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JoeLee
10-18-2014, 04:01 PM
I have a 1/2" square tool bit that I'm grinding to true up some cast iron pulleys. One end is 38 deg. and the other end is going to be 34 degrees when I find a faster and easier way to grind this stuff. The material is Vasco Supreem. After some help from some of you guys I was able to identify this stuff. It contains about 13% tungsten. That's why it's so tough to grind. I should have a silicon carbide wheel but I don't. Alum oxide wheels will cut it but it's slow going and you have to watch the heat. This stuff does a good job of dressing the wheel also!!
But my question here is how would you go about centering the cutting end of the bit so it's not ground more to one side???
Below is my fixture set up. I set the fixture to the appropriate angle and the set the other axis for the side clearance which in this case is 5 degrees, I probably should have went with 2 or 3 degrees and it would have been less grinding. After I grind one side I flip the bit around and tilt the fixture 5 degrees the other way. By doing this I never have to change the fixture axis that is set for the bit's angle. If the side angle is off a half degree or so it's won't matter. The only way I can come up with as far as centering is just to scratch a line across the bit where the first side angle ended and grind the other side to meet the line. That gets me really close. But since I don't have any way of keeping tract of my down feed it has to be done by eye. I used this same method to rough out the bit on the pedestal grinder and finished it up on the surface grinder.

JL.................

http://i911.photobucket.com/albums/ac317/JoeLee09/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image002_zpsd2e16b78.jpg (http://s911.photobucket.com/user/JoeLee09/media/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image002_zpsd2e16b78.jpg.html)
http://i911.photobucket.com/albums/ac317/JoeLee09/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image006_zpsaba46552.jpg (http://s911.photobucket.com/user/JoeLee09/media/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image006_zpsaba46552.jpg.html)
http://i911.photobucket.com/albums/ac317/JoeLee09/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image007_zps04df3108.jpg (http://s911.photobucket.com/user/JoeLee09/media/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image007_zps04df3108.jpg.html)
http://i911.photobucket.com/albums/ac317/JoeLee09/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image008_zpsb36f9a99.jpg (http://s911.photobucket.com/user/JoeLee09/media/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image008_zpsb36f9a99.jpg.html)

Gary Paine
10-18-2014, 04:27 PM
Although I usually do it by eye like you have, the experts here will have some tricks of the trade for you, I think. If you have the angle right, a measurement of the length of the new flat should be the same on both sides. That you could get pretty close with a caliper.

That's a pretty large cutting surface on such a form tool. I'd probably have ground it narrower than the groove so I could cut only one side at a time rather than plunge that in. That said, maybe chatter bumps in the groove surface of a pulley could increase the grip on a V-belt ????

JoeLee
10-18-2014, 06:06 PM
It is a pretty big cutting surface for a form tool. I can still cut one side at a time as I've done in the past on other pulleys. The form tool acts as a gauge for proper depth and width of the groove. In the past when they start to chatter I turn the lathe spindle really slow by hand and it scrapes any chatter marks clean. I'm just cleaning up some step pulleys that have worn slightly so I won't be taking big cuts.

JL...................

Old Hat
10-18-2014, 06:27 PM
With a coarse soft wheel, take the wheel nearly to the depth of cut.
now use hand cross-feed, and fairly fast table feed.
Advance the cross-feed into the part only a few thou per occilation.
Your wheel will perish nicely and keep exposing fresh gritt.
Feel how agressively your cross~advance should be once you've started,
Only go half way across the part.
Now go behind the part / bit and work toward you.

I can take a quarter inch off the lenght of a 5/8" ejector-pin in one pass
in no time and never over-heat the pin.... grinding in this method.

Incidently.... put some grime in a shaker and sprinkle a little around in your shop.
It's so clean it's almost un~nearving.:eek:

oldtiffie
10-18-2014, 08:37 PM
Use any old HSS tool bits and grind them by hand using a shop protractor - the vernier on which reads to 1/10 of a degree (6 minutes of arc).

But as the material is cast iron I guess that a common TC insert would do the job.

It is really three jobs - one (or several) plunge cut/s - to remove the bulk of the centre of the groove and two simple taper-turning faces - using the compound/top slide.

With vee-belt grooves the sizes are not too "fussy" but the depth of the groove, the angles of the sides and the width of the groove at the OD are all that is needed.

Cast iron, aluminium and free-turning brass are my preferred materials with hot or cold-rolled mild steel coming up last.

Why not heat and forge (bloody big hammer on an anvil and quench it - not temperature-fussy at all) it roughly to size, use a good angle grinder to "rough" it and finish-off on your pedestal grinder.

QED.

JoeLee
10-18-2014, 08:38 PM
There is no way I can sink the wheel into this material as you described. Just hovering over a spot with .0002 DOC generates an incredible amount of heat and leaves burn marks. I'm using a 60 grit wheel H hardness. Softest one I have.
A couple passes and I have to stop and dab it with a Q-tip and some ice water.
PS......... the shop is a pig pen.............. I can't move any more. Thanks for noticing!!!!

JL.....................

BigSpike
10-18-2014, 08:42 PM
That fixture is cool. What is it? Where did you get it?

Fasttrack
10-18-2014, 09:27 PM
Those tungsten tool steels are very tough to grind but once you have the form they are great for abrasive materials. I highly recommend a soft silicon carbide wheel to keep the heat down, or consider coming up with some kind of wet grinder. Always meant to do that... I've got a big drawer full of Tantung-G, etc., including some huge 1" by 1" pieces. Not very likely I'll be grinding those anytime soon... :)

Old Hat
10-18-2014, 09:32 PM
There is no way I can sink the wheel into this material as you described. Just hovering over a spot with .0002 DOC generates an incredible amount of heat and leaves burn marks. I'm using a 60 grit wheel H hardness. Softest one I have.
A couple passes and I have to stop and dab it with a Q-tip and some ice water.
PS......... the shop is a pig pen.............. I can't move any more. Thanks for noticing!!!!

JL.....................

No you missed it. Go near depth outside the bit, and traverse across it....
while the table is cycling. The wheel corner cuts and yeilds grit as it goes.
It's a form of side-grinding realy.

Of couse you can't plunge into the bit!
I wish I could just show you.:(

oldtiffie
10-18-2014, 09:33 PM
If I were grinding that or most tools on the fixture on a good tool and cutter grinder (which the OP has) I'd be using a good "cup" or "saucer" wheel - type and grade of medium/"grit" at the OP's discretion - use a "side" grinding instead of a "face" grinding technique.

Old Hat
10-18-2014, 09:53 PM
cross~grindind at depth.
http://i126.photobucket.com/albums/p92/swadge/Turret%20Bridge/crossgrinding_zps4419832d.png (http://s126.photobucket.com/user/swadge/media/Turret%20Bridge/crossgrinding_zps4419832d.png.html)

It's hard to explain, it's not hoccuss poccuss.
A wide ranging toolmaking practice. Even D2 succomes to it.

http://i126.photobucket.com/albums/p92/swadge/crossgrinding-Copy_zpsf31f7b52.png (http://s126.photobucket.com/user/swadge/media/crossgrinding-Copy_zpsf31f7b52.png.html)

oldtiffie
10-18-2014, 09:56 PM
One of the groove angles is 38 degrees. If using the top/compound slide the setting angles are: ((180 - 38)/2) = 142/2 = 71 degrees (or perhaps 90 - 71 = 19 degrees).

Axkiker
10-18-2014, 10:22 PM
What kind of fixture apparatus is that. It looks like something I must have!!! I can think of about 10 different projects I could use one of those on.

JoeLee
10-18-2014, 11:50 PM
cross~grindind at depth.
http://i126.photobucket.com/albums/p92/swadge/Turret%20Bridge/crossgrinding_zps4419832d.png (http://s126.photobucket.com/user/swadge/media/Turret%20Bridge/crossgrinding_zps4419832d.png.html)

It's hard to explain, it's not hoccuss poccuss.
A wide ranging toolmaking practice. Even D2 succomes to it.

http://i126.photobucket.com/albums/p92/swadge/crossgrinding-Copy_zpsf31f7b52.png (http://s126.photobucket.com/user/swadge/media/crossgrinding-Copy_zpsf31f7b52.png.html) OK, now I see what your talking about. I'll have to give it a try when I finish grind the other end of the bit.

JL.............

BigSpike
10-19-2014, 01:44 AM
What kind of fixture apparatus is that. It looks like something I must have!!! I can think of about 10 different projects I could use one of those on.

Looks like it's a K.O.Lee Universal work holding fixture B789V
pretty expensive...

Found a build log for one Applescotty's Scrapbook (http://applescottysscrapbook.blogspot.com/2008/06/universal-grinding-fixture.html)
I added it to my ever growing list of stuff to make :eek:

oldtiffie
10-19-2014, 07:30 AM
What kind of fixture apparatus is that. It looks like something I must have!!! I can think of about 10 different projects I could use one of those on.

That fixture/tool is/was called a Universal grinding tool/head at Shars.com.

It is not on Shars web site now.

I suggest you contact Shars and show them this link on/from JoeLee09:

http://s911.photobucket.com/user/JoeLee09/media/Grinding%20Tool%20Bit%20with%20KO%20Lee%20Fixture/Image006_zpsaba46552.jpg.html

tlfamm
10-19-2014, 08:38 AM
Still available at Shars for US $139.95:

http://www.shars.com/products/view/414/Univise_Universal_Vise_Mill_Grinder_Fixture

rowbare
10-21-2014, 10:13 AM
Shar's sells them on eBay for $99

They can be had on eBay for even less though. $69 here: http://www.ebay.com/itm/Universal-Grinding-Fixture-Milling-Machine-Vise-/221395637672?pt=BI_Tool_Work_Holding&hash=item338c3555a8

Of course this guy only ships to the US grrr...


bob

DR
10-21-2014, 11:58 AM
I believe that type fixture is a copy of an old Delta Univise. But, for all I know Delta may have copied somebody else. It's common to have multi-axis adjustment on grinding fixtures.

Google on "Univise" for pictures and variations of the vise.

DR
10-21-2014, 12:39 PM
If it was me, I'd forget the form tool. With the chatter issue it's very likely the grooves won't be trued concentric to the bore. The groove form may be correct though.

I would also use a softer cutting tool. No point in fighting to grind a difficult tool steel when it isn't necessary.

JoeLee
10-22-2014, 08:31 AM
If it was me, I'd forget the form tool. With the chatter issue it's very likely the grooves won't be trued concentric to the bore. The groove form may be correct though.

I would also use a softer cutting tool. No point in fighting to grind a difficult tool steel when it isn't necessary. The grooves weren't concentric to the bore from the factory. I've indicated them to be off by as much as .013. When I'm done they will be right on. Must be they weren't too fussy about these at the factory. So I'll be correcting two problems with one operation, V angles and concentricity.
As far as the tool bit being as difficult to grind as it is, it's probably the better choice of tool steels for CI and I have 12 grooves to recut.
HSS dulls quickly when cutting cast.

JL..............

Boucher
10-22-2014, 09:01 AM
A belt grinder cuts faster and cooler for rapid roughing a tool bit. I make simple grinding jigs from HDPE.
http://i109.photobucket.com/albums/n50/boucherbyron/IMG_0296Small.jpg (http://s109.photobucket.com/user/boucherbyron/media/IMG_0296Small.jpg.html)
Try it you will like it.

Doozer
10-22-2014, 12:00 PM
Old Hat knows what he is talking about.
He even made some graphics for us all.
More people need to learn this way of surface grinding.
This take 2 tenths max bullshlt wastes time and shows
a lack of knowledge.
-Doozer

Toolguy
10-22-2014, 01:15 PM
I have done it Old Hat's way lots of times. It works fine for me.:)