That surly is an ambitious build, especially for a first machine!
Do you work in composites? Both the machine and method of construction suggest so.
I look forward to its completion.
Nic 77
Thank you for all your calculations/information. I am indeed familiar with rodless cylinders, as I had said in an earlier post. They have some cons, one of which is cost. You should not discount pulley systems so readily as 'DIY', they are a cornerstone of mechanics. This whole build could be regarded as 'DIY' as we are doing it ourselves, but, as we are reasonably competent mechanical engineers building a commercial use machine I would argue that nothing on the build could be considered as 'DIY' in the context that you have used the term. Another poster said "I have had good luck with gas struts..." well, we do not rely on luck, rather good engineering and intelligent thought.
Air over hydraulic - I do not believe that a hydraulic ram is a good solution for a high speed system (1.0 m/s).
As you have gone to the trouble to provide all that information, I propose that we fully indulge your fetish for counterbalances by giving you correct parameters to work with. I suggest that we should consider the following configurations:
1) Single acting pneumatic cylinder 400mm stroke / 4:1 pulley system.
2) Single acting pneumatic cylinder 500mm stroke / 3:1 pulley system.
3) Single acting pneumatic cylinder 750mm stroke / 2:1 pulley system.
4) Rodless pneumatic cylinder 1500mm stroke.
Parameters:
Z-Axis mass = 120kg.
Z-Axis travel, use 1500mm.
Z-Axis travel velocity: 1.0 m/s.
Available factory air: 80cfm / 100 psi.
Factory air receiver capacity: 0.5m3 + 100m of 1.5"NB Schedule pipe reticulation system.
Additional air (spindle tool change, etc): 2nd stage compression - 175 psi / 5 cfm / 50L air receiver.
Note #1: We can fit an appropriate additional air receiver / accumulator dedicated for the counterbalance system, or,
Note #2: We can consider using the factory air system as the accumulator, or,
Note #3: We can consider using the main frames as the dedicated air receiver / accumulator, capacity = 22 meters of 200x200 RHS.
Note #4: I would suggest a safety factor of 1.5 should be applied to the ram size calculations.
Have I forgotten anything?
Regards
Jono
Ps: merry xmas all
Last edited by jono5axe; 12-26-2017 at 09:31 PM.
That surly is an ambitious build, especially for a first machine!
Do you work in composites? Both the machine and method of construction suggest so.
I look forward to its completion.
Sven http://www.cnczone.com/forums/diy-cnc-router-table-machines/320812-aluminium-1250x1250x250-router.html
Still on counterbalances.
Interestingly, i found this set-up.
It is a air over hydraulic system (and supposedly fast). It employs a standard ram, with a pulley system at the top of the rams. Looks like twin pulleys, so a 3:1 or 4:1 ratio. Maybe this is how they get speed.
[EDIT - On second look it appears that while there are twin pulleys and cables on each ram, both cables are terminated. So, maybe two cables/pulleys were required for load capacity rather than gearing ratio. Therefore ratio appears to be 2:1.]
Jono
Last edited by jono5axe; 12-28-2017 at 09:02 PM.
In reading through this post again, what is the point of using glass AND carbon fiber in the gantry?
Sven http://www.cnczone.com/forums/diy-cnc-router-table-machines/320812-aluminium-1250x1250x250-router.html
- To potentially modify the thermal expansion coefficient of the two combined materials to a mid range value (more similar to steel, concrete).
- To make it more robust, as carbon is delicate, easily bumped and damaged, and fails in a catastrophic mode.
I would say that this beam can be regarded as 'experimental'. I re-thought a few things as I made it that would change for the next ones, minor stuff, but nothing is really relevant until it is operational and I can determine if it is stiff enough, or not. But, standing in front of it, and knowing what is inside it, I am pretty comfortable at this stage. And it comes in well under my design weight, which was unlikely in steel (AL is too high thermal expansion).
J
Ah, hadn't thought of that one, good one. So you put the glass on the outside then?
Another thing, did you plan for some kind of straightening the surfaces for the linear rails?
Sven http://www.cnczone.com/forums/diy-cnc-router-table-machines/320812-aluminium-1250x1250x250-router.html
Yes, I have three or four options on how to set-up the machine beds, i.e. machining the steel, shimming, epoxy chocking, epoxy granite castings, etc, none of which I have really got excited over just yet. I would like to just machine the steel, but this is a big job (over 4.0m long beds, x 4 beds, transport, etc) and not many places that can do it, and an expense of a reasonable magnitude. Does anyone know of a stock material (metal, or hard) that comes in a toleranced/finished stock, say 150mm x 10mm section?? Some pre-finished tooling steel maybe?
Last edited by jono5axe; 01-15-2018 at 12:15 AM.
Gauge plate steel or tooling plate / mic6 aluminium.
Re the earlier counter balance questions, I bought this air ram a couple of weeks ago, so that can be put to bed for a bit....
Jonathon Clarke
www.solpont.com
A couple of progress pics.
X-Axis main members finished and ready for filling with epoxy/aggregate. The beams are upside-down in the pics. The bolts/plates are for bolting on to the main legs/frames, leveling adjusters, etc.
(That is the composite gantry beam in the background).
Jonathon Clarke
www.solpont.com
Lots of info and questions on the forums about epoxy-granite, so I will post some more general info stuff here....
These are some pics of some samples & methods of epoxy-aggregate that I have done as sample mixes for filling the cavities in the router steel frames. The stone that I have used before for 'engineering stone' and that we have readily available is NZ Greywacke. It is very hard/durable and is supposedly 100 million years old, so fairly stable i would expect. It is available as washed aggregate in various size grades.
https://flexiblelearning.auckland.ac...greywacke.html
Top left = aggregate 20mm
Top right = sand (SiO2)
Bottom right = aggregate 7mm
Bottom left = aggregate 13mm
Sample #1: 25%-13mm, 25%-7mm, 40%-sand, 10%-resin. Mixed with a 1" metal spatula and left to cure in the 800ml mixing container.
[Note 1: No 20mm aggregate in mix due to requirement to fill internal corners and features]
[Note 2: I over added resin, to approx 13%. This was an error due to the mechanical scale sticking]
Sample #1: removed from mixing container and cut with a 125mm cutoff disc.
Note 1: The sand has migrated to the outside / corners very successfully.
Note 2: Very few voids.
Note 3: The aggregate has settled and the excess resin has formed a layer at the top surface of the sample. This confirms that 13% resin content is excessive for this mix, even considering the greater content of 'fines' (sand).
Note 4: The aggregate settled even though there was very little tamping down action applied with the mixing spatula.
Sample #1: Showing the cut faces.
Sample #1: Showing sample removed from mixing container (flash photo).
Note excess resin at top.
Sample #1: Showing cut faces (flash photo).
Sample #XX: 25%-20mm, 25%-13mm, 25%7mm, 25%sand (=100% aggregate), + 7% by mass resin.
[Note 1: dryer mix, some voids present].
[Note 2: There was no tamping down action applied with the mixing spatula]
Jonathon Clarke
www.solpont.com
X-axis drive mock-up.
Jonathon Clarke
www.solpont.com
Very interesting. Good luck with it.
Looks great Jono! Please keep the updates coming as I too will be building a 5 axis though not quite as huge as this monster!
Epoxy concrete filled the first x-axis frame rail yesterday. Endcap bonded on with the epoxy conc mix. All worked good, and looks good (pic - rail on floor).
I thought that I would just do this myself, nice Saturday job. But it was a job and a half, to be sure... Had to manually carry all that concrete mix up the stairs to pour it into the top. I will not be doing something like that again single handed.
Stood the beam vertical to get the mix in..........
Jonathon Clarke
www.solpont.com
That's some ingenuity right there! Great Job Jono! Cant wait to see her going together.
Thought I should post an update, to help keep me motivated.....
....... cutting and welding, making up the x-axis support frames & feet.
[That is a sheet of ply in the background (for scale) ]
.
Jonathon Clarke
www.solpont.com
Finally making some progress. Main steelwork finished and painted. Hopefully will get this installed this week, then can start on setting up the slides and drives.
All taking longer than planned, but I suppose anyone who has built a machine before knew that already.
Jonathon Clarke
www.solpont.com
Mactec54
Thanks, it is good when there is finally something to see for the work.
At that stage now, will make some decisions this week.Where you able to machine the top Beams on these portals for the Rails Etc to mount
Yes, it worked out pretty much as planned.Did the filling of the Beams work as expected, and what mix did you use
- the cross section of the steel RHS is now stabilised.
- the internal components are all fixed in place by the epoxy mix.
- vibration dampening seems very effective from what I can determine at this stage. If I knock the beams with a wooden mallet it makes a very muted dull thud, whereas if I knock an unfilled large RHS section with the mallet it rings like a church bell in an echo chamber.
But, something to consider, the epoxy concrete part of it was quite a lot of work and time consuming (but I suppose everything has been quite a lot of work, everything has more detail that consumes more time than I had planned).
Mix used was:
- aggregate = 1/3:1/3:1/3 of sand, 7mm & 13mm (by volume)
- plus resin at 8% of aggregate by weight.
Each main beam has approx 300kg of epoxy concrete in it. Hopefully we will see some benefit from it when trying to cut good surface finishes on 3D shapes in duratec'ed and/or aluminium patterns.
Last edited by jono5axe; 04-28-2018 at 11:50 PM.
Jonathon Clarke
www.solpont.com