Noob needs help with custom HSS tool.

[Opieshuffle]

As I dial in and play with my (new to me) Atlas 618 I wanted to ask about this single tool. Based on everything I'm reading online, it looks to me like the PO (previous owner) created several tools in one. Side 1 looks like a "threading tool". The bottom of side 3 as a cutting tool (l-r or r-l?) But when I look at side 4bc (on the right of the picture) it also looks like something. Facing? Smoothing? Side 4c is a close up of the opposite end.

The lathe did come with a new set of carbide tipped cutters, but they don't seem as good on steel as this HSS tool. I have used it, but have no idea if I'm using it correctly.

Can anyone shed some light?

I read a lot about buying a pre-cut set to start but the only on epopping up is this set from BusyBee.
Anyone have any other suggestions?

Busy Bee
Thanks! Chris

 

[mickeyf]

The bottom end (in the photo) of side three has a chip breaker ground in. For that to do anything it would have to cut from left to right so that the edge with the chip breaker was advancing into the work.

Side one might be a threading tool if the angle on it is 60 deg, but in the photo it looks like that end slopes up from left to right, which means it would be cutting from left to right, which ordinarily would give you a left hand thread. In any case, if you are going to single point thread you should have a thread gauge to set your tool correctly oriented to the work. Example: https://www.amazon.ca/Quality-Stainless-Fishtail-Cutting-Comparison/dp/B07QN568VD

If the carbide cutters are brazed on rather than inserts (which the cheap sets generally are), they may not be sharpened correctly, or at all. Carbide for brazing likely does not have proper clearances angles built in; whoever put them together did not know what you were planning to cut with them.

Rather than buying a pre-cut set, I would suggest reading up on tool geometry and grinding your own tools. Buy blanks (cheaper!) and also feel free to modify the HSS ones you already have. Try a few, discover what does not work, and refine your angles. After some practice you will have tools that work well and have a good understanding of tool geometry that you can't get by buying pre-cuts.

 

[David]

I was fortunate to be included in a HSS grinding example scheme that Hobby Machinst had. They sent around examples of three well ground HSS tools, but ground in keystock.
A general purpose tool for turning/facing, a knife tool for facing and thin work and a standard 60 degree threading tool.
On receipt of the examples. you were expected to grind a set of examples for yourself and send the originals to the next person on the list.

The 189-page thread is here. It is an excellent read and well worth the time. The originator, Mikey has since passed away but he was able to do some amazing work on his Sherline lathe using tools like those below.

Models for grinding HSS Lathe Tools

In a recent thread by @Darkbluesky, http://www.hobby-machinist.com/threads/lathe-accessories-tools-ideas-of-what-to-buy.62043/#post-511618, @ttabbal joked about sending me blanks to be ground into lathe tools ... he was joking! But it got me to thinking ... yeah, I know it's not a good thing...

www.hobby-machinist.com

 

[Susquatch]

I second @mickeyf's advice.

I've never seen the thread @David linked, but I would fully expect it to be excellent.

There are also excellent threads on our forum.

The trouble with preground blades is that you don't know who ground them or for what. That one you have is a great example of that. I can't look at your photos and confidently tell you what that was for. Maybe if I was holding it, but I'm not.

I think it's better to start with an objective (eg cutting R to L), read some good references, and have at it. My first grind was at least 55 years ago.

If you google "grinding hss lathe tools pdf" you will find numerous good documents on the subject. Or if you are a YouTube fan, I think Blondihacks has a good one.

Best of all would be to find a member near you and have some fun together.

 

[trlvn]

On a small lathe like the 618, you usually want a tool with both back rake and side rake to make cutting easier. (Threading tools are different: the shape of the thread is the primary concern. Thus, no rakes.) For absolute best results, each rake angle might be 'tuned' a little higher or lower for specific metals, like high carbon steel versus gummy aluminum, etc. But start with a tool ground for common steel and it will likely work fine unless it is getting dull. In which case, a few swipes with a small diamond sharpening stone can work wonders.

The "general purpose" and "knife" tools that David shows above are the tried-and-true shapes. To grind them, it just takes three grinding steps plus optional rounding of the cutting nose. See attached.

I wouldn't say that the tool you showed is well ground on either end. I wouldn't hesitate to regrind. Also, I recommend to set your grinding rest to the necessary angles and/or draw lines (on the blank and the grinder rest) to help you get the faces ground the way you want. Later, you may just freehand everything but it is perfectly OK to use training wheels when starting out.

If you want to come out to Oakville, I can show you how I do it. (And provide a couple of HSS blanks.)

Craig

 

[Opieshuffle]

Thanks for the replies and awesome resources everyone.
Craig... I may just take you up on your offer.

 

[SightlessSeer]

I was fortunate to be included in a HSS grinding example scheme that Hobby Machinst had. They sent around examples of three well ground HSS tools, but ground in keystock.
A general purpose tool for turning/facing, a knife tool for facing and thin work and a standard 60 degree threading tool.
On receipt of the examples. you were expected to grind a set of examples for yourself and send the originals to the next person on the list.

The 189-page thread is here. It is an excellent read and well worth the time. The originator, Mikey has since passed away but he was able to do some amazing work on his Sherline lathe using tools like those below.

Models for grinding HSS Lathe Tools

In a recent thread by @Darkbluesky, http://www.hobby-machinist.com/threads/lathe-accessories-tools-ideas-of-what-to-buy.62043/#post-511618, @ttabbal joked about sending me blanks to be ground into lathe tools ... he was joking! But it got me to thinking ... yeah, I know it's not a good thing...

www.hobby-machinist.com

I recently ground a turning tool as Mikey describes in post #104 (page 11). I would definitely recommend it. I had to turn down some 4140 from 2" down to 1 5/8" across a 17" length. I was doing about 0.075" DoC with my Atlas 10" and it worked very nicely for roughing.

You can get some really good results with a little practice grinding by hand. Remember that you don't have to be bang on the angles described by either Mikey, or any other reference to get good results with a HSS tool. My bench grinder doesn't have an adjustable tool rest, so I end up doing everything completely free hand and it normally works alright.

If you don't already have a copy of the Atlas Manual of Lathe Operations, it's probably worth tracking down the PDF (I'm 99% sure that Vintage Machinery has it). It has some good pictures and descriptions of lathe basics. I found it very handy when I first got my lathe.

This was already mentioned earlier, but it's worth repeating. Make sure that your tool is sharp! After you've ground the tool take a stone to it and give it a quick hone. It make a huge difference, especially on smaller lathes.

 

[Susquatch]

My bench grinder doesn't have an adjustable tool rest, so I end up doing everything completely free hand and it normally works alright.

Neither does mine. I agree with you for the most part. However, at the risk of nit picking, I think that sometimes it does matter but when it does, I use a protractor as a guide for my hands and that has always worked just fine. My hss cutters are rarely beautiful, but I can often get the job done much better with hss than with carbide. In fact, there are times that carbide just doesn't work while hss does.

This was already mentioned earlier, but it's worth repeating. Make sure that your tool is sharp! After you've ground the tool take a stone to it and give it a quick hone. It make a huge difference, especially on smaller lathes.

I think this is a little like your point above. Usually a really sharp tool makes a big difference. But I have found that the bigger the cut, the less it matters. Sometimes I think a comparatively dull edge does a better job of carrying heat away in the swarf. I'm not sure why but I suspect it relates to the way the metal tears away with a bigger cut vs being sliced or sheared away by the sharper edge. Something to be aware of anyway. I do mostly agree with you.

 

[SightlessSeer]

Neither does mine. I agree with you for the most part. However, at the risk of nit picking, I think that sometimes it does matter but when it does, I use a protractor as a guide for my hands and that has always worked just fine. My hss cutters are rarely beautiful, but I can often get the job done much better with hss than with carbide. In fact, there are times that carbide just doesn't work while hss does.



I think this is a little like your point above. Usually a really sharp tool makes a big difference. But I have found that the bigger the cut, the less it matters. Sometimes I think a comparatively dull edge does a better job of carrying heat away in the swarf. I'm not sure why but I suspect it relates to the way the metal tears away with a bigger cut vs being sliced or sheared away by the sharper edge. Something to be aware of anyway. I do mostly agree with you.

Agreed on both points. I was trying to speak generally, not to be rigorously correct, although to your point about deeper cuts, that is less relevant in the context of an Atlas 618. I haven't used one of them myself, but I would expect rigidity and power to come at a premium with a small lathe like that, both of which work against you in terms of taking deep cuts.