Bridge Gantry Profile

[JAZZCNC]

Just wondered if it was up to the job from a technical perspective (ignoring better/cheaper designs).

Well If you have too much money then go for it.! . . It will work that's for sure but it would be a dumb thing ignoring better cheaper design don't you think.?

Problem with this stuff thou other than cost is it's light duty thin wall stuff so could resonate or twist/flex in longer lengths. It won't allow much easier build because there's more Drilling and tapping involved because the slots don't allow easy ballscrew mounting. Drilling and tapping profile is a pain on thick walled stuff but this thin walled stuff is rubbish for tapping and holding threads.

Also don't think just because you have vacuum that the shelf won't collect enough chips and fine dust to be a pain.!! . . . It will collect very quickly esp on material like MDF that produces fine dust. . .You'll need a very good Vacuum and dust shoe to contain every thing.

Personally I don't see the point of using this stuff has it's not really making anything easier costing 3 x times the price and is inferior in strength.!

[John McNamara]

Hi

Steel is three times stiffer than aluminium and for machinery stiffness is more important than strength in most cases. Any sort of deflection will add to the "Error budget" for the machine. Remembering that (Among others) the sum of all errors for misalignment, frame deflection, bearing slop and temperature have to be added together to calculate the maximum error.

Google search compare Steel to Aluminium: https://www.google.com.au/?gws_rd=cr...ared+aluminium

Regards
John

[~andy]

Well If you have too much money then go for it.! . . It will work that's for sure but it would be a dumb thing ignoring better cheaper design don't you think.

I'm not ignoring a different designs outright. Just looking at the options.

Problem with this stuff thou other than cost is it's light duty thin wall stuff so could resonate or twist/flex in longer lengths.

I can't tell with extrusion, and I don't know enough to be comparing section modulus and moment of inertia figures over other designs. It's a very strong cable tray really after all.

It won't allow much easier build because there's more Drilling and tapping involved because the slots don't allow easy ballscrew mounting. Drilling and tapping profile is a pain on thick walled stuff but this thin walled stuff is rubbish for tapping and holding threads.

I was thinking of drilling and tapping to a plate, and mounting off that to get the correct height.

[JAZZCNC]

I was thinking of drilling and tapping to a plate, and mounting off that to get the correct height.

I understand your thinking and desire to makes things that bit easier if your time or equipment challenged and i'm not trying to put youoff profile or push you into any particular design but the point I'm trying to push is if you must use this Profile for time and tool reasons then you won't save any work over the L design that uses Profile costing third the price. You will actually create more work and less strength/stiffness.

I use both steel and profile and like my comments before I know 100% the L design along with profile works perfectly for the application of cutting light to Medium hardness materials. Steel would be my first choice every time if heavier duty machine required or Budget was limited has it's simply the best way to achieve both. It's just time intensive compared to profile and needs more equipment/skills to work.

Like John says there's much more to successful machine than material strength and I can tell you for sure building a machine with the mindset of compromising machine strength or design in favour of easy building is recipe for a under performing machine.!

[EddyCurrent]

~andy, I too explored several designs and went from one to the other then back again, this was after much deliberation regarding ease of build and mainly a good sturdy design with cost being somewhat secondary. I therefore came back to the L design and 'borrowed' a lot of the ideas from Matt's build, http://www.mycncuk.com/forums/router...ine-month.html.
One advantage I like with this design is the lack of gantry sides which you will need in your proposal, although on mine I made add some triangulation here for added strength.

If you still want to go the extrusion route these are some links I found while researching that.

http://www.extrusions-aluminium.co.u...xtrusions.html
http://aluminium-profile.co.uk/
http://www.valuframe.co.uk/
http://www.motedis.co.uk/shop/Slot-profiles:::1.html
http://www.metallin.co.uk/shop/
http://www.8020cnc.com/
http://www.boldman.co.uk/aluminium-profile-system/
http://www.damencnc.com/en/component...inium-profiles
http://www.zappautomation.co.uk/en/6...ium-extrusions

[~andy]

~andy, I too explored several designs and went from one to the other then back again, this was after much deliberation regarding ease of build and mainly a good sturdy design with cost being somewhat secondary. I therefore came back to the L design and 'borrowed' a lot of the ideas from Matt's build

Truth be told, I think that this is a great design with simple materials. One I've studied many times.

I think I've browsed most of those extrusion sites!

[EddyCurrent]

Well you seem to have made your mind up from the outset and the reality is it will most likely do your job so go ahead.

[~andy]

No. Not at all just exploring options. The base will be extrusion for sure, plate for the Z. Not fussed about the gantry, I just want something that is straight forward and easy to build.

Thought someone might have used that profile, or might be able to tell me how the numbers compare.

[EddyCurrent]

Did you look at that stiffness spreadsheet ?, at first I thought extrusion was not included but I found it in version 7 of the spreadsheet

[Boyan Silyavski]

No offence but this profile is a crap. Its not a heavy duty profile, just look at the design of it, with these holes and how the ribs are situated inside of it.

Of course depends how strong your machine you want to be.

Simply put: the ideal gantry alu profile is not born yet.

IMHO there are nice alu profile designs in the forums and the good ones have steel reinforcing plate on the gantry, one way or another.

The best so far alu implementation in a gantry i have seen is what Dean/JAZZCNC/ builds, so if you are for tidiness look there. And is not a profile.

This is the american way-bolting together profiles and having fear from some soldering. Shiny expensive useless machines. I was also a bit infected, thanks Dean that he cured me from the rack and pinion desire.

steel profile+square supported rails+ball screws=good machine worth spending some money for the build.