Releif carving bit sizes

[tomj]

Hi all! I just wanted to get some input on what is a go or no go for bit sizes for releif carving in wood - oak, maple, etc. I would like to get as much accurate detail as possible with the shopbot but when do you say when? That is as far as how many times do you step down in diameter? 1/8"? 1/16"? 1/32"?

Just curious as to what every one is doing.

Thanks,

Tom

[rookie432]

1/8" is pretty standard Tom. When you get down to 1/16" (depending on the size of the relief) your cutting times could be extravagent. What takes 2 hours to cut with an 1/8" cutter could take 4+ hours for a 1/16" cutter. You will sacrifice some detail for cut speed but in most cases its neglegable unless your model specifically requires a very high level of detail.

Hope this helps
Bill

[jeff_rowley]

Depending on what software you are using, it is possible to do a first pass with say a 1/8" bit and then do touchups in the required areas with a smaller bit. Artcam calls this 'rest machining' and you can set how much detail difference is required to trigger another pass, etc.

Depending on the size of your relief will affect what size tool you need. Sign work, etc. you can get a surprising amount of detail with the 1/8" ball (I really like the tapered 1/8" ball available through Shopbot, it lasts forever). For lithophanes, etc. you can definitely use a 1/16" or even 1/32". A good site for the smaller sizes is www.precisebits.com (http://www.precisebits.com). I've bought from them several times (usually buy 1/32" bits in batches of 10 or more).

[rcnewcomb]

You may want to also consider the merits of using hand tools to put in the finer detail. After all, what else are you going to do while the 'bot is running?

Seriously, try carving with a 1/2" ball, then try carving the same design with a 1/8" ball. While the 1/8" project is running add detail with hand carving tools on the one that was carved with the 1/2". Compare the results.

[jsfrost]

If you have some skill with hand tools,a few strokes of a sharp chisel in selected areas is often quicker, and in my opinion better, than more machining with a smaller bit. The 1/8 inch ball will leave softly curved hints showing where the detail should go.

[tomj]

Thanks guys! It seems to be along the same lines that I was thinking (and hoping!). I'm glad to have a little reasurance and some direction.

Thanks for the link Jeff - I will check into it shortly.

Take care and have a great weekend!

Tom

[jsfrost]

Randall,
Looks like we were typing at the same time. Since your method looks faster than mine, I'll see what I can do with larger bits, and even more hand work.