The Home Machinist!

A site dedicated to enthusiasts of all skill levels and disciplines of the metalworking hobby.
It is currently Sat Oct 25, 2014 12:26 pm

All times are UTC - 5 hours




Post new topic Reply to topic  [ 9 posts ] 
Author Message
PostPosted: Sun Nov 07, 2010 6:33 am 
Offline

Joined: Wed Nov 03, 2010 2:21 pm
Posts: 11
Location: Cape Town
I have seen one or two projects of fabricating your own Carbide Tip Inserts Tool Holders. Some of them was just flat (positive rake bit), but some of them specify for the tip to be on an angle (negative rake tip) to determine the rake.
I would like to get hold of some of these plans to make some myself.

Here in South Africa the tool holders are so expensive that a hobbyist can not afford them.

I have even welded the tips off some concrete drill bits and brazed them on square rods and that also seems to work as a cheap alternative.

I am also looking for info on boring bars.

I have even seen a plan how someone made a cut-off blade from a piece of saw blade on which there was a TCT, but I lost it.

_________________
Regards
Johan


Top
 Profile  
 
PostPosted: Sun Nov 07, 2010 8:46 am 
Offline
User avatar

Joined: Sat Jan 04, 2003 8:33 pm
Posts: 2232
Location: 40 Miles West of Chicago/near DeKalb
Johon:

A set of these toolholders can be purchased in the USA for around $20.
They are not the best toolholders because the inserts are held in place with a small screw against a single edge. But I still use them and made a few of these holders myself.

Image

Do you have a way to sharpen carbide?

Jim

_________________
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

www.outbackmachineshop.com


Top
 Profile  
 
PostPosted: Sun Nov 07, 2010 10:01 am 
Offline

Joined: Wed Nov 03, 2010 2:21 pm
Posts: 11
Location: Cape Town
I can only sharpen brazed on carbide tips. I have yet to try the replaceables. I still keep the chipped ones for this purpose.
I have a green stone to grind them.

_________________
Regards
Johan


Top
 Profile  
 
PostPosted: Sun Nov 07, 2010 11:54 pm 
Offline

Joined: Thu Jan 26, 2006 11:48 pm
Posts: 145
Location: Alameda, CA
I have a set like the ones shown by Jim Glass and fabricated some extra holders out of 1/4" key stock. Very easy to make. I ground the end to match the angle of the insert, milled a small sliver off the end to keep the insert from moving, drill, and tap. The hardest part is not breaking the tap. :)


Top
 Profile  
 
PostPosted: Mon Nov 08, 2010 1:27 am 
Offline

Joined: Fri Dec 20, 2002 11:02 pm
Posts: 13709
Location: Onalaska, WA USA
Jors wrote:
I can only sharpen brazed on carbide tips. I have yet to try the replaceables. I still keep the chipped ones for this purpose.
I have a green stone to grind them.

Jors,
Speaking from the position of a guy that has worked in commercial shops, using both diamond and the green silicon carbide wheels you mentioned, you may be pleasantly surprised to discover that a diamond wheel, now not all that expensive, performs at a rate so much better than the green wheels that you would most likely be dumbfounded. Silicon carbide isn't all that much harder than tungsten carbide, so it tends to beat off the pieces instead of cut them cleanly. The end result is a cutting edge with limit life expectancy, and, often, inferior surface finishes due to the ragged edge created by the wheel. Wheel life is relatively short with silicon wheels, of necessity, in that they are bonded softly to break down quickly--constantly exposing new, sharp grain, to replace those that are dulled quickly by contact with carbide. Of uppermost concern is that the dust from green wheels is very damaging to one's health, possibly leading to silicosis.

China is exporting diamond wheels that are very affordable (and adequate, I might add). It might pay you to explore the possibility of obtaining one that would serve your needs. I recommend one that is resinoid bonded, and in the neighborhood of a 200 grit wheel. I personally use a 220. It is coarse enough to remove carbide rapidly, but fine enough to yield a decent finish on the tool.

Such a wheel must be operated wet, which can be accomplished by a simple drip system, although a recirculation system, very small in size, allows for a constant cooling stream. That prolongs the useful life of the wheel and insures clean and rapid grinding, keeping the wheel free of swarf.

Harold

_________________
Wise people talk because they have something to say. Fools talk because they have to say something.


Top
 Profile  
 
PostPosted: Mon Nov 08, 2010 1:42 am 
Offline
User avatar

Joined: Fri Apr 02, 2010 4:06 am
Posts: 8
Location: Christchurch, New Zealand
Harold_V wrote:
Jors wrote:
I can only sharpen brazed on carbide tips. I have yet to try the replaceables. I still keep the chipped ones for this purpose.
I have a green stone to grind them.

Jors,
Speaking from the position of a guy that has worked in commercial shops, using both diamond and the green silicon carbide wheels you mentioned, you may be pleasantly surprised to discover that a diamond wheel, now not all that expensive, performs at a rate so much better than the green wheels that you would most likely be dumbfounded. Silicon carbide isn't all that much harder than tungsten carbide, so it tends to beat off the pieces instead of cut them cleanly. The end result is a cutting edge with limit life expectancy, and, often, inferior surface finishes due to the ragged edge created by the wheel. Wheel life is relatively short with silicon wheels, of necessity, in that they are bonded softly to break down quickly--constantly exposing new, sharp grain, to replace those that are dulled quickly by contact with carbide. Of uppermost concern is that the dust from green wheels is very damaging to one's health, possibly leading to silicosis.

China is exporting diamond wheels that are very affordable (and adequate, I might add). It might pay you to explore the possibility of obtaining one that would serve your needs. I recommend one that is resinoid bonded, and in the neighborhood of a 200 grit wheel. I personally use a 220. It is coarse enough to remove carbide rapidly, but fine enough to yield a decent finish on the tool.

Such a wheel must be operated wet, which can be accomplished by a simple drip system, although a recirculation system, very small in size, allows for a constant cooling stream. That prolongs the useful life of the wheel and insures clean and rapid grinding, keeping the wheel free of swarf.

Harold


Hi Harold,

You mention China is exporting diamond wheels that are very affordable.. What can be said about the quality? Are you meaning a wheel that would go on a grinder?


Top
 Profile  
 
PostPosted: Mon Nov 08, 2010 2:45 am 
Offline

Joined: Fri Dec 20, 2002 11:02 pm
Posts: 13709
Location: Onalaska, WA USA
oiad wrote:
You mention China is exporting diamond wheels that are very affordable.. What can be said about the quality? Are you meaning a wheel that would go on a grinder?

Well, I hope I didn't open my mouth before getting my brain hooked on. I have been installing slate flooring, and using a 10" diamond blade for cutting. Those I recommend highly. A new one costs only $30 US, which is an absolute bargain. Performance is very acceptable. Diamond wheels are one of the commodities that have come down drastically in price, unlike almost everything else we encounter.

So then, I may have misspoken about wheels, in that those I have purchased recently are all diamond saw blades (including some nice 4" diameter blades, for use on a small angle grinder). On sale, HF, three blades for $10. An excellent buy, and very acceptable quality.

However, it is possible to purchase a 6" wheel, suitable for grinding carbide tool bits, on sale, for as little as $120. Here's a link that describes such a wheel.

http://www.use-enco.com/CGI/INSRIT?PMAKA=317-1070

Note that the price here is higher by a generous margin. The description, however, is exactly what one should seek, assuming they wish to buy a 220 grit wheel.

The thing to consider is that such a wheel, back in the late 50's, would have cost in the neighborhood of $600. Considering the buying power of the dollar, now, as compared to that period of time, the wheels effectively cost only about 10% of the old price. They truly are a bargain.

If a person buys a wheel such as this, and uses it in the home shop, keeping steel away, running it wet, with no abuse, it could easily last 40 years. Even in a commercial application, my first wheel ran for more than 16 years before it was replaced. Best of all, I didn't have to breath dust from silicon wheels, and the end result is superior in ways that are hard to imagine.

Harold

_________________
Wise people talk because they have something to say. Fools talk because they have to say something.


Top
 Profile  
 
PostPosted: Mon Nov 08, 2010 3:03 am 
Offline
User avatar

Joined: Fri Apr 02, 2010 4:06 am
Posts: 8
Location: Christchurch, New Zealand
Harold_V wrote:
oiad wrote:
You mention China is exporting diamond wheels that are very affordable.. What can be said about the quality? Are you meaning a wheel that would go on a grinder?

Well, I hope I didn't open my mouth before getting my brain hooked on. I have been installing slate flooring, and using a 10" diamond blade for cutting. Those I recommend highly. A new one costs only $30 US, which is an absolute bargain. Performance is very acceptable. Diamond wheels are one of the commodities that have come down drastically in price, unlike almost everything else we encounter.

So then, I may have misspoken about wheels, in that those I have purchased recently are all diamond saw blades (including some nice 4" diameter blades, for use on a small angle grinder). On sale, HF, three blades for $10. An excellent buy, and very acceptable quality.

However, it is possible to purchase a 6" wheel, suitable for grinding carbide tool bits, on sale, for as little as $120. Here's a link that describes such a wheel.

http://www.use-enco.com/CGI/INSRIT?PMAKA=317-1070

Note that the price here is higher by a generous margin. The description, however, is exactly what one should seek, assuming they wish to buy a 220 grit wheel.

The thing to consider is that such a wheel, back in the late 50's, would have cost in the neighborhood of $600. Considering the buying power of the dollar, now, as compared to that period of time, the wheels effectively cost only about 10% of the old price. They truly are a bargain.

If a person buys a wheel such as this, and uses it in the home shop, keeping steel away, running it wet, with no abuse, it could easily last 40 years. Even in a commercial application, my first wheel ran for more than 16 years before it was replaced. Best of all, I didn't have to breath dust from silicon wheels, and the end result is superior in ways that are hard to imagine.

Harold


We use "Alumina" wheels at work for grinding our tungstens for the tig welder, I know exactly what you mean by the dust.. my fingers/hands/overalls get covered in it!

I had thoughts in my mind of the bench grinding wheels like you mentioned in the enco.com website but a solid wheel, not a metal cage with the diamonds/material on the outside.. I see ALOT of chinese product that is REALLY substandard in the radiator world here (I'm the fabricator welder for a radiator shop here in New Zealand who has repaired THOUSANDS of chinese aluminum race radiators).. I had thoughts about quality with picturing high RPM wheels spinning, heh.


Top
 Profile  
 
PostPosted: Mon Nov 08, 2010 4:28 am 
Offline

Joined: Fri Dec 20, 2002 11:02 pm
Posts: 13709
Location: Onalaska, WA USA
oiad wrote:
I had thoughts in my mind of the bench grinding wheels like you mentioned in the enco.com website but a solid wheel, not a metal cage with the diamonds/material on the outside..

To my knowledge, there are no diamond wheels constructed that way. They are typically made on an aluminum body, with the working surface covered in a diamond bearing matrix (ideally, for carbide tool grinding, a matrix commonly known as resinoid). That is very unlike the inexpensive diamond wheels you may enounter that are a thin layer of diamond plated (with nickel) to a steel wheel. I don't recommend those, and for various reasons. One of them is that a metal bonded wheel is not a great choice for grinding carbide tools. It can be the source of chipped edges. Resinoid bonded wheels are extremely resilient, yet offer a softer surface, one that does not chip carbide.

Quote:
I had thoughts about quality with picturing high RPM wheels spinning, heh.

I can easily assume you have been looking over my shoulder.
Just a week ago I bought a cheap 4½" angle grinder and a diamond cup wheel, both from HF. I had need to grind a 24" radius on several pieces of slate. The diamond wheel, 4½" in diameter, shook so badly that it was impossible to use.

Taking note that the matrix ran true, but the steel backing plate did not, I faced the backing plate, back side, until it cleaned up, then I attached a small screw through one of the holes in the plate, in an attempt to balance the wheel such that it would be serviceable. The preliminary placement of the screw proved to be one hole off, but the second hole yielded a wheel that runs quite nicely. I shuddered as I considered the consequences of a wheel, running @ 11,500 rpm, coming apart. I've seen grinding wheels fail before. Not a pretty site.

Harold

_________________
Wise people talk because they have something to say. Fools talk because they have to say something.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: easymike29 and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group
Americanized by Maël Soucaze.