My First Wooden Cut

Hello,

I am very new to the world of CNC, I have been drawing for a few weeks now and been cutting some polystyrene foam with my router for a few days which has been working quite well.

Yesturday I drew up a profile which is to be cut out of wood (MDF). The attached picture shows the result of that. I have also attached my .cad and my gcode file in the hope that someone could tell me why it has turned out this way.

The wall in between the big holes is 10mm on the drawing but only about 2mm on the actual wood. Also the edges are all fury, I did use an old blade which may be quite blunt, is this the cause for that?

Sorry for such a long post. If you have made it this far, Thank you. I appreciate any help you could give a begginner.

Did you use an 8mm bit? If so, you need to offset the lines in the drawing by the tools radius, as the center of the tool travels down the lines. Try a new sharp bit to get rid of the roughness. And use carbide, not HSS.

Use new tools to get the best cuts. Cut fast in MDF or slow the spindle down if your machine isn't up to it. Your tool is "chewing" the MDF instead of cutting it.

Looks like you need to do a few things. Try using a straight cut bit ( one that is sharp ) or a down shear bit. It also looks like you may be getting a little burning which could mean 2 things, either you are feeding to slow for the RPM you are turning or your bit is just that dull. Also I think that if you use G41 or G42 to activate tool radius value it will make your holes the size you are aiming for. G41 and G42 should offset the tool center line by the radius of the tool.

Hope this helps.

Andrew

Thanks for all the help guys I think I am getting there now. In my drawing I have offset by the radius of my tool and used those lines as my toolpath. I have not yet run this on the machine as the simulation shows different to what my cut should actually be. Do I have to set the compensation in the tool setup dialog? or is there anything else I am supposed to do to get the right results.

Thankyou for all your help,

Dan.

I'd stay away from using compensation until you have the basics down. In what way is the simulation different?

When cutting MDF you need to run you inside edges clockwise inside and your outside edges counterclockwise outside using a down spiral cutter.

Hope that helps

CVV

I would say use a down cut spiral bit, but MDF has no grain orientation. You don't have to observe feed direction for internal/external cutting.

Quote:

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Originally Posted by jabguit

I would say use a down cut spiral bit, but MDF has no grain orientation. You don't have to observe feed direction for internal/external cutting.

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From my experience, you'll get a slightly better cut using conventional cutting MDF.

MDF will still frays and by using a down cutter and observing directions you will have a cleaner cut. Since he is pocketing he can use the down cutter for a clean look. He can also get a Mortising compression bit to assure a clean cut on both sides and use it to pocket.

CVV