Day 1 Practice - lessons learned. 12/30 update

[mram10]

I have the nut still, but kinda like the handle. Break corners?

Danny, that is a nice looking tool

 

[carlsbad]

broken corners

 

[mram10]

Gotcha. I softened them with a file then hit them with some sand paper.

 

[Curious]

Gotcha. I softened them with a file then hit them with some sand paper.

Typically a 45 degree inside/outside chamfer tool is used to break the edges.

Chamfers can vary from very small if it is to soften an edge to bigger ones if they are to act as a lead to introduce things to one and other. Its very rare to see a sharp edge in machining although not unheard of. Chamfers and good surface finish (not a surface that has been polished to death with paper) are signs that you are working well along with the obvious dimensional accuracy.

 

[linekin]

I'm not as qualified as some here as I don't consider myself a true machinist. Having never taken any training other than by a few mentors on the job. Having said that I have been basic machining for over 20 years, alot of which involves threading.
I struggled threading early on & messed up my fair share of parts. Then one of my other mentors, "Uncle John", showed me how to thread with the compound. Which his brother who owned the shop, also a mentor, never did. Until then I threaded with the cross feed. Uncle John explained the 29 1/2 degrees to me as you want the leading edge of the tool doing the work. He also explained that some like to grind some relief on the back side of the 60deg. tool to ensure this.
Remember too that the compound is facing the chuck for an external thread, away from the chuck for an internal thread. Not that that matters yet here.
Once I began threading with the compound thing became much easier. My threading better. To each their own though. Seen it done both ways with good results, but I'm a believer in only the leading edge doing the work. I feel like its easier on the tooling this way.
I mostly used Aloris tooling early on & still do some but prefer a standard post. Mostly because I do a lot of parting & don't like the Aloris for it. I mention it because I do still do some threading with this & may be something to consider as you have a wedge type holder. (I agree, replace the handle with a nut.)
https://www.ebay.com/i/111228071845?chn=ps
The good thing about them is the last a long time & allow for quick, easy resharpening. Especially for those of us that aren't Master tool sharpeners.
The one thing I noticed in your last threading picture, & it may be a camera illusion, is that your post doesn't look parallel to the chuck & it looks like more than a 1/2 degree. Are you using a center finder to set your threading tool up?
All in all you're doing a great job learning & I've enjoyed the thread. Keep up the good work!
Keith

 

[mram10]

Curious, copy. I usually stick a little file on all the edges when the part is done. I’ll make sure to hit all edges lightly

Linekin, the crossslide way came from watching my friend. He’s 73 and been doing this since the 70s. He also uses carbide inserts at 70rpm to thread. Go figure. I have tried both way in the last week, but agree the compound makes sense with regard to the cutting edge. I’ll go do one with the compound and my newly ground tool. I used a fishtail to line up my work. Weird that the post looks off, yet the tool is correct. Probably the way I ground it.

 

[GenePoole]

Curious, copy. I usually stick a little file on all the edges when the part is done. I’ll make sure to hit all edges lightly

Linekin, the crossslide way came from watching my friend. He’s 73 and been doing this since the 70s. He also uses carbide inserts at 70rpm to thread. Go figure. I have tried both way in the last week, but agree the compound makes sense with regard to the cutting edge. I’ll go do one with the compound and my newly ground tool. I used a fishtail to line up my work. Weird that the post looks off, yet the tool is correct. Probably the way I ground it.

They say a picture is worth a thousand words. I drew this up real quick and hopefully it illustrates why 29.5° on the compound is a better way to go.

As you can see, as you plunge straight-in, you are cutting on both sides of the tool. As you get deeper, there is more force on the sides and more of a chance that the tool will bind and chatter, not to mention that the chips will collide with each other and possibly roll under the cut.

Ideally, you would cut at exactly 30° on the compound, but if you are even slightly more, then you can end up with a stair-stepped cut on the right side. By going with 29.5° you ensure that you are definitely not over 30° and that you'll be taking no more that a very thin shave off the right side with each pass.

I love it when you take a cut and get a perfect curly chip. They usually fall into the chip pan, but this one stuck to my coolant mag base:

 

[mram10]

Here we go again. All measurements are correct for the action with .300 lug. Did the relief at .280 from shoulder. Compound only today. No cross slide. I’ll try the same setup with smaller passes near the end instead of .005.

 

[carlsbad]

Ok. After looking at your consistently wavy results for days I'd say you still have a rigidity issue. Dud you adjust the ways on the new lathe? My new Taiwanese lathe came with the ways very loose.

PS the compound is the most suspect.

 

[Stan Taylor]

Curious, copy. I usually stick a little file on all the edges when the part is done. I’ll make sure to hit all edges lightly

Linekin, the crossslide way came from watching my friend. He’s 73 and been doing this since the 70s. He also uses carbide inserts at 70rpm to thread. Go figure. I have tried both way in the last week, but agree the compound makes sense with regard to the cutting edge. I’ll go do one with the compound and my newly ground tool. I used a fishtail to line up my work. Weird that the post looks off, yet the tool is correct. Probably the way I ground it.

They say a picture is worth a thousand words. I drew this up real quick and hopefully it illustrates why 29.5° on the compound is a better way to go.

As you can see, as you plunge straight-in, you are cutting on both sides of the tool. As you get deeper, there is more force on the sides and more of a chance that the tool will bind and chatter, not to mention that the chips will collide with each other and possibly roll under the cut.

Ideally, you would cut at exactly 30° on the compound, but if you are even slightly more, then you can end up with a stair-stepped cut on the right side. By going with 29.5° you ensure that you are definitely not over 30° and that you'll be taking no more that a very thin shave off the right side with each pass.

I love it when you take a cut and get a perfect curly chip. They usually fall into the chip pan, but this one stuck to my coolant mag base:

Glenn I have the same set up as far as threading but I use hss but if I decide to play with the inserts what speed are you running them at.

 

[Stan Taylor]

Mram I looked at your pictures is that a 3 jaw set up or 4 could not really tell but if you decide on high speed tools let me know mail me your hss tool bits I would be glad to grind you some thread inserts that way you could see the difference in what you are grinding we are here to help.

 

[mram10]

Stan, thanks. It’s a 3 jaw. I haven’t been indicating, just throw the scrap in, turn and thread.
Jerry, I have messed around with cleaning, adjusting drag, etc but don’t know exactly how to adjust the ways. I’ll look it up. Before I do real barrels, I’m going to mount it to the floor. I ordered some aluminum for a spider and some 1/2x13 Allen heads. Won’t plan on real stuff till I’m set up and waves are gone. I have a couple carbon barrels waiting....

 

[Stan Taylor]

Stan, thanks. It’s a 3 jaw. I haven’t been indicating, just throw the scrap in, turn and thread.
Jerry, I have messed around with cleaning, adjusting drag, etc but don’t know exactly how to adjust the ways. I’ll look it up. Before I do real barrels, I’m going to mount it to the floor. I ordered some aluminum for a spider and some 1/2x13 Allen heads. Won’t plan on real stuff till I’m set up and waves are gone. I have a couple carbon barrels waiting....

Being you said 3 jaw how long are the scrap pieces you are using an are you clamping straight off the 3 jaw the length might be causing less rigidity if the work piece is to long an don't have a spider or some support according to how long you are working with to me that would definitely cause the chatter we ar seeing like I said we are here to help.

 

[mram10]

Stan, just 6-8 inches long.

 

[Stan Taylor]

Stan, just 6-8 inches long.

Does this scrap have have a hole in it if you have a good live center for tail stock it is not really practical but you could hold the ads end of a piece of scrap run the tailsock against the end of it turn a shank length an thread it but don't loosen up Chuck till you are done an see if the rigidity is the real culprit here

 

[ridgeway]

broken corners
View attachment 1030333[/Q

Before I do real barrels, I’m going to mount it to the floor.

As in bolt the lathe to the concrete?

 

[carlsbad]

I'm talking about chamfering the internal corners to promote smooth feeding of the round into the chamber. --Jerry

 

[Curious]

View attachment 1030350 View attachment 1030351 View attachment 1030352 Here we go again. All measurements are correct for the action with .300 lug. Did the relief at .280 from shoulder. Compound only today. No cross slide. I’ll try the same setup with smaller passes near the end instead of .005.

The chatter you are getting here is chronic, the problem is it could be coming from a number of different sources.

Play in the ways, either carriage, cross-lide or compound, play on the tool post, the toolkits to holder, the holder to tool or even the headstock bearings to name a few.

Another possibility is as I said earlier your tool grind, poor relief angles or blunt tooling. It will cost you $75 or less to buy an indexable set-up or why not show us your tool grinding?

Im sure someone could send you a nicely ground HSS tool bit if you didn't want to buy carbide?

Your thread form is good now, screw cutting usually isn't that challenging, its a set-up issue of some kind now rather than a technique one.

 

[mram10]

Stan, they do have holes.
Ridge, correct. It’s in the middle of the pad
Jerry, I’ve been doing that.

 

[mram10]

Just did this one. Used smaller bites on the threading. Also used the longitudinal feed for the first time for the shank. Really like that. Again, this is all with hss tools I made so I will post pics when I get my iscar inserts