PDA

View Full Version : HSS Basic Lathe Turning Tool



OaklandGB
11-15-2018, 11:47 AM
Just getting into machining and tools to use in the Lathe, a small PM 10x22. Had some success grinding a basic turning tool in 3/8" HHS that worked leaving what this amateur thinks was a reasonable finish on round 3/4 inch mystery metal used for foundation layout stakes. Hey, its cheap, and makes for a lot of practice chips.

Anyway, I noticed that some "experts" leave the "leading" or left edge of the tool parallel, or in line with the shank, with no angle just the relief below the edge, whilst others will provide a small 2 to 4 degree angle to the right. That would not allow for a 90 degree shoulder in the resulting cut. I opted for a couple degree angle to the right on mine. Various experienced sources on YT show both as their "basic" cutting tool.

Is this just a personal thing or is one preferred over the other? I'm just starting out...slowly...so thought I'd ask.

Thanks for any thoughts or comments on this very basic question.

Gary

754
11-15-2018, 11:57 AM
Clearance, clearance, cleararance.. if you have none it won't cut.

MattiJ
11-15-2018, 11:58 AM
Just getting into machining and tools to use in the Lathe, a small PM 10x22. Had some success grinding a basic turning tool in 3/8" HHS that worked leaving what this amateur thinks was a reasonable finish on round 3/4 inch mystery metal used for foundation layout stakes. Hey, its cheap, and makes for a lot of practice chips.

Anyway, I noticed that some "experts" leave the "leading" or left edge of the tool parallel, or in line with the shank, with no angle just the relief below the edge, whilst others will provide a small 2 to 4 degree angle to the right. That would not allow for a 90 degree shoulder in the resulting cut. I opted for a couple degree angle to the right on mine. Various experienced sources on YT show both as their "basic" cutting tool.

Is this just a personal thing or is one preferred over the other? I'm just starting out...slowly...so thought I'd ask.

Thanks for any thoughts or comments on this very basic question.

Gary

In MY experience and MY lathe the angled tool is less prone to chatter with heavy cuts. Even better if I put some negative back rake on the tool. Radial cutting forces are bigger if you use tool like this and it cuts "oversize" but at least on my lathe its less prone to chatter.
Maybe depends what parts of the lathe are loose and made of noodles.

lynnl
11-15-2018, 12:38 PM
....

Anyway, I noticed that some "experts" leave the "leading" or left edge of the tool parallel, or in line with the shank, with no angle just the relief below the edge, whilst others will provide a small 2 to 4 degree angle to the right. That would not allow for a 90 degree shoulder in the resulting cut. I opted for a couple degree angle to the right on mine. Various experienced sources on YT show both as their "basic" cutting tool.


Gary

To get a 90 degree shoulder you'd simply rotate the compound tool rest to present that leading tool edge at a perpendicular angle to the lathe axis.

754
11-15-2018, 12:51 PM
If you give it a few degrees ckearance toward rfw back the it always works put it in a holder and go.. if cutting edge is parallel then you have to always angle it, or risk not machining the face square to the work.

JCByrd24
11-15-2018, 01:53 PM
Side cutting angle can be made independent of lead angle or they might be the same. I like to set my QCTP square with a parting tool and leave it there until I have to adjust the compound for some reason, then set it square again, so my side cutting angle tends equal my lead angle. The same is true with most insert tooling.

I linked to some info about lead angle below, but mainly it's been discussed. A bit of positive lead angle thins the chip, protects the nose radius, and tends to chatter less, but can't cut a shoulder or face. It's very handy for quick jobs to be able to turn and face with the same tool in the same position.

I think 754 is describing a negative lead angle whereas the OP was talking about positive. A negative lead tool, such as an MCLN toolholder for 80 deg diamond inserts is very handy as a universal turning and facing tool. In fact this type of tool is my primary tool and I have 2 loaded with different inserts for different materials and go to first unless I really need to do some roughing.

If I'm using HSS I tend to grind with 0 deg side cutting angle and primarily side rake (seen this referred to as knife tool). I then set the blank in the QCTP holder to give just a little negative lead so I can face/turn to shoulder. This could also simply be accomplished by turning the toolpost. Both of which are easier than grinding in a negative lead into a tool blank.

The one issue with this type of grind is it's trickier to maintain that edge by hand grinding, so you'll often end up with an angle one way or the other, but it really doesn't matter. In reality you don't ever want/need to set the tool to dead zero lead. You either want a couple degrees negative for facing or several degrees positive for heavy turning.


http://www.mitsubishicarbide.com/en/technical_information/tec_turning_tools/tec_hsk-t/tec_hsk-t_technical/tec_turning_cutting_edge

J Tiers
11-15-2018, 02:12 PM
Actually, a dead zero lead, or as close as possible to it, has uses. If you want to turn part of a part to a very small diameter, leaving the rest larger, you really have an issue doing this with standard tools. Something like a countern=bore nose, that mas a thin stem that holds it, but a fat nose to fit the hole that is to be counterbored.

The standard tool has a good deal of radial force, due to the angle and the nose radius. This will mean tiny cuts as you approach the final size, to avoid bending the thin stem portion of the part.

If you use a near zero nose radius, and a dead radial edge with a good deal of rake to the right, you can take the entire diameter reduction in one step, assuming your lathe will handle it. That means the thin stem is always supported by the thick stock, up until it is reduced to final size. Bending and failure is essentially eliminated.

The only other way to make such a part that is fairly risk-free is to make in two parts, shrinking or loctiting the stem and nose parts together.

OaklandGB
11-15-2018, 02:47 PM
I think I see. Leaving no side cutting angle puts added stress on the tool and rigidity of my machine. The Mitsubishi site helps illustrate it. Perhaps that is where the chatter came from before I reground the tool with a small side cut angle. Way more smooth with the angle there. More to learn and experiment with. With each new understanding comes 3 or 4 additional areas to explore. Maybe that is what makes this hobby, even in its most basic form, so intriguing.

The folks on this site are so helpful...and patient.... Really provides a new hobby machinist with the inspiration to take the next steps no matter how small they are.

Thanks!!!

Gary

JCByrd24
11-15-2018, 02:47 PM
Yes I shouldn't have used the word ever, rarely is that a good idea. Point being if you need to set to zero lead it can be done even if you goof the factory edge of your tool blank so you have a little side cutting angle one way or the other. I think I've seen one of the youtube machinist demonstrate just as you say and make a very long thin part by taking it in one bite with a zero lead tool with a lot of side rake.

3 Phase Lightbulb
11-15-2018, 02:49 PM
Just getting into machining and tools to use in the Lathe, a small PM 10x22. Had some success grinding a basic turning tool in 3/8" HHS that worked leaving what this amateur thinks was a reasonable finish on round 3/4 inch mystery metal used for foundation layout stakes. Hey, its cheap, and makes for a lot of practice chips.

Anyway, I noticed that some "experts" leave the "leading" or left edge of the tool parallel, or in line with the shank, with no angle just the relief below the edge, whilst others will provide a small 2 to 4 degree angle to the right. That would not allow for a 90 degree shoulder in the resulting cut. I opted for a couple degree angle to the right on mine. Various experienced sources on YT show both as their "basic" cutting tool.

Is this just a personal thing or is one preferred over the other? I'm just starting out...slowly...so thought I'd ask.

Thanks for any thoughts or comments on this very basic question.

Gary

Also if you're not a big fan of grinding your own HSS, look into getting some insert holders and some carbide inserts.

OaklandGB
11-15-2018, 02:53 PM
JCByrd24,

From the humorous, beginner's perspective, I tried taking the "one bite"...but it was an accident, not intentional. However, I still learned from it...namely about stalling the lathe!! :o

Onward I go!

BCRider
11-15-2018, 03:00 PM
.....If you use a near zero nose radius, and a dead radial edge with a good deal of rake to the right, you can take the entire diameter reduction in one step, assuming your lathe will handle it. That means the thin stem is always supported by the thick stock, up until it is reduced to final size. Bending and failure is essentially eliminated......

This part in quotes from JTiers' post works extremely well. I've used it on a few occasions now to produce very small pins on larger stock.

Oakland, what you're seeing in the differences are the preferences that have been around for years from the days even before HSS where the cutters were done with regular high carbon tool steel and care was needed to avoid heat and tempering of the edges. Some of it has distinct advantages such as a dragged back angle for heavy cuts and others are about angling the cutter to allow getting very close to the chuck jaws without fouling the old style lantern tool posts and holders against the chuck and without a lot of overhang. Or as mentioned there's some good reason for raked back cutters used for hogging away a lot of waste. And for others it may be related to wanting a square edge but without the need to shift the base of their tool post around.

I've even gone with a slightly different option. About 15 years back I made a tool post somewhat similar to a four way. But the slot which was to be used for my standard turning tool was done with an angle to it. This angle was cut so I could use a basic shim or no shim and adjust the height of the cutter by the amount of protrusion. The piece of 1/2" square HSS is then sharpened back with all the rakes and clearances sort of like a pencil so I never need to do anything more than a light touch up of the three faces and add a slight nose radius with three small touches then a lick from a small sharpening stone.

I am looking at a new idea now for a new block which will both angle and twist the main cutter so the top would never need any grinding at all. Just the end and front for rake and clearance angles. Then adjust the protrusion after each sharpening to restore the tip to the center height.

J Tiers
11-15-2018, 03:40 PM
Practical example:

Making the test cut to check size before doing the actual cut

http://i.imgur.com/4W0EYcs.jpg (https://imgur.com/4W0EYcs)


The cut completed. You can see the wide chips on the tool

http://i.imgur.com/rWOisi7.jpg (https://imgur.com/rWOisi7)


The part that I wanted to make, a soldering tool. It had to fit the soldering iron to be used, which is why the thin stem.

http://i.imgur.com/2Lq8B8f.jpg (https://imgur.com/2Lq8B8f)

PStechPaul
11-15-2018, 03:52 PM
Is that copper plated steel? Usually soldering tools are iron-clad copper. Is the difference in color caused by lighting?

OaklandGB
11-15-2018, 04:17 PM
It is clear to me now that no side angle introduced unacceptable chatter in my small lathe. I'm sticking with HSS as I find it interesting to experiment and see what happens. Next up is likely a chamfer tool. We'll see what works for just general edge relief. Thanks for all the comments, all are very helpful.
Gary

JCByrd24
11-15-2018, 04:40 PM
What type of lathe do you have, or more importantly perhaps what type of spindle bearings? No side angle in and of itself should not cause chatter normally in a modest cut. However, no side angle results in axial forces being very dominant over radial as depicted in the earlier mitsu link. Clearly there will also be a vertical component, but what you may be experiencing is the lack of radial force allowing your spindle to rattle around ever so slightly in it's bearings, whereas when you add some angle and radial force the spindle is forced to one side of the bearing and runs vibration free. If you have an old plain bearing machine this is more likely, but can also happen if roller or ball bearings are not properly preloaded.

J Tiers
11-15-2018, 05:00 PM
I get some chatter with the end cutting, but it really causes no issues, because the cut face is not generally used for any purpose, chatter just looks a bit ugly. This machine is ball bearing, preloaded. Looseness is somewhere else.


Is that copper plated steel? Usually soldering tools are iron-clad copper. Is the difference in color caused by lighting?

Lighting only It's just steel, good enough as is

3 Phase Lightbulb
11-15-2018, 05:21 PM
Lighting only It's just steel, good enough as is

You should make a how-to video of your steel soldering tip. It might give AvE's exotic nut+bolt video a run for his money.

BCRider
11-15-2018, 05:21 PM
What type of lathe do you have, .......

From Oakland's first post in the thread....


Just getting into machining and tools to use in the Lathe, a small PM 10x22........

Oakland, JCB does raise some good points on tuning up your lathe spindle. Or at least checking it. There's procedures for each aspect of it all if you need hints.

I'd also add to this that you want to check the gibs on the cross and compound slides for proper settings. With a mag base and dial gauge you can check for play or looseness in the main shaft and dovetails by levering the parts in alternating directions and looking for "clicks" in the travel of the needle. Some flex will and should be apparent. But if you get a "clicking" back and forth of the needle in any axis then there's play in the setup that needs to be eliminated. With any play in any spot the stage is set for chatter and inaccuracy in your work. So it all needs to be gone and things made play free with minimal but some preload in the bearings and dovetail gibs.

On top of this realize that even the heaviest blobs of cast iron or other metals are all like springs. So set up your machines and tooling for minimal overhang and try to always achieve the most direct possible path from the tip of the tool through to the bed of the lathe. Constant attention to this will reward you with less chatter and generally better cutting action.

thaiguzzi
11-15-2018, 10:08 PM
Also if you're not a big fan of grinding your own HSS, look into getting some insert holders and some carbide inserts.

Wrong Answer.

LKeithR
11-15-2018, 11:01 PM
Also if you're not a big fan of grinding your own HSS, look into getting some insert holders and some carbide inserts.

I agree. I know we're gonna get chastised for saying it but I honestly don't understand why people fool around with
HSS when there is so much good insert tooling available now. HSS is pretty much a thing of the past...

J Tiers
11-15-2018, 11:25 PM
I agree. I know we're gonna get chastised for saying it but I honestly don't understand why people fool around with
HSS when there is so much good insert tooling available now. HSS is pretty much a thing of the past...

It does not chip and crack as much as inserts, and if it does, it can be ground back to shape. And the cracking does not cost $3 to $5 when it occurs, IF it occurs.

I have quite a bit of trouble with cracking off of the tip, since the lathe is a flat belt machine. Gear head machines probably do not do it. Problem is that if the spindle stalls, it rotates backwards when power is cut. Breaks the tip every single time, and trying to pull the tip out of the work before cutting power ALSO breaks the tip every time..

Happens most with materials that you NEED the insert for, of course.

PStechPaul
11-15-2018, 11:28 PM
I am getting used to the carbide inserts and holders for my lathe, but there are many places where I prefer HSS tooling. HSS may have been replaced by carbide for production, but for home shop and hobby purposes, HSS is more versatile and cheaper. You can grind your own profiles as needed, and not need to stock a huge inventory of different shape and size inserts. Carbide is needed (or at least much preferred) for machining hard materials and stuff like fiberglass and garolite.

754
11-16-2018, 12:02 AM
Keith have you ever cut Whitworth thread, square thread, acme thread.
Would be a lot of tooling cost.
And how long would it take ?
It's pretty good to get a job in and get it out same or next day.. not wait up to a week for a holder and inserts to come in..-

It would be hard to make money if I bought a carbide for the 10 to 15 or more corner radius tools I use, and every grooving tool..

J Tiers
11-16-2018, 12:09 AM
Keith m have you ever cut Whitworyh thread, square thread, acme thread.
Would be a of of tooling cost.
And how long would it take ?
It's pretty good to get a job in and get it out same or next day.. not wait up to a week for a holder and inserts to come in..-

It would be hard to make money if I bought a carbide for the 10 to 15 or more corner radius tools I use, and every grooving tool..

Same for stuff like a gear profile fly cutter.... just grind it to fit an example profile in a few minutes, at low cost.

For general turning, use whatever. But I use HSS a lot.

For material too dirty to use HSS (rusty, etc) I have "beater" brazed carbide tools. For nasty stuff to cut, like 4140 PH, I may use a beater tool to rough out, then an insert tool to finish. HSS often will not last one entire pass in 4140PH.

OaklandGB
11-16-2018, 11:27 AM
BCRyder,

I think I had 2 issues on my small Precision Matthews 10x20 lathe, both due to my inexperience with machining and tooling. First is the tooling, already discussed here, and I think corrected by introducing the side angle on the tool. That immediately eliminated the chatter I found on the first pass without the side angle.

The second issue, not mentioned by me, was I had about a 3/4 inch work piece sticking out over 2 inches.:o I guess I just wasn't thinking about my set up when the chatter started. First thing I focused on was what did I do wrong when grinding this first tool? In the past couple months, I figured out that the shorter the stick out, the less likely to get chatter due to work piece flex. I now keep it as short as practicable, little if any chatter if I keep the cuts in line with this machine's capabilities. Still learning every time I power it up.

To all, I realize that this is some really basic stuff and appreciate that even highly experienced machinists take the time to offer comments. They are a tremendous help.

Thanks!! from a newbie.

Gary