micro lathe from scratch - maybe

[Arbalest]

Will you be using Precision ground stainless?

[zeeprogrammer]

Thanks Chuck. I'll need to keep that in mind. I'd be able to do those cuts but not sure about other people.
Thanks frazer.
Arbalest...don't know at this point.

Tim...
You're the first I've come across who knows anything about Rhino.

I worked for Rhino for 9 years (1982 to 1991). I was Chief Engineer (easy title given there was only one other engineer - although at one point we had half a dozen).
I designed the Mark III and Mark IV controllers - soup to nuts except for the box. Both hardware and software.
It could control the standard articulated arm or a SCARA.
I saw that they had moved to Ohio. Not sure if it's the same owner but I think so.
What they are offering is the exact same thing that we were manufacturing in 91.
I don't know if they're still making them...or still selling inventory. I suspect the latter. They might not be doing anything actually.
I've seen that site for a number of years and haven't noticed any changes.
The Mark III was based on a 6502 and written entirely in assembly. Used an Apple II for development.
The Mark IV used an 8188 and some 8051s and was written in 'C'. Used an IBM XT for development.

BTW...one of our robots was in the opening of 'Short Circuit'. It's the one picking up the phone.

There are better small systems out there now.

I also worked on some slant bed lathes that we designed and manufactured. But my involvement was pretty limited and I'd left soon after.
We also had a small mobile robot (Scorpion) and...for whatever reason...a motorized wire cutter.

Ain't it funny how things come around? Now I'm playing with lathes.

[dieselpilot]

I just spent a lot of time looking for 8mm ground but not hardened shaft. You can buy chromed/hardened 8mm ground shaft all over the net. The stuff is used in many 3D printer kits. Some kits use ground drill rod. For this project I would use the hardened and chromed shaft even if it means you have to cut it with an angle grinder or mount a cut off wheel on your bench grinder. The key words for google are "metric TGP shaft" or "metric precision ground shaft" and don't waste your time with what look like industrial sellers, they have minimums and want PO's and such. VXB offers a good shaft in a few lengths. I bought one a while back to replace an RC motor shaft.

It's an interesting project. I think the trickiest part, if you'd like others to emulate it, is finding a suitable spindle of some sort that's off the shelf. What's your plan here?

[zeeprogrammer]

Thanks dieselpilot.
First approach will be to use what's easy to get/cut/etc. just to get something together. Then see if better material is warranted.
My mechie friend at work has a 3D FFF printer and good knowledge of shafts, rods, etc. as well as knowledge of where/who to purchase from.
So I'll depend on him a lot.

As for the spindle...yeah. That's the question. Whether to provide a through hole or not. For now I'm looking (and have ordered) a 2" 3-jaw. It has a 1/2-20 thread in back. Will see what can be done with that. I'm not worried about gearing and drive other than what motor to choose.

As it turns out...there's a whole lot of information out there of similar projects. A friend of mine sent plans for one that is very similar to the idea I have. But as I find out...most (if any) were never completed.

Another area of question is CNC. This is an area I know next to nothing about. I understand the general process and end-result but how to get a free/open source program to take a model and generate g-code that is appropriate for this design...I have no clue.

First step is to provide manual input. Something like a knob attached to a quad encoder that can be fed to the control board to drive the motors.
If there's sufficient interest in this then maybe someone else will be interested in providing CNC capability.

Whether this (like others) is successful or not won't be answered for some time. In the mean time...it's fun.
And I'm very used to having fun-filled failures. 

[gmac]

Carl;
Here's some inspiration;

http://machineshop.olin.edu/resources/documents/Prison%20Camp%20Lathe.pdf

I started down this path - lathe build, not prison camp - and did a lot of searching. At the time I couldn't locate a used lathe (small town) and considered building a simple one. Soon started to realize the cost was getting up there. Out of the blue I found a used Taig lathe for $175 and didn't look back. Anyway some of the stuff I found that included plans;

Building a Tabletop Lathe   Phillip Gates  Model Engineering 16 Nov 1962
A Lathe You Can Build        John K. Mold  Model Engineering  o1 August 1965
Constructing a Simple Lathe  Martin Cleeve  Model Engineering 15 Sept 1955

Martin Cleeve's stuff is particularly good; and most of these articles are valuable from the point of view of understanding the methodology of building the lathe.

This set of plans is particularly simple and quite cleaver in it's use of standard auto parts and stock material. Probably a quick/cheap way to get your feet wet if you want to get serious about a lathe build;

Midget Metal Turning Lathe A.D. Mayo   old Popular Science or Popular Mechanics article

Good luck and post results either way. Now you've gone and peaked my curiosity about the subject again - RATS........ 

Cheers Garry

[zeeprogrammer]

Thanks Garry. Good information.
I remember the story of that fellow. Pretty amazing isn't it?
Thanks for the info.

Now you've gone and peaked my curiosity about the subject again - RATS........ 

Hee hee. One goal accomplished. 

Just received the little 2" 3-jaw. Cute.
Fits my mini-lathe tailstock so it might not be a complete waste.
A bit tight. We'll see if it works out.
Looks like a tad of rust too in a couple of holes where the 'wrenches' are used. But otherwise looks decent.
From Grizzly H5934 but with no 'Made In ...' anywhere.
Certainly can't use this in 'reverse'. It'll spin right off (but I think some of you have lathes with the same consideration).

Anyone else have one of these?

[mklotz]

I see it uses tommy bars (what you called wrenches) like the Unimat 3-jaw does.  They can be a pain if you use the chuck a lot.  You may end up deciding to make a couple of pin spanners.

If it doesn't work out for your project, you can use it as is in the TS to hold reamers/whatever that exceed the current TS chuck capacity or...

make a fitting to attach it to your live center and you can support parts that don't or can't have a center hole.

[zeeprogrammer]

I see it uses tommy bars (what you called wrenches) like the Unimat 3-jaw does.  They can be a pain if you use the chuck a lot.  You may end up deciding to make a couple of pin spanners.
 or...
make a fitting to attach it to your live center and you can support parts that don't or can't have a center hole.

Tommy bars. That's it. Thanks Marv.

What would be a 'pin spanner'?

I didn't understand that last bit about attaching to a live center. Would you mind explaining more?

Glad to see you pop in. I have to admit I was wondering.

[mklotz]

I'm thinking of a device that looks like this:

http://www.use-enco.com/CGI/INSRIT?PMAKA=307-3642&PMPXNO=8577656&PARTPG=INLMK32

Doesn't need to be adjustable as that one is for your chuck.  It's a doodle to make two of them.


On many live centers it's possible to attach "stuff" to the part of the live center that rotates with the work.  Sometimes it takes a bit of ingenuity to design a suitable interface but most times it can be done.

Now imagine you want to machine a large armature with integral shaft.  The shaft is hardened so you can't drill a center hole in it but the part is long enough that it requires outboard support.  So you grip the TS end of the shaft in your 2" chuck attached to the live center and Bob's your mother's brother.  The armature is just an example.  Other situations requiring this approach crop up, admittedly infrequently.

[zeeprogrammer]

Whew. Two of those wrenches is more expensive than the chuck.
The chuck is fairly cheap. Very stiff and hard to remove/reverse the jaws.
I don't know if it will get better with use.
Should come in handy though.
Your suggestion of using it on the tailstock is something I'd thought about when I considered the purchase.
If the lathe idea doesn't work out...I thought it would still be a handy bit of tooling.

[mklotz]

Whew. Two of those wrenches is more expensive than the chuck.

No, no, no.  The picture was just to show you a spanner so you'd know what I'm talking about.

For your chuck, the expectation is that you would make your own spanner(s).  A quarter segment of metal with an ID to match the chuck OD, a pin to fit the tommy bar hole, and a handle and you're done.

[zeeprogrammer]

Got it. Thanks Marv. Yes quite do-able. It's in the rountoit 

[Firebird]

Hi

I'll throw in another couple of ideas if I may. I mentioned earlier that I collect the inserts from old car shock absorbers. Heres a selection.



The smallest is 11mm followed by 13mm  20mm  and 28mm. Very useful stuff and beautifully ground.

This is the high speed head I made for my Myford lathe, it gives me a 9 x increase in speed



Its works ok but I still have a big cumbersome lathe. I'm thinking of using it on a stand alone lathe with its own motor.

The spindle is an R8 - 2MT adapter. machined to go through 2 taper roller bearings. Screw cut on one end to take an adjustment nut and screw cut on the other end to take Myford chucks and collets, from memory 1 1/8 whitworth. They are quite hard but will machine.

The following photo shows the one I machined first, not quite right the myford thread is a bit rough so was abandoned and another onee made. Its shown along side an R8 adapter, slightly different in length to the one I used but you can see where I had to machine it.



Cheers

Rich 

[zeeprogrammer]

Thanks Rich. Some good food for thought.

But gee...I feel bad you are taking time away from your daughter's table and chair and your wife's kitchen handles for me.  I am hardly worth it. Your projects will get done while this one may never start. 

[fcheslop]

Not necessarily these but Iv seen a simpler set up just cannot remember at the mo
http://www.festo.com/cms/nl-be_be/21071.htm
cheers