Steel frame cnc router design/build

[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]

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

Erm.!! . . . It's ok but there's not much holding or supporting that top rail piece. 5mm Ali has no strength in it so your gaining nothing from that really and the Steel plate doesn't add any strength.
The triangle piece on the X axis is about the only thing supporting it and that's not enough it will flex under cutting and transfer to finish quality.
At the very minimum I'd have 2 triangle pieces at each side, really i'd make the gantry sides wider and tie the end of both rails into sides has well as double triangles on each side.

On a plus note you could drop those pieces between the rails and steel has you can drill & tap the steel directly. You only really need those when using Alu profile.

Beef the holding of the cross rails and it will be ok.

[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

[JAZZCNC]

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

Actually they could be M10, I've forgot now but I've still got one frame part built so can check.!!

To be honest Joe I could have saved loads of time and made things easier by just using large hole cutter creating access holes on out side of frame for access with a Socket and bolting together, I just think it looks neater. In your case it may be better to take this route and put rubber grommets in the access holes.

Regards top rails then yes I welded the middle nuts but could have easily done the same thing here. I wasn't concerned if the top rail distorted because I epoxy level the top rails anyway.

[Swarfing]

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.

I've got M12 bolts in 3mm box steel holding bearing blocks in place and never moved?