Day 1 Practice - lessons learned. 12/30 update

[mram10]

I will definitely take him up on it. Seems like a great offer, but I am trying to figure it out without bugging anyone other than advice. I ordered some Iscar turning and threading tools last week an they should be here soon. That way I can take my subpar hss skills out of the equation. Thanks again for the help guys and great offer Stan.

 

[carlsbad]

I didn't bore this one. It was a bar stock with a big hole drilled in the end. I made a hss parting tool this morning. Not a very good one, but it works ok. I am threading on the lowest speed of 90rpm. I used only the cross slide to take the compound out of the equation. Started with .005 then worked my way down to /001 passes with a spring cut at the end. I'll do another with compound only tomorrow.

One thing to keep in mind, once chatter starts, it will tend to propagate to the next cut. When does it start? I'd assume that it isn't there on the first few small cuts. but if it starts on one of your .005" cuts, then it will still be there for your lighter cuts.

.005 should not be too much cut for your lathe but maybe you bit, as you suspect, isn't perfect. .005 is really just .0025. My lathe is stiffer than yours but I like to stay away from the .002 and smaller cuts whenever I can, especially on stainless, since the surface tends to work harden. For example, if I measure and I need to take off another .0105", I'll take off .005", confirm that my setup is giving me .005" when the dro says .005", then I'll dial in .0054" for the last cut (my dro moves in .0002" increments) and take the last cut that way, avoiding the work hardened surface layer.

--Jerry

 

[mram10]

Did this one of on the cross slide only. .005 first 2 cuts, then adjusted to .004 for a couple, etc. At the end I did probably 10 passes of .001 and 1 spring pass if I remember right. They are all running together

 

[carlsbad]

when does the chatter first show up?

 

[mram10]

It doesn't seem to chatter on the threading, just the boring bar for the bolt nose recess. I don't notice any on the threading.

 

[carlsbad]

I'm referring to the waviness in your photos. That is a type of mild chatter--it probably doesn't make any unusual noise. May even be hard to see if you've using a lot of cutting oil. Blow it off between passes to see what is happening. --Jerry

 

[mram10]

I have been using differential oil for my cutting fluid, blow off after each pass and add more oil. I understand there is chatter there, I just don't know how to sense it till after the work is cleaned off. I'll get real cutting oil and some good bits to see if it goes away.

 

[hoz53]

I'm referring to the waviness in your photos. That is a type of mild chatter--it probably doesn't make any unusual noise. May even be hard to see if you've using a lot of cutting oil. Blow it off between passes to see what is happening. --Jerry

it seems like last tenon i did once i got the threading started i was taking at least .015 a pass on the compound. No chatter but after reading you guys stuff i will try one with not over .005 and see how it turns out. Seems like that would take a long time. I use ridgid

 

[Curious]

Sorry if this question has been asked, Ive searched the thread and couldn't see the answer.

What lathe do you have?

Is it old or new?

Can we have some pictures of the machine?

Does your cross-slide graduation show how big a cut you are taking from one side or the overall diameter reduction?

 

[Stan Taylor]

I have no idea. He has been in the barrel business for a long time and he offered his help. It's a win, win for mram10. I learned a long time ago that those offers got two chances. In most cases it's a good deal for you. If not you are not out much, but you learn. Personally I'd purchase tooling as I do and that's from the big tool manufacturers, like Sandvik and if necessary, Kennametal. I can't afford to sharpen tooling let alone pay my employees to do it.

Tra I can grind hssfor about any style tool holders we have a variety of style cutting tools in shop inserts of carbide an some has ones I grind for certain machines here is a few maybe between us all here we can help old Mram out I thread between centers but have indicated 4 jaw for primarily internal threads making holders for barrels that have threads in case I have turn a barrel to a different contour here is 20inch threads I cut with this pacific tool in a rocker style holder.PS the tool in last pic I tried to take a good pic to show the type of draft I try to include so to not pressure on the trailing edge

 

[mram10]

Sorry if this question has been asked, Ive searched the thread and couldn't see the answer.

What lathe do you have?

Is it old or new?

Can we have some pictures of the machine?

Does your cross-slide graduation show how big a cut you are taking from one side or the overall diameter reduction?

Eisen. Supposed to be the same as a PM and made in the same factory. Taiwanese. Brand spankin new buddy. I'll post some pics in a bit. Overall diameter.

 

[mram10]

I cleaned the 3 jaw, locked in the compound, had 2” hanging out of 3jaw and shortened the length of the threading tool sticking out of the holder. Ignore the relief cut mishap

Carbide at 780rpm has a better finish than my hss tool on the shank. Hss threading tool at 135rpm seemed to do better after the adjustments.

 

[carlsbad]

OK. Looks like your issue was a combination of less-than-optimal setup. Shorter is always stiffer. I'd say you're done with this now and you can move on to the next step. I would now focus on getting dimensional accuracy. Do you have a thread pitch micrometer? How do you plan to check your thread fit?

And of course there is the setup....

--Jerry

 

[mram10]

Jerry, I was just going to fit the action to it. If it screws on with no slop, I’m happy. I get my barrel vise today so I will be able to tear down an action and try fitting all of these.

 

[boltman223]

Carbide at 780rpm has a better finish than my hss tool on the shank. Hss threading tool at 135rpm seemed to do better after the adjustments.

Carbide at 780rpm has a better finish than my hss tool on the shank. Hss threading tool at 135rpm seemed to do better after the adjustments.[/QUOTE]

Your HSS will probably have a better finish if get up closer to 300 rpm.

I was thinking back to when I first started, if you havn' t already it's probably a good idea to practice picking up threads now so you don't have to do it for the first time on a barrel you plan on using.

 

[mram10]

Been practicing picking up threads. Tried my carbide with 1100 and 1600 and leaves a great finish

 

[boltman223]

Been practicing picking up threads. Tried my carbide with 1100 and 1600 and leaves a great finish

Faster with carbide..that's usually the case. Did you try faster rpm's (to at least see if it helps)than 135 with HSS? Are you going to be threading up to a shoulder at 1100 rpm or even 780? If you are I want to see a video.

 

[carlsbad]

BTW, if you're running 1600 and getting a good finish, your lathe is pretty stable on the floor. Gonna post a photo of it?

 

[Eddie Harren]

What's that smell?

 

[mram10]

1600 was turning down shank, not threading. I’m a turtle slow threader. I have tried from 90-200 with the hss. Not sure if finish changes or not. I’ll try it out. My carbide threading tool came with the wrong insert, so I’m waiting on new ones .... again. It had a flat tip.
Been trying up the lathe today. Ran a 1ft piece of 3/4 from the 3 jaw to a center. The diameter on the left was .021 larger than the right. After adjustment it was within .001. Very happy. One thing fixed.