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  1. #1
    Join Date
    Nov 2009
    Posts
    15

    Small mill for making alu parts

    Hi Guys,
    i was looking at rockcliff plans and thn was thinking about more rigid construction. I wonna (i plan) build someday a small mill for my rc needs, to make some holders, motor mounts and stuff like that. So it should be small enought and rigid to mill alu alloys.

    Please could you suggest some plans or ideas?
    Thank you

  2. #2
    this forum is a great resource. start reading
    start thinking about what you need: work envelope, tool size (rpm), accuracy, speed, budget?

  3. #3
    Join Date
    Apr 2006
    Posts
    169
    hi Alex any mdf plan well be good for a start it well gave u good Experian's
    One More thing to ad to Mr. will Gilmore u should have enough space to host the mill

  4. #4
    Join Date
    Oct 2005
    Posts
    375
    Hee Alex,
    been designing and reading for over 4 years now, that mill you want isn`t the most easy, you need precision!!!

    To make real nice rc parts for cars you should look at the minitech.com concept.

    The machine will need 20000+ spindle, preloaded ballscrews, preloaded linear bearings etc.

    A dovetail china mill will be a waste off money for the project.

    Maybe you cann read older threads and post of me to get some more info.

    Look at the mills of arie kabaalstra and jason (zealcnc.com)

  5. #5
    Join Date
    May 2007
    Posts
    767
    Hi Alex

    I guess this is to be as a hobby and that expenditure has to be low. If you are wanting to make parts for another hobby then I suggest you fix by answering these questions:-

    1. Fix how much you can (want to ) spend on the Mill and halve that sum to give some cash for tooling?

    2. Decide how big the machining envelope needs to be. X,Y and Z axis

    3. Decide on the accuracy and dimensional repeatability you need.

    I would not be too hasty to pass over the far east drill mills. These are low cost and there is a wealth of CNC conversion information and parts available. Used with care and understanding accurate parts are with in the capability of these drill mills. A lot of the comments on poor quality relate to early examples and the quality has increased a lot from the early 2000's. Since you are in Europe you will find a number of different sources for these far east mills in addition to those of the Seig factory. Some of these are better in that they have not only greater machining envelope (X,Y and Z dimensions) but also have more ridgidity in their castings, slide widths etc. These start at arround the 350 euro mark for a basic manual up to 4,000 euro for the latest CNC ready to go.

    I suggest going with a far east drill mill unless you have access to some machinery on which to make your first machine. You can then convert the base drill mill to CNC and make other mills and RC bits as the fancy takes you.

    Hope this helps narrow the choice.

    Regards

    Pat

  6. #6
    Join Date
    Nov 2009
    Posts
    15
    Thanks
    you are right with precision, but not for that price
    I was rather thinking about what is better? buy a sherline 5100 mill or some cross table as a base.
    Or some all-custom-made mill from alu profiles.

  7. #7
    Join Date
    Oct 2005
    Posts
    375
    Quote Originally Posted by wildwestpat View Post
    I suggest going with a far east drill mill unless you have access to some machinery on which to make your first machine. You can then convert the base drill mill to CNC and make other mills and RC bits as the fancy takes you.
    You hit the nail right there Pat, maybe my conclusion was to fast, i was thinking in my own situation. I`ve you have CAD and know how to use it things get better, the ballscrews, linear bearings and spindle can be bought in ebay for around 1250 euro, then the machine controler with motors etc. will be another 750 euro.

    The problem is lets say the 20 parts you need machined to bold it all together,
    been trying to find a nice shop overhere in europe to do the job, all between 3 and 4000 euro. Now i`m talking with China, quotes between 4 and 600 dollar are here with shipping, all machined on expensive nice precision machines.

    So a minitech one off cann be done for around 2500 euro, but a lot off patience and reading is needed. The China mills are nice but another leaque then the minitech, its a different machine concept....

    I would advice you to read a lot overhere and dont make the decision to fast.

    Regards,

    Roy

  8. #8
    Join Date
    May 2007
    Posts
    767
    Hi Alex

    I still think you need to work out how you are going to make the initial machine. The way many people start is with a far east mill drill or a combo lathe/mill/drill either new or second hand.

    The Sherline 5100 as a starter pack is arround the 1,000 euro mark with no CNC. CNC conversions are available and will double that price and more.

    Yes you could build an X-Y trolley arrangement using precision slides and screws but don't expect to have any change and you still have no mast for the Z axis and you will need to get the mounts for the screws machined some where or try and find a suitable kit of parts. This option is going to be expensive as the precision trolleys and ground rail are aimed at the production tool market and this is not known for its cost sensitivity as making rejects due to poor performance is the major design driver not cost.

    There are some very cheap X Y vices that may have caught your eye. These are available for arround 30 euros but are not precision tools. The ridgidity might just about be OK for a bit of very light milling in plastic or alloy using a drill press for the Z. BUT and it is a very big but the accuracy will be poor and the chances of getting a satisfactory finish will be difficult as neither the drill press or the cross feed vice are adequate for milling. This set up would be suited to drilling holes in a pattern within the accuracy of the lead screws of the X Y vice traverses - think 0.1 mm tolerance at best. You could do as well by eye after a little practice.

    The alloy sections that are available are certainly capable of building good machines provided the sections are heavy duty and of adequate cross section. However this will turn out to be expensive particularly if you have to buy bearing mounts and other parts. There are a number of good build threads for such machines on CNCZone.

    Suggest you think long and hard about the three requirements I outlined in my pervious response. If you have no machining experience or local help the Sherline is a no risk route as there is a strong following for these mills in the various on line forums. The same comment applies to the X1 - X2 and X3 machines which cost a lot less.

    Think twice and buy once.

    Regards

    Pat

  9. #9
    Join Date
    Nov 2009
    Posts
    15
    have no exp at all and that is why i'm here, you guys opening my eyes widely, and it is better to get direct feedback rather than just reading and thinking about it with no exp behind.

    Wonna buy lather as first machine, i think C0 is enought for me, price is good, rigidity is ok for my needs. Before that i was looking at TheCoolTool/Xendoll kit, but realized it is not good enough (http://cnczone.com/forums/showthread...158#post688158)

    So maybe SX1 (coz X1 has no tilt) or SX2/X2 (SX2 just more powerful motor) is for me, just need to get some quotes here in EU.

  10. #10
    Join Date
    May 2007
    Posts
    767
    Hi Alex

    The C0 lathe is a little on the small size and its bigger cousins C2 and C3 represent better value and would permit you to do some lathe type milling with the appropriate vice. The tilting of the head or mast is a little used feature for most operations where the three axis are needed to be as exactly at 90 degrees as possible. If you need to machine angles then holding the work on the table at the appropriate angle will get you out of most situations. X1 & X2 have a tilting masts and X3 a tilting head. However X3 has a quill and this has issues about play but can be worked around by clamping the quill when required. If you have the cash there are also the lathe / mill combos which whilst not as ridgid as individual machines are capable of machining alloy and steel if the feed rate is kept low.

    Suggest you view the MIT workshop videos that have been prepared for students taking degree courses in robotics as these cover most of the basic machining operations and give a very good feel of what is involved. Look at all the videos as I have only posted a link to one of the set. All are worth a quick view.

    http://techtv.mit.edu/genres/24-how-...machine-shop-5

    Hope this helps

    Pat

  11. #11
    Join Date
    Nov 2009
    Posts
    15
    so you are saying c2 with x2 is best i can get for that money?
    Thank you very much for vide links, will download them and look at.

    P.S. off topic, is it possible to install brushless motor and esc from rc world into those?

  12. #12
    Join Date
    Oct 2005
    Posts
    375
    Quote Originally Posted by Alex.G View Post
    P.S. off topic, is it possible to install brushless motor and esc from rc world into those?
    No, that in`t possible, if you begin with cnc machines i think it is smart to look at control throough stepper motors.

    You make a design in a CAD program, than you open that part in a CAM program, here you make a strategie how to mill youre part out off stock.
    This CAM program makes a code in a Wordpad file (code is called G-code)

    This G-code is loaded in a machinecontroller software (MACH3 by Artsoft)
    This machinecontroller software gives a signal called a pulsetrain (With direction) through the parallelport of youre PC.
    This pulsetrain goes through a wire to the drive that will turn the steppermotor, this steppermotor turn the screw that makes the table move.

    RC motors aren`t suited for this.

  13. #13
    Join Date
    May 2007
    Posts
    767
    Hi Alex

    In a roundabout way I think C3 with the milling vice might do most of the work you need to start out. The C3 is a bit stronger than the C2 but still needs to be used for light cuts. To use the phrase bang per buck it is down to you how much you can spend. I am trying to point out that my take is C2 or C3 with an X2 might meet your needs for RC bits and pieces but the C3 + mill vice might do with out the mill. You could then go on to make a very nice router spindle mill as you would then be able to do your own machining.

    Just a word of warning CNC can be come very adictive and divert you into a new hobby!

    Stay safe and have fun as CNC is good sport.

    Pat

  14. #14
    Join Date
    Nov 2009
    Posts
    15
    im using Rhino for some years.
    I was not meaning rc motors for as stepper, i mean as a main drive (like new Super lath and mill from sieg)

  15. #15
    Join Date
    Oct 2005
    Posts
    375
    Also for maindrive a rc motor is no good, gets too hot.

    Better use a BLDC motor.

    Like my machine, preloaded c3 screws (kuroda), Preloaded P-class THK HSR12 linear guides, Chinese Spindle 800watt are allready here.
    Parts are beiing machined in China as we speak.

    Base off the machine will be epoxy granite.
    totalprice 3000 euro (special for rc car parts alu/carbon)
    Attached Thumbnails Attached Thumbnails HFMILL.JPG  

  16. #16
    Join Date
    Nov 2009
    Posts
    15
    Cool project, but 3000eur is not in my pocket and definetely will not start with such a thing.

    I was thinking about brushless rc motors, like this - http://www.hobbycity.com/hobbycity/s...idProduct=7870
    it has 170kv, so with 12v input it will give ~2000 rpm, or more kv but with some hard pinions/spurs to gear it down.

    Pat, are you talking about M4 or M6?

  17. #17
    Join Date
    May 2007
    Posts
    767
    Hi Alex

    The Brushless motors used by the Radio controll fraternity are certainly suited to DIY spindle motors. There is a thread on CNC Zone currently devoted to a DIY build using a similar motor. The very high speed of these RC motors is not suited to driving the axis motion as you will have most lost most of the power in the gear box. The building of high input shaft speed reduction gear boxes is a very difficult task. Driving an air screw for an RC plane requires very different motor characteristic to that of accelerating the axis on a mill.

    Brushless motors designed as servo motors rotate at at just a few thousand rpm under full power - high starting torque is a prime requirement. This is achieved by using a high number of poles and this makes for an expensive motor. The more poles the slower the rpm. In addition to use a bushless dc motor for axis control requires the use of axis position encoders and these cost more than the RC motor.

    The low cost option for CNC on a small mill is to use stepper motors adequately sized but not so big as to cause problems - suitable driver circuit for step and direction with power supply - using Mach3 or similar software running on a PC. Suggest you download the Mach3 installation manual as this gives a nice description of how these bits are set up. Think in terms of a stepper motor at 35 euro + electronic driver at 50 euro + coupling to the lead screw. You could use your existing lead screws and convert to ball screw at a later date. There are a lot of other ways of getting into CNC milling but this is probably the lowest cost introduction for making small alloy parts.

    To power the axis you should be looking at stepper motors when you get as far as modifying for CNC operation. You can then make the parts on the mill / lathe under manual control prior to starting the conversion. Suitable stepper motors can be bought new from reputable sources for under 40 euro. Try and find a local supplier like www.Arceurotrade.co.uk.


    Sorry don't know what you mean by M4 or M6 as to me they are metric screw sizes!

    This is a link to the vertical slide that would enable a lathe to carry out milling of small parts.
    http://www.chesteruk.net/store/vertical_slides.htm
    The slide mounts on the cross slide in place of the compound and the end mill is mounted in the headstock and rotates. There are a lot of suppliers / stockists of similar parts and this is just the first one with nice pictures!

    Regards

    Pat

  18. #18
    Join Date
    Nov 2009
    Posts
    15
    Hi Pat,

    cool.. need to find that thread about rc motors
    I ment M4/M6 from Sieg - http://www.siegind.com/products.php?sid=3

    but i think you were talking about an attachment, and wanted to paste a link to?

  19. #19
    Join Date
    May 2007
    Posts
    767
    Hi Alex

    Yes the M4 and M6 are lathe mill combos of the type I was suggesting. There are other suppliers than Seig and which you can get hold of with out excessive shipping will I guess determine what you buy. The last post from me had the link to the lathe milling slide.

    Regards

    Pat

  20. #20
    Join Date
    Nov 2009
    Posts
    15
    Pat
    last time you post was not so big, maybe you edited it
    other suppliers? can't find any here in EU with a reasonable price and shipping (shipping is damn high, coz of gross)
    Euro Arc: Unfortunately, we do not ship this machine out of the UK.

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