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Garmic
(@garmic)
Joined: 2 years ago
Posts: 13
2020-02-23 19:33:19  

I made a hammer and several spring guides for my 2240 and 50.

EDDE81EB 77F4 42E8 B13C 8C9AE2ADB1BF

I had just got a two stage trigger and rather than fill the striker with epoxy I used some stainless I had. I free handed the cocking pin and it worked.

The spring guides were delrin, I also made one for the trigger on the original 2240 trigger set


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Garmic
(@garmic)
Joined: 2 years ago
Posts: 13
2020-02-24 20:06:09  

If you notice I had some trouble getting a smooth finish on the SS.

I had sharpened the HSS cutter but maybe I should have used carbide, also I was turning around 500rpm so I dont know. The piece I started from wasnt much bigger than the hammer so I didnt have to take much off.


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Garmic
(@garmic)
Joined: 2 years ago
Posts: 13
2020-02-24 21:17:33  

Maybe I had the tool sticking out too far, I may try another one after I get my drill press set up. I have a cothran stainless 2260 tube and I want to go pcp but the tube wasnt drilled for pcp so I Im going to give that a go as well as drill and tap the valve for extra screws.


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scratchit
(@scratchit)
Joined: 2 years ago
Posts: 182
2020-02-24 21:27:35  

Sounds like a HiPac looking for a place to happen ......(grin)


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Bigbore
(@bigbore)
Joined: 2 years ago
Posts: 68
2020-03-16 17:02:49  

 I need to get going with my hammer project. Maybe this will prod me.


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Gratewhitehuntr
(@gratewhitehuntr)
Joined: 2 years ago
Posts: 645
2020-03-17 06:48:57  

̶I̶F̶  When my work looks like that, I try a differently shaped cutter, like round.

Next strategy, auto-feed, frequently combined with traveling the tool AWAY from the chuck. Same with threading, I work AWAY from the chuck whenever possible.


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KWK
 KWK
(@kwk)
Joined: 2 weeks ago
Posts: 26
2020-03-19 21:52:28  

Stainless usually machines very nicely. High speed steel can give an excellent finish. Unless your steel is hardened. Is it destroying your bit? Does it cut with a file? Similar to other mild steel? A rough finish would be typically caused by your bit being ground at wrong angles. Look online for some help attaining correct angles. The angles don't have to be perfect! But they shouldn't be WAY wrong either. Practice making bits and try them on scraps. Leaded steel 12L14 is free machining and leaves a very nice finish. If you are getting a good finish on mild steel the same bit will do great on stainless. A stainless bolt from the hardware store for instance should give a real nice smooth finish. Unless it's hardened! Pictures are of a new tailstock feedscrew I made from leaded steel. The turned part on the right side is not polished. That's the kind of finish stainless can give  or even better. We normally machine towards the chuck. That's what the thrust bearings in the headstock are usually set up for. Not towards the wimpy live center bearings in the tailstock. Round nose or radiused bits are ok but they chatter more readily if you are taking deeper cuts and you cant cut squarely into a shoulder. I rarely use them. Learn to make HSS bits and you can machine about anything any way. Anytime. How often do you turn anything hardened? I pretty much never do. I never use carbide. The size part you are turning should be ok at 500 rpm or even more. Learn to calculate your surface feet/ minute. SFM. And look at a chart for your particular metal.

   The Acme threads were cut with a HSS form bit I ground. The backlash in that tailstock is about .002! I nailed that one. Goes to my other South Bend 9 lathe I just finished rebuilding. Has a rare for a SB9 hardened bed. I added the feed dial from a South Bend 10k tailstock so I needed a longer feedscrew. The ways and slides are nearly like brand new. 

Notice I use a lantern tool post. They they aren't rigid. Aren't any good any more. Can't take a deep cut. Bla Bla Bla! Watch me. They're my favorite in my home shop. 

Lathes are fun. Keep practicing with it.

 

 

IMG 2805
IMG 2817
IMG 2822
IMG 2823
IMG 2824
IMG 2825
IMG 3301

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Garmic
(@garmic)
Joined: 2 years ago
Posts: 13
2020-03-20 18:19:28  

Very nice work, I dont think I will ever be up to that level of workmanship. I have been grinding my hss cutters and I have had success in the beginning, even with stainless. I have to resharpen and make one for cutting away from the chuck. That piece of stainless is scrap from who knows where and its quite shiny, I need to tighten the gibs and try a freshly sharpened cutter. It was a cold winter day in an unheated shop and I didnt give it the proper amount of attention.

I have a barrel blank coming so I better get my act together before starting on it. I ordered a qctp but this isnt a good time to shop on line Im afraid so I dont know when anything will show up. Mostly Im concerned about cutting the leade, Im planning on reshaping a drill bit.


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KWK
 KWK
(@kwk)
Joined: 2 weeks ago
Posts: 26
2020-03-20 19:14:06  

Once again, you do not normally cut away from the chuck. Only when necessary. To avoid feeding toward the tailstock  cutting this left hand thread I ran the lathe in reverse and put the Acme form bit I ground on the back side. On a South Bend 9 or same basic lathe light 10(10k) There is a ball bearing thrust bearing to take the load when cutting toward the chuck. Cut away from the chuck and there is only a fiber washer against cast iron taking the thrust. Sometimes supplemented by a small cheap thrust bearing in your Chinese live center. Most lathes are engineered to cut toward the chuck.

Some worry about cutting in reverse with a threaded chuck. You see me doing it don't you? Tighten it up good first and don't get crazy. Cutting larger diameters can bite you. Use some sense.

Don't adjust your gibbs too tight. Just feel a slight drag. For threading I tend to snug the compound just a little bit. 

What kind of lathe are you using? Most any lathe in decent condition should allow you to make nice parts. 

A small tapered carbide burr should give a good start on machining the lead for your barrel. Make sure the BORE is turning concentric. Or try putting the burr in a chuck and carefully cut the lead by hand.

IMG 2810
IMG 2808

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Garmic
(@garmic)
Joined: 2 years ago
Posts: 13
2020-03-20 22:07:07  

I have a Grizzly 8x16 G0768


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nervoustrigger
(@nervoustrigger)
Joined: 2 years ago
Posts: 224
2020-03-21 08:50:00  

@Garmic, I just wanted to let you know your story sounds familiar. I was in the same boat...I got a mini lathe a few months ago and one of the projects I wanted to do was a LW barrel retrofit to a QB79 HPA conversion. It was a .177cal (4.5mm) so I used a simple unpiloted 4.6mm reamer to cut the leade. This operation is removing the tiniest amount of material, essentially just wiping out the rifling.

This vendor has inexpensive reamers in 0.1mm increments.
https://www.aliexpress.com/item/32535264032.html

I didn’t know what to expect for such a low price but I’m pleased to say it worked great. I know Scott S. (motorhead) has described using a standard drill bit for this operation after blunting the sharp corner at the tip of the bit. That prevents it from digging in and wandering off course, ensuring it stays centered on the boreline axis. The cut won't be as smooth as a reamer but that can be sorted out with a polishing cone or wet/dry paper. FWIW, I went slow and used plenty of lube and withdrew it frequently to make sure the flutes didn't get clogged, and I was pleased with the quality of cut. I've since done the same with a 5.6mm reamer on a .22 cal LW barrel with similarly good results.

Then 400 -> 600 -> 1200 grit on a dowel to break the leading edge into the rifling to ensure pellets swage gently into the rifling rather than getting cut.

Then for the chamber so to speak (actually just an enlarged portion to accommodate the bolt), I stepped up one numbered bit at a time. The results were as good as I could have ever hoped. Perfectly centered and the barrel shoots great with almost any decent pellet.

Note I did use a 4-jaw chuck and indexed to the bore using a gauge pin and a dial indicator, but I expect that’s not critical. The drill bit or reamer will pretty well find center when taking a tiny bite like this.

I did a writeup on the project here if you're interested.
https://www.gatewaytoairguns.org/GTA/index.php?topic=162112

Good luck and let us know if you have questions.


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Gratewhitehuntr
(@gratewhitehuntr)
Joined: 2 years ago
Posts: 645
2020-03-21 10:35:31  
Posted by: @kwk

You see me doing it don't you? Tighten it up good first and don't get CANCER. Cutting larger diameters can bite you. Use some sense.

Maybe, just maybe, we should not conflate medical issues with poor judgement in selecting speed/feeds, or a lack of sense. Given that cancer is either hereditary OR environmental (smoking, other carcinogens) it is definitely in the realm of things you are either born with, or do to yourself.

"Crazy" might be hereditary, a result of things that happen to you, or things that OTHER people DO TO YOU.

I'm not trying to attack you, simply to provide some enlightenment that this word should not be used to describe anything other than someone experiencing medical problems. Otherwise, it is a slur. Thanks for considering this point!

 

Do you really run a Chinese live center on that gem of an American machine?

You could add to your list of projects, a more substantial live center, wheel bearings come to mind.

 

IF your machine has some setup issues, or excessive flex, it can definitely bite you in the ̶a̶s̶s̶ work. I've nearly ruined work by reversing direction of tool travel on a light finishing cut, ended up with the tool biting and chattering. Of course, that was only the 2nd or 3rd thing I ever made on a lathe.

Otherwise, a spring cut away from the chuck isn't going to hurt anything, most of the force is still perpendicular to the axis of the work. I learned to cut threads away from the chuck from a 90yo machinist who'd been doing it that way since before WW2. Personally, I'm more worried about a crash than bearings.

 


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Garmic
(@garmic)
Joined: 2 years ago
Posts: 13
2020-03-21 14:40:10  

I will use my 4jaw chuck for sure, those 5.6 reamers appear to be out of stock at the moment. I read Motorheads post but I thought he cut back the corners not the tip, in anycase I will take  it slow. This blank is 26” and I need 18” minimum so I have a bit to practice with. Also thanks for the help and suggestions everyone it gives me confidence going forward


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