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IndustryArena Forum > MetalWorking Machines > CNC "do-it-yourself" > Milli a new composite mill kit
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  1. #1281
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    Re: Milli a new composite mill kit

    Morning All - I have made a model using iso 100mm thick Al for the base and walls. It gets 14/16/60N/um. I think a lot of the deflection is in the Z axis not the walls. So I am going to leave the walls and base and move to the gantry. I can get 6" thick 6061-T6 which cleans up to 100mm thick nicely. So that's going to be the basic building block. I'm moving my router at the moment and it has reinforced the idea of parts being less then 50kg. The base is about 200kg and I'm having trouble finding 3 guys to help lift it into my truck... So the rules are use 100mm max al plate or thinner, parts <50kg make it as stiff as possible. The 20N/um target maybe too high for such a machine. Target envelope 400x400x400m or 350x350x350mm.

    ISO13 walls weigh 43kg each and the base is two pieces weighing 45kg each. I can make the webbing a bit thicker and still be under 50kg... I'll also have to speak to the machinist about the depth of cut and tool diameters. Say 80mm deep and a dia20mm tool gives me a part rad of 10mm in the ISOgrid that sounds OK... but thats a 4:1 ratio tool maybe a bit long.. back to my day job - Peter

  2. #1282

    Re: Milli a new composite mill kit

    Since you don't need to hold really tight tolerances and it's AL, you should be fine with a 4x diameter cut on a long endmill. Even 8-10x diameter is possible with bigger cutters that have mass-spring dampers incorporated into the tool.

    Always just best to consult the shop, just cause it can be done doesn't mean they'll want to do it (or believe it can be done).

  3. #1283
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    Re: Milli a new composite mill kit

    Hi Strawb - Andrew is a can do machinist. He does large thin wall electrical enclosures for Boeing. About 80mm deep with 2mm wall and an o ring groove. I always like to ask about the best/easiest way to do stuff. Will integrate fixturing features as well when the time comes. I've started on the gantry...Peter

  4. #1284

    Re: Milli a new composite mill kit

    Freaking fantastic to have someone like that available!

    We had a guy do similar wall thickness and depth, only to about 60mm deep though, for a... frankly I don't remember what it was for and I'm sure it was stupid (on me) since it had those tall thin walls. A bit earlier in my career.

    Anyways, the guy had a stub fluted mill made with a long shank that was relieved about 10% of the flute diameter. The tooling company made a stress relief transition for the different shank diameter very nicely. Kind of like a side cutter but not much bigger than the shank.

    He did full flute axial depth of cut and walked it in radially until totally finished, then went down another layer with only a 0.5% overlap or something. In this way he was always milling at the rigid base of the feature until he got all the way down. We only asked for a +/-0.020" and he gave us +/-0.001 top to bottom just to strut his stuff.

    Those are the best people to know. That guy did a lot of job stuff for us, only using a basic Haas VMC he got used years before when he stopped working as someone else's machinist. Just knew his stuff.

  5. #1285
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    Re: Milli a new composite mill kit

    How are you going to fix the base bits together?

    Will the user then have to flip the base? Defeats the 50kg goal.

    (I think I've said this before, but don't think multiple bits that need to be bolted together by end user is a good idea. Alignment is a major issue. Metal mill is a whole different ball game than a wood router.)
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  6. #1286
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    Re: Milli a new composite mill kit

    Hi Pippin-
    Currently no flipping. Bolted and dowelled together from base up. base is two pieces to keep each <50kg and <450mm wide so it fits in the mill. Parts will be bolted together, finish machined dowelled then pulled apart. Should go together at users end close to perfect or perfect. Understand a Mill is different to a router but mills are bolted together as well. Peter

  7. #1287
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    Re: Milli a new composite mill kit

    Quote Originally Posted by peteeng View Post
    Morning All - I have made a model using iso 100mm thick Al for the base and walls. It gets 14/16/60N/um. I think a lot of the deflection is in the Z axis not the walls. So I am going to leave the walls and base and move to the gantry. I can get 6" thick 6061-T6 which cleans up to 100mm thick nicely. So that's going to be the basic building block. I'm moving my router at the moment and it has reinforced the idea of parts being less then 50kg. The base is about 200kg and I'm having trouble finding 3 guys to help lift it into my truck... So the rules are use 100mm max al plate or thinner, parts <50kg make it as stiff as possible. The 20N/um target maybe too high for such a machine. Target envelope 400x400x400m or 350x350x350mm.

    ISO13 walls weigh 43kg each and the base is two pieces weighing 45kg each. I can make the webbing a bit thicker and still be under 50kg... I'll also have to speak to the machinist about the depth of cut and tool diameters. Say 80mm deep and a dia20mm tool gives me a part rad of 10mm in the ISOgrid that sounds OK... but thats a 4:1 ratio tool maybe a bit long.. back to my day job - Peter
    Are you sure you want to do it this way? There's a reason spaceships and rockets are built this way but wont it be way overpriced for a small mill to do? Unless you have some altruistic machinist... mind introducing him to me? I could use someone like that.

    Is there a price range you're aiming at with your machine?

  8. #1288
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    Re: Milli a new composite mill kit

    Hi Ard - No price target yet. This project is a moonshot project to investigate materials and processes. Originally I intended cold casting parts from a material I was developing. Turned out that material could not get the stiffness I needed so the design took a left turn a while ago. Its not wise to make cost decisions in this sort of project. eg the base is two machined parts done in one shop that looks like they could be expensive (but I don't know yet). The alternative is having blanks laser cut then CNC profiled then edge machined and some would need post work like adhesive bonding. All of the second method takes time energy and $$$ that will add up. Unless I design both, cost both I won't know. But I take the line of the 2 piece part is better then the 16 piece solution. So I'm making quality and technical decisions to design the "best" machine then worry about the $$$ later. Milli may never be built but its been a good journey.so far. Thanks for watching - Peter

    Oh I could go titanium stiff E=110Gpa and realtively light at 4400kg/m3 vs steel. Then there would be some $$$$$$$$ I'll give Titan a call.

    The dowels will be light press fit knock thru. The isogrid allows bolts and dowels..

    dowelling info - What the Beginning Machine Designer Needs to Know about Dowels | Weld Fixture Design 101 maybe a H7 p6

    and Ard - I can still cast the parts in UHPC but take the stiffness drop from 70GPa to ~35Gpa thats still in the back of my mind....

  9. #1289

    Re: Milli a new composite mill kit

    That's a good approach, machining the dowel holes after assembly and using the h/p fit to get repeatability. If they can manage it, doing an h/r fit on the lower of the two and an h/m to h/p on the upper will accomplish the same goal but almost permanently fix the dowels in one piece. Then you can even consider pressing the dowels in while still fixtured to avoid alignment issues during single piece install. Aluminum can deform enough that if the dowel doesn't get pressed in almost totally straight it can stick in a very slight angle (assuming a ground steel dowel).

    If you go titanium you might try Saunders Machine in the USA as a lower fame cost that might have a machine to do it and also works with titanium. NYC CNC works with titanium all the time, but in small pieces. I don't know if they have a large format machine.

    But yeah, might be cheaper to additive the titanium and only machine critical dimensions... assuming you pulled that approach out of the sarcasm bin.

  10. #1290
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    Re: Milli a new composite mill kit

    Quote Originally Posted by peteeng View Post
    Hi Ard - No price target yet. This project is a moonshot project to investigate materials and processes. Originally I intended cold casting parts from a material I was developing. Turned out that material could not get the stiffness I needed so the design took a left turn a while ago. Its not wise to make cost decisions in this sort of project. eg the base is two machined parts done in one shop that looks like they could be expensive (but I don't know yet). The alternative is having blanks laser cut then CNC profiled then edge machined and some would need post work like adhesive bonding. All of the second method takes time energy and $$$ that will add up. Unless I design both, cost both I won't know. But I take the line of the 2 piece part is better then the 16 piece solution. So I'm making quality and technical decisions to design the "best" machine then worry about the $$$ later. Milli may never be built but its been a good journey.so far. Thanks for watching - Peter

    Oh I could go titanium stiff E=110Gpa and realtively light at 4400kg/m3 vs steel. Then there would be some $$$$$$$$ I'll give Titan a call.

    The dowels will be light press fit knock thru. The isogrid allows bolts and dowels..

    dowelling info - What the Beginning Machine Designer Needs to Know about Dowels | Weld Fixture Design 101 maybe a H7 p6

    and Ard - I can still cast the parts in UHPC but take the stiffness drop from 70GPa to ~35Gpa thats still in the back of my mind....
    What a coincidence, dowel pins are also essential for my build. I recently discovered a 'tool' an instant parts quote, you just upload the file, input materials and quantity and get an instant automated quote. I had to change my design a bit after finding out that some of my parts were way too expensive to make.

  11. #1291
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    Re: Milli a new composite mill kit

    Hi Ard - Yes first round design often has cost shocks.
    Hi Strawb - Would love to do an additive Ti mill build. Would have to have the pockets of Mr Musk. A friend of mine makes Ti/CF bicycle frames and it costs about $2k for the printed Ti pieces and they weigh 200g... Have a look further back in the thread for the images... Peter


    https://www.compositesworld.com/news...erience-center

  12. #1292
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    Re: Milli a new composite mill kit

    Hi All - When I was making bike frames I used to get high spec aluminium, titanium and magnesium from accurate alloys in California. That was a long time ago... 20 years plus ago... Peter

    Perforated Sheet Metal - Expanded Metal Mesh - Wire Cloth - Grating | Accurate Alloys, Inc. - CA

  13. #1293
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    Re: Milli a new composite mill kit

    Evening All - I have built an isogrid block model to check its has the right stuff. The stiffness is 17/23/57 which is OK. Needs detailing especially the z column to accommodate a spindle. All the parts except the saddle are aluminium. The saddle is steel. I think I'm going to rest Milli for a while. I have a router and a workshop to finish and Milli has been a long slog, which has moved away from where I thought it would land ie in my postcode vs the moon. So I'll think about its future. Its also complicated via covid as many resources to produce Milli at the moment are out of reach across a hard border. Everything has become harder and takes much more time then it should... So the Moonshot has slowed guys... while I knock over other projects... Peter

  14. #1294
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    Re: Milli a new composite mill kit

    Evening All - Thinking about Milli in total I think a lot of the Grail has been created by chasing the 20N/um number. If I had picked 10 I would have been there nearly straight away, if I'd picked 30 or 50 I would have said that's silly after about two rounds and reviewed the number.. So for a small machine maybe 15 is the design target with 10N/um still being the reality number. Project resting and some thought consolidation needed before the reboot. Maybe start the Frankenrouter thread as that's the next design/build... With Covid I also need to get back to my first premise of casting parts so I do them in my workshop vs across the border... but the cement or epoxy distributor is over the border, so the couriers will do well.... Evening All ~ thks for watching Peter

  15. #1295
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    Re: Milli a new composite mill kit

    Here's my attempt at a tiny mill, all parts under 200kg(UHPC 150kg + steel), so that 3 dudes can carry it. Work area 700x300x300. Envelope 1400x1400(huge!).

    Looking forward to your next round of passes in the near future.

  16. #1296
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    Re: Milli a new composite mill kit

    Evening All - Thanks Ard (you will need 3 big duds!) - I keep looking at my test castings and they reinforce the idea that this is the way to go. I'll have to get my head around a smaller machine and the 30-35GPa material... perhaps I do a test part in Frankenrouter say the gantry... I've decided its envelope will be 2500x650mmx200mm I want it that long so I can make future gantry moulds... But YaG will be able to make Frankies gantry or its mould... Peter

    On that front I have started looking for cheaper aluminium powder. Then I'm back to a cold castable machinable material. Just not as stiff as I would like it. Probably around 30GPa, also there's the CF casting, still waiting for news on the fibre sample... Peter

    Ard - your machine looks like one that kicked me off onto this design see combo mill. But yours is a little bigger...
    Attached Thumbnails Attached Thumbnails combo mill.JPG  

  17. #1297

    Re: Milli a new composite mill kit

    A couple of guys at work hoard scrap A356 parts because they can resmelt it and recast with essentially perfect properties.

    You might see if someone has an old cast aluminum scrap heap of something to hack and test chunks of for the casting.

  18. #1298
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    Re: Milli a new composite mill kit

    Hi Strawb - Milli is a production machine. It has to be made from commercially available materials to be repeatable and matketable. I have played with aluminium swarf in the past, all doable but scrap products are not commercial. eg I have a lot of scrap carbon fibre and could make nice one off parts but I couldn't make 20 of them... Peter

  19. #1299
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    Re: Milli a new composite mill kit

    Afternoon All - The short carbon fibres have arrived at the distributor. Very exciting. Can't go there to pick it up as its across the razor wire border. They are putting it in the post... Post is very slow at the mo as well... Peter

  20. #1300
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    Re: Milli a new composite mill kit

    Hi All - I have been using a new infusion epoxy as a test in my washroom build. I've been painting the wall panels with it but its been staying tacky. Done some tests and its the low temp here at the moment (<20C daytimes <10C overnight) So I have to put things out in the sun to warm them up, preheat the resin (30-35C) then coat. This epoxy is a very low activity one. My other ATL one is fine. But this one is for thicker casts. The CF sample was put in the mail today so will be able to make a CF plank soon... May have a new answer for Millis material...Peter

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