Author Topic: Building a New Lathe  (Read 152504 times)

Offline vtsteam

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Re: Building a New Lathe
« Reply #250 on: May 14, 2015, 02:56:18 PM »
Volunteer work Eric -- training for teaching the next section of natural science demos in school (once a month), and then right after, school district union finance committee meeting in the next town.

Fabulous day outside today, trees leafed out flowers everywhere, makes the winter worthwhile!

Not getting much done on the lathe again -- too nice to go into my blockhouse shed!
I love it when a Plan B comes together!
Steve
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Offline awemawson

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Re: Building a New Lathe
« Reply #251 on: May 14, 2015, 03:56:04 PM »
I know that feeling Steve - I seem to have only a passing acquaintance with my workshop these days  :bang: Amazing how much time bottle feeding lambs can take up, but the spring springing all around makes it worth while  with thing bursting into life and at last the grass growing.

One possible benefit of this lack of time (but no doubt it'll cost me an arm and a leg) - I packed the digger with the hydraulic leaks off to a commercial transport garage to fix today. The 360 degree rotary coupling between the track base and cab assembly is the cause and needs pulling and new seals fitting, a friend offered the use of his HUGE John Deere tractor and flat bed plant trailer to get it there and while there they are replacing all (ten) track rollers and welding up the dozer blade for me. We caused a major traffic hold up in Rye when we got there in convoy  :lol: I'd given myself significant back ache crawling under doing the diagnosis so it's probably worth getting someone else to work on it. Anyway they have the right kit. It went straight onto a massive lorry lift, and was floated up in the air effortlessly - so much for aches and pains  :clap:
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Building a New Lathe
« Reply #252 on: May 14, 2015, 10:41:37 PM »
It will be nice to get it back in working order Andrew instead of making it another project when you've got five more on your mind! I think that was a good decision -- would have been frustrating otherwise.

More goldbricking for me tomorrow -- we teaching volunteers are invited upstate to a walk in the woods, nature drawing lessons, and other fun stuff plus lunch as an end-of-school year thank you, so I'm carpooling up there and won't get back til afternoon.

I think I'll be raring to get back on the lathe by Saturday. I need to put the bottom slide retainers on, and fit the gib and gib screws.

I've been looking at 3 jaw chucks on ebay. Can't afford anything fancy. Undecided whether it ought to be 4" 5" or 6" on the lathe -- lathe capacity is 9". The present cross slide might just by a hair fit under a 5" chuck. Not sure if it will. Certainly wouldn't clear the jaws if they protruded.

It isn't absolutely essential that a cross slide fit under the chuck, but I think it might prove handy some time. The 4" would surely do it. The 6" is thicker which reduces the bed length capacity, and adds to overhang and the possibility of chatter. It would be nice to have a 6" for capacity, but I think the turning drawbacks might be regretted later.

I'm thinking 5" probably....
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #253 on: May 16, 2015, 10:26:45 PM »
I have the retainers made up, drilled, countersunk, the carriage drilled and tapped. Put it all together with the need for only a single  ,001" brass shim on one side (normally I shoot for two on each side to allow adjusting down the road for wear).

But at supper time the carriage was still a little tight, so I'll need to adjust things tomorrow. I might have to give a little more relief in the carriage sides  for the retainers, because I think one of them is just touching on one side. And maybe add another shim. Then I need to make a gib. I sent for some socket head screws to use as gib screws.

I ordered a 5" 3 jaw plain back chuck.

I'll be making a backing plate. I'm thinking of recessing in it the entire spindle flange, not just the spindle flange register. That would shift the backing plate back and reduce overhang, and if it's a shrink fit, I think it might be stronger than just the bolts alone. It would just look like a bigger flange on the spindle.

I do regret that I didn't look more carefully at the mini-lathe spindles before I bought one -- I didn't think about the fact that they don't have a screw mount, but have bolt mounts instead. I guess it's more involved changing chucks as a result.

I was curious to see if there were any backing plate adapters for mini-lathe spindles that had a male threaded section for using threaded back chucks, but they don't seem to exist.
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #254 on: May 17, 2015, 09:39:42 PM »
Cross slide is working smoothly now, but I don't have gib screws for it yet.

I spent some time today trying to decide what to about the cross slide upper surface. I thought about tee-slots but I didn't like the thought of weakening the nice 3/4" thick surface I have now. If it was an inch thick to start with, I might have milled the slots in.

I could add more metal and fabricate tee slots that way, as I did for the Craftsman boring table I made a couple summers ago. But that raises the table itself, so you can't do as much with it.

I'm considering just drilling the top with a regular grid of tapped holes. Those leave the table much stronger than tee slots, and it gives me a big flat surface to mount things on as well as keeping the table lower.

I'm also thinking carefully about what kind of tool post I want. I already have both lantern style and a round post Norman QCTP with toolholders made up for both the Craftsman and Gingery lathes, so it would be logical to go with that QCTP.  style.

But I've long wanted to try out the style of tool holders and system written about by Robert M Rose in M.E (Nov 1972: 3452, 3453, setting Aug 1972: 3446). These are just simple tall blocks that clamp directly onto the cross slide (or top slide) no dovetailed QC tool holder or round post and block holders.

I like the simplicity and flexibility of positioning, and the fact that they do a better job of supporting the tool than the post and block type can, yet take up little space and are easily removed for other kinds of table operations

Another advantage I see in trying to figure the geometry of where to mount things along the cross slide-- It is easier to move these toolholders anywhere along the table to keep the cross slide clear of wide diameter work. I like the design of the base of the toolholder resting directy on the cross slide when the topslide is not needed. There is total support with no bending force on a post.

Much of what I've done in designing this lathe is to increase the rigidity and support of every part, and I think these toolholders will advance that philosophy. They are slightly less convenient than the usual types of QCTP, but for a small lathe like this I think they have the advantage of minimal overhang and solid bearing. A larger lathe can feature a massive enough QCTP that rigidity is not an issue, but I believe a small lathe like this can see a benefit.

Another nice thing about both the grid holed table, and the Rose style toolholders is that both are even easier to make than the usual types we see these days.
I love it when a Plan B comes together!
Steve
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Offline PekkaNF

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Re: Building a New Lathe
« Reply #255 on: May 17, 2015, 11:48:16 PM »
Toolpost rigidy is an issue and I noticed huge difference when I replaced the topslide with a sandwich block. I made two screw holes to mount QC toolholder to two different locations, other location allows tool well towards the tailstock (for boring and max diameter turning) and the other to bring the tool tip to front shear and right over cross slide way for maximaal stiffness. I had before huge problems with parting off, now motor power is more of an issue than toolholder/post.

Pekka

Offline awemawson

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Re: Building a New Lathe
« Reply #256 on: May 18, 2015, 03:02:25 AM »
Steve,
A matrix of holes is very versatile in that you can mount sub-tables with t slots or special fixing as you wish..
It also keeps a degree of 'post design design' letting you change your mind as the project develops
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Building a New Lathe
« Reply #257 on: May 18, 2015, 09:33:00 PM »
Thanks Pekka, Andrew  :beer:!

Andrew making bolt-on upper tables eg. T-slot type is something I hadn't thought of! That might come in very handy for a few things I've been mulling over.

For instance, I'd like to maintain the maximum vertical distance between the cross slide and the lathe center in order to be able to bore pieces that are fixed to the slide, using a fly cutter on an arbor mounted between centers. Looks like I have 2.5" + distance for that, now.

But for lathe tool holders clamped to the table (as in the Rose system mentioned earlier) 2.5" is excessive for the tool holder height. I'd rather they were say 1.5" maximum. If I bolt a short 1" thick auxiliary table to the carriage top, I can now reduce that distance by an inch, and also gain the advantage of T-slots for positioning the clamp.

Likewise I could make an auxiliary table with large round recess to take the foot of the topslide ways, so it can be rotated.  Normally that would be a recess cut into the cross slide, again, reducing stiffness -- so the cross slide normally must be heavier sectioned to accomodate it.

But with a bolt-on table top, the cross slide/boring table can be thinner (as it is here @ 3/4'), yet stiffer than a thicker section with a recess, plus the bolt-on topslide fixed base adds to it instead of subtracts from its thickness.

I like it! Thanks Andrew :bow:
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #258 on: May 19, 2015, 05:37:10 PM »
I drilled and tapped the cross slide for gib screws today, made up the cross slide gib, and installed some temporary long round head screws. I could then align and lock the cross slide to the carriage. With that in place, I could mark the centerlines for height and and horizontal location of the cross slide leadscrew.

I then pilot and step drilled the leadscrew holes in both cross slide and carriage. This was all done with an electric hand drill by eye while they were mounted on the lathe bed. I spent a lot of time checking with straightedge and square as I was going  for all the drill steps.

Once I'd opened the carriage out to the tap drill size, it was time to bring out the homemade acme tap and start tapping. Again checking frequently with square and straightedge to start with and making corrections to get a good start:

« Last Edit: July 11, 2017, 03:34:18 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #259 on: May 19, 2015, 05:44:33 PM »
The tap cut beautifully and surely, and I was extremely pleased to see the leadscrew center all the way through the channel, and turn by hand with a slight resistance (no handle) and no feeling of play or backlash. I doubt I could have got a better alignment with a drill press setup, trying to drill the carriage end-on vertically, even if I had enough range on my drill press -- which I didn't! 

A great relief that things all worked as well as I could have wished!!  :ddb:  :beer:

« Last Edit: July 11, 2017, 03:36:15 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline DMIOM

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Re: Building a New Lathe
« Reply #260 on: May 19, 2015, 05:56:54 PM »
The tap cut beautifully and surely, and I was extremely pleased to see the leadscrew center all the way through the channel, and turn by hand with a slight resistance (no handle) and no feeling of play or backlash. I doubt I could have got a better alignment with a drill press setup, trying to drill the carriage end-on vertically, even if I had enough range on my drill press -- which I didn't! 

A great relief that things all worked as well as I could have wished!!  :ddb:  :beer:

 :clap:  :clap:  :clap:  :clap:  :clap:  :clap:  :clap:   :beer:

Offline vtsteam

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Re: Building a New Lathe
« Reply #261 on: May 20, 2015, 09:22:10 AM »
Thank you Dave.  :beer:

I have to teach today, but hope to get a little more done on the ledscrew after.

I love it when a Plan B comes together!
Steve
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RobWilson

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Re: Building a New Lathe
« Reply #262 on: May 20, 2015, 02:23:29 PM »
 :clap: :clap: :clap: :clap: Just loving this project Steve  :thumbup: 


Rob

Offline vtsteam

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Re: Building a New Lathe
« Reply #263 on: May 21, 2015, 07:11:59 PM »
Thank you Rob! :beer:

Today's bits:

Made use of the core print in the ball handle. I turned it to 7/16" O.D. and drilled and reamed to fit the reduced end of the cross slide lead screw. Then 2 pieces of scrap brass bar were turned, and one drilled and reamed to fit the lead screw, and the other to fit the ball hande shaft. A set screw was put into the ball handle and a flat milled on the leadscrew to match:


« Last Edit: July 11, 2017, 03:36:50 PM by vtsteam »
I love it when a Plan B comes together!
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Offline vtsteam

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Re: Building a New Lathe
« Reply #264 on: May 21, 2015, 07:26:34 PM »
And putting them together this is pretty much how I think it will go. The inner disk will be the bearing and pointer, screwed to the carriage, and so, stationary. The other disk will be graduated. Leadscrew is 10 tpi, so i need 100 graduations.

I don't have a working dividing head. I do have a 5C spin indexer, but it is divided in degrees, and 100 into 360 isn't a go.

Today it ocurred to me I could probably take the graduated collar off of my mill carriage and rig it onto the lathe spindle, set up a pointer, and then cut the graduations with a tool in the tool holder. The mill dial also has 100 graduations, and it is several times the diameter of the new lathe collar, so it should be reasonably accurate, if I have me glasses on!

« Last Edit: July 11, 2017, 03:37:16 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline Joe d

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Re: Building a New Lathe
« Reply #265 on: May 21, 2015, 08:12:01 PM »
I like the looks of that one, Steve! :thumbup:

Of course, it's brass.  Brass parts are like puppies, impossible not to like....

Joe

Offline vtsteam

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Re: Building a New Lathe
« Reply #266 on: May 22, 2015, 10:52:57 AM »
Thanks Joe!  :beer: I've been hoarding half a nail keg full of scrap brass and bronze odds and ends bought at auction that I've hardly touched in 6 years. I decided lately I'd better stop storing it and start using it, or it wouldn't ever amount to anything but scrap!  :wack:

Thought a little more about simple dividing to 100 divisions, and decided I didn't even need to pull the division ring off the mill handle. Just work up a 100 division circle graphic in Sketchup 7, print it out, and contact cement it to a sheet of aluminum, thin ply, or acrylic. This gives a direct division plate, and it can be screwed to a collar to fit an arbor with a setscrew, or whatever.

Figured someone else here might find it useful, too, so I made a pdf of it, attached below. This prints to a 6" circle if you print from acrobat reader with no scaling and no "fit to page". You can scale it smaller, if need be in Acrobat reader. Or just print it out full size and cut it down with scissors.

6" gives divisions about 3/16" (5mm) wide so it should be possible with a pointer to direct divide by eye reasonably accurately. I'd say to within a tenth of a division or better. (Or in my case, +- .0001" in slide movement -- probably less than the thickness of the engraved line itself on the collar.)
I love it when a Plan B comes together!
Steve
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Offline awemawson

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Re: Building a New Lathe
« Reply #267 on: May 22, 2015, 11:28:33 AM »
Now if you had a 100 tooth change gear all you'd need would be a detente.

Nice handle and shaft Steve  :thumbup:
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Building a New Lathe
« Reply #268 on: May 22, 2015, 09:06:10 PM »
Thanks Andrew!  :beer: No gots on the gear. Drove tractor most of the day mowing and tilling.
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #269 on: June 02, 2015, 08:13:23 PM »
Yesterday I cleared some space under the shed roof extension so I could cast with the propane furnace. Today because it was still raining, I couldn't continue work with the tractor. So back on the lathe!  :thumbup:  I did a quick casting of some stock for some needed bolt-on bearings in ZA-2.

To save metal, greensand and time, I decided to cast it as its own sprue, in a soup can as a flask. No taper on the pattern. I just rapped it as I filled and packed the flask, so it was never too tight. Then I continued rapping as I drewthe pattern out -- very carefully. I had packed the sand quite tightly because as an open mold, it was naturally vented through the top. It left a very good impression in the greensand:

« Last Edit: July 11, 2017, 03:38:25 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Building a New Lathe
« Reply #270 on: June 02, 2015, 08:27:04 PM »
I overpoured because ZA-2 shrinks quite a lot just before freezing, and there is no sprue or riser to prevent a cavity in the part. This worked and using the method I got a very sharp casting with good clean corners using the tin can. It was very quick to ram up a mold this way, and used about a fifth of the greensand and no sprue. Without draft there is less machining necessary and less allowance needed, also saving time and material. I was very happy with this quick casting today. The part will yield 2 or 3 bearings when sawn into sections:

« Last Edit: July 11, 2017, 03:39:01 PM by vtsteam »
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Offline vtsteam

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Re: Building a New Lathe
« Reply #271 on: June 04, 2015, 01:06:37 PM »
Another casting, this time in copper alloyed aluminum. It will serve as a mount for the stepper motor attached to the shears at the headstock end of the lathe. I used aluminum here because of its good heatsinking properties.

« Last Edit: July 11, 2017, 03:39:27 PM by vtsteam »
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Steve
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Offline mattinker

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Re: Building a New Lathe
« Reply #272 on: June 04, 2015, 02:00:41 PM »
Another casting, this time in copper alloyed aluminum. It will serve as a mount for the stepper motor attached to the shears at the headstock end of the lathe. I used aluminum here because of its good heatsinking properties.



You should find that it machines nicely without the "gummyness" of the pure Al.

regards, Matthew
« Last Edit: July 11, 2017, 03:42:23 PM by vtsteam »

Offline tom osselton

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Re: Building a New Lathe
« Reply #273 on: June 04, 2015, 04:21:37 PM »
That is a nice surface on your casting.   :beer:

Offline vtsteam

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Re: Building a New Lathe
« Reply #274 on: June 04, 2015, 04:37:53 PM »
You should find that it machines nicely without the "gummyness" of the pure Al.

regards, Matthew

Yes, it did Matthew. Slightly "crunchy" with very granular swarf that I noticed last time. It still isn't harder than any other aluminum I tried scratching it against, but should be if heat treated (which I won't do), as I discovered last experiment.



Tom, thank you!  :beer: I've been reducing draft down to nothing and getting away with it lately by rapping "artfully". It works in these castings so far. Sand has been just on the borderline of dry for my usual ram up. So I have a lot of cleanup sometimes. But it seems to be working to give very sharp square corners -- really cuts machining alowance down (and machine time, too). I'm liking this!  :headbang:
« Last Edit: July 11, 2017, 03:40:14 PM by vtsteam »
I love it when a Plan B comes together!
Steve
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