South Bend questions

[gunnerwrench]

Alot of teh brazed carbide tool bits don't come ready to use . You need to grind your clearances in part that goes in the tool holder , If you don't grind them they will rub like you have found . Don't be afraid to work on them some just don't take off too much directly under the cutter , you need to leave some meat there for rigidity .
animal

So is the clearance angle critical? Or just have the right amount without taking too much?

 

[john.k]

The positive rake carbide inserts from China in diamond or triangle shapes do work good with hobby lathes .........they are meant for ally and have very sharp edges that cut nicely at any speed........downside is only three or two edges ,but the inserts are cheap................I can remember the days when if you needed a new insert ,the old one had to be shown to the manager ,who would inspect it with a jewellers loupe,and pushing his hat back hed say......John lad ,this is the third insert this month..tsk...tsk...tsk......these carbides dont grow on trees ,ya know!................then he would get out a big bunch of keys ,and open up a big bank safe in the office,get you out one carbide insert,and make you sign for it.

 

[gunnerwrench]

Carbide-Tipped Lathe Tool, Micrograin Carbide, 5/16" Wide x 5/16" High Shank

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

This was set that they originally ordered. At the time it was $38.00 I think they have gone up.... they worked ok but now knowing that I have to dress up the clearance they'll probably work better. The downside to my shop is that it's only a benefit when they say so. During the lock downs we couldn't get certain things. I figured out how to make them. But now even if we can't get the items. It's still a hard won battle to get the time to make anything.

 

[packrat2]

That looks like a good set of carbide tools, but better used with a quick change tool post, not a old school lantern tool holder...

 

[neanderthal mach]

At that price which is still pretty good for what they are and being listed as what should be decent micro grain carbide as well as being from that vendor they should be properly ground to the correct general angles and honed. I highly doubt that set would need any further corrections by the end user other than maybe slight changes for material specific angles. At the learning stage I'd leave well enough alone and concentrate on getting your center line height correct as the most important. But just as Packrat said they would be much better used in a qctp or I'd add even the standard 4 way solid tool post and shimming the tools to the lathe C/L. Lantern style tool holders "generally" have the square tool holder hole pointed uphill although neutral tool holders were also available. If yours do set the tool on that uphill angle, those will also set those pre sharpened carbide tools at a completely incorrect angle. From what you've said so far I suspect that's a large part of your current problems and why your tools might be rubbing. That's also something to keep in mind while sharpening your own HSS tool blanks, if those tool holders are pointing the tool shank upwards then the grind angles have to be compensated for that as well.

Refer to both the South Bend book and that Hercus PDF for the correct angles for sharpening HSS tool blanks because they are extremely important. While those lantern style tool posts work and proved that over multiple decades when they were pretty much the only type around, technology moved on. Even those cheap solid 4 way tool posts are vastly superior to what your using. And even though I have qctps on both my lathes as well as almost enough tool holders. If I do want the very best accuracy and surface finish I'll still sometimes use the OEM 4 way my lathes came with simply because there's no other tool post design that can support the cutting tool with the same rigidity they can. The usual qctp so many seem to think is an absolute necessity on any lathe isn't always the best in every situation. There main benefit is obviously the speed of tool changes, but like almost anything else there's at least some trade offs to gain that function. In an actual business situation then obviously speed is everything so a qctp is the only type that makes sense, if you can afford a bit more time, then those 4 way tool posts will still get the job done.

 

[animal12]

There's some reading & tubed time here that may help ya out some .

Theory of brazed carbide lathe bits

They used to sell lots of brazed carbide tools silver soldered onto steel shanks. Now for the most part replaced with inserts. Looking at them I do not see any great cutting angles since they just have a flat top with no chip breakers. Similar HSS tools were held in lantern type holders that...

www.practicalmachinist.com

Sharpening Brazed Carbide lathe tooling - The Home Shop Machinist & Machinist's Workshop Magazine's BBS

When I first stepped into "machinist world" twelve years ago, everybody praised HSS cutters for my lathe and wanted me to stay away from carbide tooling. For many years I did exactly that, but gradually I have leaned away from HSS in favor of carbide cutters. My lathe is not small, it's a 12" x...

bbs.homeshopmachinist.net

animal

 

[gunnerwrench]

At that price which is still pretty good for what they are and being listed as what should be decent micro grain carbide as well as being from that vendor they should be properly ground to the correct general angles and honed. I highly doubt that set would need any further corrections by the end user other than maybe slight changes for material specific angles. At the learning stage I'd leave well enough alone and concentrate on getting your center line height correct as the most important. But just as Packrat said they would be much better used in a qctp or I'd add even the standard 4 way solid tool post and shimming the tools to the lathe C/L. Lantern style tool holders "generally" have the square tool holder hole pointed uphill although neutral tool holders were also available. If yours do set the tool on that uphill angle, those will also set those pre sharpened carbide tools at a completely incorrect angle. From what you've said so far I suspect that's a large part of your current problems and why your tools might be rubbing. That's also something to keep in mind while sharpening your own HSS tool blanks, if those tool holders are pointing the tool shank upwards then the grind angles have to be compensated for that as well.

Refer to both the South Bend book and that Hercus PDF for the correct angles for sharpening HSS tool blanks because they are extremely important. While those lantern style tool posts work and proved that over multiple decades when they were pretty much the only type around, technology moved on. Even those cheap solid 4 way tool posts are vastly superior to what your using. And even though I have qctps on both my lathes as well as almost enough tool holders. If I do want the very best accuracy and surface finish I'll still sometimes use the OEM 4 way my lathes came with simply because there's no other tool post design that can support the cutting tool with the same rigidity they can. The usual qctp so many seem to think is an absolute necessity on any lathe isn't always the best in every situation. There main benefit is obviously the speed of tool changes, but like almost anything else there's at least some trade offs to gain that function. In an actual business situation then obviously speed is everything so a qctp is the only type that makes sense, if you can afford a bit more time, then those 4 way tool posts will still get the job done.

I believe from the information you have provided your suspicion is correct. Being a novice I have assumed maybe I just didn't have a good understanding of how to set up the equipment. The more I learn the better I see that there is more to it! Thanks for sharing your knowledge.

 

[animal12]

Experience is something you don't have until the day after you need it .
animal

 

[gunnerwrench]

Experience is something you don't have until the day after you need it .
animal

I've been in my industry for 15 years and that is the truest statement I have ever heard! Well said.

 

[animal12]

Just remember " when your through learning , your through "
I read that on a sign in my great uncles bar when I was 5 years old . I think about it every day .
animal

 

[neanderthal mach]

99% of machining is the set up, then order of cutting operations so you maintain as much part rigidity and something to hold it by until it's completed, and finally problem solving that's best done by analyzing what the root cause of any issues are and then solving them logically. Once all that becomes habit you'll find it gets a whole lot easier.

 

[animal12]

I'm still a certified rookie & I have been screw more by order of operations more than I care to admit . But like i said experience ....Now when I have a project I spend more time then I should trying to work out order .
animal

 

[michiganbuck]

QT Op: (Generally speaking I am the only person that has used the lathe for anything productive.)

There is nothing wrong with a rocker tool post on an infrequently used lathe, and nothing wrong with HSS bits and a bench grinder.

When you look in How to Run a Lathe and see all the kinds of cuts a lathe can make..It is not likely your boss is going to buy all those shapes.

It would take me 15 minutes to hand-copy the gear change.
https://www.ebay.com/itm/334589862146?hash=item4de71c2102:g:g84AAOSwxb5jRZFX&amdata=enc:AQAHAAAAoIRAVUcxpPrBbvmFfJTXZ35xAoYYzVeC54N4O0+S81nbM/eKs18zoQ5tFGxVZlN4EjFDEUMgXTALD9NgrUlpVK8r7nJzqrYHNSIXmFCGlJJfJxEyaUjTHPiNpAaw9q2qvkOZNN9C65G7wl4amXJv6hemrUMJeGSxO8GZZ1SxKm2L4uQpH57ZXRsnF2Cp3DF1S+CKr3jjRGEz153sGFQbPxY=|tkp:Bk9SR8rc8L_9YA

QT: (It has a taper attachment that has about 40 years of dust)... If you give the machine an oil rag wipe .after a time it will look good.

*It might be a great asset in your future to know how to do anything/everything possible on a lathe.

 

[michiganbuck]

Brazed carbide tool bits are not best for a few-up lathe.
Likely you don't have the equipment to sharpen them.
You need a fish gauge to use with a rocker tool post lathe, so to set your threading bits..a magnifying loop to see close up.
One good method to learn tool bit sharpening is to buy a bunch of used bits and hold each to a parked wheel to get the feel for angles. Angles are mostly ballpark except for threading and parting bits
Bits get hot at sharpening..

It's not uncommon to match your bit to the tailstock center to be on center.

 

[michiganbuck]

The book How to Run a Lathe shows the many different lathe functions that a lathe can do. Trying each of these is a good way to become a skilled lathe hand.
Inserts only can restrict one's lathe talents/abilities.

 

[gunnerwrench]

Well sheesh it's been a long winter season for our shop. I wanted to say Thanks! To everyone here that helped me get going on this fine piece of equipment. I have managed to learn a few things and produce a few tools for the shop and repair some long damaged tools that could not be easily replaced. These are custom bearing race drivers for the over sized hubs on our newer rigs.

 

[animal12]

looks like yer gettin it
animal

 

[SteveM]

You don't need a mill to make the T-nut - you can do it on the lathe.

It will look like this:



Look here for the steps:

Making a T-Nut on the lathe

I would get a quick-change toolpost, replace the nut on top with one with a handle so you can get it on and off easy, then install / remove as needed.

I would suggest making a tray to hold the toolpost and several toolholders so you can just grab it out of your toolbox, go to the lathe, do your work, then carry it back and lock it up.

If anyone wants to borrow it, point to the decal that's probably already on your toolbox:


Steve

 

[gunnerwrench]

I put all the tooling that I have in a small tool box that fits in the bottom drawer of my main tool box. And so far that has worked pretty well. I have been working on getting a grinder set up for HSS but have been practicing with key stock to help get the angles down. The set up I got from Packrat has made a tremendous impact on how fast I can get set up for a job. The machine is lacking a threading dial and missing the plates for the change gears. so that adds a challenge for thread cutting. But so far it hasn't mattered much.

 

[SteveM]

The machine is lacking a threading dial and missing the plates for the change gears. so that adds a challenge for thread cutting. But so far it hasn't mattered much.

The only thing a threading dial is for is being able to move the carriage and re-synch it.
If you keep the half nuts engaged, and reverse the lathe to move the carriage back, it will be a pain but it will work.

Steve