Thread: homebrew CNC-van norman mill

How bad would it be to run the ballscrews on the outside of the dovetails instead of in the center of them like a conventional machine. I know it is creating a bending moment, but I could do it just soooo much faster.

Need CNC capability for a few parts I make, but dont want to have to entirely remove all of the normal machine "guts"...just disengage them. I'd like to be able to swap back in a short period of time for manual operations.

-Jacob

What? Do you have a problem with commitment? Uh oh. Didn't you just get married recently?

The tone in your message already indicates you're not too hopeful about the proposition. I wouldn't know, but it doesn't seem like a good idea on the surface. Someone else may have actual experience to back up this suggestion.

Chad

I guess it's a problem with commitment...it could also be a problem with organization.

I dont want to take all the parts off the mill, then lose them. If it was just removing the screws, I could keep them nice and easily organized...anything else, I'm afraid they would disappear.

Not that the mill has much resale, I just hate seeing something go to the scrapper...and I dont intend to keep this mill forever, I would rather see it go to someone else as a garage machine for a heckuva deal.

-Jacob

The old piece of crap Beaver mill where I work has the cross feed lead screw located on the right side of the saddle. Don't know how well it worked when it was in good shape but now it's very hard to crank.

Wonderful old K&T 2CH has the saddle screw way off to right - outside dovetail (well, in a groove for the purpose)

Works fine. Naturally if you loosen up the gibs you will notice some "cocking"

Old machines that have done the deed for fifty or sixty years and face an uncertain future can benefit from thinking outside the box. Fear not. If it don't work, you will have learned something.

You probably know about rolled ball screws that are a little more bearable to buy.

John

Personally, I wouldn't... it bothers my mechanical sensibilities...

But, I wouldn't be afraid to do a full CNC conversion, but I'd put a nice MPG on it and "machine-by-wire" for manual stuff (which is what I do with my Shizouka - but, I use a trackball as the MPG with DiamondBack).

[img]smile.gif[/img]

Jacob, it doesn't sound like a real good idea to me as the ball screws would be open to swarf and dirt which could really mess them up in short order. Thats my 2 cents

Andrew

How would you disengage the normal screw to use the outside ballscrew?

Move the screw all the way to the right side, then remove the nut that holds it and the right side mount.

The Y axis will be coming off, but it comes off as one unit, not as a bunch of parts.

-Jacob

Snowman-
Would using a small cnc mill fulfill your needs? Could you sub the parts to someone with CNC?

OK- I know thats not what you want. But, after re-inventing several wheels, myself, I wonder if this effort is worth it. I've lurked here for quite awhile; been constantly reminded that making manual machines into CNC isn't a good idea. The cantilevered load with offset screw might be qwirky, let alone the other issues.

Could you create, convert or locate a salvage table/ saddle assembly? Motorize/ convert screws & attach this assembly to your existing Van Norman when you want CNC? I assume we're talking 2 axis.

Just a lazy old fart, daydreaming.

mike

It's considered "not a good idea" from a time-vs-cost consideration for industrial use; many people here would say that just spending $20K to $50K for a used or new CNC is better, because you can spend the time you would have used to do the conversion making parts, which will (according to this analysis, anyway) more than pay for the price of the CNC.

However, as I have pointed out in the past, that analysis is only valid when you can, in fact:

a) Spend $20K to $50K
b) Make up the purchase price by making parts (meaning you actually have enough customers, who pay you enough in a short enough length of time).

The other factor is the productivity of a new machine - which must be considered in light of the above criteria: does making two or three times as many widgets per hour make a difference? If your market is not saturated, then it makes sense to run the machine 24/7, as each additional widget made will be sold (however, if it is an elastic market, you can potentially end up driving the price below the cost-to-produce that way). However, if the market is saturated, additional productivity above that required to maintain market saturation is useless - your product will sit on the shelves (and, if the capacity under discussion is split amongst competing suppliers, the result is often a price war as supply exceeds demand).


So - if any (but not necessarily all) of the following describes your situation, then perhaps a conversion makes sense:

You don't make very many parts, and you will not be increasing production.
You have little capital to spend.
You are interested in a secondary machine.
You are just getting started and need a low-cost-risk approach because you are using personal funds.
This is only a part-time occupation.
This is not for profit.
You are interested in learning about how a CNC works.


Well, that's my view, anyway... [img]smile.gif[/img]

I think that me saying that I expect this machine to perform as well as a Haas minimill would be a complete lie.

What I have, are a bunch of parts that could be made on an ironworker, cnc plasmacutter and CNC router very efficiently. Or a CNC mill very unefficiently.

I think hammerhead hit it on the head though, my market is saturated, if I sell one a week, I'm lucky. Being able to produce 1000 a week vs 10, isn't really going to make me any extra money.

I could get them all farmed out, and again, buy in large bulk,, but at that point, I would have to charge what all the "retail" establishments charge, and at that point, who is going to buy from the independant?

For me, it is a self supporting hobby that was created such that I could pay off debt and continue to buy machines without the fiance saying "what do you need a $xxxx machine for? Granted, I could get a job that pays 20-25 bucks an hour, and probably pay off the debt much faster...but it would be a job that I wouldn't like, and I wouldn't be able to "do my own thing".

-Jacob