Cutting with a diamond cnc engraving bit?

[unkn]

Disclaimer: Totally new to the world of lathe cutting. I just barely starting to do initial investigation in some peoples homemade record lathe setups, so I don't really know much yet and may be asking a dumb question.

From what I have read so far it seems like generally what is used to cut or emboss is either a hard gem or tungsten. I think i saw somewhere that the gems are not shaped like a cone, but people use cone tipped tungston rods. I also noticed that there are cnc machine engraving bits which have a conical diamond tip, and was thinking maybe its possible to use these cnc bits in a homebrew cutting head.

So I have 2 questions really.

1. Does anyone know why diamonds for record cutting are not shaped like a cone (or if this is totally incorrect and they actually are conical)?
2. Has anyone tried using a diamond tipped engraving bit for cnc work as a record cutting needle?

Example product: http://www.widgetworksunlimited.com/Replacement_Tip_for_Diamond_Engraving_Bit_90_p/cnc-dmnd_engrv-rb_90.htm

[rsimms3]

A conical tip does not actually force any material to be removed from the resulting groove, it simply moves past or around the rounded tip. A cutting needle has a flat front to force material to come out of the resulting groove instead of simply passing around it. It's sort of like the difference between a cow catcher on an old train and a snow blade on a tractor. The cow catcher wants to deflect things off the left or right of the train whereas a snowblade actually wants to push things into a pile.

[unkn]

Thanks for clearing that up for me. That does make me curious if decent cutting can be done with an appropriately shaped metal needle then. This thread seems to indicate that some people may have tried before, so that may be something I experiment with in the future when I start diving further into the hobby.

[evildrome]

Diamond engraving bits are frequently not actual cones but are in fact multi-faceted when you look at them closer.

Bits without a cutting face can be used for embossing rather than cutting.

You definitely can make cutting needles from steel.

Here is one I prepared earlier with a geometry for 78s.

IMG_6703.JPG

Cheers,

Wilson.

[juba bc]

hi, I can make good cuts with a metal needle, but they don't last long and lose the cut, in the past I did a lot of tests with needles that I did on tungsten carbide
https://www.youtube.com/watch?v=eQF7X8_Hh-Y

[grooveguy]

Hi, Juliano, very nice YouTube video. Are you actually cutting (removing material) or doing very aggressive embossing? It didn't look as if there was enough chip/swarf coming out of the groove. However, my experience has been with commercial lacquer mastering discs, hot stylus and a vacuum; perhaps with the blanks you are using the material coming off is different and seems less.

[juba bc]

I was making a cut, for me it is very visible the chip in the video ... here another video also of cutting but using a chip cleaner this time https://www.youtube.com/watch?v=FIjNbc1HDkk

[grooveguy]

Yes, good demonstration... and you are getting splendid results. Congratulations!

[evildrome]

Very interesting... I take it you made the cutting head yourself?

[juba bc]

yes, homemade cutterhead

[grooveguy]

...and 'homemade' with what looks like impressive performance!

[juba bc]

I can do a step by step of how to make and what materials to use, but I hate the way of posting photos here

[juba bc]

[url=https://postimg.cc/jwZqW2

[grooveguy]

Quick question on your head, Juba, mainly that V-shaped bracket that secures the stylus holder and is held in place by those two threaded standoffs. Is that a loose coupling (nuts not tight or rubber grommets) or do the screws simply flex? I'm assuming that a stiff wire goes from the stylus holder to the backplate to prevent front-to-back motion.

[juba bc]

the screws are very tight, holding the V spring very firmly, only the spring can flex, the pen holder is fixed with a rigid wire on the rear support, the whole set is very rigid and also very light

[juba bc]

[evildrome]

Thanks for posting the pictures.

Those cones look very nice. How did you make them?

[juba bc]

made with beer can, I made a metal mold to get this shape

[grooveguy]

A beer can? Now THAT is impressive. I'll bet you could make a crumpled car door look like new.

[juba bc]

making a cone for a good cutterhead is not an easy task, after many attempts and finally you can make one and soon realize that you need 2. I created my way of making and making as many as needed, always everyone is the same size and a lot lightweight, but it was necessary to create a tool in the shape and size of the cone