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  1. #61
    JAZZCNC's Avatar
    Lives in wakefield, United Kingdom. Last Activity: 10 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 5-6 years. Has a total post count of 5,878. Received thanks 914 times, giving thanks to others 37 times.
    Quote Originally Posted by njhussey View Post
    Jazz, in your opinion would the router be better at a slight angle (15 in this case) or at 90?
    Yes defiantly have inclined just helps hold material better while fastening other than that there's no advantage.

    Model looks nearly there. Don't think you'll need the tray that wide and If your not using coolant then wouldn't make it part the machine just use removable plastic bins which you then use to take chips to out in. My bins stick out from front of bed about 6-8" when cutting and I just slide them back a bit while loading material.

    One thing you want to build into machine is a bump stop at the bottom where you park the machine when not using it. This takes the load off the ballnuts and belts.
    My machine doesn't drop when stood without power to motors but only takes the slightest of push to make it drop. Only really required when leaving over night or several hours stood still and in normal use IE: between jobs etc I just park gantry at the top in the home position and it's fine.
    I home the machine to top left corner when facing the machine. I have a park button on my screen and it goes to the bottom and rests against the end stops.
    I don't use limits only home switches has I never normally get any where near them in normal use and rarely cock up bad enough to get near them these days so it's not a problem with tripping switches. If you where using limits then you'd have to build limit override into the parking routine which is easy enough.

  2. #62
    Cheers Jazz, the tray will be a removable metal one (I’ll get the local tin bashers to knock one up from 2mm steel and run a weld up each corner to seal it and it’ll be loose in between the frame so I can lift/slide it out. I’ve still got to detail things like all the stepper mounts, end stops, limit switches etc. but didn’t want to go into too much detail before getting the basics done! I’ve quickly added a couple of stops at the bottom of the rails and added/changed the stepper mounting brackets for the X and Y axis.


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    I’ve half a mind to make the leaning frame in one piece and the router bed in one piece and bolt them together. This way I’ll be able to separate them in the event of a move (very likely in the not too distant future) so I won’t need a Hiab to lift it over the back wall to get it out of the garden!!


    I now have a few questions to ask before I get going on ordering bits and pieces for the build so again would appreciate the benefit of everyone’s combined knowledge!

    I’m going with SBR20 rails for all 3 axis with SBR20UU carriages. X is 1300mm long and Y is 750mm long, Z is 400mm.


    Ball screws. I was thinking of 1605 (from Chai) driving them with belts at 2:1 ratio on the X & Y axis and 1204 for the Z being direct drive from the 3Nm stepper. Is the 1204 ball screw OK for the Z or is it better using the 1605? I’d be happier using the 1204 to use the smaller ball nut and therefore getting an extra little bit of length on the X axis.


    For the Stepper motors I was thinking of 4 of the 60BYG301B 3.1Nm motors from CNC4YOU? Any others to consider, the SY60STH86-3008B from Zapp? Any difference (I can’t see any in the specs particularly) in the two apart from price?


    I’m thinking of going with either the CW-885 Drivers from CNC4YOU or the AM882 Leadshine from Zapp. I’m leaning towards the AM882 but what are your thoughts? I take it that I can drive the 2 X axis steppers from the same driver so will only need 3 drivers? Is the performance of these drivers much better than the 50V drivers? I think I’d rather spend a bit more and have better “future proofing” even though for cutting balsa and thin ply the 50V drivers will be fine I’m sure I’ll be cutting Ali and all sorts after a while!


    Which BOB would you recommend?


    Power supply. Is it best to buy one readymade, i.e. the PS806-5 from Zapp, or have a go at making my own? Is there a significant saving to be made?


    I was going to do this all on a shoe string budget (see first post on this thread!!) but now don’t have to so would rather buy decent equipment (without going completely over the top!)
    Last edited by njhussey; 10-07-2013 at 01:30 PM.
    Neil...

    Build log...here

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  4. #63
    JAZZCNC's Avatar
    Lives in wakefield, United Kingdom. Last Activity: 10 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 5-6 years. Has a total post count of 5,878. Received thanks 914 times, giving thanks to others 37 times.
    Quote Originally Posted by njhussey View Post
    Ball screws. I was thinking of 1605 (from Chai) driving them with belts at 2:1 ratio on the X & Y axis and 1204 for the Z being direct drive from the 3Nm stepper. Is the 1204 ball screw OK for the Z or is it better using the 1605? I’d be happier using the 1204 to use the smaller ball nut and therefore getting an extra little bit of length on the X axis.
    No wouldn't do that go with 10mm pitch and if around 1500mm then I'd go with 20mm screw, chai now sells these.
    Yes 1204 will work ok for Z axis, my machine uses that size. That said I always tend go with 1605 on machines I build has they are more readily available and bit more meat for pulleys etc, they also allow slightly higher tuning.

    Quote Originally Posted by njhussey View Post
    For the Stepper motors I was thinking of 4 of the 60BYG301B 3.1Nm motors from CNC4YOU? Any others to consider, the SY60STH86-3008B from Zapp? Any difference (I can’t see any in the specs particularly) in the two apart from price?
    Either there's very little difference, I've used both.

    Quote Originally Posted by njhussey View Post
    I’m thinking of going with either the CW-885 Drivers from CNC4YOU or the AM882 Leadshine from Zapp. I’m leaning towards the AM882 but what are your thoughts?
    Not used the CW-885 but they will have to be very very good top beat the Am882 so for me it would be the tried and known AM882.

    Quote Originally Posted by njhussey View Post
    I take it that I can drive the 2 X axis steppers from the same driver so will only need 3 drivers? Is the performance of these drivers much better than the 50V drivers? I think I’d rather spend a bit more and have better “future proofing” even though for cutting balsa and thin ply the 50V drivers will be fine I’m sure I’ll be cutting Ali and all sorts after a while!
    NO Bad idea Each motor needs it's own drive. You could in theory run 2 drives from one signal output but don't run 2 motors from 1 drive. I wouldn't recommend using one output has it leads to timing issues and inaccuracy's etc and not worth the hassle.

    Couple of reasons for not running 2 motors from 1 drive. The drive ratings are split between both motors so 80V 8A would only allow 80V and 4A for each motor. Most 3-4nm motors are around 4-5A so not enough and plus it's working the drive very hard shortening it's life quite a bit.
    BUT bigger reason is the Resonance handling of the drive can not work properly and doesn't know which motor to apply resonance compensation too and gets very confused with result being the other motor gets pushed into resonance.
    Believe me you don't want resonance issues they are a night mare, resonance can/does cripple the performance of a machine.
    By the way the AM882 are fantastic at handling resonance, you can hear and certainly see the smoothness compared to Analogue and some of the cheaper digital drives.

    Another thing to consider when using slaved motors on a Axis is that you will want some way to square the gantry and for this you need 2 Inputs for home switches because each screw needs to be turned individually while homing.


    Quote Originally Posted by njhussey View Post
    Which BOB would you recommend?
    No contest PMDX 126 hands down the best. . . Cheap NO.!!

    Quote Originally Posted by njhussey View Post
    Power supply. Is it best to buy one readymade, i.e. the PS806-5 from Zapp, or have a go at making my own? Is there a significant saving to be made?
    Again no contest build your own this way you can have the exact voltage and Amps required plus it works out cheaper because you'll need 2 of the PS806-5. Will build your own for less than one PS806.
    Last edited by JAZZCNC; 10-07-2013 at 02:01 PM.

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  6. #64
    I might go a single stepper on the X axis and use belt drive for both ball screws then.

    Got a quote from Chai today for the SBR20 rails/carriages and the 1610 machined ball screws, ball nuts, BK & BF bearings etc. and its very reasonable (just a bit over half the price I worked out getting it from the UK would be) so will get those on order soon. Am moving house this week so will wait till the end of the month till I have done that and unpacked a bit!

    Should give me time to go through the design and make sure all dims etc are correct and print cutting lists off for the steel.
    Neil...

    Build log...here

  7. #65
    Another question. I was planning on using 3" x 2" x 1/4" Aluminium box for mounting the rails on (X & Y axis) but noticed that others have used steel in their builds. I was always under the impression that steel was not straight enough? I'd prefer to use steel as it's cheaper and I can weld the frame up and I need 3 lengths of it for the existing frame so wouldn't have as much waste.
    Neil...

    Build log...here

  8. #66
    JAZZCNC's Avatar
    Lives in wakefield, United Kingdom. Last Activity: 10 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 5-6 years. Has a total post count of 5,878. Received thanks 914 times, giving thanks to others 37 times.
    Quote Originally Posted by njhussey View Post
    Another question. I was planning on using 3" x 2" x 1/4" Aluminium box for mounting the rails on (X & Y axis) but noticed that others have used steel in their builds. I was always under the impression that steel was not straight enough? I'd prefer to use steel as it's cheaper and I can weld the frame up and I need 3 lengths of it for the existing frame so wouldn't have as much waste.
    Man wish I'd got for every time get asked this.. .Lol

    What makes you think Ali box is any straighter or flatter than steel.?. .. It's not.!! Also contrary to popular belief often neither is Alu profile.! . . Steel is far stronger and cheaper and with careful selection can be very straight and flat. It's also very easy to work with if it's not perfectly flat.

    There's very few off the shelf materials that you can use without some form of correction for inaccuracies and that includes Alu profile. People think profile is straight and flat but in reality it's often not, yes it can be better than extruded profiles like Alu box but it will still need some form of correction to the surface at some point. It's also 5x the price.

    The main area of concern is for the rail surfaces being straight and flat. Extruded Alu like Box is rarely straight or flat enough to use without work so will need some form of correction, either filling or sanding high spots.
    This also the same for steel but the difference being steel is quite easy to scrape,file,grind,sand than Ali has being harder it doesn't clog tools etc.
    In my experience steel box has just the same inaccuracies that Alu box does but steel is much easier to correct. Often all it needs is a quick run over with grinder knocking off any high spots, Low spots can be filled. Then just shim the rails to get perfect.

    If your using the Chinese round type rail then I can tell you with 99% certainty the base will not be flat or straight and will have more error than the steel your fastening it to.!!. . And thats without correcting the steel.!!

    Have no fear of steel, it's cheaper,stronger and very easy to work with and manipulate to your needs. Other than being lighter Alu has just the same issues steel does and unless you have special welding equipment is actually harder to work with.
    If you bolt together while bit easier to drill alu suffers from crush and hole deformation much more than steel does. Unless it's thick material doesn't hold tapped threads very well like steel does. Steel will easily hold fine threads in 3mm thickness for fastening rails etc and allow decent torque on bolts, try that in Alu.!

  9. #67
    Quote Originally Posted by JAZZCNC View Post
    Man wish I'd got for every time get asked this.. .Lol
    That's I owe you then

    What makes you think Ali box is any straighter or flatter than steel.?. .. It's not.!!
    Just presumed that as lots have it for the Y axis that it was straighter, never used it really so presumed others knew best!!

    In my experience steel box has just the same inaccuracies that Alu box does but steel is much easier to correct. Often all it needs is a quick run over with grinder knocking off any high spots, Low spots can be filled. Then just shim the rails to get perfect.
    Can do all that in our works, Was thinking of welding some 50x5 flat to the 50x50 box and get a local engineers to skim the surface so it's flat.

    If your using the Chinese round type rail then I can tell you with 99% certainty the base will not be flat or straight and will have more error than the steel your fastening it to.!!. . And thats without correcting the steel.!!
    Nice, I look forward to that!

    Have no fear of steel, it's cheaper,stronger and very easy to work with and manipulate to your needs. Other than being lighter Alu has just the same issues steel does and unless you have special welding equipment is actually harder to work with.
    If you bolt together while bit easier to drill alu suffers from crush and hole deformation much more than steel does. Unless it's thick material doesn't hold tapped threads very well like steel does. Steel will easily hold fine threads in 3mm thickness for fastening rails etc and allow decent torque on bolts, try that in Alu.!
    I have no fear of steel, it's my preferred material of construction as that's what we use at work to build the oil systems I quote, see the pic of a system we did for Ratcliffe Power Station ID fan blowers.
    Click image for larger version. 

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    Neil...

    Build log...here

  10. Neil,

    Nice power station reminds me of the days when I worked as pipe-fitter in Industrial tool trade in the Detroit area. I use AM882's and unless you are planning on going to the feed back loop stepper motor/drive combo I strongly suggest them. They run well and stay cool even after a good long day of cutting (14 hrs). Unless you have access to industrial power supplies I would suggest building one with a toroidal transformer, I get a really nice smooth power off my set up and once the transformer got charged it has been running very nice (looking at adding a fan to cool everything down just a bit, for safety measure).

    Nice design and should do everything you are asking of it and more. Hope the move goes well. -Michael
    Life is Live it

    CAD software VIACAD Pro v10 with Power Pack v10, Also Aspire v8.5
    CAM Software Aspire v8.5, PhotoVCarve, CamBam
    Machine: Custom built see build log: http://www.mycncuk.com/threads/3661-...Second-machine
    Work with Solid Surfaces, Acrylics, Woods, Foamboard.
    Work Computer: Lenovo D20 2x Quad core CPU's w/ 64GB RDIMM and Quadro 2000

    www.marino-customs.com

  11. #69
    Quote Originally Posted by m.marino View Post

    I use AM882's and unless you are planning on going to the feed back loop stepper motor/drive combo I strongly suggest them. They run well and stay cool even after a good long day of cutting (14 hrs).
    I'm not planning on using the feed back loop combo, not sure I'll run the machine that hard as it's for hobby use. For what I want it for the AM882's will be more than good enough.

    Unless you have access to industrial power supplies I would suggest building one with a toroidal transformer, I get a really nice smooth power off my set up and once the transformer got charged it has been running very nice (looking at adding a fan to cool everything down just a bit, for safety measure).
    I'll probably ask for help when doing the power supply. I think I've subscribed to a thread where one is made but failing that I'll ask for help.

    Nice design and should do everything you are asking of it and more. Hope the move goes well. -Michael
    Cheers Michael, I'm hoping that I don't get a rush of blood to the head and re-design it again I'm quite happy with the design now, all I think I'll be doing (unless anyone points out any major flaws) is doing the minor details, checking everything fits as it should and then detailing the pieces with the bolt holes, machining etc.

    Just been checking the 10mm aluminium sheet I got from eBay a while back (2200mm x 950mm) as I've moved it to temporary storage and after cleaning some dust off I discovered it's 6082 grade so happy with that!! Just waiting for my other bargain eBay bit of 20mm thick Ali to be sent!!
    Neil...

    Build log...here

  12. #70
    Got a shed coming soon (well they call it a log cabin, 28mm thick wood) for my workshop. Managed to start doing the base for it yesterday afternoon, until the rain started! Still got a couple of weeks till the sheds here so plenty of time to finish it. Will need the time if all the rain we're forecast materialises!

    Click image for larger version. 

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    Still got the noggins to put in and the OSB to put on top. Going to anchor it in the ground with 4"x4" fence post bits 400mm long postcreted in the ground, going to put more posts under the bit where the CNC machine is going for support.
    Neil...

    Build log...here

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