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CNC boat kits...?

Aluminium for stables? Perhaps a slab of oak would be more appropriate? I am cutting slices off old oak fence posts for use as coasters and think I can engrave them using the 'boat motor cutter' - so long as the cut is not deep. A laser would be ideal - but the cost and the danger mean that it needs a bit of thinking about. I must look up the Rumba and mega2560. One issue I have with the Uno and GRBL is that the software does not do 'tool radius compensation'. You have to do this in your conversion, and Dfx2Gcode does not do this either. I do not know if there is a GRBL version running on the 2650 which does do this. Essentially you need a GRBL which implements G41/2 commands, or you will have to do the compensation in your original drawing. I am using sub-milimeter for balsa, so the compensation required is negligible and can be ignored, but when cutting ply I may need to worry about it. Your TMC2130s may not need endstops, but the limit switches are also used for homing. You will find that if you want to cut lots of parts out of a single sheet of material, it helps to be able to home accurately. GRBL allows you to have a 'master machine home' and then several subsidiary homes. So, when cutting, I start with the cutter in the master home position in the top right corner, then move it to a secondary home position which is directly over the workpiece top right, then do all of my cutting in relation to that secondary home position...

5 years ago by DodgyGeezer

Forum

CNC boat kits...?

Having successfully used the machine to make the workholding support for the wood sheets, I started on the final leg - getting the machine to actually produce parts for a model boat. It's just going to be used for EeZeBilt balsa parts initially, until I understand a bit more about and feed rates. I'm not using a 'professional' spindle motor (which can cost well north of £100), but just an old model boat motor with a cheap Chinese chuck and milling head. You can see a couple of examples in the pictures below. The first material I tried to cut was cardboard. I wanted something really weak, because the are very narrow, and I did not know how much sideways force they would take. Turned out fine, though. Further pictures show the first attempt at cutting balsa sheet, a whole sheet of 1/8 balsa being cut, and a couple of parts which have just been cut. Points to make: 1 - you need a high RPM from the cutting motor if you want a fast feed speed. Boat motors work, but a high speed brushless would be better. As it is the edges of the balsa are a bit ragged... 2 - Probably the best way to keep all the parts in the balsa sheet is not to use tabs, but just to cut 90% of the way through. I left about 5 thou on the balsa part, which meant it stayed in place but could easily be pushed out... 3 - you need a soft surface under the balsa sheet in case you do cut deeper by mistake. I thought of felt but that gets caught up in the blade too easily. You could use another balsa sheet, but I used a bit of Correx. Depron would be fine... So there we are. I have now cut a complete kit out of balsa and will start to make it up. I can recommend this machine if you want to just sit and have a beer while all the hard work of cutting parts is done for you...!

5 years ago by DodgyGeezer