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Limestone Seahorse

Posted: Sat Sep 15, 2018 3:55 pm
by Rcnewcomb
This is during/after the roughing pass with a 1/2" ballnose @15K with a 15% stepover. Started at 30 IPM and worked my way up to 83 IPM. Tomorrow I do the finish pass with a 1/8" bit at 7% stepover

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 4:49 pm
by mtylerfl
Very cool, Randall. I haven't worked up the guts to try limestone carving yet. Afraid of dust getting into the spindle, I guess. Do you "spritz" with water or just carve "dry"?

I'm looking forward to the finished photos!

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 6:02 pm
by IslaWW
Michael T...
These ATC spindles use pressurized cases. So there is little or no worries about getting the fine stone dust in the lower bearings like the fan cooled versions.

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 6:40 pm
by mtylerfl
IslaWW wrote:Michael T...
These ATC spindles use pressurized cases. So there is little or no worries about getting the fine stone dust in the lower bearings like the fan cooled versions.
Thanks, Gary. Here's a pic of my spindle (label)...

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 7:01 pm
by IslaWW
Michael...
The low end HSD spindles do not pressurize the case, most non-ATC don't. If it were, there would be air lines to the spindle like the 2 on the front of the attached pic
GCnC ATC Spindle Mounted.jpg

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 7:14 pm
by mtylerfl
Yup. Hence my concern (mine’s not pressurized).

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 8:17 pm
by IslaWW
Michael...
Randall is going to run a finish pass and like me, you will be envious. Would you like to place an order? :lol:

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 8:18 pm
by mtylerfl
:D

For a limestone seahorse or new spindle or ATC or all of the above??

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 9:38 pm
by Rcnewcomb
Finish pass with a 1/8" ballnose @ 16K and 7% stepover. About 75 minutes. Since I didn't have any dull ballnose bits this was cut using one of the $1.50 ballnose bits that tend to break while inserting into the collet.

The first photo is still on the machine. The second is outside in daylight.
SeahorseIMG_3294.jpg
SeahorseIMG_3296.jpg

Re: Limestone Seahorse

Posted: Sat Sep 15, 2018 9:48 pm
by mtylerfl
That came out great, Randall. Thank you for showing us the pics!

I’m getting in the mood to carve a seahorse in Pine or MDF and apply a faux marble finish - and it’s your fault! :D

Re: Limestone Seahorse

Posted: Mon Sep 17, 2018 3:38 am
by Rcnewcomb
Here is a 24 second video of the roughing pass. ->Link

Re: Limestone Seahorse

Posted: Mon Sep 17, 2018 2:09 pm
by dwilli9013
Wow, that looks stunning. Thanks for sharing.

Randall I hope Gary is giving you some discounts on tooling with all the PR you have be doing for the Ultimate Machine. :lol: :lol: :lol:

Re: Limestone Seahorse

Posted: Wed Sep 19, 2018 10:24 am
by johntech
Are you using a special bit to mill into the limestone or a regular bit? I would have thought you would need a diamond bit to do stone with water or a water-soluble lubricant.
Looks like an interesting project!
Thanks

John

Re: Limestone Seahorse

Posted: Wed Sep 19, 2018 3:56 pm
by Rcnewcomb
I cut it dry with a regular carbide bit.

Adding water just turns the stone dust into a cement slurry that sticks to everything.

Bits that are too dull for wood work fine for stone. But once I've used a bit on stone I never use it on wood again.

Re: Limestone Seahorse

Posted: Wed Sep 19, 2018 4:13 pm
by Tailmaker
I like that and would like to try as well...although I am a bit hesitant to mess up my machine with the dust.
Also wondering if this could be carved with a v-bit. I just bought one of the relatively cheap Chinese PCD bits on eBay thay are intended for hard stone like granite (but in that case with a lot of water).
In the Aspire simulation for such a flat tip V form tool the seahorse did not look much different from a small ballnose. Maybe I should try something like that in wood first and then use it on stone with an extra vacuum for the dust.