Mid range design #1

[CNCadmin]

Mid range design cnc machine router discussion

[mikeschn]

Thanks for starting this thread Paul...

As you guys can see, we are serious about developing a decent open source design.

This is the thread for the mid range design. Benchtop size.

So what do you guys think lends itself better to a midsize design...

Igus W bearings?

Split bushings on supported rails?

Your thoughts?

Mike...

P.S. Here's an Igus design concept...

[mikeschn]

Does the 80/20 bearings suggest a mid level design, or because of the precision, should that be considered an entry level design?

(See attached)

Mike...

[ViperTX]

mikesch....the 80/20 linear bearing would be an entry level.

[mxtras]

I would personally recommend drawer slides for a machine before I would use the 80/20 bearings - for an entry level machine, that is.

Scott

[achiestdragon]

ok , think this is a more suitable thread for this ,
this is the design of a machine im working on , sorry that the fonts are out in the dfx files , it seems to make them bigger than the original , trying to sort that , but not had time yet
most of it is mdf with some steel parts
i do not have many tools available , so limited to having a hand drill and hand tools.
as to steppers and controls i purchased a www.stepperworld.com fet 3 economy system , i could of used other steppers and built my own controller but in the end decided to go for that package as it seems a good deal , and just left me with the machanical bits to make

theres 5 dfx files that should be attached the drawings are not complete i still have a couple of parts to draw, and assembly views of the machine , i am photographing it in verious construction stages but not uploaded any as yet

its my first cnc machine so any comments would be helpfull

for the cutting tool i am planning on using a bosch pof500a router
the steppers are 60g ones and hope they will have enough power
but the fet 3 controller would easy drive bigger ones if needed

is it just the machanical bits or are you looking at the controller also
i have been conidering developing my own stepper driver board but have not had reason to do so as yet but may have to yet
i have been considering a usb based one (that would offer com port emulation in software so programs like kcam may be used with it
i seem to have a problem with kcam and my laptop's printer port so may need a different controller if i do not manage to solve it

not shure how accurate this machine is going to be but anything has got to be better than my work , that beeing the other problem i have tryed to solve in making it , in that critical cuts to the mdf can be made at the cutting shop , and not left to me and a saw (well 10degrees out for me is about right on a bad day as is drilling with a -+ 5mm accuracy )

hence the need for a cnc that can work better than that

Dave

[Darren]

A while back I gathered several parts necessary to build my CNC machine. I acquired Thompson linear rails for X, Y, and Z axis. 48" X 24" table. I have 3 Servo motors and quite a bit of plate aluminum. All this has been sitting for about a year as other things came up. Would this be considered the makings of an intermediate or mid-range design? I'm really out of the loop and would like to get this up and running. I need controller boards and screws, and software. I have the router and a computer.

Let me know if this is the right place for me to watch or if I should be in the beginner area or whatever.

Thanks.

Darren

[mikeschn]

With Thompson rails, I would consider what you have as the beginnings of a high end machine, especially with that pile of aluminum you've got.

You could watch all the open source threads, they will all give you design inspiration.

I would like to see a high end thread someday, but somebody needs to come to the plate with the knowledge, and the parts to build it. Maybe that somebody is you?

Mike...

[Darren]

I don't think I'm the guy I am very handy and am quite capable of building this machine but I know little to nothing about CNC. I just know what I've read on the forums on this site and have forgotten most of it over the last year. I'm trying to ease back into it though so I can get this investment up and running. I hate seeing it sitting there in a pile. Last I remember is I was trying to find a deal on Gecko boards... a bit of an investment. I'll keep an eye on this forum though as it should be interesting.

[achiestdragon]

still not shure if my post is in the right thread , think by the way things are going here 2 threads may be a good idea , for a midlevel design , one for simple construction and one that requires machining of parts ,

my design is almost in the hardware store catogory but seems its to big for there

its a 900mm *500mm *100mm cutting aria design that could be made with minimal tools
and i am working to a budget of £400 (including controls and steppers)
and thats all parts new ,
it would just fit on a table top as the dimentions of the base are 1136mm * 930mm
hmm 47" * 38" approx if my conversion is right

its mainly for working with wood and ply , but trying to build it with enough strenth to mill alluminium also so i have basicaly uprated the Igus design a bit , and some minor changes to make it look a bit better and put the cutting tool more centered on the x axis
as to accuracy well if i can get +-0.5mm from it it would suit my needs but hopefully it will be a lot better than that
with m10 bar i get should get 0.005mm per step with stepers at 1.8deg per step


to darren , sounds like thats going to be one nice machine your making , but from the tools i have to build one from i would need a cnc to make the parts

as to rails i decided to use a steel tube with bearings as runners as this seems to offer good strenth , and easy enough to make ,
i ended up using 20mm staneless bar as it was available from a local suplier , but could use up to 30mm dia bar or tube , depending on the use

sorry about dimentions all being metric for a rough conversion theres 24 mm to 1"

[mikeschn]

I'm not seeing the enthusiasm for a mid level machine like I am for the hardware store design.

I thought a mid level machine would be built from igus rails and bearings, or supported precision ground shafting and split bearings... but the interest doesn't appear to be there.

Is it the cost, or is the the precision required? A mid level machine is probably a skill level "mill 1", i.e. requires you to already have a mill to machine parts with.

What do you think?

Mike...

[achiestdragon]

Originally Posted by mikeschn I'm not seeing the enthusiasm for a mid level machine like I am for the hardware store design. I thought a mid level machine would be built from igus rails and bearings, or supported precision ground shafting and split bearings... but the interest doesn't appear to be there. Is it the cost, or is the the precision required? A mid level machine is probably a skill level "mill 1", i.e. requires you to already have a mill to machine parts with. What do you think? Mike...

well after all the chatter there about what bits are available from local hardware stores , and then listing tools required to complete the design

ok heres my 2 halfpence worth
i need a cnc , so set about building one , i looked at some of the construction methods used on a number of machines , and took into consideration the tools and equipment needed to build it , then i spent some time sourcing parts ,
it needs mdf for the main structure ( available form local hardware store or wood shop) i have to add here that a lot of hardware /wood shops offer a wood cutting service as long as the cuts are at 90 deg so square /oblong pieces end up accurate , although on this design i have still a lot of cutting out to do to shape some of the pieces but you get what you put in
some effort with a hand saw makes it worth it in the end

i decided to use steel angle iron for suports and bearing holders , these reqire drilling and fileing , no milling
the pricision rails well i originaly designed the machine to use 30mm dia 1.5mm thick tubeing , so something like curtain rods may be used although by using this method anything from 20mm to 30mm bar or tube could be used if it has a good surface , i opted to take an expencive route of using 20mm stainless steel bar for these , as i want to be able to machine aluminium
the size is scailable , and there is a +200mm axis requirement for the lenth of the carrage

i do not have a mill , and only hand tools to make the machine from the only singal part that is going to be a problem to make is the coupler to mount the threaded bar to the stepper motor , this is going to need a pillar drill i think
it could be built using a hardware store only , the steel parts could be made from aluminium angle if , but not shure if it would offer the strenth so opted to use steel

from the sounds of it hardware stores in the uk do not offer the same as in the us , but there is a good base of steel stock ,bearing suppliers here in the uk that makes all the parts available reasonably localy or online so do not see the problem there

but there draw slide version seems a good idea, but would say that the big diy/hardware stores in the uk do not seem to offer that style of slides

anyway i managed to fix the problem with my dxf export for the files
and uploaded them to my website http://www.whipy.demon.co.uk

cost well you get what you pay for , if i used 9mm mdf instead of 18mm and used tube instead of bar for the rails and aluminium angle instead of steel then it could be built cheaper , but would be more suitable to a dremill than a 500w router for the cutter , and would limit the materials that could be cut , then almost all the parts would be available from the local B&Q or Homebase here in the uk , the exception being the threaded bar but CEF a trade supplier also throughout the uk stocks this and offer cash over counter for it , and bearings well google for a local supplier theres quite a few

anyway i'm going ahead with this design so feel free to comment on it ,
or come up with something copleatly diferent ,i guess once i get it built there will be problems that need iroing out , i just descovered that the router mounitng will also accept my drill so gives me more tooling options

Dave