Steel frame cnc router design/build

[JoeHarris]

Yes there's a 10mm thick plate with holes tapped it.The holes in legs are drilled oversize for clearance. The 10mm plate is tacked in place to hold.

The main bed frame is heavy so there's 4 lead screws (2 each side) to help lift up and down and roughly get into position. Then there's 8 angle plates(4 each side) fastened to bed frame with 2 holes in each so 16 Bolts total that bolt into uprights with 10mm tapped plates inside.
It's simple and easy thou to be honest it's not something you do very often has usually you'll settle on a position that allows 90% of what you want to do.!. . . . It's just nice having the flexibility to do oversize things when needed.

Cheers. What thread are those then? I think I read somewhere that you favour m5 due to number of threads but they look bigger? What do you tend to use for plated connections?

[reason I ask is my 4.2mm bit is knakered and I'm looking at replacing it with a taper bit as my chuck is not the best... If m5 is not the way to go I may not bother just now..

Joe

[JAZZCNC]

Cheers. What thread are those then? I think I read somewhere that you favour m5 due to number of threads but they look bigger? What do you tend to use for plated connections?

[reason I ask is my 4.2mm bit is knakered and I'm looking at replacing it with a taper bit as my chuck is not the best... If m5 is not the way to go I may not bother just now..

Joe

They are M10 Joe. I only use M5 for linear rails where they tap direct to steel box. Most other stuff like Z axis then M6 or M8 depending on plate size.

Wouldn't use a taper drill for threads there not accurate enough really, Ok for general holes.

[CraftyGeek]

On the x-axis I am going to use 2 leadscrews with a single motor.

Ok - i'll draw up a revamped steel gantry...I have a slightly revised approach in mind now...i'll be back with a design for you to tut at later :-p

[JoeHarris]

They are M10 Joe. I only use M5 for linear rails where they tap direct to steel box. Most other stuff like Z axis then M6 or M8 depending on plate size.

Wouldn't use a taper drill for threads there not accurate enough really, Ok for general holes.

Thanks Jazz, What about where you are joining the various sections of the steel frame together? I am going to be tapping directly into 3mm wall steel for most of my connections...

[CraftyGeek]

Ok - I have a gantry drawn up now that i'm feeling much happier about.

Weight as it stands currently is approx 28.5kg...obviously z-axis & spindle etc still need to go on.

Motor mount shown is rough & a guide only.
Leadscrew is guide only.

Teal parts: 75 x 50 x 3 steel box
Green parts: 60 x 5 steel flat bar
Bearing mounts: 15mm ecocast
Front vertical plate: 5mm aluminium plate
End braces: 15mm aluminium plate
Rails are mounted on 50 x 10 aluminium flat bar

Hopefully this is a decent blend of strength, precision/alignment & weight.

Bracing for impact...thoughts?

[jcb121]

here's another idea for the ganrty, a bit more expensive solution though as the sides need to be machined/watercut.

Attachment 9513
Attachment 9514
Attachment 9515

so 20mm alu plate reinforced with solid 25mm square bar. 20mm plate all around.

to attach the ballscrew nut, you'll need some sort of hanger or place the ballscrew on top of the linear rails and make it go through the gantry 20mm plate :D

saves material and very elegant .

all criticisms welcomed / encouraged!



what software are you using? it looks interesting.

[CraftyGeek]

Interesting approach - but I think it'll work out a lot more more expensive than the current draft above. As it stands above its about £78 material cost...I can't see that aluminium version being in double figures.

[CraftyGeek]

Bumpety bump for my gantry design above...any thoughts?

[JAZZCNC]

Thanks Jazz, What about where you are joining the various sections of the steel frame together? I am going to be tapping directly into 3mm wall steel for most of my connections...

Joe I've drilled holes just less than dia of M12 nuts so tight fit then knocked the nuts into holes just below surface with bolt in threads to protect then weld in place then grind welds flush.

Edit: That was for in middle of sections. At the ends were I could reach I just drilled M12 hole for bolt put nut on inside and welded from inside.

[JoeHarris]

Joe I've drilled holes just less than dia of M12 nuts so tight fit then knocked the nuts into holes just below surface with bolt in threads to protect then weld in place then grind welds flush.

Edit: That was for in middle of sections. At the ends were I could reach I just drilled M12 hole for bolt put nut on inside and welded from inside.

Little more involved than I was Intending but I guess m6 with only 3threads engaged is a bit measly when I think about it! Are those bolts in your photos earlier on this thread m12 then? They look smaller somehow.

On the x axis RHS presumably you don't weld bolts in place - what do you do there? Hope you don't mind giving away all the trade secrets!!

Cheers
Joe