Homebuilt CNC lathe with linear rails

[mwood3]

Spot on Mwood3, unless the head and tail bases are bolted down to a DEAD flat metal surface it'll twist, worst case scenario for any lathe, the tailstock also has no centering adjustment too.

The headstock front bearings appear to be just two ball races with no thrust adjustment.

I haven't worked out how to attach a link as the note on the Borer is in todays emails and I haven't worked out how to attach an email link yet.

You could try accessing SJH's history to see the threads he's active on and get the thread URL from there.

The email was A horizontal boring/mill machine build - Page 5 - CNCzone.com-The Largest Machinist Community on the net! so I hope you can access it...pretty awesome piece of work, and there were some videos of the CNC lathe working at cutting some threads too.
Ian.

Wow, that thing is a beast...so much going on there its difficult to take it all in. I think I will start much...much ....simpler

[mwood3]

I want the sindle to be belt driven on timing pulleys I believe. I guess I can purchase the mini lathe head stock assembly and gut the insides and then add a timing pully, would this work, is there a better way? also was thing of upgrading to the tapered roller bearings off the rip.

if anyone has a perfered setup feel free to post, Im still in the idea stage so lots of examples are desired.

Another topic that will most likely open up a can of worms here...Building material.

I have read all the debates on Steel VS. Cast Iron VS. Aluminum... I was leaning towards 3/4" to 1" thick aluminum slabs for the "bed" and most of the support structure. I was thinking of a common slab 1" thick for the head stock and linear rails to all bolt to. Cut out a channel between the Z rails to form a coolant chute, then take 4 slabs of ~3/4" AL and construct a box 6-8" high to mount to the bottom and form a base. I would also add ribbing as needed of course.

again, Ideas, comments, suggestions and flames welcome.

[handlewanker]

Hi mwood3, material is the branch in the road, make with steel....it needs welding, make with alluminium...it needs thicker sections and screwed together.

I would first of all "design" something on paper with the desired size you want to build to, to get the feel of proportions, then adjust the design as ideas on construction/materials etc come to light.

EG, you might want to adopt the spindle design with two back to back angular contact bearings at the chuck end of the headstock and two floating (axially) sealed plain ball races at the far end.

Drive could be with a plain Vee belt, no reason to go to a timing belt unless you want to have the spindle position under CNC control too for milling.

Lets have some simple hand drawn sketches as a preliminary opener, or if'n you have a graphics pad and graphics program (MS Paint will do for "simple sketching, but Photoshop is better), then it becomes a simole job to mix and match different combinations of bed shape, headstock layout etc......all depending on your metal working skill and machinery/time available, and a bit of cash for scrap yard prowling...LOL.

I'll post a simple mill layout to show what a graphics pad can do for getting something visible....I use a Wacom graphics pad and Photoshop 7 for all my doodling, saved in Jpeg format, and it makes life easier when you want to doodle without having reams of paper full of scribble lying about.
Ian.

[cyclestart]

Wow, that thing is a beast...so much going on there its difficult to take it all in. I think I will start much...much ....simpler

It's very well executed with a high attention to detail but it's not complex. Just to be sure we're on the same page here's a more direct link to that mini-lathe build.
http://www.cnczone.com/forums/vertic...the_build.html

Conversions usually run the z screw in the same location as the original lead screw. With a scratch built it may make sense to run it between the rails, although it tends to be a bit of a messy spot.

The tapered rollers...... the job is the same amount work done now or later ? Looks so to me.

[mwood3]

It's very well executed with a high attention to detail but it's not complex. Just to be sure we're on the same page here's a more direct link to that mini-lathe build.
http://www.cnczone.com/forums/vertic...the_build.html

Conversions usually run the z screw in the same location as the original lead screw. With a scratch built it may make sense to run it between the rails, although it tends to be a bit of a messy spot.

The tapered rollers...... the job is the same amount work done now or later ? Looks so to me.

Nice, almost exactly what I was thinking of making...I had not seen that one I was refereing to the previously listed link of the horizontal bore machine...

I think I would run my Z scew behind the bed kinda like the Haas V1's

[cyclestart]

A pic of of some of my spare parts.

For any lurkers wondering about the size of HSR25 rails, there's a rail and 2 blocks leaning against the headstock. For perspective that's a 5/8" ballscrew. These things are heavy metal and huge overkill but that's part of the fun The spindle housing is off a mini-mill but it's the same casting as a 7" lathe with a different spindle.

My dream was a servo powered lathe with a large camlock spindle. It's time to face my financial and time limitations and start building something

S_J_H's mini-lathe uses an intermediate set of pulleys to drive the spindle. What are the advantages over driving directly ?

[cyclestart]

S_J_H's mini-lathe uses an intermediate set of pulleys to drive the spindle. What are the advantages over driving directly ?

Originally the build shifted high/low, later the build evolved to a single belt. The builder has some good thoughts on the need for very stable rpm.

Nothing like replying to your own question lol

[doorknob]

I have seen that before, I like the machine but its a bit over my head at this point. Im looking to make a basic lathe with some static gang tooling and index/thread cutting ability...

I'm curious about what you are thinking of using for the gang tooling holder.

I've looked at a lot of turret designs but I'm also thinking of possibly mounting gang tooling in place of the compoound on my mini lathe.

[mwood3]

I'm curious about what you are thinking of using for the gang tooling holder.

I've looked at a lot of turret designs but I'm also thinking of possibly mounting gang tooling in place of the compoound on my mini lathe.

some single dovetail style mounts and holders will do fine...I will post pics when i get em

[handlewanker]

Hi all, I was just browsing on Utube from one of the links about a CNC lathe home build that got posted, (finished and working), and as usual with Utube, you go from one video to another and that leads onto another set of videos and another etc, but it also pointed out the advantages on one build of second op milling from the turret with a motorised head, doing the job in one hit without removing to go to second op milling.

This is "relatively" simple, that is it's already being done, no invention needed, just design factors in the lathe build, which highlights the need to START with the end result you want and go from there.

I would make the headstock drive by direct drive, IE, no belt drive, direct drive with VFD big enough to handle the workload, and build in the aspect of milling as well to a turret head......the milling head COULD be a single tool that gets attached in place of a single turning tool in a holder that caters for quick change single tooling that gets manually changed for each operation in place of a highly complicated turret mechanism....slow but it gets there, quicker build too and quite versatile, and more versatile than a gang miller set-up.

I think if'n you wants to drive a Rolls Royce, Lincoln Continental, Mercedes Benz or VW...whatever, you've got to design, (be it ever so humble or exotic), with that aspect in mind.

Why build another SJH wonder lathe....he's already proved it can be done and the how, but unless you have a bed and slide like Steve had you'll have to go to option 2 and design from there....fabrication all the way.

Most if'n not all of us can weld steel plate with a simple stick welder, so fabrication is not a problem and given enough weld, the thing won't fall apart...LOL.

The body of the lathe does not have to be precision alligned initially, (similiar to a rough casting), but it must be rigid, and it can be machined in spot areas to accomodate the slide rails whatever the type, but Hiwin or round linear bearing types all have their requirements for mounting, but you have to have the starting point to mount them on.

There's going to be a certain amount of "pawning of the Family jewels" unless you have a wad somewhere or borrowing/repay capacity, but even then I'd buy the bits and pieces over a period of time, even if'n it took stop start stages to get it to finally fly.

The Wright Bros, were bicycle mechanics, and look where they went...the sky was their limit...LOL.

So, for preference.....Alluminium or steel...the fork in the road.
Ian.

[cyclestart]

Another topic that will most likely open up a can of worms here...Building material.

One nice thing about aluminum is it doesn't have the same kind of internal stresses found in rolled steel. Steel can really boomerang when you start to cut into it. Welding can mean adding some additional stress. Raw cast iron is also stressed.

Pound for pound aluminum compares well to the other metals in stiffness. Other factors such as thermal expansion and the ability to dampen vibration ? Hmmm..... things to think about.

[mwood3]

One nice thing about aluminum is it doesn't have the same kind of internal stresses found in rolled steel. Steel can really boomerang when you start to cut into it. Welding can mean adding some additional stress. Raw cast iron is also stressed.

Pound for pound aluminum compares well to the other metals in stiffness. Other factors such as thermal expansion and the ability to dampen vibration ? Hmmm..... things to think about.

Yeah im really leaning towards Aluminum...so easy for me to machine and much easier for me to obtain...I have a local scrap yard that sells it for ~$2.00/LB... + I get to browse through rows and rows of surplus machine parts that all sells for scrap metal prices ~ $0.65/LB

If I do go with steel, My Brother is a pro welder, so Id get him to weld it all up then do the final machining and surface grinding. I know its still hard to gaurantee the material will be flat but better chances this way.

Also for the alignment of the rails I was thinking of adding 2 datum pins to one rail as a "master" then indicating the other in to it. I think doing this on both the Z axis and X axis would lead to less frustration and an easier time aligning everything.

thanks for the input everyone and please keep the idea coming, im taking notes!