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  1. #11
    Hi Silyavski

    Would a support under the hammer help?

    Effectively an anvil that could be formed against. Ideally different anvils for forming groves or depressions of a certain shape.

    This would also mean you could work rectangular or other shapes as well.

    The anvil moves in unison with the top hammer so it should not be too difficult to incorporate it. (Although being able to rotate the anvil and the head in unison would be an advantage)

    Have you seen this video?

    Ford unveils new CNC prototyping process for metal parts | Manufacturers Monthly

    Last edited by John McNamara; 28-09-2013 at 12:26 AM.

  2. #12
    Metal spinning and Flow forming lathe DENN model ZENN 80 CNC - YouTube
    Have you considered flow forming ?------A lot of Automotive parts done this way now

    The other option is the Robot because you don't need 7 axis with rail but only 6 -Part on the fixture and hammer on the Robot --2nd hand they are not so expensive now especially if single channel
    Last edited by Ulsterman; 28-09-2013 at 01:48 AM.

  3. #13
    I guess the question is this machine a special purpose machine that has only one task making dished circular parts, or is it to be more general purpose?

    Is the reason that only hammering will work, not flow forming as in Ulsterman's post or the Ford Link I posted, because of the sound qualities of the finished object when struck?

    I guess the hammering introduces stresses that cause various resonance effects as in symbols.


  4. #14
    Hi guys,

    Thanks for the interest and the help.

    Let me answer some questions:

    1. Please don't forget its a DIY machine and i don't have a machine shop, though can use some services where necessary. Also i don't have the budget for robots, CNC machining centers and so on. I am into making that musical instrument, but still learning, so as i am not a successful maker yet, the main purpose of the machine will be to sink the shells so i am not tired after 4 hours of precise manual sinking and so i have time to learn to tune it, which is much more difficult task.

    2. 2 in 1?
    I have a small belt driven CNC and i need bigger machine urgently. I am still thinking that if the machine is well designed, it can be a 2 purpose machine. Lets say 25% normal CNC and 75% special purpose.

    3. What you call Flow forming is Supported ISF/incremental sheet forming/ . Unfortunately i aim for introducing particular stress in the material which can be achieved only with hammering. You guessed right that it affects dramatically the later capabilities of the musical instrument.

    In fact support head bellow or a fixed form is not needed. They use this type of ISF for achieving precision and faster programming time. I dont care for that, as i know what i am doing and will take the material springiness in count, that's what they want to eliminate using the anvil.

    That examples are another reason that i believe i could go without 5 or 6 axis. The air hammer will 1/2 ISF and 1/2 introduce stress meanwhile, carefully adjusting the pass depth and the pass pattern. With a properly designed tool head.

    4. But lets look at the 5 or 6 axis design. I have no idea about these. What CAD and CAM? Now i use Aspire and mach3. I think they can not support this type of machining?

    Also can somebody point me to a good DIY design of additional axis? I saw only 2000$ axis as the cheapest in the net

    5.My worries about Z backslash are based on that the vibrating hammer will f///k the ball screw if let oscillate meanwhile back-slashing

    6. So HIWIN 30 roller bearings. Do we rule out totally the Frelon SBR like supported plain bearings? Why they are not widely used on DIY CNC? They support a lot of load, are fast, self cleaning and support oscillating vibrations

    7.And what about an rotary 4rth axis which rotates the mounted shell left and right only 15+15 degrees? Then always the head will be 90 degrees to the shell And the Z could be normal. I am talking something like my manual sinking stand? Driven by motor at the shafts

    Click image for larger version. 

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    Last edited by Boyan Silyavski; 28-09-2013 at 02:49 PM.

  5. #15
    I am more and more inclined to make a special machine for the purpose. Anyways still contemplating it.

    Nevertheless i have to start buying. So i decided to go backwards. The spindle first.

    Need some help with the choice:

    Now the big question is 3kw or 2.2kw spindle? I am more inclined to the 3kw. As a brand name inverter will be expensive this size, i am looking into the chinese vfds. Are they reliable enough, Dean mentioned somewhere that now they make them good. Should i know how to distinguish them or what? I see some have aluminum backs some not.

  6. #16
    I recently bought a 2.2kW spindle + VFD from Chai (ebay: linearmotionbearings2008) as part of a larger order. I've not had a chance to fire it up yet but it came well packaged and all appears to be in order. The price came out to be a few pounds more than the cheapest I could find but I found a number of very bad reviews for the cheapest seller (things not turning up, etc). From what I've read the spindles are normally ok, they all claim Japanese / German bearings but it's luck if they are. The standard VFD's are also normally ok but they seem to vary in quality more although I think the quality has improved a lot in recent years, it seems they either last for ever or go pop in the first few weeks.

  7. #17
    Guys, i have to start sooner this build as everyday i change my mind.

    Now here is the deal. i have decided to make the machine with working area 1200 x 2500 and at the same time make it fast and rigid. Till now the problem was limited space and problems in moving the machine.
    Now the funny part. I bought yesterday a towbar and am looking to buy a suitable platform trailer, so i will mount directly the machine on the trailer
    I did not want to cut myself short just because i could note move it from home to home. So its decided.

    I will definitely go with the Johnathan design of a gantry just make it suit my needs and abilities. maybe even add one more beam at one side like a standart gantry, as Dean suggested somewhere.

    So here is where i need help:
    When the machine was small it was clear that 1605 screw for the z and 1610 for X and Z.

    Now some options for the gantry:
    1. make it from 2 100x100x4 = whole gantry below 50kg

    2. make it from 3 100x100x3 / 2soldered together/ - 1m=9kg, so whole gantry will be ~ 65 kg

    3. make it from 3 100x100x7 = whole gantry 80-90kg

    -So, the big question is how to move the gantry at 2600mm length?
    -What screws, what motors?
    -Servo maybe ? I know nothing about servo, can you point me to good money wise servo for the long axis?
    -What drive relation 1:1 , 1:2, 1:3
    -unfortunately i can not machine rotating ballnut. Could somebody help me here? any other options?

    So now i am a bit confused between 2 options, make a sturdy beast 1250x1250 or make a sturdy beast 1250x2500 with your help. I mean an exemplary sturdy beast for the generations to come
    Last edited by Boyan Silyavski; 01-11-2013 at 11:01 AM.

  8. #18
    If you are going to put this in a trailer you'll need to make sure you add some way so you can jack it up on sturdy legs. If it's resting on the trailer wheels I think the machine will probably shake itself to bits.

  9. #19
    Quote Originally Posted by Wobblycogs View Post
    If you are going to put this in a trailer you'll need to make sure you add some way so you can jack it up on sturdy legs. If it's resting on the trailer wheels I think the machine will probably shake itself to bits.
    I agree with you. i will take off the wheels and hard mount the trailer to the floor, and the machine will be hard mounted on the trailer. The trailer idea is to use it only when i change rented houses. Will not drive it around

  10. #20
    Hi there. Almost finishing my design.

    Basically i decided to go Big.

    I designed quite an unusual gantry and Z with the main idea of eliminating as much overhang as possible, light as possible and easy to build as possible.

    Another thing is that affected by Jonathan's build i could not help but contemplate an extreme machine with 3rd gantry beam. See picture 6. I believe Jazz sugested something similar, if i am not wrong.

    The gantry would be driven by rotating nuts/2510 ball screw/ if Jonathan or somebody is kind enough to make them for me, i know free time is an issue there.

    The gantry design as tested by me will have less than 0.01 flex and bend /twist/ and will weight 2 beams -40kg +Z weight or 55kg+Z weight if triple.

    For the moment i am very inclined to invest in the Leadshine hybrid 220V AC drives, though maybe i will start with Geckos as i have them. Depends what would cost me for rails and ballscrews for 1250x2500. Still have not decided. But if i make it only 1250x1250, definetly the 3 beam design and the AC drives.

    What worries me most is the bed, as i dont have money for 20mmm alu bed. I am contemplating how to make a strong cheap bed with strong channels.

    Now please tell me what do you think? My main idea is to build something exceptional if possible, cheap as possible where possible , and as simple as possible, so when i share the plans it could easily be repeated by other people.

    PS. The Z design is just a sketch, is not finished, will be lightened and i will try to move the ball screw further to the center without messing with the spindle. Another point is that now the plan is for 100mm diameter spindle, as i assume most people would choose for such a machine.

    Click image for larger version. 

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    Last edited by Boyan Silyavski; 06-12-2013 at 12:38 PM.

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