A question for the actual machinists here about tool pressure.

[Greg Y]

If you're worried about it, chuck up a barrel stub and gauge it before you sug it up....and after. Cut a chamfer or make a cut and check runout.....repeat till you get movement, then you know.

15 minutes to solve the mystery.

 

[LVLAaron]

Iscar IC908

Nice. I have a box of inserts that grade showing up tomorrow.

 

[Carl S]

You don't need a breaker bar to tighten your spider pins up.a decent pinch is enough.four pins opposite each other at each end of the barrel is sufficient to hold most thing's you want to turn.your machines rigidity will play a key part.a heavy 3phase machine.will turn and thread a tennon alot easier than a light single phase one.more torque and rigidity is better.tool set up and work piece set up.you don't want your tennon sticking out further than needed.keep it as close to the head stock as possible.dial everything in as perfect as can be.use quality tooling.the cheap micky mouse stuff is no good.turn and thread to your machines capabilities.dont get greedy with your cuts.

 

[DaveTooley]

Let get in the weeds for a moment. The spider is used to allow the barrel to pivot. So by design a 4 screw spider allows some work piece deflection dependent of the distance from the contact points and the cutting pressure. That also means there is movement on the inboard side of the spider. I was doing some barrels yesterday that the threads were 1.900" long. I know that the pitch diameter is tapered ever so slightly. No way around it except to grind the threads. One neat thing about my Haas is it displays the loads for the spindle and X & Z axis. The load on all three are very similar when turning.

 

[SKWERLZ]

These are the inserts I use on steel:

10pcs Kennametal DCMT11T304LF KC5010 DCMT3251LF CNC Carbide Inserts Original | eBay

Find many great new & used options and get the best deals for 10pcs Kennametal DCMT11T304LF KC5010 DCMT3251LF CNC Carbide Inserts Original at the best online prices at eBay! Free shipping for many products!

www.ebay.com

They're miles apart from anything else I've tried, Although I have some ingersol inserts on the way (They actually have a very nice easy to decipher website)

Most importantly they dont mind being run slow.

I ordered a few to try.

 

[Hal]

Where the best place to buy the inserts and tool holder, eBay?

Do you notice my difference between the 3/8” and the 1/2” tool holders as far as quality of finish ?

The endless amount of inserts is a whole different world. Thanks for the guidance.

Thanks
Hal

 

[LVLAaron]

KC5010 is the grade of coating not the profile. Both profile and coating influences how the insert works.

https://www1.mscdirect.com/images/solutions/kennametal/grade_system_for_cutting_materials.pdf

I use this Kennemetal insert with the KC5010 coating. They will take very small cuts at pretty slow speeds on a manual machine but they are fragile. They were recommended to me by gunsmith Bill Myers years ago who had a friend that worked for Kennemetal at the time. I met him but I don’t recall his name. Bill needed an insert to work with the Ti he was machining at the time for his actions. They work very well on other materials as well.
View attachment 1656699View attachment 1656700

That profile looks nice. Going to see if I can find one in the size I run

 

[LVLAaron]

Where the best place to buy the inserts and tool holder, eBay?

Do you notice my difference between the 3/8” and the 1/2” tool holders as far as quality of finish ?

The endless amount of inserts is a whole different world. Thanks for the guidance.

Thanks
Hal

Ebay for the inserts. I like 5/8 holders.

 

[boltfluter]

My insert of choice for 416 stainless is actually made for aluminum. Positive rake, razor sharp, and cuts 416 like butter. 416 really is not much different than 7075 aluminum..050 depth of cut is a piece of cake. I can post a pic of the inserts if anyone is interested. Basically razor sharp carbide. Let me know.
Paul

 

[SKWERLZ]

My insert of choice for 416 stainless is actually made for aluminum. Positive rake, razor sharp, and cuts 416 like butter. 416 really is not much different than 7075 aluminum..050 depth of cut is a piece of cake. I can post a pic of the inserts if anyone is interested. Basically razor sharp carbide. Let me know.
Paul

Please do as I need to order some as we use those on our CNC wood lathe and I’m looking for options.
a few have talked about those for crowns in the past as well.

 

[LVLAaron]

My insert of choice for 416 stainless is actually made for aluminum. Positive rake, razor sharp, and cuts 416 like butter. 416 really is not much different than 7075 aluminum..050 depth of cut is a piece of cake. I can post a pic of the inserts if anyone is interested. Basically razor sharp carbide. Let me know.
Paul

I use a lot of polished inserts meant for aluminum in stainless as well. Sharp as a cats claw. Dirt cheap on ebay. I like them for crowns especially.

 

[boltfluter]

I use a lot of polished inserts meant for aluminum in stainless as well. Sharp as a cats claw. Dirt cheap on ebay. I like them for crowns especially.

To break the edge on the crown/bore I love the solid carbide Micro 100 boring bars. Razor sharp and lasts forever if just kept for this small job. Just throwing it out there. N/C. Lol!
Paul

 

[LVLAaron]

To break the edge on the crown/bore I love the solid carbide Micro 100 boring bars. Razor sharp and lasts forever if just kept for this small job. Just throwing it out there. N/C. Lol!
Paul

I have a number of the teeny tiny ones to pre-bore lands.

 

[SKWERLZ]

To break the edge on the crown/bore I love the solid carbide Micro 100 boring bars. Razor sharp and lasts forever if just kept for this small job. Just throwing it out there. N/C. Lol!
Paul

I currently use a micro 100 brazed carbide for that, keep it nice n sharp

 

[DaveTooley]

Here's a couple of screen shots that are typical of work around here.

 

[boltfluter]

 

[Hal]

LV
Thanks for the reply.
I see if it will fit.

Hal

 

[AlNyhus]

Here's a couple of screen shots that are typical of work around here.

View attachment 1657004View attachment 1657005

Dave, what is the high lighted 'G71' line telling you? Amazing! -Al

 

[boltfluter]

Dave, what is the high lighted 'G71' line telling you? Amazing! -Al

Al, the G71 is his roughing cycle before the actual finish cut. It is a canned cycle that repeats until the roughing dimensions are cut. His depth of cut is .025 per pass at .0065 feed per revolution. I am sure Dave can explain it better as it's been a while for me.
Paul

 

[DaveTooley]

G71 is a canned turning cycle. The only thing that matters to me is the depth of cut, .040" and the feed .007"
G96 set's the constant surface feet. I run between 225 and 300 SFM. usually around 250 SFM. The M03 tells the machine to turn the spindle clockwise. And I'm no programming wizard. I use the conversational system and build the program one operation at a time. It may take a few seconds longer to do it that way but I have to change tools as different operations are done. Facing, turning, chamfer are done with the same tool. Then it's a grooving tool to cut the tenon to length, then threading, then roughing out the chamber. Drop my little tailstock on the tool post, run the finish reamer in, counter bore or cone breech face, polish and I'm done. What we do is simple stuff.