Diamond Grinder, and Low Cost Diamonds.

[RayG]

At the Heidelberg West auction a few weeks back I picked up a nice little GMF Diamond Grinder, I've been wanting one ever since the scraping course.

One of the problems with diamond wheels is the cost, typically hundreds of dollars for a diamond wheel... but then Phil ( Machtool ) told us about these diamond lapping disks, they are made for the rock trade ( lapidiary?) and a 150mm diameter diamond encrusted disk is just $19..

http://www.cutandslice.com.au/diamond-laps

They have a good range of different grits and also ones with magnetic backing, so they'll stick to a steel backing disk. There are also aluminium backing plates.
I've tried 180 and 600 grit, diamond, I think I'd like to try 1200 and see how that goes for final honing on carbide.


342946342947342948342949342950342951

The motor needed the star point bought out, and so while it was in bits, I put new bearings in, I'm using one of the group purchase $50 VFD's and it works well.

I'm still waiting on the silicon carbide recessed wheel to go on the other end.. Turns out the one I wanted is a non stock item, minimum 5 wheels, and 10-14 weeks delay.

Ray

[Anorak Bob]

That sure is a nice little grinder Ray. The exact one I've always wanted, even the right colour. :2tsup:

Thanks for the disc link. From memory these wheels have to turn slowly or was that only the aluminium lapping wheel?

BT

[BobL]

Looks good Ray.

Any problems with the slowdown on your group buy VFD?
Have you got the VFD that has <1s braking time as the only stopping prion?
My group buy VFD worked fine until I put a grinding wheel on and after several stops it popped the caps.
The HY unit works fine on a 10s slow down.

These are the laps SWMBO uses
http://www.thk.hk/online-cart.php?cid=36&sid=39
US$8.50 for the 6" and US$15 for the 8"
SWMBO bought a range of 6" laps and some other diamond cutting items and the shipping was US$14.
She has used one lap in 2 years so I have played around with a couple of the others.

I was thinking of getting an 8" lap but I like the way that a lap can be put on the same arbor as a CBN wheel like this.
For anyone that hasn't see the mod thread on this its here http://www.woodworkforums.com/showthread.php?t=188429
http://www.woodworkforums.com/attachment.php?attachmentid=329886&stc=1

[RayG]

Looks good Ray.

Any problems with the slowdown on your group buy VFD?
Have you got the VFD that has <1s braking time as the only stopping prion?
My group buy VFD worked fine until I put a grinding wheel on and after several stops it popped the caps.
The HY unit works fine on a 10s slow down.

These are the laps SWMBO uses
http://www.thk.hk/online-cart.php?cid=36&sid=39
US$8.50 for the 6" and US$15 for the 8"
SWMBO bought a range of 6" laps and some other diamond cutting items and the shipping was US$14.
She has used one lap in 2 years so I have played around with a couple of the others.



Hi Bob,

I just swapped out the VFD, for another Heng Tai HT1000B it popped the RCD, and I know the motor is good having megger tested it earlier today... so the jury is still out on Heng Tai. :)
I don't have a solution the the acceleration problem, but I've got a couple of ideas that I'll try out. For now I just wind the pot back and switch off.


I'm grinding HSS on the diamond as an experiment to see if it reduces the life of the wheel, I wouldn't do it on a $500 wheel, but for $19.. I'll do the test. The theory is that diamond, being carbon is soluble in steel, and so grinding steel erodes the diamonds ..

Thanks BT, you are right, they are just a nice clean little grinder, very heavy, and built like a tank.. runs as smooth as silk.. you are on the right track looking for one. if I see another I'll let you know.

I don't know what sfpm you should use for grinding carbide with diamond.. should be something on line though.

Ray

[RayG]

I don't know what sfpm you should use for grinding carbide with diamond.. should be something on line though.


Most seem to be around the 5000 sfpm mark for grinding carbide with diamond, so a 6" wheel would need to be doing 3180 rpm, the motor is 2850 at 50 Hz, so that's close enough if I run the vfd at 60 Hz.

Ray

[Ueee]

Having been playing around with belt grinders/linishers a lot of late i have found nothing beats a ceramic belt for grinding HSS. Course belt shapes way faster than the wheel, and a fine belt leaves a better finish than a 46g wheel. What more would you want? I tried grinding carbide on an SiC belt but it did nothing but ruin the belt......

[BobL]

Having been playing around with belt grinders/linishers a lot of late i have found nothing beats a ceramic belt for grinding HSS. Course belt shapes way faster than the wheel, and a fine belt leaves a better finish than a 46g wheel. What more would you want? I tried grinding carbide on an SiC belt but it did nothing but ruin the belt......

Have you tried a CBN wheel?
They're very fast and generate much less abrasive grit than a regular wheel.
I'm not sure what you mean by a ceramic belt but CBN also generates less grit and is slightly faster than the Blue Zirconia belts.

[Ueee]

Have you tried a CBN wheel?
They're very fast and generate much less abrasive grit than a regular wheel.
I'm not sure what you mean by a ceramic belt but CBN also generates less grit and is slightly faster than the Blue Zirconia belts.

Green (Hermes) or orange (Norton Blaze) belts. I have not tried CBN but they would have to be out of this world to be better than the belts. The best thing is you can change grits so easily, and still use the same rest and angles you have set etc.

[BobL]

Green (Hermes) or orange (Norton Blaze) belts. I have not tried CBN but they would have to be out of this world to be better than the belts. The best thing is you can change grits so easily, and still use the same rest and angles you have set etc.

I agree about the ease of change of grits, but even Norton themselves say that CBN is the most efficient way to grind tool steels like HSS.
I'm not sure about "out of this world", but Norton use the term "Superabrasive" to describe CBN and Diamond.

Here is a chart from the Norton Website comparing the hardness of various materials
CBN sits in between carbides and diamond and well above any carbides / ceramics.
The means CBN is able to grinder harder materials easier, cooler and quicker than ceramic materials, and they also last s long time, but given their price they would want to do that.
I really like the way there is no belt grit or wheel grit, bonding agent, or fillers to be turned into dust and sprayed around a workshop.

http://www.woodworkforums.com/attachment.php?attachmentid=342981&stc=1
I am surprised that more metal workers aren't using CNB abrasives as it has really started to take off with woodturners
The wheel I have is an 80 grit and I was considering purchasing a 180 but I'm finding the smoothness on an 80 grit acceptable for what I do.
Using a CBN wheel even just to preshape HSS tools and then performing the final finish on a fine belt would save time.

[RayG]

Green (Hermes) or orange (Norton Blaze) belts. I have not tried CBN but they would have to be out of this world to be better than the belts. The best thing is you can change grits so easily, and still use the same rest and angles you have set etc.

Hi Ewan,

I've been using blue ceramic wheels on the SG and they do a good job. I've been reading up on the Norton Blaze (http://www.nortonindustrial.com/NarrowBelts-BlazeR980.aspx) belts, I must get some to try out.

Are you selling your belt grinder yet? If so, how about a link.... or at least a few pictures. :)

Ray

[.RC.]

CBN grinds cooler as a lot of the heat goes into the wheel and not the workpiece...

Downside is, if you were using a CBN wheel on say a surface grinder, the wheel itself will get hot and expand causing a deeper cut rather then the workpiece getting hot and expanding...

I have been thinking about getting a CBN wheel, but never know what grit to get... As they are not cheap, do not want to get the wrong grit...

[RayG]

Hi RC,

I grind a LOT of M2... hundreds of chisels and plane blades... generally a softer wheel is recommended for HSS, (Norton 5SG) but I'm currently liking the blue ceramic wheels, I think they give a nicer finish, http://www.travers.com/radiac-ceramic-surface-grinding-wheels?Category=abrasives,%20files%20%26%20deburring:297879||wheels-bonded%20grinding:297892||surface%20grinding%20wheels:297966||UserSearch=block%20id%2034283%20and%20class%20level3%20id%20297966||AttribSelect=Size=12%22%20x%201%22%20x%203%22

I don't use CBN on the surface grinder, but I do use the CBN wheel on the bench grinder.

A bit of googling and I found Ewan's Multitool upgrade.. https://www.facebook.com/84engineering looks pretty slick, and it looks like production is ramping up, I think you'll need a CNC shortly :D Great looking product. :2tsup:

Ray

[.RC.]

What grit CBN wheel do you recommend Ray for finishing rather then raw stock removal...

Or two.... One for raw stock removal and one for finishing?

[RayG]

What grit CBN wheel do you recommend Ray for finishing rather then raw stock removal...

Or two.... One for raw stock removal and one for finishing?

Hi RC,

Not sure I know the answer... maybe I can answer part of the question, the 180 grit wheel is perfect for stock removal and shaping, And leaves a pretty fair finish.. Certainly way better than the finish off an Alox wheel. For lathe tooling I mostly just use it as is straight off the grinder. No further honing.

Aiming a bit higher for a razor sharp mirror finish... I am going to get a 1200 grit diamond wheel for doing scrapers and touching up carbide tooling, I have a 600 grit diamond wheel, and that's looking pretty good, but I'm looking for that next level of mirror finish on carbide... a bit like what you get from the diamond lap.

Also the plan is to use that 1200 grit diamond on HSS as well, and see if it lasts, or chews up the diamonds.

If you are only buying one CBN wheel, I'd think I'd get the 180 grit.

Ray

[BobL]

This one looks pretty good.

http://www.cwsonline.com.au/shop/item/vicmarc-200mm-x-40mm-x-180g-cbn-wheel

[Ueee]

A bit of googling and I found Ewan's Multitool upgrade.. https://www.facebook.com/84engineering looks pretty slick, and it looks like production is ramping up, I think you'll need a CNC shortly :D Great looking product. :2tsup:

Ray

Yeah thats me......
I have not really been very active here due to time spent on the Aussie blade forum, although at least one member here owns one now.

The CNC plasma is getting closer......

[KBs PensNmore]

Nice work that you do:2tsup:, love the different set ups you have for the linisher.
Regards
Kryn

[.RC.]

This one looks pretty good.

http://www.cwsonline.com.au/shop/item/vicmarc-200mm-x-40mm-x-180g-cbn-wheel

sniff... more $$$$ gone from me... :D

[BobL]

sniff... more $$$$ gone from me... :D

There there, . . . . just wait till you get it and then you'll be able to tell us all about it.

I got myself an 80 grit because I use mine mainly to shape bits - and it leaves a reason to buy a 180 in the future :)

[.RC.]

Unfortunately Bob, if the 180 grit is as awesome as everyone says, I can see myself getting an eighty grit as well...

I have spent next to no time in the shed for the past month and a half now... :C At this rate I will have forgotten how to turn the grinder on when it arrives...

[eskimo]

sniff... more $$$$ gone from me... :D

just remember ...you cant take it with you

[Steamwhisperer]

just remember ...you cant take it with you Very true Eskimo. Phil

[Stustoys]

just remember ...you cant take it with you
His bull managed to.

[.RC.]

Yea rub it in Stuart..... :D:D

Anyhoo, the wheel has turned up... They have a 1.250" centre, good for the TC grinder..

the main part is solid steel and balanced, so it spins for about half an hour after you shut it down..

The CBN is electroplated on bit I am not familiar with CBN wheels but it appears to be only 1 layer thick.. Once that exposed layer is gone the wheel is worn out..

Even though it is 180 grit it certainly removes the metal and is cool cutting...

343618

[.RC.]

Came up with a way to use these wheels...

I rough out on a very very coarse wheel and finish the grind on the CBN wheel... As there is then limited exposure of the steel to any heat on the extreme edge that often suffers when grinding on normal wheels...