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  #11  
Old 11-27-2017, 09:57 PM
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Shade Tree Welder Shade Tree Welder is offline
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Brian, the better way to do it is the 29° in feed. Generally you will get better
chip control and finishes. It is also known as flank in feed. On CNC you can
do a modified flank infeed where you feed in 29° left then 29° to the right.
Cannot do that on a manual.
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  #12  
Old 11-27-2017, 10:44 PM
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There is no doubt in my mind that HSS tooling is fast becoming obsolete. Working shops simply can't afford to waste the time it takes to grind and touch up tooling. I haven't used HSS tooling in years. Well, maybe once in a blue moon if I need some really oddball profile but there is so much good insert tooling available today that there's just no need to fiddle around with HSS.

I do all my threading using only the cross-slide with straight in feed. I rotate my compound about 30 degrees and leave it there for everything--can't remember the last time I actually moved it.

To get good threads you need a sharp tool with the height set as close to centre as possible and also perfectly perpendicular to the workpiece. Get this right and it's hard not to make good threads. One other thing to consider is the material you're using--it's tough to get good threads in ordinary mild steel or even 1018. Stepping up to 1045 or beyond will make a big difference...
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  #13  
Old 11-27-2017, 11:47 PM
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Quote:
Originally Posted by LKeithR View Post
There is no doubt in my mind that HSS tooling is fast becoming obsolete. Working shops simply can't afford to waste the time it takes to grind and touch up tooling. I haven't used HSS tooling in years. Well, maybe once in a blue moon if I need some really oddball profile but there is so much good insert tooling available today that there's just no need to fiddle around with HSS.



I do all my threading using only the cross-slide with straight in feed. I rotate my compound about 30 degrees and leave it there for everything--can't remember the last time I actually moved it.



To get good threads you need a sharp tool with the height set as close to centre as possible and also perfectly perpendicular to the workpiece. Get this right and it's hard not to make good threads. One other thing to consider is the material you're using--it's tough to get good threads in ordinary mild steel or even 1018. Stepping up to 1045 or beyond will make a big difference...


One thing that sticks in my mind about having the compound setcatv30 degrees is that for every .001 you turn that in, it will cut .0005 or 1/2 in a facing cut. Helps when you need to make a part a certain length and you are able to Mic it or use calipers to determine the length. Although, this lathe I am using has a dial on the carriage hand wheel. I just need to get it cleaned up so I can read it. But I will be making some holders for my disk indicators to mount if I find I need to hold those tight tolerances. From what I was seeing today, it does not appear that I need to be super precise, or they are just being easy on me to start.

I have to learn more about the material. I know it has a chrome coating on the shafts, that they tell me is hard. Some shafts have a thicker coating that they will sometimes uses different inserts for. I have a lot to learn yet.


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  #14  
Old 11-27-2017, 11:54 PM
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Quote:
Originally Posted by Shade Tree Welder View Post
Brian, the better way to do it is the 29° in feed. Generally you will get better

chip control and finishes. It is also known as flank in feed. On CNC you can

do a modified flank infeed where you feed in 29° left then 29° to the right.

Cannot do that on a manual.


29 degrees is what I remember too. No CNC for me.

The shop bought a new lathe 2 years ago I think. They scrapped out one to make room, (wish I would have been able to get that one) The senior machinist is running that one. It has DRO on it. I haven’t checked it out too close yet, but reason they hired me is to take over for the senior machinist when he retires in a year. Maybe I will get to move up to that lathe then. Til then I will learn the other 2. And all other parts of the shop. I see a lot of opportunity to help make this shop more efficient, if I get some down time from running the lathes.


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  #15  
Old 11-28-2017, 12:08 AM
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Here is a drawing I made up for a hammer design. Give me practice building from a blue print too, even though I don’t think we do that much. Mostly just measure and copy worn out shafts to rebuild cylinders.Click image for larger version

Name:	Image1511845556.717398.jpg
Views:	63
Size:	116.8 KB
ID:	142314


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  #16  
Old 11-28-2017, 12:17 AM
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https://www.sandvik.coromant.com/en-...s/default.aspx

https://www.sandvik.coromant.com/us/...ed_methods.pdf
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  #17  
Old 11-28-2017, 01:08 AM
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It never hurts to even do a quick sketch up when 'copying' a part, gives you a chance to think about how you're going to make it. A spot for notes and calculations, and if there's a 'rough' filing system (kept in order on a clipboard, or a binder/notebook for example) it can become a reference to look back on.

In a hydraulic shop I'm going to guess the majority of the work will be replacement shafts, as that's what seems to be 'kicking' around the hydraulic shops I've been in.

Yes, that first cut will be through chrome and possibly case hardening, and can be hard on tooling, especially until you learn what does and doesn't work.

I agree with Keith, in a modern shop of any sort, HSS is long gone for lathe work, other than the odd occasion for a specialty profile. Even then, some places I've been at, we'd make our profile stuff out of carbide too.

The odd thing I use HSS for is intermittent cuts. Carbide tends to prefer a constant load, so if I get into something like a piece of square, or maybe a flame cut profile, I may use HSS to at least get it cleaned up.
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  #18  
Old 11-28-2017, 07:03 AM
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Ron, thank you for the homework. I need to do some research on the insert bits we have at the shop, I now realize. There are a lot to choose from. Nice thing is, if I think there is a different one that will work better for a certain application, my new boss will get it with no problems.


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  #19  
Old 11-28-2017, 07:07 AM
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Quote:
Originally Posted by greywynd View Post
It never hurts to even do a quick sketch up when 'copying' a part, gives you a chance to think about how you're going to make it. A spot for notes and calculations, and if there's a 'rough' filing system (kept in order on a clipboard, or a binder/notebook for example) it can become a reference to look back on.

In a hydraulic shop I'm going to guess the majority of the work will be replacement shafts, as that's what seems to be 'kicking' around the hydraulic shops I've been in.

Yes, that first cut will be through chrome and possibly case hardening, and can be hard on tooling, especially until you learn what does and doesn't work.

I agree with Keith, in a modern shop of any sort, HSS is long gone for lathe work, other than the odd occasion for a specialty profile. Even then, some places I've been at, we'd make our profile stuff out of carbide too.

The odd thing I use HSS for is intermittent cuts. Carbide tends to prefer a constant load, so if I get into something like a piece of square, or maybe a flame cut profile, I may use HSS to at least get it cleaned up.


Thank you Graywynd for your comments. It is helping me to remember my early teaching and helping me get into the full time machining groove. And I am picking up new pointers with everyone commenting, or at least it is making me think about what I thought I knew, and what others are telling me now.

Everyone, please keep the comments coming!


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  #20  
Old 11-28-2017, 02:57 PM
Rob65 Rob65 is offline
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Default Lathe threading...

Brian,

If you are going to be doing a lot of screw cutting you might want to look into a lifting tool holder. Here is an example

https://youtu.be/YZkRNdXFYB8

All you need to do it take a cut, reverse the lathe, whilst the carriage is running back to the start position put on the depth of the next cut by your perfected method (cross or compound slide) and then put the lathe in to forwards and make the next cut. No withdrawing of the tool or disengaging of the lead screw is necessary.

I have seen an M12 thread about an inch long cut in about 2 mins using one of these tools.

I'm not sure it does the lathe any good crashing from forwards to backwards rotation too quickly but I guess increased wear on the clutches is a price some are prepared to accept in the interest of getting the jobs out of the shop door as fast as possible.


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Last edited by Shade Tree Welder; 11-28-2017 at 03:36 PM.
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