CNC lathe bed & headstock project

[The Blight]

First a little explanation of what I'm trying to do, and why.

I have just started working on a project at my school, where I'm supposed to design a lathe bed with headstock for DIY purposes. I am to figure out what people want from such a machine, and construct it. So that's why I need your help to figure out how this machine will be constructed (features, size..etc).

[Update with more information on the project]
This is a fictional project where I'm supposed to design a potential product for sale. In this case, I have targeted the DIY group, and perhaps some benchtop cnc companies. For this project I need to get information from the target group, and thats what I'm doing here now with this topic. When I have enough suggestions, and features that people want, I can start drawing the lathe bed.

I have made two topics here, and one of these is this one, and the other is in the "Mini Lathe". This topic is for those who have built a lathe from scratch, or have bought some sort of lathe for converting it to CNC. I will be asking a few questions, and you can answer these with as much details as you want. The more information I can get, the better.

If the project turns out to be something I can actually produce, and looks feasible, I might make a couple and sell them to those who want it. This is not something that is demanded of the project, but it could be fun to do as a learning experience. I will also have to say that I love these little machines!
You can use these questions as a guideline, but if you can, please just tell me what you want from a machine like this.

First some questions related to the construction of a lathe and CNC conversion.
Would you have done it differently if you could?

Were you pleased with the result of your project in the end, or did you have to make some modifications?

Did the project turn out the way you wanted it?

Tell me about your proejct!
-Please tell me with your own words what you have made, post a link to your topic or pictures, tell me your experiences.

And some questions related to the design of a machine bed specific for CNC projects.
If you were to buy a bed for the purpose. Size & shape.
Z axis length:
X axis length:
Swing over bed:
Max Weight:
Way placement:
-Vertical, horizontal or at an angle
Other:
 
Components for conversion.
What type of ways would you use?
-Linear rails, dovetails, box ways...etc

What type of spindle would you use?
-Mini lathe spindle or other?

How should the spindle be fitted?
-Installed from factory, bearing mount, machined by user...etc

What type of axis motor?
-Servo, stepper, NEMA size..etc

Placement of Z axis motor?
-Headstock side, or tailstock side

Connection type
-Coupler or timing belt

End support for leadscrew?
-Mounting holes, block..etc


And some general design questions.
Should I focus on making it simple for the user to make an enclosure for the machine?

Handles for lifting? Should it be so light that a couple people can lift it without the aid of a winch or other equipment?

Cable canals for placement of cables throughout the machine?

What would you focus the most on when buying a lathe?

How much would you pay for it?

Anything else you would want from it?

Thanks for your help guys! I hope I can make a good and fun project of this. I will be posting the results here in the end.

Questions, comments and everything you want to say regarding this project is welcome.

PS. For the admins/mods/JRouche:
I sent you a PM JRouche some time ago asking about making these topics. Please move or remove if you feel it necessary. Thanks.

[will gilmore]

Here is my build log: Granite surface plate lathe

I designed the lathe to be gang tooled with no tailstock. I will probably add some kind of tail stock for long thin parts but it would have been better to design it in from the start.

If you want things like waycovers, enclosures, chip pans etc they should be designed in from the start.

This is more into headstock design but think about a servo/stepper indexing the spindle maybe with a brake.

I built my project entirely on a fairly worn out bridgeport using pre-ground steel plate. Think about what tools people will need to complete the project.

A big question you need to answer is why buy (use) your machine bed rather than buying a 7x10 or 10x22. Bigger, smaller, lighter, heavier, etc.

What type of ways would you use?
One option I see is having a flat base with a precision shoulder to align a master linear rail. The end user could buy there own rails on ebay and drill mounting holes without needing precision tools.

I might also be interested in a scrape-your-own box or dovetail lathe kit.

What type of spindle would you use?
How about setting up the z axis and using it to bore the headstock. You do the design around and existing spindle and the user makes it.

What type of axis motor?
For small lathes I think the "crevice reamer package" G540 and keling steppers is a good fit.

--Will

[The Blight]

Thanks Will!

I will make a quick reply to do some more explaining.

I ask these questions to figure out what the user wants. The potential buyers of these lathe beds. And with this information, I will make a product that fits these requirements and wishes.

I have built a lathe from scratch, so I know a lot of the pitfalls and difficulties involved in such a machine. The thing I need to know, is what the user expects of such a product as this, and then make a product that fits these wishes.

Here is my build log: Granite surface plate lathe

I designed the lathe to be gang tooled with no tailstock. I will probably add some kind of tail stock for long thin parts but it would have been better to design it in from the start.

If you want things like waycovers, enclosures, chip pans etc they should be designed in from the start.

Thats good information. Something I can consider in the design process. When the potential user expresses a need for something like this, I can justify putting it in the final design.

Long X axis for tooling.

Potential tailstock. I will have to see if anyone else wants this.

Enclosure friendly design. Something that would be easy to add later.

This is more into headstock design but think about a servo/stepper indexing the spindle maybe with a brake.

I built my project entirely on a fairly worn out bridgeport using pre-ground steel plate. Think about what tools people will need to complete the project.

A big question you need to answer is why buy (use) your machine bed rather than buying a 7x10 or 10x22. Bigger, smaller, lighter, heavier, etc.

Thats one of the considerations I'm going to make. What tools does the user have to work on this with. I'm going to assume as little as possible, so that most of the thing has been made from the factory.

About the lathes you can buy:
Because those machines are not made for CNC conversions, and therefore will not allow optimal placement of components. If this lathe bed could compete with those in price, and supersede them in quality & functionality, why not pick a machine made for the purpose? I see quite a few people buying a lathe only to convert it to CNC. This is something that would fit those peoples requirements better. So I want to find out what those people want from a machine such as this.

And a question for you about your lathe: Why not do the same? Why did you go with a granite plate when one of those lathes could have done the job?

What type of ways would you use?
One option I see is having a flat base with a precision shoulder to align a master linear rail. The end user could buy there own rails on ebay and drill mounting holes without needing precision tools.

I might also be interested in a scrape-your-own box or dovetail lathe kit.

Thats one possibility, and a good suggestion.

Scraping is a special interest, but I will include this if more people want it.

What type of spindle would you use?
How about setting up the z axis and using it to bore the headstock. You do the design around and existing spindle and the user makes it.

This requires machinery and skills a lot of people don't have, but it is something I will consider. A ready made spindle would be a better option unless more people say they can do this. A factory made headstock will have more precision then what most people can achieve at home.

What type of axis motor?
For small lathes I think the "crevice reamer package" G540 and keling steppers is a good fit.

--Will

So NEMA23 motors. This also tells me a bit about the size of the machine.

And thanks again Will! Great information!

Would it be okay if I used a couple pictures and information from your project in my report? I want to get as many lathe designs to work from as I can.

[will gilmore]

And a question for you about your lathe: Why not do the same? Why did you go with a granite plate when one of those lathes could have done the job?

I like to think my lathe is better, smoother, more functional, rigid, accurate, precise etc than a chinese sliding way lathe but the real answer is that I enjoyed the design and execution of the project.

Would it be okay if I used a couple pictures and information from your project in my report? I want to get as many lathe designs to work from as I can.

Sure thing.

I'm curious how you are going to design the bed without including a things like linear rails or ballscrews which many people get surplus.

--Will

[The Blight]

Thats why most of us do these projects I guess. It's not like it's saving us any money or time, but damn its fun!

The way you suggested is a good option. A precision ground surface with a mounting shoulder. The user can either drill their own holes, or they can order it drilled from the factory.

And thanks!

[RotarySMP]

I CNC'd a 7x. The only reason I bought a 7x was because of space. The lathe is on a 1m bench on my inner city balcony, so nothing bigger would have worked.

It is a pretty crappy machine. but better than having none

I have:
Burnt out the cheap Chinese DC motor and replaced it with a 3/4 HP 2 pole and VFD direct driving at 1:3 belt reduction. I will probably make a gearbox for it to give me more lower speeds with more grunt for threading without loosing the top end.

Removed the compound and have an AXA Wedge type on a steel block.

Replaced the cross slide with a T-nut table.

Increase cross slide travel.

Replaced the Z screw with a ballscrew.

Tried to improve the horrible tail stock

Filed and scraped the underside of the bed casting to constant thickness.

Fitted X and Z axis home switches but then removed them again as I wasn't using them.

Made the Nema 23's drive through 2:1 belt reductions, which are enclosed to keep swarf out.

Made an enclosure with perspex panels which keep cracking an breaking.

Use TurboCNC as I don't have space for a monitor or desktop PC on the balcony, and Dos seems to deal better with the flakiness of laptops than EMC or Mach 2.

Hate TurboCNC V4.1 tool offset system. It does not work for me at all, so I can't set up a tool table for my 20 AXA tool holders.

Initially powered 137oz steppers off a NC-Step 297 based three axis stepper driver kit and 32V PSU. Now the drives are Phytron ZMX's and teh Z motor is a 287 ozin Keling. The x stepper will be replace next month, and I am replacing the 32V PSU with a 48V Chinese switching unit.

I am not a viable customer. I would not have bought a CNC lathe or a conversion kit. I really think the lathes you two have built are cool, but am more interested in doing a conversion of a tool room lathe, rather than a production lathe. Manual tool changing on the AXA is a benefit if you are only doing one off work, and using the lathe with collets, three jaw, four jaw, face plate, between centers, for also milling, fly cutting, tapping, threading, turning polishing drilling etc.

[The Blight]

Wow Thanks Mark! Lots of great information!

Now that you mention it, I have seen quite a few listing space as an important factor when buying a machine (lathe or mill).

As I'm only designing the bed and headstock, this lathe could be made to fit your own specifications. Attach whatever tool post you would like, whatever spindle you would like and make whatever feature you would like. I'm trying to cover as many scenarios as possible without it being too much.

There will be no motors, rails, screws or anything on this lathe. The only possible thing that would be on the machine from factory is a spindle. At the very least bearing seats for a spindle.

So instead of buying a mini lathe for cnc conversion, you could buy this bed that suits the purpose better. We will see if this becomes true in the end, or if it turns out to become a flop. An imaginary flop, so no money lost

So in the end, I'm only designing a building block for diy people who want to build their own lathe.

Thanks again for your time! Great feedback and information. Lets hope your project becomes something you are satisfied with in the end. Seems like you have put a lot of effort into it.

[Jason3]

Cool project!

I'd like to see a 7 x 12 size bed and headstock, with rebate ready to mount linear bearings (nice idea, Will), seats for the ball screw bearing mounts, provision for Nema 23 servos, direct drive, Z axis servo at the headstock end to keep it compact. Horizontal bed is fine for me, and I like the headstock with spindle and bearings option. A decent size through bore would be good, 5C collet nose with provision for a jaw chuck. Not too lightweight, solid enough to be a production machine for small parts would be great.

I built a really small lathe, about 2 x 6" a while back, it's posted here somewhere. It's big enough for 90% of the odd jobs I'd use it for if I hadn't sold off the servo drives a while back! Just a bit bigger would be ideal for me.

Oh yeah, yes on the tailstock.

Best regards,

Jason

[RotarySMP]

This guy has done a very thorough job of improving a 7x lathe bed:
Home

[The Blight]

Thanks for all the information Jason!

I'm wondering about one thing. Maximum weight? How much is too much?

I have a link to your lathe, and it is a nice little machine. I like the headstock

One more for the tailstock. I will be implementing this into the final design.

Thanks again to you Mark! Link has been saved.

[Guldberg]

Have you taken a look at the Tormach blog lately Tormach Lathe Developments « Milling Around They are cooking up a slant bed lathe for the same market as their mill

[The Blight]

Thanks Guldberg! Seems like they have many of the same goals as what I have come to. Will be interesting how that turns out.