steel tube build concept - 1500y,1000x,250z

[outtastep]

hi
Ive been lurking a bit on youtube and openbuilds forum,
was keen to get some vsolt extruded aluminium to build router

have noticed this site has some very interesting threads that ive yet to read.......

I have some experience using a hobby built MDF router, stopped using it due to noise and space constraints - then i thought id build a soundproof shed for it - then i realized it is a bit crap and i should upgrade or start from scratch

my old machine has 3 motors and lead screws and electronics. and not much else to reuse

a couple of nights ago i saw a steel tube machine on youtube and imagined i could magically acquire the skills to build such a unit

anyways heres a drawing ive been playing with today.....1660616607166081660916610166111661216613 16614166151661616617anyway thanks for looking, cheers ben

[outtastep]

photos are a bit all over the shop , this is the most recent version- 16606most of the steel, like deck and y rails and gantry sides was to be 100x50mm steel maybe 2 or 3mm thick, with the gantry maybe 150x50. The X carriage is envisaged as a aluminium plate perhaps 10mm thick with lots of bearings either side, z bit aluminium plate made into a bit of a box. was hoping to get 250mm travel on Z. Gantry is 300mm above bed/ deck/base. Might be pushing it a bit with Z.
With the base i was thinking of 5mm steel plate. there is also steel plate in corners of and holding ball screw ends/ motors.

im a bit concerned with having this type of supported rail as i have read some bad things about the here, also probably not the best having them on their side as per my x axis ?
cheers ben

[Clive S]

Welcome to the forum Ben what do you intend to cut with this machine also it might be a good idea for you to read through some of the build logs on here.

[outtastep]

Hi Clive,
Im not 100% sure what ill be doing with machine. I have made signs in the past and some architectural models
So mainly thinking of a machine for timber - but i like using some hardwood timber so would like machine to be robust ,
I like the idea of having a bit of room to work with thicker materials, was even dreaming of having room for a rotating 4th axis to do something sculptural in the distant future !!!!!
also is it a huge leap to attach plasma cutter to unit ? (good way to burn down a shed perhaps)
cheers ben

[njhussey]

Hi, welcome to the forum! I'f you're thinking of mostly machining wood then I'm guessing that 95% of the time you'll be cutting at full extension. This is going to create one hell of a lever with your current design of gantry and Z axis. I'd be inclined to think about making the gantry shorter and having some sort of adjustable table so that when you do want to cut thick materials (probably the 5% of the tine it's used) you can lower it.

[outtastep]

hi Neil, Yeah the z has me worried. Like you say i was thinking of making a box for building up height if cutting sheet product,
Just wanted the option to cut thicker stuff, but i supposed there is a limitation in depth of cut due to length of router bit ?

With the deep table i was thinking i could leave options for future 4th axis to turn timber,

(Also perhaps a water bath if machine could cut some steel plate attaching plasma )

all dreaming, just priced 16 mm screws and rails at over $800au$ (not including 1 1500mm Y ballscrew)

maybe i should price up vslot extruded aluminium option.....
cheers

[njhussey]

Where you getting your rails and ballscrew from?

I cut mostly sheet stuff and if I had to put a box there it would be a PITA. Plus you'd have to make the bix so strong that it would be like a second bed anyway to stop vibrations....

[outtastep]

good point about vibrations Neil
Think i might shorten travel by 75-100
as for hardware, bit out of my budget at the moment- maybe i should build intermediate machine that reuses stuff i have.....
have a good one, cheers
ben

[outtastep]

stiffened x carriage166241662516626 connection to gantry by having rails top and bottom

[outtastep]

reasons for wanting high z - adaptable for possible plasma bath, box to cut thin stuff, 4th rotating axis166271662816629

[njhussey]

Ok, there's a few things you need to look at. How are you going to get to all the bolts to fasten on the bearings to the gantry and Z axis?

Are you welding everything, if so how are you planning to take the inevitable distortion out if the frame, gantry and Z axis? Epoxy? Shims?

The Z axis with the back plate does nothing for stiffness, think of a cornflake packet with the top and bottom cut off, and only makes it harder to align everything as adds more complication.

What thickness steel are you using? There's no problem in using steel but it will need bracing to stop it bending and twisting.

On an all steel machine (if thats what yours is?) you'd be best connecting the steppers to the ballscrews with belts and pulleys, this will stop any resonance from feeding back to the stepper motor.

Can't comment in the plasma thing as no experience with them, I'm sure a dual machine could be built but as with anything that doesn't do just one thing, there will be compromises.

[outtastep]

all good questions , ill attempt to bluff my way through
......
Ok, there's a few things you need to look at. How are you going to get to all the bolts to fasten on the bearings to the gantry and Z axis?

gantry - steel tube 3mm, drill and tap thread , or weld threaded rod to tube ?
x carriage - aluminium plate and angle bolted togeather, rails bolted through
z axis - maybe thicker plate 20mm ?



Are you welding everything, if so how are you planning to take the inevitable distortion out if the frame, gantry and Z axis? Epoxy? Shims?

i worried about this, maybe only weld below y rails and shim them out to put y rails on then above this bolt together


The Z axis with the back plate does nothing for stiffness, think of a cornflake packet with the top and bottom cut off, and only makes it harder to align everything as adds more complication.

so better just to have stiffer plate ? and forget sides



What thickness steel are you using? There's no problem in using steel but it will need bracing to stop it bending and twisting.

3mm , lots of jigs and clamping


On an all steel machine (if thats what yours is?) you'd be best connecting the steppers to the ballscrews with belts and pulleys, this will stop any resonance from feeding back to the stepper motor.

very good suggestion, my current machine has no issues like this as it is so sloppy no resonance builds up !
Can't comment in the plasma thing as no experience with them, I'm sure a dual machine could be built but as with anything that doesn't do just one thing, there will be compromises.
thanks for persevering with my somewhat undeveloped project :smilet-digitalpoint,
cheers
ben

[njhussey]

all good questions , ill attempt to bluff my way through
......

That's all I do :friendly_wink:


gantry - steel tube 3mm, drill and tap thread , or weld threaded rod to tube ?
x carriage - aluminium plate and angle bolted togeather, rails bolted through
z axis - maybe thicker plate 20mm ?

3mm is not thick enough to tap, unless you're using M4 bolts, you'll either need to use thicker section or glue a strip behind and drill and tap into that. Whilst steel Z axis can be done (see Boyan Silyavski's builds) it's far more common practice on here (not saying it's correct, but just what gets done on here as it works!) to use a 20mm plate for the Z axis, both for the back plate and the front.



i worried about this, maybe only weld below y rails and shim them out to put y rails on then above this bolt together so better just to have stiffer plate ? and forget sides

Welding the frame is fine. You can, with a bit of thought, weld sections that bolt together which then allows for shimming to get the frame square. You can also file/scrape/fill the steel to get it flat or use the epoxy method and either use metal putty to set the steel rail supports at the correct height or pour slow setting epoxy on the top of the rails (like I did) and this (should) then be a flat surface to put the rails onto. Have a good look through the build logs and see what others have done, this should give you some ideas and will show how others have overcome the issues they encountered.



3mm , lots of jigs and clamping

Again 3mm isn't much good for tapping holes into, it's too thin so you won't have enough thread engagement.


very good suggestion, my current machine has no issues like this as it is so sloppy no resonance builds up !
Can't comment in the plasma thing as no experience with them, I'm sure a dual machine could be built but as with anything that doesn't do just one thing, there will be compromises.
thanks for persevering with my somewhat undeveloped project :smilet-digitalpoint,
cheers
ben

Keep the changes coming, if you see my build from what I originally planned and drew to what I ended up with you'll see how all this questioning and re-drawing is good!!

[JAZZCNC]

My suggestion is forget Plasma the cost is too high and by that I don't mean cost in money but strength/performance/hassle.
The high Z axis will cripple this machine for anything but light duty cutting. Plasma is messy, smelly and expensive to do right. Your electronics will need to be geared towards it other wise you'll have potential for major hassles from EMF and is area where taking short cuts or cost cutting will bite you quickly.
Plasma and Routers just don't play well together and best kept separate. Also Plasma machine is basic in strength requirements and building required so easy enough to build a low cost stand alone frame to do the Job. Just make the Electronics interchangable with Din plugs and have Plasma profile Setup in software.

Having a High Z for 4th axis is also costly in performance/accurecy terms but often desired thou seldom used in practise so why cripple the machine for something you'll maybe use 5% of the time.?
This doesn't mean you can't have 4th capabiltys just design the machine in such a way that the 4th axis is off the machine. Either at the side or on then end then design the gantry or frame so you can reach it.!

No harder to build really just different but with no compromise in strength or accurecy as router.

[outtastep]

thanks Jazz,
appreciate the advice re. plasma
with the high Z, I know what you mean it is a real weak point- ill reduce this
I would however, like to keep the option of having large material fit under the gantry, (300mm)

if i reduce z travel by 100 mm and bring material up with a raised bed do you think the machine is more solid or still compromised by gantry height?

cheers ben

[JAZZCNC]

if i reduce z travel by 100 mm and bring material up with a raised bed do you think the machine is more solid or still compromised by gantry height?

Yes provided you keep the Distance or Z axis extension short then you won't have a problem. But this is still a slight compromise on overall machine stiffness because you still need to create that height in the first place which weakens the machine to some degree compared to short stubby design but it is the lesser of two evils I suppose.!

For machines like what you want then having a moving bed is best option because it gives the best of both worlds but keeps the machine stiff compared to just packing the Bed up.