Introducing myself and bit question

[rvowles]

Hi everyone,

I purchased a Shopbot Desktop in May, and only this holidays (I'm southern hemisphere - Auckland, New Zealand) have I managed to get time to actually stand up and use it. Its been frightening and thoroughly amazing at the same time.

I have a few items I am designing for niche markets and I am also starting a Makerspace for the local community.

Part of the problem I have is that readily available wood is NZ Pine (Californian Pine I believe) - in 10mm and 19mm cuts. Now the only bits I have that cut without too much waste are the 1/8" bits - a 1/16" inch ball nosed came with the machine (like everyone I suppose). I wasn't paying enough attention and got singed wood when the bit went too deep (the single flute seems to get the most work here).

I have taken to using a 1/4" to drop the height of my wood to 12.5mm and the 1/8" and 1/16" to then do further work. This doesn't seem very efficient - and I'm happy to have 19mm thick pieces, I just only have 1/4" bits that seem long enough. Is this just a fundamental issue or are there other bits I'm not finding that I should get?

After a hairy episode with the 1/8" bit trying to hammer itself into the zeroing plate, I know I need to get backups, but I suspect someone on here has some better advice. The parts that I am cutting are fairly intricate, and I'm trying not to waste the wood.

Another issue I am finding is that I don't get a chance to put the magnetic shoe on in the standard program when changing bits. This has caused me to export my cuts into one part file per bit. Is this what other people do?

I appreciate any advice!

Richard

[Roy Harding]

I don't know what you're cutting - but it sounds like you have issues with a few things:

1. You need to set your "pass depth" properly for each bit. As a general rule, and a good point to start at - set your pass depth to the diameter of the tool. So - for a 1/4" (6mm) tool, set your pass depth to 1/4" (6mm), for a 1/8" tool, 1/8" (3mm), etcetera. Over time, you'll be able to change those depths to whatever makes sense in the particular wood you're cutting - but start from there.

2. IF you're carving 3D (actually - 2.5D) patterns, you need to provide a "roughing path" before using your finishing tool. I tend to go up an increment from what my finish tool is. So - if I intend to finish with a 1/8" tool, I'll rough with a 1/4" tool. If I intend to finish with a 1/16" tool, I'll rough with a 1/8" tool. Once again - experience will provide more precise answers for you - but this isn't a bad place to start.

3. I tend to create individual toolpaths for each bit - that's a personal preference thing, you can create toolpaths which require tool changes - I just find it more convenient to separate the tool paths out to individual files. Once again - experience will tell you what works for you.

Make sure that you understand "chip load", and how that relates to RPM and cut speed - there're many threads on this board related to that subject, and Google will help you out there as well.

Best of luck to you - and have fun!!

[Brady Watson]

After a hairy episode with the 1/8" bit trying to hammer itself into the zeroing plate...

You should get into the habit of ALWAYS touching the Zzero plate to the tip of the bit BEFORE running the Zzeroing routine (C2). Look on the Red DRO screen & make sure Input #1 lights up. If it doesn't, you don't have continuity between the bit and ground (earth). Be sure to clip the grounding clip to either the top of the bit or wherever you are able to have a reliable ground for Zzeroing. I have mind clipped to one of the leveling feet & it works well. Coated bits can sometimes prevent the Z plate from working too - since they can electrically insulate the bit.

If the Z should not 'hammer' and the best way to avoid this is to touch the plate to the tip of the bit, and observe input 1 lighting up. The bit size makes no difference. I've used tools as small as .015" in diameter on both my large 5x16' tool as well as the DT. Both work fine. No broken bits from Zzeroing - ever.

For tooling selections, try to network with the other kids from OZ - there are many here that have DTs & they can tell you the most economical sources for tooling.

-B

[scottp55]

Richard, Use the 1/2"straight that came? with your starter set for getting your material to depth. 40% stepover 3,.5,12K works well. Make sure it's rastering with the grain of the wood on that ply level it's cutting. Dont forget to ramp into the cut! Make a boundary box for a pocket cut big enough to let the bit go completely off the material if you can or you'll get an against the grain cut when it steps over. Maybe get a 3/4" if you do a lot of surfacing.
Not quite understanding your dust foot problem- Just raise Z? Use one of your preset buttons to position off material to change bits and put foot on?
We do a separate toolpaths because quite often we have to repeat a cut to clean up bit deflection and get rid of "Fuzzies" as we hate sanding teeny stuff.

[rvowles]

Hi guys,

Thanks for the responses, I'm still taking time to parse them. My son and I are working through an absolutely must do list that will be wall attached next to the 'bot.

Nice tip on the touching the Z plate to the tip. Will add that to the list!