Hohner M260 Comb.jpg (51.22 KB, 885x569 - viewed 145 times.)

* Hohner 270 Sq MP.jpg (127.69 KB, 968x630 - viewed 136 times.)
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kvom
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« Reply #3 on: February 14, 2012, 22:10:06 pm »

With a ball cutter there will always be scallops.  At some point the scallops can become smooth enough to meet requirements, but the smoother the surface the smaller the stepover and thus the longer time for machining.

You may find it better to design fixtures for holding the work so that the ramp can be milled with a flat endmill.

Alternatively you can buy or make cutters with angular cutting edges to match.
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m.marino
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« Reply #4 on: February 20, 2012, 10:41:44 am »

I use progressively smaller end mills to do the cutting (going down to 1mm in some cases), that is not the issue for me. The issue is getting the sections cut as sections and not as one piece. As every time I have cut it as one piece you get drag from the cutter at some of the right angle sections and it is not acceptable for the final product. So I need to be able to cut the ramps at the bottom while cutting each pocket as a individual section. Yes, I know this is a bit of a tall order. Just asking how to do it as I am pretty sure from what I am seeing Cambam can do it, I am just coming up short on the how to get it to do it.

My apologies for not having responded sooner as wiring up the new gantry router in the shop and that is taking up a good bit of time right now.

Michael
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atwooddon
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« Reply #5 on: March 01, 2012, 15:04:08 pm »

When you use CamBam to machine 3D pieces, you can control the cut area using the 'Boundary' settings of the 3D MOP.  If you wanted to restrict the area a 3D MOP would cut, you could draw a 'box' around the area and tell CamBam to use that box as the boundary.  There are examples here in the Forum and I believe the documentation shows it's use.

Don
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m.marino
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« Reply #6 on: March 02, 2012, 07:36:55 am »

Don I will go back through the documentation as I missed that option when I read through it all the first time (Yes I am one of those Read The Manual folks). I am very thankful for that information as that should allow me to do what I need.

Michael
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m.marino
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« Reply #7 on: April 05, 2012, 09:32:41 am »

OKay,

I am not finding the examples here in the forum. Which means I am not using the right search words or combination of them. Also been trying to draw in lines and arcs onto the .stl model for the 3D milling and not having much progress there. I have also tried putting lines into the .stl file to use as boundaries and still no joy.

SO asking please for a link to the thread here for doing this kind of CAM set up and/or a link to youtube showing how it is done. I need to learn it, as the code I am getting from CamBam seriously is improving the finish and decreasing cut time versus the other CAM program I am using, minus this one very important part.

Michael
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atwooddon
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« Reply #8 on: April 05, 2012, 15:41:19 pm »

Try doing a search for 'boundary', bounding' and 'clipping'.  I am not at home right now so can't search for examples but those search words will bring up threads about using these functions to limit how far milling will go in area or depth.

Will do some searching for examples when I get home.

Don
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atwooddon
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« Reply #9 on: April 05, 2012, 17:22:53 pm »

Attached is a quick and dirty example of 'boundary' use.  I took a 3D file and then restricted the area I wanted CamBam to machine.  If you play with the values of the Boundary settings, you will see how it affects the machined area.  Click on the 3D MOP and then look at the Boundary section of the MOP to see how I set it using 'Selected Shapes'.  This is just one example of how to accomplish this.  You can also use Clipping Area Max or Min to control the machining area.

Don

* SingleFlourishTest.cb (2708.52 KB - downloaded 92 times.)
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m.marino
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« Reply #10 on: April 05, 2012, 21:10:40 pm »

Don,

Thank you, thank you, thank you, as in saving me huge amounts of head ache thank you. Have found the information you have referenced and tested it out. Will need to generate an run code but if the code is the same quality as the rest of the code I get from CamBam I am cooking with gas now.

My many thanks

Michael
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atwooddon
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« Reply #11 on: April 06, 2012, 00:03:25 am »

Michael, you are quite welcome.  Just returning the favor so many have done for me when I was first getting started with CamBam.

Don
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