Beginner facing steel on lathe

[glinscott]

Hi all,

I'm new to the hobby, and have been reading/watching videos for a while.  Finally at the stage of actually starting to make some parts!  I'm attempting the tender of the Kozo A3 (and expecting to scrap quite a few parts along the way...).  I have a small lathe - 7x16 from LittleMachineShop.  The tender wheels are first, and I'm using 12L14 steel, with a HSS bit (picture below).  I centered the tip by lining up with the dead center on the tailstock, and that seemed to go well (no pip left at center).  Also had some cutting oil on the work.

Kozo advises 150 rpm for the facing operation, and 0.01" cuts.  However, I was seeing the lathe stop/grab at those speeds!  It was the end of the stock, so was quite rough.  I increased the speed just slightly, to around 250 rpm, and it seemed to go better.  It was producing a decent amount of smoke though, is that expected?  My finish was also terrible, which is probably expected, but it would be nice to get better finish.  Any tips there?  I've just realized my cross-feed handle is really stiff, so that's probably contributing to the finish not being great.

Thanks!
Gary

[Jasonb]

The preground tool you are using is not one for facing, you are pushing the non cutting edge of a chamfer tool into the work

 Look at the second image in this link which gives the uses for the tools, you want to use the left hand one and mount it so it is lengthways to the lathe

https://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Lathe-Turning-Tools/8pc-High-Speed-Steel-Turning-Tool-Sets

[Jo]

Other Lathe tool suppliers are available  As Jason keeps reminding us: ArcEuro give  Jason his various tools so he has a habit of Arc product placement 

If he was a good boy he would only show us the tools 



Jo

[Jasonb]

He has also bought more tooling from ARC over the years than they have given him and what was given was in return for the rights to my text and photos to go into the book.

I think ARC are the only ones who actually give the uses for this set of tools so that is another reason to link to them rather than box shifters.

Anyway sounds like the OP is in the US so unlikely to use ARC anyway, But may be worth buying the Book "Lathework for Beginners" which LSM stock as that also names the preground tools and describes their uses

[glinscott]

Yikes, well, off to a poor start.  On the good news side, I've got plenty of material left to improve the finish (or maybe even just use this one as a practice...), so I will give it another shot with the left-hand knife tool and report back.

Thank you!

[glinscott]

Anyway sounds like the OP is in the US so unlikely to use ARC anyway, But may be worth buying the Book "Lathework for Beginners" which LSM stock as that also names the preground tools and describes their uses

Yes, I'm in the US .  I had read through "The Amateur's Lathe", but was still unclear on exactly which tool to use for facing.  The author does mention using the knife tool for 90% of operations, which was a pretty big hint I missed (although the pictures are not the easiest to interpret).

[rustychip]

This is the tool shape you seek. put in the tool holder with the point facing towards the left or facing the chuck, also it can be used the machine the undercut in the wheels, you will have to clearance the bottom of the tip so it doesn't rub on the bigger diameter. I borrowed  the pic from Kim's excellent build log to show what I mean.

[Kim]

Hi Gary,
Yeah, with 12L14 you should be able to get a really nice finish.  Go with a tool more like what Rustychip showed.  That gives a very nice finish.  I used that tool for panning out the inside shape of the tender wheels.  It gave the nice rounded shape at the hub and the rim.  That's also the reason it has such a small part protruding out - otherwise the lower part of the tool rubs on the inside of the rim of the wheel and gives you all sorts of problems.

For basic facing, you can use different tooling and get good results, but for panning this one worked well to get the depth and the corners.  But as Jason said, the shape you have there isn't very good for a facing cut.  I tend to use a tangential tool for most facing operations.  But I've also got a set of tools like Jo and Jason show.  I believe I got mine from Grizzly, but you can get them from Little Machine Shop, Victor Tools, and probably almost any other machine tool vendor.  I got a lot of my tooling from LMS and Victor when I was first starting up.  McMaster is good and sometimes has better shipping, but they tend to have higher-end tooling so it's more expensive.  LMS caters to the hobby machinist so has more budget-priced tooling.

Looking forward to seeing your progress on the tender wheels!
Kim

[Jasonb]

One other point that came up in your post is that of stalling the lathe, I don't know what lathe Kozo uses but suspect it is either belt or geared drive which will mean the motor is giving it's all in any one of the chosen speeds so his writings may need to take into account the modern variable speed lathes and old Sparey's book certainly won't be based on them.

A combination of slower rpm and increased work diameter are both working against you on a variable speed lathe so firstly if it is a two speed minilathe make sure you shift gear into the low range. Secondly look up the cutting speed for your material and run at the top end of that speed range. Thirdly consider carbide tooling which will allow you to run the lathe approx three times faster and put the motor closer to it's sweet spot. If going the carbide route then use the polished inserts intended for aluminium on steel and iron too as being sharper they need less cutting force.  A range of inserts with various corner radii will also leave you a nice fillet on the internal corner of your wheel flanges.

Also when you come to regrind those tools the three with the chipbreaker groove should really only be ground on the end ( shown red)otherwise you soon loose the chip breaker. You could just touch up the other edge on a fine diamond stone

[john mills]

looking g at that picture of the steel is that the end off the bar that has been cropped or sheered off   that is always awful to machine and
hard to get a good finish .that piece should be discarded the material there is never good .the next piece that has been sawed will be the proper material and cut much better.
John 

[glinscott]

This is the tool shape you seek. put in the tool holder with the point facing towards the left or facing the chuck, also it can be used the machine the undercut in the wheels, you will have to clearance the bottom of the tip so it doesn't rub on the bigger diameter. I borrowed  the pic from Kim's excellent build log to show what I mean.

Thank you!  I haven't ground any tools myself yet, so will be reading up on that.  The tools I've been using so far are preground from Grizzly.

[glinscott]

For basic facing, you can use different tooling and get good results, but for panning this one worked well to get the depth and the corners.  But as Jason said, the shape you have there isn't very good for a facing cut.  I tend to use a tangential tool for most facing operations.  But I've also got a set of tools like Jo and Jason show.  I believe I got mine from Grizzly, but you can get them from Little Machine Shop, Victor Tools, and probably almost any other machine tool vendor.  I got a lot of my tooling from LMS and Victor when I was first starting up.  McMaster is good and sometimes has better shipping, but they tend to have higher-end tooling so it's more expensive.  LMS caters to the hobby machinist so has more budget-priced tooling.

Thank you for the details!  And very impressive work on the full Kozo A3, your build log is incredible .  I got some preground ones from Grizzly as well, but will need to learn how to grind new ones.

One question actually, how often do you sharpen your HSS bits?

[Kim]

One question actually, how often do you sharpen your HSS bits?

Um... not often enough?  :embarrassed:

I've heard that unless the tip has been damaged a little work with a diamond hone helps keep the edge.  But I generally don't think about it till the tip has been damaged in some way and I have to grind a new edge on the tool.  Don't be like me!  :embarrassed:

Kim

[glinscott]

One other point that came up in your post is that of stalling the lathe, I don't know what lathe Kozo uses but suspect it is either belt or geared drive which will mean the motor is giving it's all in any one of the chosen speeds so his writings may need to take into account the modern variable speed lathes and old Sparey's book certainly won't be based on them.

A combination of slower rpm and increased work diameter are both working against you on a variable speed lathe so firstly if it is a two speed minilathe make sure you shift gear into the low range. Secondly look up the cutting speed for your material and run at the top end of that speed range. Thirdly consider carbide tooling which will allow you to run the lathe approx three times faster and put the motor closer to it's sweet spot. If going the carbide route then use the polished inserts intended for aluminium on steel and iron too as being sharper they need less cutting force.  A range of inserts with various corner radii will also leave you a nice fillet on the internal corner of your wheel flanges.

Also when you come to regrind those tools the three with the chipbreaker groove should really only be ground on the end ( shown red)otherwise you soon loose the chip breaker. You could just touch up the other edge on a fine diamond stone

Thanks for the details!  Good to keep in mind going forward to take Kozo's recommendations with the difference in motors in mind.  The lathe I have is this one: https://littlemachineshop.com/products/product_view.php?ProductID=7350, it doesn't have a low/high gear, just a variable speed control.

RE: regrinding - that will be a new adventure, so many things to learn .

I did get some carbide bits with the lathe, so I will try those as well and see how it goes.

[glinscott]

looking g at that picture of the steel is that the end off the bar that has been cropped or sheered off   that is always awful to machine and
hard to get a good finish .that piece should be discarded the material there is never good .the next piece that has been sawed will be the proper material and cut much better.
John

Ah, good to know, thanks!  Well, this one has become the practice wheel now .