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Grinding your own lathe cutters

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Chris TickTock14/08/2019 09:21:23
222 forum posts
8 photos

Hi, am I right that no heat hardening is required for HSS tool blanks that are used to grind cutters for my Sherline lathe? Obviously just checking otherwise once ground they could be too soft?

regards

Chris

Michael Gilligan14/08/2019 09:28:51
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14236 forum posts
621 photos

HSS was formulated to work at temperatures in excess of what you are likely to produce by grinding.

... Don't worry.

MichaelG.

Chris TickTock14/08/2019 09:39:10
222 forum posts
8 photos

Thanks Michael, just crossing the t/s and dotting the i's.

Regards

Chris

Bill Davies 214/08/2019 09:53:25
117 forum posts
10 photos

Back when I was in industry, we made large HSS tools. It was considered very bad to have any grinding burns. On the other hand, other sites have reported brazing HSS onto shanks.

If off-hand grinding, it's considered good practice to avoid heating too much, with frequent dipping into a can of coolant, or alternatively to grind dry. The issue is more about thermal shock causing small cracks, rather than causing a tempering or annealing of the material.

Bill

AdrianR14/08/2019 09:55:34
272 forum posts
20 photos

Dont let it get too hot and then quench, the sudden cooling can cause micro cracks that weaken the tool. So if you are quenching, quench often before it gets too hot.

John Reese14/08/2019 23:14:39
797 forum posts

I am glad to see someone grinding his own tools. Too many folks start off with carbide which, with a few exceptions is ill suited to hobby lathes.

Even getting the bit hot enough to turn blue will not harm it. I have silver brazed a steel rectangle to the side of a HSS parting blade with no ill effects.

Lainchy15/08/2019 07:18:44
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153 forum posts
39 photos

I'm learning this fast (Carbide on hobby lathes that is) I've been using it for roughing cuts without issue, but the insert tooling certainly doesn't like taking 2 thou off something as much. I've not been at it long, but very much seeing the benefits of HSS, and just venturing into trying to grind my own tools.

JasonB15/08/2019 07:32:54
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Moderator
16522 forum posts
1755 photos
1 articles
Posted by Lainchy on 15/08/2019 07:18:44:

.............. but the insert tooling certainly doesn't like taking 2 thou off something as much................

Get yourself some half decent **GT inserts, they work well on small lathes and can be used on all metals.

Lainchy15/08/2019 08:10:39
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153 forum posts
39 photos

Cheers JasonB, will look into these. I'm currently using TCMT which came with the lathe.

AdrianR15/08/2019 08:10:43
272 forum posts
20 photos

Have you heard of tangential tool holders? Lots of designs around if you want to make one and I am in the middle of trying to design my own. Eccentric Engineering make one, see the adverts on this site, and there are some youTube videos about tangential tools.

The big advantage of this type of tool holder is you only need to grind one face.

Adrian

Lainchy15/08/2019 08:37:53
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153 forum posts
39 photos

I have Adrian, and seen one in use. Not used one myself though yet.

Howard Lewis15/08/2019 20:31:33
2440 forum posts
2 photos

Made my first Tangential Tool to a set of drawings in an article in MEW, a long while ago. Was so impressed that I bought the Eccentric Engineering model. Sharpening is an absolute doddle, with only one face to grind, and a jig to hold it in the right orientation, for grinding.

Used almost all the time, except for hardened material, when carbide tips are necessary. The only carbide tips in regular use are CCMT0604 in a Boring bar, and the holder for the 100 degree corner, when the 80 degree corners in the Boring Bar become chipped. This is then used for roughing.

The parting tool used for almost all jobs is HSS. This blade must be over 20 years old, and still about half length!

HSS toolbits are ground up for any specialised jobs, like chamfering, screwcutting, etc

HSS seems to be cheaper in the long term, in that grinding is pretty easy, and nothing like like replaceable carbide tips.

Howard

Vic16/08/2019 11:56:31
2323 forum posts
12 photos
Posted by AdrianR on 15/08/2019 08:10:43:

Have you heard of tangential tool holders? Lots of designs around if you want to make one and I am in the middle of trying to design my own. Eccentric Engineering make one, see the adverts on this site, and there are some youTube videos about tangential tools.

The big advantage of this type of tool holder is you only need to grind one face.

Adrian

This is the one I made. No plans just made it up as I went along!

2d0b018b-b839-4ed9-bf71-8fb9217db03c.jpeg

John Reese16/08/2019 21:31:29
797 forum posts

I am a fan of tangential tools, as well. Notice the tool stickout on Vic,s tool. You can get to the bit with a stone to keep it sharp. It might even be possible to grind the bit without removing it from the holder. Unfortunately, when I made my tangential tool holder I kept the metal around the bit too high to allow stoning.

Chris TickTock17/08/2019 09:38:42
222 forum posts
8 photos
Posted by Vic on 16/08/2019 11:56:31:
Posted by AdrianR on 15/08/2019 08:10:43:

Have you heard of tangential tool holders? Lots of designs around if you want to make one and I am in the middle of trying to design my own. Eccentric Engineering make one, see the adverts on this site, and there are some youTube videos about tangential tools.

The big advantage of this type of tool holder is you only need to grind one face.

Adrian

This is the one I made. No plans just made it up as I went along!

2d0b018b-b839-4ed9-bf71-8fb9217db03c.jpeg

Nice because its simple. Having made it like everything else how would you now make a better version?

Chris

Chris TickTock17/08/2019 09:44:34
222 forum posts
8 photos

I am looking for a simple, diagramic explanation to carbide code designations that I can refer to. To date I have a few but I am looking for what is the simplist / easiest to work from. Anyone got a favourite?

Regards

Chris

Barrie Lever17/08/2019 09:56:09
323 forum posts
2 photos

Chris

You really should get yourself a copy of the book written by Joe Martin who was the owner and real driving force behind Sherline, although not the creator.

The book is called 'Tabletop Machining' ISBN 0-9665433-0-0 and covers exactly the points you ask.

The book is a complete inspiration on using small machines.

I visited the Sherline factory about 6 years ago, they make a superb product that punches way above it's weight.

If you are going to buy the book, you can borrow my copy until yours arrives.

Regards

Barrie

Vic17/08/2019 10:06:21
2323 forum posts
12 photos

The Tangential tool pictured is version three, the one I use.

With retirement approaching I considered the relatively high cost of inserts compared to a piece of HSS. I made a small tool that took 1/8” HSS but it didn’t work too well. I got the angles right but I don’t think I ground the HSS correctly. I considered the cost of buying the Eccentric Engineering one would soon be recouped so invested in one. It worked very well with both round and square tool bits. And loaded with carbide easily deals with tough materials. One thing I didn’t like though was that the head was cranked over at an angle (they have now changed this). As a result I decided to make another one with a straight shank but I didn’t allow enough clearance around the cutting edge, this was V2. Version three is as you see it with plenty of clearance. Could it be made better? Yes, I’ve seen a version made by one enterprising individual where he simply flips the hole unit over onto a flat surface to set the tool height. In place of this I made and use a dedicated height gauge. They are fun to make and in my experience work very well for both turning and facing.

3cc85565-514d-4879-a16f-79c56048ce02.jpeg

Chris TickTock17/08/2019 10:22:38
222 forum posts
8 photos
Posted by Barrie Lever on 17/08/2019 09:56:09:

Chris

You really should get yourself a copy of the book written by Joe Martin who was the owner and real driving force behind Sherline, although not the creator.

The book is called 'Tabletop Machining' ISBN 0-9665433-0-0 and covers exactly the points you ask.

The book is a complete inspiration on using small machines.

I visited the Sherline factory about 6 years ago, they make a superb product that punches way above it's weight.

If you are going to buy the book, you can borrow my copy until yours arrives.

Regards

Barrie

Barrie, very kind offer, let me have a look through my books first which as I have not needed to to date I have not read. My policy is never borrow a book as it lead to falling out if it gets forgotten, but your a mate for offerring.

Chris

Chris

Chris TickTock17/08/2019 10:29:47
222 forum posts
8 photos

OK guys I have come across the CarbideDepot's insert table and they do for me. Looking at the table I have a few silly questions which you guys will know the answers to:

(1) Looking under the Shape table is a Greek Symbol...anyone care to explain

(2) What is the difference between Ansi and ISo as in the Size table, they are obviously 2 standards, Ansi is I think American and ISO probably international?

(3) whats the best mnemonic or memory aid anyone knows to remember order of designation of Code?

meanwhile I shall look up the book recommended

Regards

Chris

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