[margni74]

Been playing around in sketchup ... I have in my possession 90+% of the parts now to really start building. after over a year watching the parts collection collect dust, it's time to put a plan into action.

Most of the structure has been layed out. I still need to sort out the bits that will be mounting to the gantry structure, but i think this is going to a workable design. It should be 4'x3' or so. The cutting area will be around 30" x 20" x 4-6"

Please point out any weaknesses in this approach, I'm sure there are many things I have overlooked.

[acondit]

I am not sure where your cutting surface will be, but if it is where it seems logical to me, then your lower gantry piece is too low. Your lower crossmember needs to be high enough to clear your thickest cut.

Alan

[margni74]

I am not sure where your cutting surface will be, but if it is where it seems logical to me, then your lower gantry piece is too low. Your lower crossmember needs to be high enough to clear your thickest cut.

Alan

Hey Alan,

Thanks, nice catch.. would have had an 1/2" of z travel.

[acondit]

Catching everything yourself can be hard. I know! I've had to do a few redesigns myself.

Alan

[Coogrrr]

Love it and with the slides you chose it should work great but that much 8020 your gonna be paying thru the nose unless you have some good deal.

Rock on and post TONS of pics of the build.

Coog

[spalm]

My recommendation would be to not actually start cutting 8020 until you know how you are going to mount your motors, screws, and leadnuts. You don’t always have to draw them in, if your cad skills are not as fast as you want, but at least pencil them in as they are a real integral part of the machine and some forethought is needed here. Cad drawings would be preferred, of course.

Looks like you are off to a good start,
Steve

[tahustvedt]

Here's what I would change. I took the liberty of drawing on one of your drawings for illustration.

1. Remove the short vertical beams and mount the traverse underslung beam under the bottom edge of the two longer side beams after rotating it 90°. This should make the lower beam more rigid in the X actuation direction and the connection between the bottom beam and the side frames stronger. It would also make the whole gantry more rigid because the long side of the beam will be better at preventing one side from lagging when you are milling on one side of the board.

2. Raise the bottom Y beam a couple of inches for a little more more work space.


Does it make sense?

[margni74]

My recommendation would be to not actually start cutting 8020 until you know how you are going to mount your motors, screws, and leadnuts. You don’t always have to draw them in, if your cad skills are not as fast as you want, but at least pencil them in as they are a real integral part of the machine and some forethought is needed here. Cad drawings would be preferred, of course.

Looks like you are off to a good start,
Steve

That's good advice, I agree. This is one of the reasons I am trying to put in the time and plan it out as much as possible in cad before I fire up the chop saw. I know there will be some "uh oh" moments, but I am trying to minimize them as much as possible.

[margni74]

Here's what I would change. I took the liberty of drawing on one of your drawings for illustration.

1. Remove the short vertical beams and mount the traverse underslung beam under the bottom edge of the two longer side beams after rotating it 90°. This should make the lower beam more rigid in the X actuation direction and the connection between the bottom beam and the side frames stronger. It would also make the whole gantry more rigid because the long side of the beam will be better at preventing one side from lagging when you are milling on one side of the board.

2. Raise the bottom Y beam a couple of inches for a little more more work space.


Does it make sense?

Yup, I see. Your method is better and requires less material as well. I've raised the cross member so I have roughly ~5.5" of potential cutting travel, minus whatever platform i end up mounting in there.. This should be good enough I think.

Here's the latest:



Thanks for the input, keep it coming!

[magick_man]

This newer version looks great.
The only thing I might recommend would be to mount the Y axis on the opposite side of the gantry.
The reason I say this is, The way it is now you will have alot of dead space on your table with the x moved all the way to the left in this picture.


I think it would move your usable table area more into the center.
Instead of being able to use one half and not touch the other.
I am not sure if any of that makes sense or not, I can draw it out if it doesn't.

But regardless it is a great looking machine.

Joseph-

[margni74]

This newer version looks great.
The only thing I might recommend would be to mount the Y axis on the opposite side of the gantry.
The reason I say this is, The way it is now you will have alot of dead space on your table with the x moved all the way to the left in this picture.


I think it would move your usable table area more into the center.
Instead of being able to use one half and not touch the other.
I am not sure if any of that makes sense or not, I can draw it out if it doesn't.

But regardless it is a great looking machine.

Joseph-

I see your point, I'll probably end up taking your suggestion, it may get me a few more inches of usable travel. The issue I have is that I have sort of a mishmash of odd ball length parts that I bought from ebay. I have a set of monstrous 4' rails, but only a 32" length long screws. check out the size of these rails. talk about overkill!

so with the 16" or so difference between rail and screw length i can compensate by moving the mount points for the screw up towards the front of the machine

[spoiledbrat]

I like your machine. Not only does it look rigid, the design seems to lend itself to adjustment. What I mean by this, is that once you have machined a few parts, your machine will be able to be "squared" to perfection in each axis.

Good luck with your build!

Rob

[bryanrabb]

i built a "hybrid" router out of 6061 3/8 plate and 80/20. It was cheaper to use the al as the end plates. Bore holes through and tap the center cavity of the 80/20 with a 5/16. You can also use AL for the upright side frames on your gantry. It was much cheaper to go this route for me, and i think it was much stronger that had I made it from all 80/20. It also gave me flat surfaces to mount my motors to.

[margni74]

i built a "hybrid" router out of 6061 3/8 plate and 80/20. It was cheaper to use the al as the end plates. Bore holes through and tap the center cavity of the 80/20 with a 5/16. You can also use AL for the upright side frames on your gantry. It was much cheaper to go this route for me, and i think it was much stronger that had I made it from all 80/20. It also gave me flat surfaces to mount my motors to.

I've seen this approach, and it looks solid. I went with 8020 because i had it on hand, and i don't really know where id get a slab of 3/8 x 32+" x ?? of aluminum for a reasonable price.

Got any pics? I wasn't able to find your build thread.

[bryanrabb]

Getting the AL Plate at a good price is pretty much luck. I found a good bit of stock on ebay. It was fall off from some shop. I will have to dig up the pictures of my router. I have it in pieces right now. I robbed some parts off of it to build another one.

[Harpye]

Nice Idea - but you spend a much of the way to m ove to the 45° strut for the portal ( is that much necessary???) another thing - the "hinge " to the X spindle is very stable in z direction - not to carry load due asymetric load on the portal... After you have this really wide distance of your X sliders - why not constructing a kind of plate under the moving parts to install the x axis spindle would work as crosstruts and would give much more stability....

understand what I mean?

Hansjoerg

[margni74]

Nice Idea - but you spend a much of the way to m ove to the 45° strut for the portal ( is that much necessary???) another thing - the "hinge " to the X spindle is very stable in z direction - not to carry load due asymetric load on the portal... After you have this really wide distance of your X sliders - why not constructing a kind of plate under the moving parts to install the x axis spindle would work as crosstruts and would give much more stability....

understand what I mean?

Hansjoerg

but you spend a much of the way to move to the 45° strut for the portal ( is that much necessary???)

By x axis, you mean green linear slide direction, correct? Not sure I follow completely. Portal == gantry? I wanted to go as wide as possible where the gantry was connected to the linear bearings. Of course, my choice of width was pretty arbitrary. I guessed and figured about 15" would suffice. I can afford to go a bit wide, because i have 4' long rails and only a 32" long screw.

another thing - the "hinge " to the X spindle is very stable in z direction - not to carry load due asymetric load on the portal... After you have this really wide distance of your X sliders - why not constructing a kind of plate under the moving parts to install the x axis spindle would work as crosstruts and would give much more stability....

what do you mean by hinge? You kind of lost me with this paragraph..

[Harpye]

Sorry - Portal - in German this way to build is called PORTALFRÄSE - my fault ( bad English - I hope this will improve by the work in this forum ) - I mean the moving part all sub parts moved on the basic axis.
I made a simple sketch for you to understand!



1/1B
Blue is your construction to carry the Y and Z axis - and green shows the way you are able to move Red si the rail with same length in both versions. The shorter the distance between the sliders the longer the way you are able to move.

2/2B parallel perspective...
Blue is nominal and Cyan shows the bending of the construction under asymmetrical load when you change your connection strut ( better than hinge?!? ) to the spindle to a plate ( in my sketch)you are much more stable and prevent bending .

Got me again.... - I think I 'll have to use the dictionary some times more.....

[margni74]

Sorry - Portal - in German this way to build is called PORTALFRÄSE - my fault ( bad English - I hope this will improve by the work in this forum ) - I mean the moving part all sub parts moved on the basic axis.
I made a simple sketch for you to understand!



1/1B
Blue is your construction to carry the Y and Z axis - and green shows the way you are able to move Red si the rail with same length in both versions. The shorter the distance between the sliders the longer the way you are able to move.

2/2B parallel perspective...
Blue is nominal and Cyan shows the bending of the construction under asymmetrical load when you change your connection strut ( better than hinge?!? ) to the spindle to a plate ( in my sketch)you are much more stable and prevent bending .

Got me again.... - I think I 'll have to use the dictionary some times more.....

ahh, i see what you mean now. I'll add another cross support underneath and possibly cut down on the distance between the two sliders. thanks for taking the time to do the diagram.

veilen danke

[Harpye]

The pic was no problem took just two minutes ... CAD is easier than English

BTW

your German seems to be better than my English!

"gern geschehen"


Hansjoerg

P.S.: If you could estimate the possible torque/ forces on the sliders... THK has very good examples in the datasheets to calculate the necessary distance of the sliders (include a saftey factor and enjoy)

Here is my rather finished machine...( photographed together with my existing hobby =) )