speeds,feeds, tools ? Any tips or advice you can give me? I know what the machining hand book says and pretty much nothing more. I'll prob use a Kent 1340 or similar size lathe.
Printable View
speeds,feeds, tools ? Any tips or advice you can give me? I know what the machining hand book says and pretty much nothing more. I'll prob use a Kent 1340 or similar size lathe.
Best advice is; do not do it. Did a stainless once, will not do one again.
Buy a contoured barrel and save the time, aggravation and effort. Contouring a stainless barrel with a hand operated shop lathe is just way too much aggravation for the difference in cost, of a CNC contoured VS a blank.
bought the blank for a school project during covid. I have one 30 cal to chamber and profile and just rented the reamer for a 358 that will require profiling fortunately they are NOT stainless.
I'm going to try a HSS insert , i can grind a traditional HSS blank and Ive got some carbide inserts , still interested in process tips
You still in school? The reason I asked is my bluer had a stroke and I have a couple of bluing jobs I need done. I live on the north side of the cities. Looking for options. I heard at one time Pine Technical let students blue for others. My stuff is fully polished. I just need to find someone that will run them in the tanks.
Barrel makers generally have a hydraulic follower rest for support. That makes it easy to contour.
On a manual lathe straight tapers are easiest. Ideally you should have a taper attachment on the lathe. If not, it can be done with the compound. Offsetting the tailstock is an option but when you get more towards the supported center chatter gets to be an issue. I mostly do SS but for either I have given up on between centers for anything over 20" unless its used in conjuction with a steady rest. I mostly do match rifle barrels that finish between 26" and 30".
For straight sections followers rest are invaluable. For tapered I have used both the compound and taper attachment. A taper attachment when used with a steady rest works well. I don't worry about minor chatter, rough finishes or minor steps. Those can be removed with a file followed by using a barrel spinner and belt sander.
It really comes down to what equipment you have at your disposal.
Yes , I can help you with that .Quote:
Originally Posted by M-Tecs
I have profiled two stainless barrels using an improvised tool post grinder. I mounted a 4 inch dewalt hand grinder on the compound rest. Used a pipe liner type wheel, fast feed, light cuts. Set the tail stock over to get the taper. No following rest. The job went pretty quick, sure made a lot of dust. Cover the lathe well. Both barrels shoot just fine (shaw and Douglas).
Super sharp high speed tool, no carbide. Lots of rake and a good chip breaker ground in. Flood coolant if you have it. Feed about .004/rev. Light cuts, no more than .025/side. RPM is whatever feels right, I never knew what the actual RPM was. If it starts chattering you can just hold the barrel ahead of the cutter and damp most of it out. If you have a taper attachment you can split it into three parts, turn cylinders, and set the taper to blend the three. Then cut the sweep to the big part with carbide, high rpm, and envision yourself as a CNC machine feeding out slow at first and faster as you get to the breech cylinder part. 416 SS is way easier to cut than chrome moly so no worries there. I always followed the lathe work with polishing on a wood lathe using an angle grinder with stick on sanding discs. That's super fast and gives a nice finish to either blast or finish polish by hand with paper.
When free handing a radius on a machine watch the radius not the cut. A tracing of the radius positioned so you can see the line behind the part helps to follow it.
Hand hone your tool with a fine stone and add a small radius to the point, the sharp point will break down faster than the radius and the radius will help blend feed lines.
Watch the center tension as this can cause chatter especially as the machining raises temps and the part gets longer from expansion, Here a spring loaded center is a big help but few have them
Good point about the center. I meant to mention that, as the barrel gets hotter it gets longer, sometimes by quite a lot. If you don't periodically release the tension on the center (not during the cut) or use a spring loaded one like Country Gent mentioned, it is possible to make a barrel straight on the outside with a crooked bore. I've seen that done a few times!
I turn barrels almost every work day. SS cuts a little easier than 4140. I use carbide and run 585 RPMs most of the time. I grind the carbide so there is no radius, a slight relief and run the cutter at 90 degrees to the barrel. Any radius will cause chatter. On tapers I use an offset center on the tail stock , a center in the head with drive dog and a steady rest in the middle of the barrel. For steeper angles I use the compound rest. A file to take out machine marks and a barrel spinner with a band sander to polish. If you don't clamp the tail stock down real hard it will move with barrel expansion. After you do a few hundred you will get feel for what works best.
Attachment 319536
Inserts with a polished positive cutting geometry like inserts intended for aluminum work well for turning long work pieces prone to chatter or on light duty lathes prone to chatter with normal inserts.
https://latheinserts.com/shop-1/ols/...m/v/4210002384
Lots of ways to skin that cat! I like seeing everyone's solutions. That offset center would be useful, where did you find that?
Thanks!
I made the offset center and gave the idea to Pacific Tool and Gauge. They have them for sale but it is not an exact copy of mine. Last time I checked they were asking $450Quote:
Originally Posted by Nobade
For those looking for the one from PTG https://pacifictoolandgauge.com/lath...tailstock.html
Amazing that Amazon has those for a hundred bucks or less, and PTG is 4 times that.
Quality US made verse Chinese made of unknown quality. Some of the low-cost Chinese stuff is pretty good and other stuff not so much. For heavy or professional use, I would go with the PTG hands down.Quote:
Originally Posted by PopcornSutton
PTG is paying US wages to produce a design that it partially developed. The amazon version is a copied design produced at communist wage rates.Quote:
Originally Posted by PopcornSutton
As M-Tecs said, the quality of such copies is ...variable.
Ive bought enough PTG to know it can require patients. I wish they'd do better job simply confirming what on the website is in stock.