Jump to content




Photo

A big Santa surprise


  • Please log in to reply
61 replies to this topic

#51 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 9,202 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 24 January 2017 - 08:03 AM

Thanks Gary.

For my first little "getting acquainted" project. I had some 3/8" brass threaded rod here (for some reason... I can't remember!?), so I got busy turning that down to .256" or so OD. Skinning off the threads was something of a deal, but got much easier after the piece got trued (the stuff wasn't straight as you might expect). Funny how (as compared to carpentry) the difference between 3/8 threaded rod and a bit over 1/4" straight rod is pretty major!   :D  

 

Then I started an end hole with a center drill in the chuck and then drilled it with the nearest undersize drill bits in two "steps." After that I finished the ID with a 5mm ream. Reaming was particularly smooth, but before reaming some nifty lube came in the mail that had been recommended to me (thanks to CJ Bugpoo for the recommendation). I learned a good deal about all this stuff in this little project so far... although I still have to part-off the pieces.

1) I learned that a live center might be a good thing... so I have one coming.
2) I learned that a piece that's "more than a little long-ish" really needs to be supported at the tail end... like whenever you can.   :)
3) I learned that, as in carpentry, the machine will tell you when you shouldn't do that!
4) I learned that... OK... I already knew, but it was reinforced... a good light is a very important thing. I ordered a magnetic base LED lamp made for sewing machines on eBay for like $10-$15 or something and it's perfect for this little machine. I can actually see what's going on, I mean really see what's going on. What a concept!

Of course, I'll never be a machinist, but I can see that I'll be "making metal stuff" with trial and error (and the help of the knowledgeable folks around here!) as time goes on, and that's PDC (pretty danged cool)!

s-l500.jpg

 

-john


  • C. J. Bupgoo likes this
John Havlicek




#52 wbugenis

wbugenis

    On The Lead Lap

  • Subscriber
  • PipPipPipPip
  • 262 posts
  • Joined: 17-December 09
  • Gender:Male
  • Location:Brooklyn, NY

Posted 24 January 2017 - 08:53 AM

John,

 

First time I reached the limits of my Sherline was with the parting tool. The ones we have to use are thin and fragile. You will get unpleasant  vibration if your set up isn't right (wrong feed rate, machine RPM, not using cutting oil, wrong cutting tool height, etc.)

 

Make the cut right next to the chuck jaws for the best support - otherwise, again, vibration.

 

Of course - no center in the tailstock  when parting.

 

Bill


William Bugenis

#53 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 9,202 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 24 January 2017 - 09:04 AM

Hi, Bill, and thanks... makes perfect sense!

 

-john


John Havlicek

#54 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 9,202 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 24 January 2017 - 09:48 AM

... oh and, I forgot to mention that I'll be getting a steady rest for sure.

 

With a piece like this, where you basically wind up with brass tubing, I'd be afraid of continually re-chucking to keep the parting tool near the chuck end. I think this would be a good way to solidly support the piece near the cut, and not have to worry about distorting the tube.  

 

Then again... I may be wrong, but I'll find out for sure!

 

-john


John Havlicek

#55 Booger

Booger

    Mid-Pack Racer

  • Subscriber
  • PipPipPip
  • 100 posts
  • Joined: 15-June 15
  • Gender:Male
  • Location:SoCal

Posted 24 January 2017 - 08:18 PM

Rule of thumb for overhang of material in the chuck......3 times it's diameter,then it's suppose to be supported.....While were talking overhang,3 times the diameter for your cutters,5 times diameter for HSS boring bar......People have been known to cheat some..... :shok:

 

If you have trouble parting and can't figure it out,it's not uncommon to part on these small lathes with the blade upside down and chuck run in reverse OR blade upside down and part from the back of the topslide,chuck running the correct direction.....When upside down,the blade can not dig in.The work is trying to push the blade away if trouble happens.

 

When parting,the piece you part off should drop straight down....If it flies off the end,your blade is not straight up/down....Check the ends of the cuts with a rule,they should be flat or damn close....If convex and concave,blade is not straight.

 

Chatter when parting can be as simple as blade harmonics...Just changing the blade overhang can change things for the better....Shorter is not always the cure.Just enough blade for the work is the norm BUT things don't always work in real life like they do on paper..... :D

 

I've only been a machinist for 40 years,none of this is THE WAY, I'm still learning also..... :laugh2:


  • havlicek, MarkH, C. J. Bupgoo and 1 other like this
Gary "Booger" Baker

#56 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 9,202 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 25 January 2017 - 07:08 AM

See...this thread is turning (no pun intended) into an excellent resource that I'm going to refer back to!  Thanks Gary!

On a side and somewhat related note, I parted off one piece with the carbide tool I have here, and not knowing where it might end up...or fly off to, I took a little precautionary measure.  I chucked up a piece of piano wire so that the free end extended into the tube held at the other end.  When the piece separated, it just sat on the piano wire like I hoped.  I don't know if this was a good or a bad thing to do...but it worked just fine, and nothing exploded, caught on fire, vaporized or shredded and I still have all 10 digits and two eyeballs!

 

-john


  • Mach9 likes this
John Havlicek

#57 MarkH

MarkH

    On The Lead Lap

  • Subscriber
  • PipPipPipPip
  • 384 posts
  • Joined: 26-November 12
  • Gender:Male
  • Location:St. Louis

Posted 25 January 2017 - 07:36 AM

Use something to catch the part when parting off is pretty common. Sometimes a wire, as your example, a drill bit or even a small basket.

 

Ditto on Gary's comments.

 

I would add if you part off with the cutting edge down the cross slide will have a force on it in the up direction. No big deal if the slide has little to no slop in the ways. As long as the force is less than that which would lift the cross slide you are ok. Most of the time this is not an issue just pointing it out if you have to have odd stuff happening when parting this way.


  • havlicek likes this

Mark Horne

SERG - www.slotcarenduro.club
"Racing is life... everything else is just waiting." Steve McQueen - LeMans
There are only two things in life that make me feel alive. Racing is one of them.


#58 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 9,202 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 25 January 2017 - 08:25 PM

Thanks Mark.  This thread will definitely be a teaching resource for me with what everyone is adding!  Also, I'm glad to hear I didn't do something stupid with the piano wire!  :D  I half expected people to say..."oh my god, I can't believe that dummy did that!". :D

 

-john


John Havlicek

#59 LolaGT

LolaGT

    Rookie Keyboard Racer

  • Subscriber
  • Pip
  • 35 posts
  • Joined: 22-December 16
  • Gender:Male
  • Location:Fox Valley, WI USA

Posted 27 January 2017 - 11:33 PM

Depending on the total size of the lathe, you might be able to go to a restaurant supply shop and get yourself a used stainless steel pan with sides about 3" high to put your lathe in. (a rib pan?) You can drill a hole in the corner of this, add an ice cream pail, find a small fountain pump and hoses and have a cheap recirculating coolant system. Great for making some custom wheels.

 

You will probably want to go to McMaster-Carr and buy a diamond faced grinding wheel soon. Why? The 6" x 1/2" one fits in a small bench grinder and is great for making specialized cutter bit shapes out of various materials. It's much cheaper and easier than buying them. Downside is these are very spendy indeed but if treated well will outlive you. Mine is ten years old and I can see no wear anywhere, even where I ground Alnico magnets on it.

 

Ken


  • havlicek likes this
Ken Lyons

#60 havlicek

havlicek

    OCD Rewinder

  • Subscriber
  • PipPipPipPipPipPipPipPip
  • 9,202 posts
  • Joined: 20-August 07
  • Gender:Male
  • Location:NY

Posted 28 January 2017 - 08:31 AM

Thanks Ken!

-john


John Havlicek

#61 Dave Crevie

Dave Crevie

    Race Leader

  • Full Member
  • PipPipPipPipPip
  • 816 posts
  • Joined: 16-February 09

Posted 28 January 2017 - 04:19 PM

I wouldn't use a diamond wheel for sharpening/shaping anything but carbide tool bits. High speed and carbon steel

tools should be done on a green wheel, 100 grit or finer. Carbon steel and high speed tools are too

soft for diamond, and will knock off the diamond grit too quickly. Also, always back grind the soft shank and braise

material from braised carbides before using the diamond to touch up the cutting edge. Be careful not to overheat

the carbide while sharpening, as very tiny heat checks will form in the carbide structure, which will cause the sharp

cutting edge to chip away. I use only M-42 high speed steel tool bits for anything that has not been hardened, including

brass, bronze, aluminum, and cold rolled steel.

 

A good investment for a neophyte machinist is the "Machinery's Handbook", available at most book stores and industrial supplies. 


  • Mach9 and MarkH like this

#62 MarkH

MarkH

    On The Lead Lap

  • Subscriber
  • PipPipPipPip
  • 384 posts
  • Joined: 26-November 12
  • Gender:Male
  • Location:St. Louis

Posted 28 January 2017 - 05:48 PM

A better book for the learning or even experienced machinist is the American Machinist Handbook. It goes through setup and cutting theory to perform many machine shop tasks. I lost the one I had several years ago and stumbled upon these at Amazon one day. I now have this front and center on my book shelf.

Here is a link to this out-of-print jewel.

 

The Machinery Handbook has long been the standard since the Machinist book went out of print, It has a ton of information, mostly Engineering stuff which sometimes you just must have to get the job done correctly.


  • Mach9 likes this

Mark Horne

SERG - www.slotcarenduro.club
"Racing is life... everything else is just waiting." Steve McQueen - LeMans
There are only two things in life that make me feel alive. Racing is one of them.






Electric Dreams Online Shop