Sunday, January 18, 2015

Running the numbers on the mill.

So I'm making the mill.

And I'm working the numbers.

And I'm thinking.

We need a better way.

Not my project here.  It's still going full speed ahead.

But I'm thinking about how a few years people used to share the reprap project.

They printed these vitamin kits as they called them.  Basically a set of printed parts that along with some electronics and hardware store parts, could be used to make another machine.

Then I'm thinking about the Daemon and Freedom(tm) books.

So our movement.  We need manufacturing and 3D printing will not cut it.  I mean it has it's place but sometimes you can't beat metal.

So this is what I am thinking.

What if I made a CNC router vitamin kit?  

Something that would work with a off the shelf plunge router.

It will work in aluminum and plastic.  

A set of parts along with hardware store parts to make a 2x2 foot router for $500-$600

Leave your thoughts in the comments.


Ok here is the situation.  I can get lasered steel and CNC bent parts done cheap. Like really really cheap.

So what do we need for this thing?

So I will break it down as to my view.

We need a box, which means if we use off the shelf plumbing parts we need corners.  Plumbing parts, (threaded steel pipe) is threaded at the ends.  We really don't want that for the corners using elbows.

Why?  Because you can not make a complete square with plumbing elbows without one corner connection having a reverse thread.

But what if we go with PVC pipe?

Then you run into issues of how do you attach parts to the PVC not to mention the obvious flex issues.   It could be stiff enough but the biggest sticking point is the attachment of the steel parts without having to drill precision holes.

Flexing could be solved by filling the pipe with fiberglass resin after assembly.

What about CoreXY?  I do not know it if it can work with the torque we need.  My CoreXY runs lightning fast but I am leery of sticking anything with torque on it. (you will have to google CoreXY for an explanation)

So what do we REALLY need?

Basically we need a steel box.  

Holes for the bearings, shafts, and guides.

Corners for the gantry.

So that brings me back to the Torchmate

It is a great machine,  but the linear slide is hard to get made cheaply.

Since we are going smaller, we can ditch the ball screw and go with threaded rod if budget is an issue.

Remember we are thinking along the lines of how did they ramp up manufacturing during ww2.  

Compare making Stens vs the Thompson SMG

So we basically need the Sten version of a CNC machine.

Once we have the router, we can use it to make bigger and stronger machines.

Gotta start somewhere ya know.

Why is CNC the first choice you ask?

Because it is easier for a noob to get up to speed making chamfers, fillets, and other shapes with a CNC than the tedious method of doing it manually.


Anonymous said...

Do it (please).

I will post this as set-up.

Thanks for thiking about this stuff.

And then doing it.


lineman said...

Have you seen the ghostgunner CNC Machine made just big enough to do AR10 and AR15 receivers...

Anonymous said...

Sounds fantastic.

Been following your posts since Dec. and learning about 3D printers as possible. I know very little but was a bit disillusioned by shortfalls in DIY 3D printers re: resolution, trouble printing unsupported spans, need to purchase prefab spools of filament (unless recycling plastic w/ another machine), and material limitations of plastic. Perhaps these are easy remedies or manageable for the most part.

Not much else to say except that a CNC kit as you mention would shoot to the top of my priority list. $1k-$2k is a bit hard for the wifey to swallow for a machine that can "just make plastic parts".

On a side note, ever thought of retrofitting a 3D printer to print in wax for investment casts? Again, no genius in this area but haven't seen any reasons why it wouldn't be possible, and saves the work of CNC on parts that would take many many movements to complete. Print 'er in wax, clean up a bit, pack in plaster, cast 'er in aluminum.

Anonymous said...

How about auto parts ?

Tucanae Services said...

As they say, "been there, done that." Don't reinvent the wheel, leverage off it. Such an item as you suggest exists. Its configurable. Its bolt together for the most part. It uses std design parts. I of course reference openbuilds. ( Just add the controller and PC of your choice.

The interesting thing about this design is that it utilizes a VSlot rail and mating wheels to provide the linear track. Add your own head (router/laser/FDM) and you have a multipurpose machine.

Anonymous said...

Printing 3D parts with metal *may* soon be within reach for an individual. claims to be building and selling small-scale (150mm on a side) metal laser sintering machines for ~$5,000.

The lack of released detail is stunning, but if there IS a working machine as described, it would be just as stunning.


Anonymous said...

Tracer mill or stock duplicator style perhaps? It probably needs to be a bit stiffer than the common cheap router duplicators of the past. Good luck.
Don't write off trim routers and die grinders as a powerhead either, one doesn't always need that plunge router kind of power and resulting bulk.

Anonymous said...

Hackaday will eat up an entire day if not careful.

admin said...

I do like Hackaday. One of my weekly visits...

admin said...

Locally the hardware store sells these clones of the Bosch Colt router. I was looking at that one. Add in a inverter motor controller and you got speed control.

Really the frame could be done in some 3mm steel plate, CNC bent and shipped as either 2, 3 or 6 pieces depending on how small you want the box. The guide rails can be made from lasered steel or water jet steel plate and bolted to the frame. I can get up to 12mm lasered but there is a bevel on the cut the thicker I go. One way around this is to laminate thinner sheets together.

Anonymous said...

It's not a big box hardware store item but we have at least one local stocking dealer in Denver:

Also, you can get unistrut at the big box hardware stores along with joining plates and a few other items. It's cheap and fairly rigid over short lengths.

Or you could go with threaded black pipe and add a union on one side to avoid the reverse thread requirement.


Vernon said...

Assume you are familiar with the Gingery books. Bootstrap machine tool building. Also, the Multimachine-Concrete-Machine-Tools group in yahoo groups. The overall concept is of a poured concrete structure with oversized openings where precision components are located. After the main structure cures, a non shrinking media is poured into the oversized openings while the precision components are held in alignment by jigs. The precision positioning jigs could be rented/shared/reused by an enthusiast community allowing high quality machines to be built with mostly local materials and relatively modest building skills. They apply it to a lathe but the idea should work equally well with a Torchmate style mill.