Need help - Fixed gantry design


Page 1 of 3 123 LastLast
Results 1 to 12 of 26

Thread: Need help - Fixed gantry design

  1. #1
    Registered
    Join Date
    Oct 2016
    Location
    Australia
    Posts
    9
    Downloads
    0
    Uploads
    0

    Post Need help - Fixed gantry design

    Hi guys.

    I'm in the process of conceptual design of a fixed gantry CNC router and would like your feedback.

    Firstly, my goals. What I want to machine capable of. Some are optimistic I know.
    +/-0.005" machining capability.
    Machine up to and including aluminium.
    To be used as a desktop machine in an apartment.... (will try fully enclosing machine with soundproofing).

    It will be an all aluminium design using 5083 plate and 6061 T6 angles/channels bolts together and machined surfaces to mount rails.
    Ideally I would've liked to have used rectangular hollow sections, but the maximum wall thickness I could find locally was 0.25" which seemed a bit thin for my liking.
    The gantry is made of 2 plates bolted to 2 c channels to create a box section. I've hidden some parts in one of the views so you can see.

    All will be bolted together with interference fit bolt and nut (no thread tapping).

    Hiwin HGR20 rails and HGH20 bearings on all axis.
    1605 ballscrews on x and y, 1205 ballscrew on z.
    2.2KW water cooled router spindle

    Cutting area: 12" x 24"
    Cutting height: 3.5"

    Overall machine dimensions: 25" (L) x 33" (W) x 22" (H)

    At a guess, this machine will cost me around $5k AUD.
    I will have to find a local shop to do the machining for me which might cost a bit.

    Would love any feedback from previous experiences.

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Need help - Fixed gantry design-01-png   Need help - Fixed gantry design-02-png   Need help - Fixed gantry design-03-jpg  


  2. #2
    Gold Member handlewanker's Avatar
    Join Date
    Sep 2006
    Location
    Australia
    Posts
    5526
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Hi....looks good........I like moving table designs over moving gantry types.

    Couple of variations I'd have........mount the Y axis rails on strips on top of the base plate not under it as you show....this makes it simpler to build and cuts down on machining.......also you don't want a swarf trap with the slotted holes etc.

    You could also make the X axis saddle longer (higher) to get a longer slide as opposed to a wider one and also make the Z axis slide narrower and longer to give you more support when the Z axis is all the way down......you can go above the X axis crossbeam with the Z axis slide length as it's in the open air.

    Before you start scaling the design prior to a build, project the spindle assembly package onto the design and Z axis slide to make sure it won't run out of slide way.

    I would also make the base as a separate box with one channel cross member underneath the middle and have the shortened sides bolted to the box sides and have the X axis crossbeam as a rectangular box bolted between the side plates at the top..

    By having separate modules bolted together you can align and adjust them in the final assembly and correct any out of squareness you might get..

    If you bolt the linear rails onto strips on the base and cross beam you can correct any flatness by careful filing where necessary.....also this will give you height clearance for the ball screw nut under the table and under the X axis saddle.

    I would also make the table from a slab of aluminium and have tapped holes instead of the Tee slot extrusions.....just my preference.

    BTW....you don't need to machine the linear rail mounting strips....just use the linear rails themselves as straight edges to reveal the high spots and work on them with a flat file etc.....this will cut down any outside machining costs as you can DIY it quite easily.
    Ian.



  3. #3
    Registered
    Join Date
    Oct 2016
    Location
    Australia
    Posts
    9
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Thanks for your input.

    So when you say mount the Y rails (moving table?) on the base plate, you mean like wade o's design below?
    DIY CNC Router Build; Fixed Gantry, Steel - Wade'O Design

    The concept I was using was from the link below. The plate with slots in it just below the moving table is only thin, to catch the swarf and stop it falling on the rails and ballscrew. With Wade O's design, it was all open and I see he later made improvements to cover the rails/ballscrew from swarf but I wasn't a big fan of it. I was going to install brushes or a thin rubber cover in the slot to try and prevent sward dropping in on the rails.
    MAKERDREAMS |HEAVY DUTY DESKTOP CNC MILL AND HIGH QUALITY 3D PRINTER EVO-ONE Desktop CNC milling machine

    Thanks for the input on the Z plate. I'll make it slightly narrower and taller to increase the distance between the bearings in the z direction.

    I was going to go a slab of aluminium for the table. Never really been a big fan of the T slot extrusions.

    I see you're from Dandenong. Can you recommend any local places for aluminium and machining? I've been to Aluminium Trade Centre, Ullrich and Capral.

    Know of any pros/cons for ATP-5 plate vs 5083 plate? Know of any Melbourne suppliers of ATP-5 plate?



  4. #4
    Gold Member handlewanker's Avatar
    Join Date
    Sep 2006
    Location
    Australia
    Posts
    5526
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Hi......sorry, can't help on the supply.......those you mention probably would have stock of various stuff, but I'm only messing with bit stuff and not large amounts of ally for projects or production etc.

    I'm not really a big fan of anything made from aluminium as it's a difficult metal to work with....that is, joining it up to other bits and pieces along with it's relative softness etc.

    I'm mainly orientated to steel for a build.....one that actually I started but put on the back burner due to the arrival at last of a mill I ordered from China....long story.

    Steel is extremely forgiving in that you can weld it, bend it, heat it, grind it and cut it with Plasma without too much drama........just my opinion.

    Aluminium has the property that if you go to a weld option the expansion capability will throw all semblance of accuracy and squareness in the too hard basket, so the only option is to bolt together and doing a 90 degree join is not easy with bolts or screws.

    The cost of steel, either tubing or plate, is far less than any aluminium sheet or extrusion, so that is how I think when machinery design comes up.

    The design I started was for a 3025 CNC moving table router to be able to mill steel, and the steel tubing for the complete frame components cost $150....that was for 2 machines as it's cheaper to buy complete lengths and cut them to your sizes at home.

    This is my opinion pure and simple, doing a build will be what you see as an ideal machine with the tools, money and skill available, and not all roads lead to Rome.....LOL.
    Ian.



  5. #5
    Gold Member handlewanker's Avatar
    Join Date
    Sep 2006
    Location
    Australia
    Posts
    5526
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Quote Originally Posted by boltzzz View Post
    Thanks for your input.

    So when you say mount the Y rails (moving table?) on the base plate, you mean like wade o's design below?
    DIY CNC Router Build; Fixed Gantry, Steel - Wade'O Design

    The concept I was using was from the link below. The plate with slots in it just below the moving table is only thin, to catch the swarf and stop it falling on the rails and ballscrew. With Wade O's design, it was all open and I see he later made improvements to cover the rails/ballscrew from swarf but I wasn't a big fan of it. I was going to install brushes or a thin rubber cover in the slot to try and prevent sward dropping in on the rails.
    MAKERDREAMS |HEAVY DUTY DESKTOP CNC MILL AND HIGH QUALITY 3D PRINTER EVO-ONE Desktop CNC milling machine

    Thanks for the input on the Z plate. I'll make it slightly narrower and taller to increase the distance between the bearings in the z direction.

    I was going to go a slab of aluminium for the table. Never really been a big fan of the T slot extrusions.

    I see you're from Dandenong. Can you recommend any local places for aluminium and machining? I've been to Aluminium Trade Centre, Ullrich and Capral.

    Know of any pros/cons for ATP-5 plate vs 5083 plate? Know of any Melbourne suppliers of ATP-5 plate?
    Hi, something like that, but without the base plate being attached to a bulky table.

    I envisage a box base with the side frames bolted to it and the rails bolted to the top of the box on strips.

    There are umpteen different configurations to apply 3 axes to one another....you just have to apply your desire to how you want to build it and what you think will work.....no two people agree on the absolute ideal configuration......not even with a commercial product.

    One word of advice........don't over engineer the specifications for something that will only ever be a hobby project, it would be another matter if it was to be a money earner......then you'd be a fool to go to war with a home made cannon.
    Ian.



  6. #6
    Registered
    Join Date
    May 2011
    Location
    Canada
    Posts
    269
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Quote Originally Posted by boltzzz View Post
    Cutting height: 3.5".
    I'm not sure what that means. Does that mean gantry clearance or Z movement? Are you going to put a vice on this at any time? You mentioned you want to cut aluminum. How you will do your work holding is important to consider in the design stage.

    You'll want to match your motors for the pitch of ballscrew. 10mm lead may be a better choice depending on your motors and the speeds you want. Why use 12mm diameter on the Z? Use 16mm minimum for everything, I say.

    So that is a 1.5" bit cutting a 1.5" thick piece with 0.5" left over? So with a 2" bit you couldn't cut a 2" thick piece that is flat on the table?

    Like I said, I'm not sure what what cutting height means in this instance, but if that is the case I think you'd want more. With a fixed gantry, I have to think you could make the height of the gantry adjustable (with a couple different bolt locations or spacers) and add some extra inches of Z movement. If you put the Z rails on the part that goes up and down, you can keep the two lower bearings at the lowest spots. That's what I'd do. Also, flat plates bend easily. At least add some angle iron to the sides of your Z (the part that goes up and down)

    I do like the concept of what you've come up with. I think many of the design options you are exploring have merit. At the end of the day, it will be easier to use a solid gantry tube. If you are concerned about the wall thickness, you can just weld some flat bar where you will mount the rails. If you can't weld, find someone who can, not alot of work to put a couple of 1.5" by 0.5" pieces of flatbar onto your gantry tube, either steel or aluminum.

    For a fixed gantry, your weight limit is what you and your friends can move into your apartment, and what doesn't pose a risk of falling through the floor. So for a small machine like this, I don't think a steel 6" x 6" x 3/8" square gantry tube is out of the question, you can probably find something at the scrap yard for almost nothing. If you're handy with an angle grinder, and have alot of patience you can even use a sandpaper flapper disk to make your mounting surfaces flat. Of course, that makes a big mess, so, do you have somewhere you can work on this? Barring that, there's epoxy. Do you have a drill press, welder, angle grinder?

    Quote Originally Posted by handlewanker View Post
    BTW....you don't need to machine the linear rail mounting strips....just use the linear rails themselves as straight edges to reveal the high spots and work on them with a flat file etc.....this will cut down any outside machining costs as you can DIY it quite easily.
    Ian.
    I'm going to agree and disagree with this. You may be able to use a file if you are working with aluminum. It could take you until doomsday if working with steel, depending on how far you are off. I used an angle grinder with a flapper disk on my build and a piece of extremely flat 2" x 3" solid aluminum that I had handy and some cosmetics to find the high spots. I disagree that you should use the linear rails as straight edges. Use a straight edge or a piece of metal you know to be straight by measuring with a straight edge. The rails become flat when you mount them to a flat surface and the flatness can be off a small amount prior to mounting.

    Quote Originally Posted by handlewanker View Post
    By having separate modules bolted together you can align and adjust them in the final assembly and correct any out of squareness you might get..
    .
    I totally agree with this statement.


    It sounds like you want something that you can get cut out of a sheet and assemble easily in your apartment with minimal tools. Not a bad idea, I just don't know the best way to accomplish it. I can only think of ways that I would do it, and I would use square steel tube, probably 6" wide for the whole thing with 1/4 to 3/8 wall, and it would have welds and bolts holding it together. I know I could get that for 30 cents / lb at the scrap yard near where I live, and build it with the tools I have. Not saying your idea is bad though, and after a couple design revisions you may come up with something that is easy to assembly and doesn't take forever to build. My stuff usually takes a long time.



  7. #7
    Gold Member handlewanker's Avatar
    Join Date
    Sep 2006
    Location
    Australia
    Posts
    5526
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Hi....on the topic of a straight edge.....two flat faces placed on each other will reveal any bowing in one or the other.....but one can be concave and the other convex and both appear to be flat ....it takes a third one to indicate the other two's irregularities.

    I would use the flat way on a lathe bed or a mill table to test a DIY straight edge......or the back side of the linear rail to see if it's good enough for one.....when the Devil drives then needs must be.

    I used a 600mm Starret combination set ruler as a straight edge because when I tested it on a granite inspection table there was less than a smidgeon (.001") over the total length.

    Rendering a steel plate flat is not an art.....going in from the mill scaled surface you use an angle grinder to lightly grind the surface in a cross hatch pattern until you get bare steel, using chalk to indicate the high spots.

    It worked for me over 60 years ago when I was an apprentice on the mines and far away from the workshop.

    The question is what design and what material.......one goes with the other in various combinations, and it doesn't pay to be completely dominated by other people's preferences.
    Ian.



  8. #8
    Registered
    Join Date
    May 2011
    Location
    Canada
    Posts
    269
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Quote Originally Posted by handlewanker View Post
    I would use the flat way on a lathe bed or a mill table to test a DIY straight edge......or the back side of the linear rail to see if it's good enough for one.....when the Devil drives then needs must be.
    I used an actual long straight edge to check the piece of aluminum I used. I've used the straight edge and aluminum against enough things to know that they are dead on. You can't really rub cosmetics against something using a straight edge, which is why something else is needed.

    In my experience, you can't use the back side of a linear rail because they aren't flat enough until they are bolted down, and if you are using it to rub for high spots, they can flex.

    Quote Originally Posted by handlewanker View Post
    using chalk to indicate the high spots.
    I never tried chalk. I used cosmetics and wax paper. If chalk works, that would be a better option as you wouldn't get as much debris sticking to it as you do with the cosmetics, which have to be wiped off in between applications for that reason. If I do it again, I'll have to try some chalk.

    Quote Originally Posted by handlewanker View Post
    The question is what design and what material.......one goes with the other in various combinations, and it doesn't pay to be completely dominated by other people's preferences.
    Ian.
    Agreed. Hopefully boltzzz will come up with something awesome that I would never think of. Not sure how he's going to bolt things together, and I think this will take a fair amount of refinement to the design to get it right, but it's a good start. Nothing wrong with considering other options and opinions too.

    I have nothing more to add to this. Good luck boltzzz.



  9. #9
    Gold Member Bubba's Avatar
    Join Date
    Mar 2004
    Location
    LaGrange, GA USA
    Posts
    1720
    Downloads
    11
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Hi,
    A few years ago, I also built an aluminum framed fixed gantry machine. Like you, I wanted bolted connections (main reason was that I had no TIG!) so instead of just bolting, I also "glued" it with Loctite product E-20NS.

    I finished fabrication back in 2011 and it is still glued together to this day! I use it mainly for etching PCBs, but have also done some plastics, Aluminum, and brass on it.

    Good luck to you in this project.

    Art
    Country Bubba (Older Than Dirt)


  10. #10
    Gold Member handlewanker's Avatar
    Join Date
    Sep 2006
    Location
    Australia
    Posts
    5526
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Hi, using the chalk to reveal high spots is just a rough and ready way to get steel plate with mill scale on it to a reasonably flat surface so that you can bolt something down on it.....the chalk stays white in the hollows and turns shiny black when a high spot is rubbed.

    If you're careful and don't dig the angle grinder disc in you can get really flat as the disc only wipes the surface when presented lightly at an angle.......don't use a new disk....older partly worn discs work better or round the corner off on a brick.

    I used this method mainly for outside in the field fabrication and construction.

    I also used it on the rough back of my lathe headstock casting to give a flat surface to mount the belt drive countershaft where there previously wasn't one.
    Ian.



  11. #11
    Registered
    Join Date
    Oct 2016
    Location
    Australia
    Posts
    9
    Downloads
    0
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    Thanks guys,

    So that is a 1.5" bit cutting a 1.5" thick piece with 0.5" left over? So with a 2" bit you couldn't cut a 2" thick piece that is flat on the table?
    Z movement of 3.5". As the router can be moved up and down on the z plate, this can allow for different length cutters and still get the full 3.5" height in Z.
    A question, what is the standard length of a cutter?

    If you put the Z rails on the part that goes up and down, you can keep the two lower bearings at the lowest spots
    It's the simple things that sometimes can make a big difference. I can't believe I couldn't think of it!
    A lot of other designs I see still have the rails mounted on the Y plate instead of the Z plate. Do you know why that is?

    I do have to have a bit more of a think of how to join the aluminium together.

    Looking at various different designs, sometimes I think it will be easier to make a strong moving gantry design. I'll keep on improving my design.



  12. #12
    Gold Member
    Join Date
    Jun 2010
    Location
    Australia
    Posts
    2798
    Downloads
    4
    Uploads
    0

    Default Re: Need help - Fixed gantry design

    pros/cons for ATP-5 plate vs 5083 plate
    ATP-5 is slightly modified 5083. There is not a lot of difference.

    Cheers
    Roger



Page 1 of 3 123 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

Need help - Fixed gantry design
Need help - Fixed gantry design