ok, first attempt using sketchup 8

[JAZZCNC]

Ok thats good but bring the screw to the front, will be much stronger having the ball-nut close the Z Axis back plate.

Have you got the 20mm steel plate.? If not I think you'll maybe change your mind when you see the price.!! It's not really needed either and I'd use ali for easy working.

[deannos]

Ok thats good but bring the screw to the front, will be much stronger having the ball-nut close the Z Axis back plate.

Ok, thats no problem, i will do that. Is this to prevent racking etc

Have you got the 20mm steel plate.? If not I think you'll maybe change your mind when you see the price.!! It's not really needed either and I'd use ali for easy working.

No i haven't got any steel plate and a quick google has made me change my mind, but if i use ali how would I join this to the steel gantry?

[JAZZCNC]

No i haven't got any steel plate and a quick google has made me change my mind, but if i use ali how would I join this to the steel gantry?

Bolt or weld Angle brackets to box then bolt thru Ali plate into brackets.

[deannos]

Bolt or weld Angle brackets to box then bolt thru Ali plate into brackets.

Excellent, an easy solution i didn't even think of.
cheers Dean

[deannos]

Right taken on board what Jazz has suggested and more or less gone back to my earlier design. Instead of 2 steppers on the X, i will use 3 belts and 1 stepper.

[JAZZCNC]

Right taken on board what Jazz has suggested and more or less gone back to my earlier design. Instead of 2 steppers on the X, i will use 3 belts and 1 stepper

Just the sides would have been enough.? How wide is this machine.? Looks wide so I'll warn you belts this wide are not easily found and you may have to get them custom made.? I did and my machine looks narrower than yours.!
Has much as I don't like slaved steppers I have to say at this width then they may be a better option,! And despite having to tune them slightly slower to stop stalling/racking then With 10mm pitch screws you'll still get decent speeds for cutting wood so shouldn't be too much of an issue.! . . If your feeling flush with cash Buy some of the lead-shine digital drives and you can even be protected from racking if you take advantage of the anti-stall feature built into them.!

While I'm here and commenting then got to say not keen on the Z axis setup either.? your putting all the weight of the stepper and screw with it's bearing blocks on the front plate.??
Looks like you have plenty of length to the back plate to switch them round putting screw and motors on the moving y axis so just ball-nut is attached to front plate. The Z axis then only has to lift it's own weight plus spindle so higher acceleration can be achieved. Higher Acceleration is very handy on the Z axis esp when it comes to 3D work or V carving etc.

Sorry to keep throwing curved balls but you keep sticking your head up .. .Lol

[deannos]

Just the sides would have been enough.? How wide is this machine.? Looks wide so I'll warn you belts this wide are not easily found and you may have to get them custom made.? I did and my machine looks narrower than yours.!

It's just over 1500mm wide, so gone back to slaved motors

While I'm here and commenting then got to say not keen on the Z axis setup either.? your putting all the weight of the stepper and screw with it's bearing blocks on the front plate.??

Changed it round as you suggested

Sorry to keep throwing curved balls but you keep sticking your head up .. .Lol

Keep throwing them Jazz, would rather i cock up on the design stage then make a lemon.

[deannos]

Went to pick up my cheap box section 100mm x 60mm and it was bent, so left it. But got 2 pieces of RSJ 160mm x 90mm x 7mm x 2000mm for £20 on ebay and local for pick up. I've done a few more workings on my last design, but as there were no replies, it's probably no good. Am i going backwards in my design, i have an idea in covering the 2 outside ball screws using tumble dryer venting duct and curtain wire, it might work.

All the red/brown areas are 40mm x 40mm steel box section, that is reasonably priced. All the ali is 20mm except for the motor mounts where i have used 10mm, milled to 3mm for clearance.




The screw lengths and rail lengths are still as quoted a couple of posts ago. I have at the moment got 1610 on the Z, reading through some other posts it seems i would be better with 1605 on Z, is that correct. Also I'm looking at going with 1:1 ratio with pulleys, would that be OK.

If i have made a big mistake with this design, please let me know. If you want the file to check it out, I'm willing to send it. I'm itching to place an order with chai.

[WandrinAndy]

I'm itching to place an order with chai.

That makes at least two of us Dean! I'm finding that the tweaking, particularly around aligning multiple pulleys and belts, is taking quite long but reckon it's worthwhile getting this right up front in the virtual world.

Btw, your design is looking great to this newbie. It amazes me how many design permutations there are... Suppose it's a good thing as it provides more ideas for us all to crib!

[JAZZCNC]

Dean go with 1605 for the Z axis for the extra resolution. Speed won't be a problem over this short distance.
Also the plate on the rear of the Y axis isn't needed and just costing money and weight it adds very little to strength. Seen has you have room on the Y axis at each side then if you want to stiffen up the joint between bearings a front plate then just use a " L " bracket plate on the side. This will add much more strength for fraction of the cost.
Thou if you use decent sized bolts then even this isn't needed.!

Regards the Gantry design then again I urge you to have some form of gantry sides that ties into the bearing plates which fasten to the RSJ. This will help greatly with twist and resonance, if you don't then I think you will have some.?
Gantry sides that dropped would allow the screw bolt to the web of the RSJ and do away with stuck up in air screw.? Both will work but dropped its out the way of chips and being caught with material etc when loading.!