Lithophane bits?

[shoeshine]

I have gone through the post threads here, and I have gotten some great advice on trying a couple of lithophanes.

But the only thing I cant seem to find is info on bits. People have mentioned needing a 1/32" bit for fine resoulution.

Does anyone have some advice on bits/suppliers they have succesfully used?

I looked on precisebits.com and there are two very different bits availble. there is a tapered 4 flute carving bit, and a 1/32 ball nose end mill. links below:

http://www.precisebits.com/products/carbidebits/taperedcarve250b4f.asp

http://www.precisebits.com/products/carbidebits/ballnose125.asp

anyone used either of these or others?

any advice appreciated.
Chris

[knight_toolworks]

actually you can do it with V bit faster and no chance of breakage. a 90 or 60 I can't remember what one it has been awhile. I think you use the same stepover as a 1/32" bit but you can cut as fast as the machine can move. there is a posting about it on the vectric site.
otherwise you would want a standard 2f ballnose bit. but the v works great and it is far more durable.

[myxpykalix]

The best bit to use is a 1/8th" ballnose bit. Look up www.centuriontools.com (http://www.centuriontools.com) . I have done several with no breakage or problems at all.

[knight_toolworks]

it depends on how big you want to make it. a small one a 1/4" ballnose would be too big.

[cnc_works]

If your image has very fine detail, like hair, or is very small in size (2" X 2" to 4" X 4") with some detail, then a 1/32" 2 flute ball mill works just fine. If it is a larger image and doesn't have very fine detail, then a 1/16" or even a 1/8" can achieve the same results. I have cut larger images like 10" x 20" with a 1/32" bit and gotten beautiful, near photo quality, but with a cut time of 3 to 5 hours. With the smaller bits, I'll usually rough with a 1/8" ball with a 50% stepover, then finish with the fine bit with a 8% to 10% stepover leaving .02" z stock to be cut by the finish cut. I'll usually leave .04" or so at the thinnest part with an overall depth of cut at maybe .14" to .17".

A v-bit would work great with a very shallow image, but the v cannot drop down enough into the fine details that have a high contrast between light and dark.

I've cut many many lithos with a 1/32" bit and as long as I don't make a mistake on my toolpath and I rough it with an eighth, I've never broken one.

I get my bits from my local machine tool supplier. They are cheaper (around $10) and work just as good as a bit categorized as a "router" bit.

Donn

[shoeshine]

OK thanks for the input gents. I already have a couple of 1/8" ball mills on hand, so I guess I'll run a test piece to see about resolution.

This is in league with a local photographer so picture quality is paramount. run time not so much as My BT48 has a fair amount of down time these days.

I'll take the tip Donn, and call the local tooling place tomorrow. that's where my 1/8" ball mills are from and you are right, they were about $8.

[calgrdnr]

Vbit from centurion has serve me well

I use PVC or aspire I cut with one pass .21 deep

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You can see some of my lithophanes on the Vectric forum Under user calgrdnr