Fossiilized Coral Necklace Tutorial

[Taogem]

Carol...... Or anyone else..

If someone has the Rio Grande tools catalog..

Page 312 shows some core type bits.

I am looking at the diamond core bits "O' and "P"

The "O" say metal bonded.

The "P" say nickel plated with diamond. The bits I just had were nickel and diamond. I understand the principle behind drilling of less material due to the bits being hollow.

The bits still each have their own types of plating on the top of the core diameter. Drilling harder material, which of these are most likely to hold up more considering I will be putting some stress or pressure on that outer area of the tip of the hollowed part of the bit.

Make sense??

I am still not so sure just beating my head against the wall in regards to drilling fossil like material. But for drilling a short 2 to 4 mm, what do ya think?

The design of the "O" bits seem quite a bit different than the "P", but the "P" are more expensive. Just sorta figure they must be the very best type of plating as bits go.

Just unsure about trying the same nickel plated diamond coated type bonded bits.

Thinking will order two each of the 2 and 3 mm, and one of the 100 ish grit round bur to start em with, and give this coral another shot.

I have a customer who would really like it if I could drill some Turritella Shell Fossil. Just from front to back. About 2 or 3 mm total.

[Lavenderfish]

Taogem,

I looked up both of those types of core drills and while I can't say I understand the diff between plated and metal bonded (is that diamonds pressed into hot metal vs. diamond mixed into metal and then dipped/adhered to the drill? ??) what I use are more comparable to the "P" type. A hollow tube with diamond grit ~100-120 I think.

The P type looks like it's actually the less expensive drill, you get 5 in a package whereas you're paying for only 1 drill of the O's. The size range is a little strange too eh? You're kinda limited there for the mm sizes you said you're looking for.

I buy core drills from a fellow in Hong Kong thru ebay and have always been very happy with both his drills and with him. His seller name is lau*** and he offers a HUGE selection of core drills either in a range of sizes in one package or sets of a single size from 3mm on up, diamond twist drill bits (I like those too) and all sorts of other diamond tools to drool over. Delivery is usually around a week.

Starting out with a ball bur is good for marking the spot where you want to drill, but when I clamp down a slab or vise a bead I just line up the core drill and just start drilling at a super slow speed to break the surface and get the hole started. Blow out at the exit point once you've drilled all the way thru can be problematic. I always hold the drill next to the stone and mark right on the drill where the top of the stone lines up. That way you know when you're getting close to drilling thru the backside and can take it easier, like trying to sneak up on it and create as little blowout as possible.

I always countersink the finished hole with a ball bur which will help to eliminate that ragged edge and so you don't have a sharp edge that can damage the cord or chain that will rub on it.  I use up to a 600 grit diamond ball then switch to Nova carving points to smooth and polish the rest of the way. That Bruneau bead I did shows an example of a finished countersunk (is that a real word?) hole.

Hopefully some of that was helpful. I think your malachite beads look great btw! Those holes look really good from what I can see in the pic.

[Taogem]

Thanks Carol..

Say..... go ahead and feel free to give the eBay sellers full user ID if you don't mind, and yes, I will remember the countersink bit too.

[Lavenderfish]

Taogem,

That really is his user ID name, lau***  or THK Diamond Tools is the store name too.

Item 180286154100 will take you straight to one of his 4mm core drill auctions if you wanna check one out.

[Taogem]

Thank you 

[Taogem]

I ordered several core bits, twist bits and a set of burr bits.

What I noticed when I got to the burr bit set is that they are made of titanium.

I'm not sure, but isn't titanium harder than diamond?

If so, wonder if they make a titanium core bit?

Thanks for the lead on the bits Carol. They should be here in plenty of time to try on some Turritella Shell fossil for someone.

[Lavenderfish]

Boy, I don't know about the titanium. Maybe those burs will last even longer & I'll be curious what you think of them after you try em out. He (Teddy) has really expanded his selections over the last year so maybe titanium cores are coming eventually.

If you email him to ask about the titanium burs or anything else, he's really good about answering back within a couple of days.

[Taogem]

I will send him a note right now 

[Taogem]

Sort of in a hurry and did not take the time to look back through the thread.

Did someone bring up or know about if there is such a thing as a 2mm core bit?

I sorta doubt it, but thought would ask.

Since the idea of the core bit is simply to reduce the area of drilling or friction, a 2 mm core bit probably would not make much sense?

So I suppose when the need arises to drill a desired 2 mm hole in earrings for the dangle part, were back to using a standard nickel/diamond coated bit.

Just rambling a bit   

[Lavenderfish]

I'm pretty sure I saw 2mm core drills somewhere once upon a time but no idea where now. I did a quick google search and found some at this link  http://www.dadsrockshop.com/diamond_drills.html

Scroll down to "Super small diamond core drills". What you're looking for, but not cheap! Gotta be more out there somewhere at a better price.

[theimage1]

Oriented diamond is the only thing "harder than diamond". Some crystal faces on diamond are slightly harder than other, and that's fundamentally why diamond can be used to cut diamond. Titanium is no where near as hard as diamond. It keeps a good edge and aids in hardening steel but is only good for relatively soft stones for cutting.

[Taogem]

I did a quick google search and found some at this link  http://www.dadsrockshop.com/diamond_drills.html

Thanks for that Carol ..

[Lavenderfish]

In this case titanium is used instead of nickel to coat the diamond particles onto the burs. Not that it's intended as the cutting agent itself. I'm tempted to get a set to see if I can tell a difference in carving. Roughing one out anyway since these burs only come in 120 grit for now.

check em out here: ebay item# 170265252179

[Taogem]

When I sent Lau a message asking about titanium drill bits, he responded by saying that they would be too expensive to make.

So i suppose these must just be for carving?