Slicing carbide…….

This topic has 14 replies, 8 voices, and was last updated 11 February 2014 at 10:28 by JasonB.

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6 February 2014 at 17:34 #143082
Rik Shaw
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@rikshaw
A while back I started a thread thus:

**LINK**

I was advised by some of you that these cutters are typically used in the aerospace and associated industries for drilling/reaming exotic composites and further research bears this out. Because of the non-standard sizes (to me anyway), they are not going to help me in the workshop.

First thoughts were to put them on *bay but I can't see the likes of any self respecting aircraft manufacturer wanting to buy their kit from that source.

So what to do with them?

If they were made from HSS I would chop them up and use for boring bar tool bits etc. but carbide brings me to a grinding halt.

I have seen a video on YouT of a commercial machine slicing carbide rods and it seemed to be making hard work of it which is no surprise given the stuffs hardness so I may have to try and move them on anyway.

Unless, – – – – unless you have a cunning plan………..??

Rik
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6 February 2014 at 17:34 #23131
Rik Shaw
Participant
@rikshaw
…….how?
6 February 2014 at 17:37 #143083
JasonB
Moderator
@jasonb
I cut up some carbide tig electrodes with a cutting disc in the dremel no problem. Thin 1mm disc in an angle grinder should do the job.

Edited By JasonB on 06/02/2014 17:38:33
6 February 2014 at 17:43 #143084
WALLACE
Participant
@wallace
Seem to remember an article in MEW about using carbides as pallets in clock escapements. Cheapo (ish) diamond saws were uused to cut and diamond paste to lap them to the correct profile if memory serves me right.

W.
6 February 2014 at 18:33 #143087
Sub Mandrel
Participant
@submandrel
Ideal for fitting taps to composite baths for Doll's houses.

Seriously, how about using a tile saw? With an end to tiling in sight, I'm looking for uses for my cheap'n'very cheerful one – perhaps slicing small geological specimens or making 1:12 bricks from big ones.

Neil
6 February 2014 at 20:05 #143095
jason udall
Participant
@jasonudall57142
Why not boring bars ( not just the cutting faces..but shaft and all)..very rigid and low Q..doesn’t twang much..so even if you braze on a carbide chip ( saves reducing the shank) to gain relief..you get a superb boring bar..if you prefer use a hss “tip”..
6 February 2014 at 22:36 #143108
Ady1
Participant
@ady1
Green grit wheel to sharpen?

They'd make great boring bars
7 February 2014 at 00:28 #143119
John McNamara
Participant
@johnmcnamara74883
An engineer friend now retired gave me a carbide cutter he had made for his engineering business. They used to make custom cutters for forming

It used a 150mm maybe 1.5mm diamond disk driven by and a quarter HP motor.

The Carbide was clamped in a jig and that was mounted on a very basic round shaft and bronze bearing slide. No feed just a small counterweight to pull the slide forward, it used soluble oil as coolant.

He told me that the best method was to keep the feed pressure fairly low and just let the wheel do its job.

I have not used it yet but am sure the device will work, it bears the scars of plenty of use.

Regards
John
7 February 2014 at 09:33 #143133
jason udall
Participant
@jasonudall57142
In the pages of this forum. . I have on more than one occasion seen “don’t machine steel with diamond ‘cos of the carbon in diamonds and steel ” ..never bough it myself..
Anyway if that were the case how would diamond and CARBIDE supposed to “react”….
Hoping to be informed
Jason
7 February 2014 at 13:09 #143163
John McNamara
Participant
@johnmcnamara74883
Hi Jason

If the iron is heated to above 1500C Diamond can be dissolved by it.

A fast turning diamond abrasive disk can generate a lot of heat, I guess it may not even be visible to the naked eye but at the tip of a diamond grain cutting against iron the temperature could be 1500C (Bright yellowish red heat) for a millisecond or two.

I have touched my diamond sharpening wheel with steel when I use it to sharpen brazed tip carbide lathe tools. I try to grind away the steel on a silicon carbide wheel first but it is easy to angle the tool a bit to much. The result is not an instant breakdown of the diamond wheel, however I have always tried to avoid ding so.

Here is a handy link re iron temperature versus colour: **LINK**

Google search: iron dissolve diamond **LINK**

Not a bad wiki on it: **LINK**

Regards
john
7 February 2014 at 16:30 #143182
jason udall
Participant
@jasonudall57142
Best explanation I’ve had so far thanks…
Btw 1500..bet that would ruin the temper of hcs..
10 February 2014 at 23:19 #143474
Rik Shaw
Participant
@rikshaw
Jason B – I tried 30mm x 1mm diamond wheel in dremmel on a bit of 6mm dia. carbide. Result? = Not only did it it not cut but it never even MARKED the carbide. You must have some very superior kit !

Rik
11 February 2014 at 09:15 #143486
John Olsen
Participant
@johnolsen79199
My father bought a machine with diamond wheels from the USA about thirty years back. It is made for sharpening lathe tools, either carbide or HSS. I inherited it about ten years back, it has been used reasonably often and the original set of wheels is still going strong. Every time it comes up for a mention at our club there is one guy who always brings up the thing about diamond dissolving in steel or whatever, despite the fact that after thirty years or so these wheels show no signs of doing so. Possibly the secret is that the wheel does not turn particularly fast and is kept wet with a detergent mix, eg mostly water but with a wetting compound. Incidently an 1800 grit diamond wheel leaves a mirror finish on carbide or HSS. There is a 260 grit roughing wheel, then 600, then the final polish.

I'd also point out that the standard method of cutting the facets on diamonds is to use a cast iron wheel with diamond powder pressed into it. I beleive that here also the speeds are kept quite low. I don't know if they keep the job wet but I would not be surprised.

So if I needed to cut up some carbide, I would be looking at using a diamond wheel, but I would not use a high speed device like a Dremel, I would turn the wheel slowly and keep it wet. Diamonds cut well, you don't need high speeds to get good results. I used a diamond hole saw to cut holes for a railing in concrete, that also works really well with the job flooded with water and the saw turning quite slowly.

There is an outfit just down the road from me that makes solid carbide router bits out of carbide bar. I haven't seen how they do it, but I can't think of anything much that would cut carbide other than diamond. (They were very helpful once with some offcuts of carbide bar.)

John
11 February 2014 at 09:19 #143487
John McNamara
Participant
@johnmcnamara74883
Hi Rick

The 150mm wheel that came with the fabricated Carbide saw I was given has the diamonds embedded within a brass ring around the periphery. It is quite old so I know it will be natural diamond. Not CBN Cubic Boron Nitride.

Many of the wheels sold cheaply at hardware stores are marked CBN Diamond (A synthetic).

**LINK**

From the above link. "Abrasion resistance and hardness are very important physical properties of an abrasive. Both diamond and CBN are almost equal, with about four times the abrasion resistance of Al-oxide. However, while CBN is substantially harder than other conventional abrasives, it has only 64 percent the hardness of diamond–45,000 N/mm2 Knoop, as compared to diamond's 70,000 N/mm2 Knoop. (Hardness of Al-oxide is 20,000 N/mm2 Knoop.)"

However CBN has other advantages.

Have Dremel used natural diamond or something else? I guess you should try a different wheel.
Most Industrial wheels have the diamond particles embedded in a soft metal rink.

Cheaper wheels just have them plated on the surface,

A general search for CBC Diamond: will be worth browsing. https://www.google.com.au/#q=cbn+diamond

Regards
john

Edited By John McNamara on 11/02/2014 09:20:47
11 February 2014 at 10:28 #143495
JasonB
Moderator
@jasonb
Posted by Rik Shaw on 10/02/2014 23:19:03:

Jason B – I tried 30mm x 1mm diamond wheel in dremmel on a bit of 6mm dia. carbide. Result? = Not only did it it not cut but it never even MARKED the carbide. You must have some very superior kit !

Rik

Rik, I did not say I used diamond just an abrasive cutting disc, probably one of the quick change ones rather than the unreinforced ones that they do. If I get time I'll cut another bit off and take a pic and confirm type of disc.

Edited By JasonB on 11/02/2014 10:29:40
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