Greg A
1 post
Jan 16, 2016
6:03 AM
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Hey guys.
Anyone have any g code as a starting place to make combs? I'd like to give it a shot. There's a cnc at work that's available to use. I just need to figure it out.
Greg A
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Greg Heumann
3156 posts
Jan 16, 2016
8:46 AM
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GCODE isn't hard to learn. Someone else's GCODE won't tell you what size block of wood they started with, how it was mounted, in what orientation, what size and shape tool they use. If you don't understand what the code does you absolutely should not try - you could get hurt, or damage the machine.
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/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
Last Edited by Greg Heumann on Jan 16, 2016 8:48 AM
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Mahcks
64 posts
Jan 16, 2016
9:08 AM
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Any recommendations on where to start learning this sort of thing? I just got a desktop cnc which I'll be able to use once I get a workshop together.
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Greg Heumann
3157 posts
Jan 16, 2016
9:34 AM
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There are many resources - just google "g code tutorial". Writing GCODE is like writing postscript or HTML - these are fairly low level languages that can be written manually, but are often written by higher level, more visually oriented tools like CAD/CAM software. I write GCODE manually for my work (in particular for personalized mic grills).
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/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
Last Edited by Greg Heumann on Jan 16, 2016 9:35 AM
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JustFuya
831 posts
Jan 16, 2016
11:17 AM
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It would depend on your machine type, tool size, raw stock and probably some other stuff. I think your best bet would be to measure one and draw what you want. 3D CAD would be best but paper sketches will do. The machinist will know what the possibilities are. The exact G-CODE will vary from machine to machine or control to control.
I would talk to the programmer or machinist about helping you out during a slow work period. A comb is not a complicated part (if you are reverse engineering) but the machining method could be. You can get a pretty good idea by reading and viewing Tom Halchek(sp?) posts and videos on machining his combs. You would have to minimize warp and the final passes would have to leave a very fine surface finish unless you don't mind a lot of hand work.
They have cheaper CAD/CAM software than MasterCAM ($30k?) which was top of the line in my days. Some are even free. It's best to simulate the process on computer to avoid machine & tool crashes.
I hired a fella who was pretty good right out of junior college after taking a few classes so I would start there for training.
Do you have a skill you could barter with? It's nice to have bargaining chips. I have worked in larger companies where G-Jobs (home projects) took priority. Unethical but true. Best to have supervisor's blessing.
BUT - In the end you might be better off buying a comb from one of the resident vendors who create in quantity and have already worked out and absorbed the high cost of development.
Many moons ago I was made to feel foolish when an old hand came by my work bench during lunch and saw that what I was working on. The forgotten piece could be purchased at any hardware store for less than a buck. I was not discouraged as he walked away shaking his head.
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arzajac
1735 posts
Jan 16, 2016
11:51 AM
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Hi Greg.
I had a little help when I started making combs, but I had to figure most things out on my own. In many ways, the process is very different depending on your machine, your materials and your goals. So the G-code I use for my combs would probably not be ideal (or even run) on your machine.
I just opened one of my G-code files for a variation of my Marine Band 364 combs and it's over 1300 lines long.
I use a vector drawing program to make the 2D design. I use another piece of software to convert the vector graphic into G code using settings that are appropriate for my CNC machines and the materials I cut.
Things to consider:
- Spindle speed - match this with your feed rate. If your spindle is too fast, you will create heat. You will wear out your bit much faster. I started a fire because of this once. If the spindle is too slow, well, it won't cut.
- Feed rate - figure out the optimum rate. Match this to the depth.
- Depth - How deep you cut. No, you usually don't cut through the whole surface in one go.
You may also consider spraying water (or another coolant) on the surface as you cut. I feed water into a needle by gravity and it's pumped by air to spray the tip of my bit. I would not use water to cut wood - that would make it swell.
It's a process of trial and error to get the optimum settings so that you get the best result, in the fastest time and wear out your bit the slowest.
Once they are cut, the real work begins. The hard work is making them flat and finishing the sides and tines so they are comfortable to play.
I flatten by hand because I can get them much flatter than if they are flattened by a machine.
I hope this gives you an idea of where to start!
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Custom overblow harps. Harmonica Combs and Tools.
Last Edited by arzajac on Jan 16, 2016 11:54 AM
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nacoran
8887 posts
Jan 16, 2016
12:52 PM
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If you Google you can find some files. I tried to find the site I'd found before. I'll look some more. I downloaded for a 3d printer to see what it would involve. I never got around to getting over to the local maker's space to try it out though.
It was higher quality, I think, than the ones in this list...
http://www.yeggi.com/q/harmonica/?s=tt
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Nate
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First Post- May 8, 2009
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JustFuya
834 posts
Jan 17, 2016
5:49 AM
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Related link:
http://www.cnczone.com/forums/benchtop-machines/279642-cnc-forum.html
@ Greg A - If I knew your level of experience my ideas would cover less territory,
I will respectfully disagree with arzajac on one point. I'm a huge fan of hand work and I have absolutely no doubt that there are people who can fabricate an excellent flat comb with a block of material, a vise, a few files and some sandpaper with a granite block and a 6" Starrett scale for inspection. But the less hand work involved (there will always be some) the more accurate and consistent the part will be.
I have dealt with many people on my road to success and excellence. Some craftsman keep secrets while some share secrets but don't deliver them on a silver platter. The harp community is a sharing and kindly bunch as a whole. I appreciate each and every one whether I agree or disagree.
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arzajac
1736 posts
Jan 17, 2016
6:54 AM
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JustFuya - The piece will only be as flat as the axes of the machine. As straight as they can be, can they make the piece flat to a tolerance where three solid pieces fit together and are airtight without a gasket?
My goal is to make the harmonica seem as if it's all one piece. A gap of a thousandth of an inch between any layer means it will feel like three pieces held together rather than a single unit.
As far as I know, even granite surface plates and straight edges are manufactured by machine but inspected and finished by hand to achieve the desired tolerances.
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Custom overblow harps. Harmonica Combs and Tools.
Last Edited by arzajac on Jan 17, 2016 6:55 AM
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Greg A
2 posts
Jan 17, 2016
7:28 AM
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Hey guys thanks for all the responses. I have an autocad drawing of a ms hohner comb. I also have some pieces of plastic brass and stainless steel. I'm using this opportunity to learn how to use a cnc. If anyone is willing to share a gcode it would help as a starting point.
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JustFuya
835 posts
Jan 19, 2016
5:11 PM
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M00
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Greg Heumann
3158 posts
Jan 20, 2016
10:58 AM
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You have an auto cad drawing. THAT can be turned into GCODE with CAM software. Someone else's GCODE won't have any relationship to your auto cad drawing. If you want to learn to make stuff you drew in auto cad, then you need to learn the CAM part of it and that will write the GCODE for you. There's no free lunch.
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***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
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