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ye I know Jonathan and wasn't really picking up or discrediting your referance about microstepping more pointing out for high resolution operations like engraving etc then it's better to use the correct pitch screw.Quote:
Originally Posted by Jonathan
I've been bouncing some of these shapes and ideas around and I'm left with the feeling that, while the idea really appeals to me, I'd end up with the combined table element somewhere in the region of 170+mm deep if I try to fit the motors in the way planned. For some reason that just doesn't feel... right. I have no idea if there is a mechanical reason for this to be wrong, it just seems odd.
This design lark is harder than it looks, especially when you have a tendancy - nay, burning desire! - to reinvent the wheel at every opportunity :confused:
Don't sound over deep to me but it would really help if we had a nice pritty drawing to look at.:whistling:
Oh I do love making pretty drawings... one on the way then, if not in the next hour then tomorrow!
Right. Cobbled something together while the rest of the family were subjecting themselves to XFactor :whistling:
Attachment 4549
I've had a glass or three of wine so you'll need to excuse a few glaring errors (yes, one of the motors is physically inside a wall as I forgot to "carry the one" while doodling numbers on the back of a fag packet...). One side is missing for visibility, and because I realised another "carry the one" error made it physically impossible :redface:
For size reference, the big blocks along the bottom are 80x80, the others are 80x40. My initial idea for the top table was to use L brackets to connect to the blocks on the rails of the bottom table. No idea if they would be suitably strong enough but it seemed like a good idea at the time (cue cutaway of top table showing L bracket)
Attachment 4550
I've not put in the Z, just roughly indicated where the spindle would be. I also want to think about what I can do to make the gantry stronger, bracing etc, for most mass and rigidity within my capabilties - so no welded steel tubes or fancy epoxies :cry:
I also realise it would be flippin' hard to clean as it, but I have plans for tackling that as well! That will be another thread later on in the year!
Hi rogue,
Ah ah I see what you mean know.? . . . Just a quicky as it's early and I'm on way to motoX.
I would scrap the top moving portion as it's too bulky, overly complicates and add's no extra strength or bennifit over the Z axis running across the fixed gantry in the usual way.
Would be cheaper due to less materials and less work.
Yes triangulate and brace the hell out the gantry and base frame.
If you have a need or want an idea for capabilty to have a high Zaxis but with absolute max strength at the cutter, so very little tool flex then let me know and I'll post a suggestion.? . . . If not then won't waste my time. . Lol
Ok time to jump on a road bike to go race dirt bike.!! . . . . .Arg I hate road bikes but got to get there fast.!!
All suggestions welcome! If there is no real benefit to the design then I'm not obsessed with keeping it. I just thought it was easier to make the table area "solid" than it would be to make the gantry "solid".Quote:
Originally Posted by JAZZCNC
:lol: hahahahahah!!!!!!!!!!!! its a problem for sure lol..... i excuse myself the trait because you never know, i might actualy be a genius and unravel a never been seen before solution to an age old problem... alas... it never quite seems to be the case though:wink:Quote:
This design lark is harder than it looks, especially when you have a tendancy - nay, burning desire! - to reinvent the wheel at every opportunity :confused:
it still beats watching the X-factor though
Anything beats watching the X-factor.Quote:
Originally Posted by blackburn mark
Hi guys, It's always a toss up as to how to go about building one of these new fangled things. Whether to fix the gantry or fix the table. I would prefer to fix the gantry myself but then you need twice the room for the table to move underneath it, but it is the strongest method. My gantry's have been moving due to space limitations but your design looks to be relatively small so fixed gantry would probably be the way to go.
On large gantry's it is a good idea to have a greater pitch for the long axis screw due to whipping if turning too fast so to move the gantry/head a certain distance the quickest way possible this method is good. You do sacrifice resolution though but you may not need 0.000001 tolerances. (arbitrary amount)
I have 10mm pitch ballscrews on my Y axis because that was the largest pitch available at the time for the price and my X axis has a 12 start 50mm pitch acme screw with matching anti backlash nut. I have geared this acme screw down to 3:1 which gives me 120 steps per mm which I think is fine for my wood working. Remember that the steppers might be out by a few arc minutes per step but they all come back to the same point after 1 full rotation. There might be small inaccuracies in that 1 revolution but geared down 3:1 it makes them smaller inaccuracies again. It all boils down to how accurate you need it to be.
Temperature comes into play if you have a very big machine as well and if your milling wood then also humidity plays a part.
What would you expect the tolerances to be for PCB routing. I've never done this but I would expect you wouldn't need anything better than 0.002" (But I may be wrong)
You could probably mill Steel, Aluminium, etc but you would only be able to use a very small chip load as your strength and vibration absorbing qualities of the gantry just wouldn't be there. You could do it but it would take ages to achieve something easily done on a bigger machine. Potentially you could mount a diamond wheel to your spindle and grind your jobs but the time taken would be an issue. (you would probably want that 1 year of your life back :-) )
Fixing the gantry will give you the greatest stability and if braced properly then you will have a fine little machine to work with and with the quality of all the parts available today you can't go wrong.
If you need to put bigger things under the gantry then make the table adjustable by being able to drop or raise it. Shouldn't add too much to the design for a small router.
The Chinese spindles are very good value for money if you are after one, and compared to the wood routers, they will give your ears a much needed rest and make your neighbors happy at the same time.
I have a plan in mind for bracing that involves a wrap-around... err.. thingy? Shell? I'll let you know how it works out. I'm moving back to a fixed gantry so the need for keeping everything under the table is less urgent. I still intend to do it, though for other reasons.
At my wife's request I've put everything non-essential on hold after a (or more specifically, another) job fell through at the start of the year. Until I'm earning again, I need to step back for the sake of my wallet and my sanity :saturn: