CNC router bit suggestions

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skimann20
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Post by skimann20 »

Yes, I did the same technique for my first mold, and it worked out great. But why should I work so hard when I have a CNC? ;-)

Made my first test cut last night and turned out fine, but I "think" my bit is a downward cutting bit that someone put in an upward cutting container, gerrr. Only 19 more longs and 20 shorts to cut and I'm pressing skis for the season. I've got three sets waiting in the wings until I get the mold completed.
mikemigs10
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Post by mikemigs10 »

I put together a cmc mogul earlier this summer and have been playing around with it ever since. For a bit I have been using a 3/8 two flute spiral up cut made by Whiteside. I am having more difficulty with learning cad and the cam programs myself. So far I have been able to drill the holes for my vacuum board and in the process of learning I can cut circles which i used to make corn hole sets. My biggest problem that I have run into is that my programs don't want to listen to the size bit I am using so I always have to adjust it myself. For instance when I was cutting the holes for corn hole I wanted a 6 inch hole to be made but after my first cuts of having a 6.5 inch hole I had to go back in and change my design to a 5.5 inch hole to get the 6 inch hole i desired.

I plan on attempting to cut molds out this week and would like to profile some cores and sidewall but I am not sure how to do that. Any tips ion how to profile?
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chrismp
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Post by chrismp »

Try to think of it this way: the middle of the router bit travels on the cut line by default. If you want it to travel left or right of the line, you need to make the corresponding setting in your cam software if it has such functionality.
mikemigs10
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Post by mikemigs10 »

Thanks Chrismp. The program I am using Mach3 which has a functionality where you can preprogram bits which I tried doing but for some reason it was not doing what I thought would happen. I have a lot to learn with cnc. I also use trubocad and lazycam (mach3/artsoft product). Any suggestions on easier/user friendly programs
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chrismp
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Post by chrismp »

I am using Rhinoceros as a CAD program, but it's not really easier than Turbocad, just different. For CAM I have to use what my CNC router runs on, so no recommendations here. For more complex stuff like core profiles, I use VisualMill, which is a great little piece of software that spits out g-code specific for your CNC calculated from a variety of CAD file formats. If it doesn't have the right post processor to give you the correct g-code for your machine, you can either tweak the output yourself or send a sample g-code to Mechsoft and have them do a custom post processor for you.
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skimann20
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Post by skimann20 »

mikemigs10 wrote: Any suggestions on easier/user friendly programs
I use to use autocad. Those days are behind me... ViaCAD is the way to go. You can try the program for free for 2 weeks. It is much more user friendly than Turbo/auto CAD. I suggest you give it a try.
switzch
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Post by switzch »

Success!

I got a nice new 1.5" straight flute router bit (per Mike's Monkey Wiki) and profiled two cores, as well as a 2" wide slab of sidewall material.
hey what are your feeds and speeds and depth of cut? did you use same big bit for the core and sidewalls? im getting setup again and last time i tried using a 1.5" bit on the umhw it didnt go so well.
winter is coming..
twizzstyle
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Post by twizzstyle »

That was a long time ago, so I don't remember (I think that post was mine...).

My feed rate is always 75ipm. I have no clue what my spindle speed was, I'd guess maybe 15krpm? That's a guess. Roughing cuts were probably around 3-5mm (again a guess), and yes I used the same 1.5" bit for the cores, and the block of UHMW. I've only machined the sidewalls separately that one time. I still prefer to epoxy the sidewalls on the core first, then machine the profile. The most important thing, for me anyways, is that the work pieces be held down VERY well. As long as things can't move at all, I feel like I can take relatively deep cuts, even with the large bit.

I don't have a vacuum hold-down, so when I do core profiling, or base drag-knifing, I use spray glue to hold things down to a piece of MDF, that is clamped to my table. I put masking tape or vinyl application tape on the base or core first, before the spray glue (you don't want spray glue on directly on anything going in your ski). it can be a pain getting things un-stuck, but it can't budge when machining.
switzch
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Post by switzch »

Thank you... one more question. Do you do the happy monkey method of leaving wood on either side of the core (see link below for reference), or do you cut the core out to shape then glue the sidewall to the core?

http://www.happymonkeysnowboards.com/Mo ... _Edge1.JPG
winter is coming..
twizzstyle
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Post by twizzstyle »

Just core + sidewalls. I used to leave wood on the outside when I used a planer, but haven't needed to with the CNC.

You can see my whole process in this video. Core profiling is around 1:47

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Head Monkey
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Post by Head Monkey »

I originally left the extra wood on the sides because of the way I hold my work down, which you can see in that picture. Still haven't gotten around to building a vacuum table.

However, the main value in the wood left on the sides is you get a free, precise clamping caul. If I ever do build a vacuum table I'll still do this. See the two articles on clamping technique here: http://www.happymonkeysnowboards.com/Mo ... _Resources
Everything I know about snowboard building, almost: MonkeyWiki, a guide to snowboard construction
Free open source ski and snowboard CADCAM: MonkeyCAM, snoCAD-X
motoman
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Post by motoman »

Hi, guys. Just build my cnc.
Have some questions about core profiling.
Now I'm experimenting with 10 mm (0.4 inch) bit for surface leveling.
http://www.djtol.com.ua/category/Frezy- ... ei-QD.html
Now I am experimenting with next parameters 18000 rpm and spindle feed is about 1000 and 2000 mm/min (40-80 ipm) step of cut 90-100% of bit diameter. Cut depth 2 mm. It takes 35 minutes to cut 4 mm of core, but in some moments it is too hard for spindle.
I have seen happymonkey's 1.5 inch bit and have next question
What is your spindles power?
And what depth you dig into wood per a set?
(my spindle has 1 kW of power, actually it is regular router, just built-in cnc))
I would like to minimize the time of core profiling and not to damage a bit.
May be I have to buy another spindle...

Thank you in advance.
gav wa
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Post by gav wa »

Hey motorman you got any photos of your CNC?
A rigid machine with a smaller spindle will always out perform a weak machine with the best spindle.
That said 1kw is a bit low in power. 1.5kw would be the smallest I would use for roughing anything out.
There are heaps of things you can do to maximize the power you do have though, less cutting edges, higher cutter rake angle etc. Looking at the images on your link those tools look like they have very little rake, maybe try a different cutter.
Your speed is pretty low for such a small cutter though, a 10mm bit could happily cut at 24,000 rpm. That's a small cutter for profiling though, I'm surprised your spindle is stalling with a 10mm tool, even at only 1kw. What timber are your cores made from? How old is your spindle and VFD?
motoman
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Post by motoman »

I did an experiment and got good result but time of work a bit long. Even sidewalls remained in place))
Right now I use 6 mm 1 flow bit for wood at the speed of spindle 18000 rpm and spindle feed 4000 mm/min. It takes aprox 1 hour to work 10 mm core.
We will buy better spindle with water cooling system a bit later 2-3 kW.
You can see our cnc in my journal.
motoman
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Post by motoman »

Even 10 mm tool is hard to work with for our spindle, since the noise during cutting is not normal. I tried to cut 2 mm depth at speed 1000 mm/min and a few times spindle stuck in the place.
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