RPMs for Lathe Work

[dwhite]

I'm glad I asked. I had no idea it was that complicated but it makes sense.  I won an old Waller graver sharpener and was wondering how to apply diamond compound.  I'm building a Rube Goldberg sharpening machine, just waiting for it to get warm enough to go out into the barn to do some welding.

[jdm]

On 1/19/2018 at 4:54 PM, measuretwice said:

the first is the rotary lap I made, it could be used for the ends of gravers, I made it for machine tool scrapers which need constant resharpening...

That is, you made the stand and adjustable plate? Could you tell a bit more how? 

[measuretwice]

3 hours ago, jdm said:

That is, you made the stand and adjustable plate? Could you tell a bit more how? 

I'd be pleased ...apologies if its is too much, but its hard to tell the story without telling the story.  I wrote a 12 part series that appeared in Home Shop Machinist magazine on scraping - the build of the rotary lap was included in the how-to series so I have a inventory of build photos.  The whole point was a way to achieve fast and perfect scraper sharpening.  I haven't had that particular lathe in a long time - this must have been built 10 or 15 years ago.

Anyway it started with a cheapo offshore bench grinder.  The tricky bit is the way the laps mount.  I made taper hubs for the rotor that are loctited on and turned in situ so the surfaces are perfectly concentric.  These are a careful fit with cast iron disks (the laps) so the laps can be removed charged and remounted.  The taper adds complexity but ensures minimal run out, not easy to otherwise achieve on something that has be taken off and remounted like this.  Failure on that would lead to lots of vibration, possibly at a dangerous level as the disk are lot heavier than grinding wheels it was designed to carry.  As it is, it runs very smoothly.

The rests and frame are simple machining/fabrications.  Here's some more photos of the build re the tapers....its tricky getting tapers to mate while also mating on a face, the process is a series of specific steps I'll gloss over slightly as its probably too tedious and OT for here.

The laps start as 6" dia drop

rough turning then I split the drop to get two disks

The disks are rough turned, drilled, taper bored and mounting holes drilled and couterbored

Note the outside the of disk get turned - I made arbor to fit the disks.  Turn in situ on the shaft would not have been rigid enough and chatter would have resulted

finished disk arbor

It gets dialed in with the 4 jaw to perfect concentricity

and the disk OD and face are machined

before removing the arbor, the compound is dailed in to exactly on the taper - so the hubs end up a match - the roughed out hubs get cemented on the rotor

and turned in situ on the lathe.  The most difficult part is achieve the right mate on the both taper portion of the hub, and the back.

 

thats pretty much it.  the frame simple cut and braze and rests very basic machining stuff - not much more to tell other than whats visible in the complete unit

Edited February 6, 2018 by measuretwice

[dwhite]

Wish I could do something like that.

[measuretwice]

5 minutes ago, dwhite said:

Wish I could do something like that.

I have no doubt that you could.   Like anything technical,  break it down into little enough steps and explain the underlying rational and it looses its mystery.   I've been at it so long I don't get how most folks get through their days with a couple lathes and mills in the garage

Edited February 6, 2018 by measuretwice

[jdm]

21 minutes ago, measuretwice said:

<... lots of awesome work that I don't fully understand :>
the frame simple cut and braze and rests very basic machining stuff - not much more to tell other than whats visible in the complete unit

Seeing your pics Ms JDM said that must be a "svitamuorzolo", whatever that means.

I was curious about the stand because I'm getting a small grinder, and such an accessory would be very useful. It may be not much to make for you but for many here, including myself, would be a big achievement.

 

[measuretwice]

ah ok, I wasn't trying to sound flippant, just that in telling more about it I wanted to show the stuff I thought the most interesting.  The stand is 1" sq tubing.  The end posts were 12L14 so I couldn't weld them, they got brazed...the rest is welded as per photos below.   The table is 1/4 cold rolled and works in either end.  At one point I'd thought to make one end diamond for carbide and maybe aluminum oxide for steel on the as its best not to use diamond on steel.  The other pieces are basically bar stock machined, I don't have much more in the way of photos but I could email you drawings if it would help.

 

 

 

Edited February 6, 2018 by measuretwice

[dwhite]

Perhaps I will someday although I'm getting old.  I've done a  bunch of things: teaching high school science, lab work, jeweler, wrote technical manuals, became a violin maker, musician, studied electrical engineering, built my own house and now learning watch repair.  Mostly I just like learning new things.  Don't know where I would get the bread for machines like that though.

[jdm]

Nice. It's a big base. All I should have to make one are the 

10 hours ago, measuretwice said:

ah ok, I wasn't trying to sound flippant, just that in telling more about it I wanted to show the stuff I thought the most interesting. 

Thanks, to make something like that all I have ATM are the clamps. But my grinder is a jeweller's type, 1/6 HP. Probably will be enough on a wooden base and fix the plate stand on it. On the other hand I don't have a lathe yet, much less the gravers.    

[jdrichard]

Perhaps I will someday although I'm getting old.  I've done a  bunch of things: teaching high school science, lab work, jeweler, wrote technical manuals, became a violin maker, musician, studied electrical engineering, built my own house and now learning watch repair.  Mostly I just like learning new things.  Don't know where I would get the bread for machines like that though.

Professional Electrical Engineering, Build a few guitars, play guitar, built a house, do closeup magic, fix watches and vintage pocket watches, lots of tools everywhere and still married:)


Sent from my iPhone using Tapatalk Pro

[dwhite]

Good for you jdrichard!