What would cause this?

[tundrawolf]

Can't help you there, I consider firearm manufacturing reprehensible.

I am sorry to hear that. Every year in America a firearm is used in the hands of a law abiding citizen to stop a crime, the fbi estimates this happens over a million times per anum. That includes women stopping rapes against much stronger men, home invasions where people would have been raped and killed, often without a shot being fired.

I have had to draw my pistol once when me and an 80 year old man were surrounded by 4 other men, one of which was assaulting the elderly man. It only took the sight of the weapon to make them back off, possibly saving the elderly man and me. I didn't fire a shot and I didn't point it at anyone, but everyone walked away. This was in the remote desert, and the men were trespassing. Had I not have had the weapon things may have ended differently.

I'm sad to hear you hate a tool, and hope that changes at some point in the future. Be safe, and thank you for your input.

 

[brino]

@tundrawolf

I agree with the above machining advice.
For any deeper insight we would need to know more specifics, like:

1. what material? (if unknown then any hints, scrap axle?, etc.)
2. what tool? (HSS, carbide)
3. what RPM?
4. what machine? (lathe size/rigidity, amount of wear, what kind of tool post/tool holder, etc.)
5. what feed?

The more info we have the better the guidance can be.
Don't give up, we'll figure it out!

-brino

 

[tundrawolf]

@tundrawolf

I agree with the above machining advice.
For any deeper insight we would need to know more specifics, like:

1. what material? (if unknown then any hints, scrap axle?, etc.)
2. what tool? (HSS, carbide)
3. what RPM?
4. what machine? (lathe size/rigidity, amount of wear, what kind of tool post/tool holder, etc.)
5. what feed?

The more info we have the better the guidance can be.
Don't give up, we'll figure it out!

-brino

Not known. It houses a recoil tube, and partially supports a buttstock, but I don't believe it's hardened at all.

It's a carbide bit, but might not be so sharp. I'm using the corner, edge.

It's a small home lathe, an atlas craftsman ten inch. The rpm isn't known, it uses a belt, and it's using a 4 speed pulley, it's the third slowest setting.

Not sure of the feed.... It uses a complicated setting of gears, and honestly I have no idea what it's set st, or how to measure it...

 

[vocatexas]

I think that remark could have remained unsaid...

 

[brino]

RPM is a very important parameter. It can be the huge difference between a decent or nasty surface finish.

Actually it is the surface feet per minute SFPM (or SFM) that is important, but since the lathe turns the work about an axis RPM is often used.
There are a number of online calculators for SFPM to RPM conversion, here's a couple:
http://www.discount-tools.com/sfm.htm
http://www.americanmachinist.com/speedsfeeds-conversions-calculator
http://www.monstertool.com/monster_tool_calculators.html

You can also get a free "cardboard slide-rule" type converter from Niagara Cutter from here:
http://www.niagaracutter.com/speed-feed-slide

I normally use HSS tools and for cutting steel I aim for around 80 sfpm, then convert that to rpm for the diameter of the part I'm cutting.
For carbide tools you can run faster somewhere around 100-400 sfpm.

Often lathes are marked with spindle RPM badges/plates, but those are only useful if the plates are still there and no one has changed the pulley sizes or motor RPM.

I found a cheap digital laser tachometer is very useful in the shop. Something like these:
https://www.ebay.ca/itm/New-Mini-LC...409617?hash=item236d2b4cd1:g:54sAAOSwXeJXewkX

https://www.ebay.ca/itm/New-Digital...277294?hash=item5d77a540ee:g:D10AAOSwRqBZplTa

Note I am not trying to recommend a specific vendor, just showing examples I found by searching ebay for "laser tach".

-brino

 

[brino]

@tundrawolf

I forgot to say one more thing...........Welcome to the Hobby Machinist!

-brino

 

[savarin]

Hi Wreckwreck, any chance of a close up of the protective clamp the steady followers are rotating upon please?

 

[tundrawolf]

@tundrawolf

I forgot to say one more thing...........Welcome to the Hobby Machinist!

-brino

Thank you so much for the excellent advice and the warm welcome! =D

About carriage speed, I see it is a simple mechanical design using a threaded shaft and a threaded collar on the carriage that can be engaged or disengaged. Of course it uses a complicated system of gears to turn the long threaded shaft that moves the carriage... How hard would it be to connect a stepper motor to turn the long threaded drive rod? All I'd need is an inductive pickup on the spindle to measure drive RPM, coupled to an arduino controller and a stepper motor driver, and I wouldn't have to worry about working some sort of witchcraft with the fragile (And already quite chipped and worn in some places...) Gears

What do you think?

 

[JimDawson]

Thank you so much for the excellent advice and the warm welcome! =D

About carriage speed, I see it is a simple mechanical design using a threaded shaft and a threaded collar on the carriage that can be engaged or disengaged. Of course it uses a complicated system of gears to turn the long threaded shaft that moves the carriage... How hard would it be to connect a stepper motor to turn the long threaded drive rod? All I'd need is an inductive pickup on the spindle to measure drive RPM, coupled to an arduino controller and a stepper motor driver, and I wouldn't have to worry about working some sort of witchcraft with the fragile (And already quite chipped and worn in some places...) Gears

What do you think?

Would work just fine. I have thought about doing that.

 

[tundrawolf]

Would work just fine. I have thought about doing that.

Depending on your Google-fu, there's is a goldmine plethora of information on it out there.

Apparently it's easy to go full CNC after digitizing the control of the lead screw, but I am still beginning, I'd rather do things by hand for now, except it'd like a little more control over the carriage feed and threading operations, and the gears that have teeth worn/stripped/broken do worry me XD I thought, why not sync lead screw revolutions electronically using a stepper motor with rotary pulse generator, and some kind of inductive sensor for the lathe spindle, and sync it with an inexpensive controller. Seems doable. I'd need to learn arduino coding but i have plenty of friends who can help me. I'd post the steps and the code when I am done and verified it works, of course

I remember when something like this was a $900-1200 dollar investment, twenty years ago- minimum, and displays of any kind were a premium. Now I can probably get everything on Ebay for under $75, including a display and control pad...

I don't have a mill, but I can source metal if I have to for the adapter plates.