[rocketflier]

I am planing to use one nut underneath the square tube (actual bolt will be longer and head will serve only to tighten screw into rail), but i have same concern avout horizontal flex... Do you have any better idea hoe to keep adjustable height and add additional support ? I'm pretty much out of inspiration ... And yes, commercial supported rails are a better solution, and are also out of my budget

Are you filling these tubes? Otherwise how are you preventing the tubes from deforming from the forces applied when you tighten the nuts?

[arizonavideo]

You don't have to fill them but if you offset them to one side you will have less flex.

[CarveOne]

You can add no-cost supports inside the tubing by cutting and grinding scrap metal tubing to a length that just slips inside the square tubing. Put the bolt back through it and tighten as needed. Small diameter water pipe or electrical conduit works fine for this. Even hardwood dowel or squares of scrap wood with holes drilled through it will work.

[HorridHenry]

One doesn't have to use any filling of the tube and a better securing can be had by using allen type bolts,you just drill a hole slightly oversize so that the stub of the bolt will go straight through the underneath of the metal and secured in the top section of the rail....like so...

[HorridHenry]

The type of bolt I'm on about.

[Phife]

You can add no-cost supports inside the tubing by cutting and grinding scrap metal tubing to a length that just slips inside the square tubing. Put the bolt back through it and tighten as needed. Small diameter water pipe or electrical conduit works fine for this. Even hardwood dowel or squares of scrap wood with holes drilled through it will work.

I tried this method on my machine that has through bolts on square steel tube, it didnt work, as the insides of the square tube are not consistent I had to keep grinding each collar until it fit. It was a huge pain, and if you had one in the center of the tube it was impossible to get it in there and aligned correctly. Also there is usually a thick weld on the inside of the tube that will also mess up that idea.

[CarveOne]

I tried this method on my machine that has through bolts on square steel tube, it didnt work, as the insides of the square tube are not consistent I had to keep grinding each collar until it fit. It was a huge pain, and if you had one in the center of the tube it was impossible to get it in there and aligned correctly. Also there is usually a thick weld on the inside of the tube that will also mess up that idea.

It has worked well enough for me, and it wasn't so difficult. For the case where I had a weld bead in the way I cut a notch in the piece of water pipe to clear the bead. I don't fit the spacers so tight that they won't slide inside the square tubing. Any gap is minimal though. I can push the spacers to the center of my 12' tubing using a 6' piece of 3/4" square scrap wood until the spacer is seen in the pre-drilled holes. Start in the center and work outward as the spacers are inserted.

[p00ky]

Couldn't you use a round piece of metal tube as a spacer inside the box section around the bolt (like a sheath). Or even just 50mmx50mm square washers top & bottem instead of small round ones.

[rocketflier]

Yeah, anything inside to prevent it squishing down. Epoxy fill, hardwood blocking, spacers,...

Thick, wide washers are another method to transfer the force to the sides.

You can also buy (or make) steel spacers which fit through a larger hole in the bottom of the tube to push against the inside of the top of the tube. That way you don't have to try and slide each one into the tube and exactly line up the hole(s).

In looking at the photo below, the idea of a coupler nut might work as well. Drill the hole large enough for the coupler to rotate and simply tighten it. This of course assumes couplers are available longer than the tube thickness.

[turpija]

current progress ...

still heavily welding



a bit of grinding



some paint



and welding some more



i think you got the pattern

[turpija]

so, here we go ...

all parts were smoothed a bit and painted

this will be a final color



after some thought i've sprayed a poliureathane foam in all parts ... should work better than without, for vibration dampening, at least that's the theory



here is completed 4th driver ... what a masterpiece of soldering



and machined thread screws that should get the job done, at least until i get ballscrews sometime in far far future



of course, a good machine needs a decent feets



still some welding and painting to do, but hopefully assembly is not so far from this point

[nainino]

All I can say is WOW !

The finished parts look so good !

Can't wait to see your machine running.

[turpija]

here is a bit of update

final welding and grinding of small parts


preparing for paint


the paint


turned out kinda sorta cool

[toneV8]

Koju boju si koristio, možeš li uslikati kanticu boje i u kojoj prodamnici si kupio.

Lijep pozdrav.

[Falcon69]

hmm, i like that paint. I might do the same with mine. How many coats of clear coat did you put on?

But why paint the inside of the threads? Might make assembly just a little difficult. Next time, shove some tissue or something in the holes :P

Hmmm, I wonder if I can get the same texture type paint, but in powder coating.

[turpija]

the paint is hammerite with effect (obvious
supposedly should go directly on metal, even light rust ...

and there is no clear coat, just gray primer and hammerite

[turpija]

it's been awhile since my last update, so let's fast forward to current state, shall we ?

start of assembly ...





and cnc made some actual first moves, but as it turnet out, screws were not too straight so whole machine started shaking and moving speed had to be very low ...
so, next logical step was to upgrade to ACME screws (as you call it i presume)


redo all the work and hope for the best ...



some cutting of aluminum ... as it turns out, not such a great quality for machining, and with not such a great tool ... but hey, i call it progress ...


and as it turns out, new screws were also not good enough, i suspect turning the ends were not accurate enough ... so, scrape em and start all over again ... but as i'm run out of hope for screws, and out of money to go for real solution - ball screws ... decision is to go another route ... belt drive !
currently there are some parts finished and looks promising but meanwhile you can enjoy this video ...
cutting aluminum of some greater quality (2000 series), and with much better endmill (single flute), and offcourse a decent motor to run it (not mine

[turpija]

here is the video ...

[wizard]

it's been awhile since my last update, so let's fast forward to current state, shall we ?

and cnc made some actual first moves, but as it turnet out, screws were not too straight so whole machine started shaking and moving speed had to be very low ...
so, next logical step was to upgrade to ACME screws (as you call it i presume)

ACME is the right term.

redo all the work and hope for the best ...

some cutting of aluminum ... as it turns out, not such a great quality for machining, and with not such a great tool ... but hey, i call it progress ...

You could work on speeds and feeds to improve quality and make use of a lube/coolant. For such a light machine it really doesn't look that bad.

and as it turns out, new screws were also not good enough, i suspect turning the ends were not accurate enough ... so, scrape em and start all over again ...

What was or is wrong with them? I'd try to get the ACME screws working properly before disposing of them.

but as i'm run out of hope for screws, and out of money to go for real solution - ball screws ... decision is to go another route ... belt drive !

A belt drive good enough to machine aluminum won't be cheap. You will need heavy timing belts with all the supporting hardware.

currently there are some parts finished and looks promising but meanwhile you can enjoy this video ...
cutting aluminum of some greater quality (2000 series), and with much better endmill (single flute), and offcourse a decent motor to run it (not mine

[turpija]

did some work on belt drive ...






how it works at the moment



10kg is whole Zaxis assembly, and apparently motor can't hold it while powered out ...