take a look at this rough design. all ideas appreciated

[axkiker]

hey everyone here is a very ROUGH sketch I have worked up for a mill that I plan on building. This mill will be mainly used to cut aluminum so needless to say it must be strong. I plan to build the main frame of the machine out or either 8"or 12" I beams. So I think I will have the strength however cutting power may be another issue. I will tackle that when the time comes. Anyways what can you see that will cause me problems with this preliminary design.

[andy_ck87028]

I like it alot.

I like the access to the cutting platform and the absence of moving parts makes for easier wiring.

Flex obviously could be an issue with the gantry but you have heaps of opportunity to beef it.

The biggest weakness that will need attending to is the possible racking of the moving table and if you look at this current thread (http://www.cnczone.com/forums/showthread.php?t=51485) , you will see how to solve it .... easily!

Good luck and keep us posted.

Andy

[axkiker]

Originally Posted by andy_ck87028 I like it alot. I like the access to the cutting platform and the absence of moving parts makes for easier wiring. Flex obviously could be an issue with the gantry but you have heaps of opportunity to beef it. The biggest weakness that will need attending to is the possible racking of the moving table and if you look at this current thread (http://www.cnczone.com/forums/showthread.php?t=51485) , you will see how to solve it .... easily! Good luck and keep us posted. Andy

Wow I read through that thread and think I know less now than before I started. LOL Someone will have to give me the short simple version of that.


Im hoping to not need much else in the way of support. Im hoping the gantry will be strong enough since im using 12" I beams for the frames.

As far as the table I am also going to make that from steel. Or I think so anyways. Possible 1/4 thick.


Anyways im just gonna build it as solidas I can and see what happens.

[Mr.Chips]

Really like the big open side and with a fixed gantry you can really cut loose with all sorts of bracing.
Not sure if you have settled on cables but if you are using twin screws this will also be a big aid in preventing racking as well as minimizing the number of moving parts.
Keep the design coming, and pictures soon.

[wcarrothers1]

Not to be down on your design.. But every time I see some one comming in and saying they want to cut metal. I keep thinking they should simply convert a round pole mill to CNC. I converted mine and it works very well...

Just getting a spindle that runs slow enough with enough torque to use on your machine is going to be hard enough.. (for cutting metal anyway.)

Course I also think to my self.. Hmm I purchased a fully functional bridgeport CNC mill for 1k. and I know others have as well. and I'd say it would be more capiable of milling metal then anything most could build them selves. So if that is what you want to do (cut metal) search around for one. You might just save your self a lot of work.

Plan on cutting wood ect... that is another story.

[axkiker]

Originally Posted by Mr.Chips Really like the big open side and with a fixed gantry you can really cut loose with all sorts of bracing. Not sure if you have settled on cables but if you are using twin screws this will also be a big aid in preventing racking as well as minimizing the number of moving parts. Keep the design coming, and pictures soon.

NoI have not settled on cables orany type of screws. I really have not researched that yet. I kinda like the idea of twin screws. Because the ridgity will be key to making this work.

If you have receommendations as to what type of setup to use feel free to speak up. Im a newbie here

[axkiker]

Originally Posted by wcarrothers1 Not to be down on your design.. But every time I see some one comming in and saying they want to cut metal. I keep thinking they should simply convert a round pole mill to CNC. I converted mine and it works very well... Just getting a spindle that runs slow enough with enough torque to use on your machine is going to be hard enough.. (for cutting metal anyway.) Course I also think to my self.. Hmm I purchased a fully functional bridgeport CNC mill for 1k. and I know others have as well. and I'd say it would be more capiable of milling metal then anything most could build them selves. So if that is what you want to do (cut metal) search around for one. You might just save your self a lot of work. Plan on cutting wood ect... that is another story.

Well I have thought about exactly what you are saying. Alot of this project is for the FUN factor and alot is because I really do need a CNC mill for some stuff I sell to the marine industry.

I have a JET knee mill here at my house. I think it has a 2 hp spindle and a
9"x36" table. Its not huge but Its perfectly cabable of cutting metal.

I have a couple issues with trying to convert it over to cnc. #1 being size. The type of stuff I cut is not that thick but fairly long a wide. I make a few parts which are roughly 24" x 25" Getting things like this setup in a knee style milling machine takes alot of time and effort. 99% of the stuff I make could be related to a piece of plywood. Its around 3/4" thick but cut into the shape desired via a cnc mill. It just happens to be aluminum. #2 is speed. Yes the knee stype mills are perfectly capable of cutting metal but typically dont at a very fast rate. Now I understand that I will not be able to cut metal at a lightning fast rate however I dont plan on slowing the spindle down to a typical knee mill speed. I plan on running something as fast as I posibly can. Yeah I will need constant coolent and chip removal but I dont see a way around it. I guess the easiest way to describe what im trying to build would be something like one of the large HAAS CNC type mills.

It may never work or work right. However im gonna give it a try and see what I can come up with. At the least I guess the darn thing will cut plywood.

im still searching for some I beams.

[wcarrothers1]

good arguments for going through with it.

I understand the speed stuff. How ever my bridgeport can rapid at 150ipm or a little more..hehe that is pretty quick

My converted is more ~50ipm

But will admit I do most things on my 4x8' which is pretty quick.

Anywho. Looks like a good project. Think the 1 armed gantry could be cool long as it can be squared with the table well enough.

b.

[harryn]

Hi, I am not an expert at all, but here are a few areas to keep an eye on:

a) Motion at the end of the arm
- I am concerned that when the spindle is fully extended, you will get more vibration and torque offset than you expect. It is amazingly easy for a multi HP spindle to move a 5 ft long beam, even the one you are showing.
- I would seriously consider designing right from the start either a brace to the back rt corner, or box in the top frame.

b) Vertical Arm
- I would skip trying to cut the vertical support post at an angle. It will cost you time and the challenges of support / stiffness are still the same.

c) Enclosure
- A machine like that has serious power, dust, liquid splashing, etc.
- The enclosure needs to be a fundamental part of the starting design, not an after thought.

Perhaps look at what companies like Haas, etc do with modern commerical machines. The frame and enclosure are sort of a unit construction to increase stiffness.

It is kind of amazing how much faster a decent mill can cut Al than a home wood router project. My brother's old manual bridgeport clone can take such deep cuts it almost scares me. The clamping forces needed to keep things still are in a different league.

I like home building, and commerical equipment does tend to be sort of large, but a lot of used machinery is out there for cheap, almost scrap pricing.

[axkiker]

well I agree with you on almost every count. I will probably design a brace for the arm. It would not be very hard at all to design something that ran from the end of the arm back to further most corner. This should add a great amount of stability if it were needed.

the angle in the beam was added more for astetics than anything. I agree I will probably do away with it unless I feel it adds to the functionality.


I do agree with the idea of a complete cabinet. I plan on building something like what the hass systems use. A totally encolsed system. I never thought about using the cabinet as a extra stability system but its a great idea.

the only thing I dont agree with is the part about is used equipment being out there at cheap prices. I have yet to find a used haas system even in poor condition for under 10k. The one I saw was beat and i dont think even worked correctly. However who knows maybe im missing out on stuff thats out there and just dont know about.

Originally Posted by harryn Hi, I am not an expert at all, but here are a few areas to keep an eye on: a) Motion at the end of the arm - I am concerned that when the spindle is fully extended, you will get more vibration and torque offset than you expect. It is amazingly easy for a multi HP spindle to move a 5 ft long beam, even the one you are showing. - I would seriously consider designing right from the start either a brace to the back rt corner, or box in the top frame. b) Vertical Arm - I would skip trying to cut the vertical support post at an angle. It will cost you time and the challenges of support / stiffness are still the same. c) Enclosure - A machine like that has serious power, dust, liquid splashing, etc. - The enclosure needs to be a fundamental part of the starting design, not an after thought. Perhaps look at what companies like Haas, etc do with modern commerical machines. The frame and enclosure are sort of a unit construction to increase stiffness. It is kind of amazing how much faster a decent mill can cut Al than a home wood router project. My brother's old manual bridgeport clone can take such deep cuts it almost scares me. The clamping forces needed to keep things still are in a different league. I like home building, and commerical equipment does tend to be sort of large, but a lot of used machinery is out there for cheap, almost scrap pricing.