Homebuilt machine design

[BodaciousBrian]

I've been giving serious consideration to making the following machine:





I plan to mill aluminum, or possibly harder metal. I just want to make/mod my own custom paintball gun frames and body's and other pneumatic parts.

There is wood in its construction, but the first thing it will make will be metal replacements for the wood. As of now i'm planning to mount my dremel too it. It measures 20" x 20" x 18" excluding motors. All the rails are 3/4 U channel facing each other ( [_] ). The screws would be 1/4" acme threads. I'm planning to use steel or another weldable metal for the frame and rails. After reading some posts it seems that a gecko 540 with 300 oz/in is the way to go.

I have never machined anything before, so there could definitely be some very obvious fault that I missed. Is there anything that wont work? Will this be able to mill aluminum? If i were to not use the dremel, what would replace it?

[mwood3]

You ---><----CNC machine designed this way...lol

just kidding with you, but seriously you will need to keep reading in this benchtop forum to get better ideas, this design is seriously unrigid/flawed for the purpose you stated or any type of cnc machining other than maybe styrofoam...

what kind of budget are you working with? that is a good starting point for advice now that we know what you will be cutting, also what is the size of the largest part you need to cut?

I think you may find it is cheaper to buy your first machine rather than build it....(im talking about the actual machine itself, not the electronics)

[BodaciousBrian]

i was hoping to stay around 600$.

the biggest piece i plan to do is 2x4x8 in. the size of a paintball gun body.

[mwood3]

if you want the G540's i doubt that $600 will even cover all your electronics.... the G540 is $299 alone (not trying to steer you away, it is a very good controller) just putting things in perspective for you. then you will still need 3 stepper motors, lets just say 3 x $59.00 a power suppy, depends on what you want but a rough estimate of $80 so just that stuff is $556.

again im not trying to discourage you at all, but if you want to keep in your budget you will have to go with low end stuff.

just for comparison purposes an average X2 CNC conversion including the cost of the machine would cost around $1500. It can be done alot cheaper or alot more expensive.

hopefully in the morning some of the more experinced guys will chime in and help you out.

GL

[mwood3]

Stolen from another thread on this forum, but this is more how a machine would need to be designed to do what you want, the size would be adjusted to accomidate what you are cutting.

Originally Posted by Joezx10r Well Ive reevaluated my needs and am thinking a smaller machine my be better for me so heres the new design using 6x6x25 1/2 inch wall tower and 5x1x20 base rails. Enco compound table and X2 head.

[SpeedsCustom]

You WOULD not be able to cut a paintball body with a machine designed that way, and 600 for an entire build. Unless you buy the low end stuff than yes, but you sacrifice quality and it will show in the parts or maybe not even at all...

Look around, do research and than design.


-Jason

[SWA Guy]

Okay here's my two cents worth of advice, and it may be worth exactly what you paid for it.

Even as a non-Engineer I see some serious rigidity/flexing issues with your design. Something like that may be a good starting point to refine the drives and motors, and learn from though.

On my local craigslist I currently see three RF-30 clone mills for sale from $400-$800. Any of these would be much more rigid than your design. They do have their own issues, but nothing that's insurmountable.

If you bought one of these heavy and relatively rigid machines, tuned it up a bit, you could actually begin machining some of your air gun ideas, in aluminum and steel, while you design the CNC conversion. You have the added benefit of several people ahead of you that have already done a conversion of virtually identical machines. They could be valuable resources of knowledge.

Good luck and keep us posted on your progress.

Guy in Sacramento

[joesz]

A dremel tool has no where near the horsepower required and the spindle bearings are not good enough to mill anything except maybe styrofoam. You would not even be able to take heavy cuts in balsa wood with that. For milling aluminum you will need a much more substantial spindle setup. Hell you can not even put a tool with a larger diameter than 1/4 inch in the dremel it would be worthless as a machine spindle. A word about Enco products they are cheap but they are junk, the slides fits will be so lose you will never hold any kind of accuracy. That whole design would end up being a dissapointment to you, there are certain requirements for a machine even if it is for light duty work and that certainly will not work for you not if you plan to machine anything but wood and dont need anything more than maybe +/-.030 accuracy in fact you would be lucky to hold that. You would be better off contacting a used machinery dealer and at least buying a base machine to start with, maybe something like a bridgeport, you should be able to pick up one fairly cheap. It may require some work on your part to get it into shape but you have the basic metal to start with, and a decent spindle.

[cnc4cheap]

Brian,

I have been involved with precision machinery for over 40 years. Neither of the two machine concepts would be capable of machining aluminum let alone steel.

Save your money until you have enough to purchase a dovetail column milling and drilling machine and then build your CNC machine on that foundation. That would enable you to build your CNC machine components with the machine that you plan to retro-fit.

Just some advice from an old man that has forgot half of what he once knew and can't remember where he put the other half.

C4C

[BodaciousBrian]

Thanks for the advice guys!

Naturally I have a lot to look up after receiving so much information.

I'm gonna go ahead and look up mill/drill machines that could easily convert to CNC.

[tjwal]

With a work envelope of 2x4x8 an X2 mill would be big enough. They can be bought new for about $500. If you can find an RF30 or larger mill for a decent price, even better. There are a number of threads that discuss CNCing these mills.

Since you haven't machined anything before start with some manual milling.
That will give you a better idea of what you are getting yourself into.

If you really want to build your own from scratch, take a look at
www.cnczone.com/forums/showthread.php?t=21872

this was designed to route wood but apparently is also capable of light cuts in aluminum.

JohnW

[LeeWay]

Originally Posted by cnc4cheap Brian, I have been involved with precision machinery for over 40 years. Neither of the two machine concepts would be capable of machining aluminum let alone steel. C4C

The second design suggested is very capable of milling aluminum, steel and anything else you might want to cut.
It depends on the type of material and mechanics, but the design is solid enough.
Been done similarly plenty of times just here at the zone.