- Thread starter outofstepper
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outofstepper
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Rocket, I see great minds think alike lol; I spent most of the weekend driving around to injection mold shops looking for old tooling plates.
No luck, but I got them curious/interested enough that I scored some great cut-offs at scrap prices. got some great aluminum and plastic
blocks that have CNC written all over them. I did get some nice clean cold rolled steel and I think I'm going to use that for now and build
the bed in 'slats'.. only problem is its 3/4" thick -- crazy heavy even for my small bed. I'm going to take a hit on this axis' speed and
acceleration for its a fine stop-gap for now .. it'll keep me playing till the right piece of metal comes along .. was hard to argue with the price.
kram: not a bad idea at all if my bed wasn't moving. I'm not sure how much a 1000 x 500 plate weighs but I think my stepper'd have a
heart attack just seeing it walk in the door.
to be honest I'm not super worried about a flat bed.. don't get me wrong it'd be nice, but most of my work will be on a riser block and
in a 4" vise.. anything bigger will likely be 2D sheet goods (wood plastic alum sheet).. and I don't think I'd sweat 5-10 thou deviation on
those parts.
I don't plan on milling an new engine block out of solid billet anytime soon, at any rate.
-Tony
No luck, but I got them curious/interested enough that I scored some great cut-offs at scrap prices. got some great aluminum and plastic
blocks that have CNC written all over them. I did get some nice clean cold rolled steel and I think I'm going to use that for now and build
the bed in 'slats'.. only problem is its 3/4" thick -- crazy heavy even for my small bed. I'm going to take a hit on this axis' speed and
acceleration for its a fine stop-gap for now .. it'll keep me playing till the right piece of metal comes along .. was hard to argue with the price.
kram: not a bad idea at all if my bed wasn't moving. I'm not sure how much a 1000 x 500 plate weighs but I think my stepper'd have a
heart attack just seeing it walk in the door.
to be honest I'm not super worried about a flat bed.. don't get me wrong it'd be nice, but most of my work will be on a riser block and
in a 4" vise.. anything bigger will likely be 2D sheet goods (wood plastic alum sheet).. and I don't think I'd sweat 5-10 thou deviation on
those parts.
I don't plan on milling an new engine block out of solid billet anytime soon, at any rate.
-Tony
outofstepper
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ps... tigging the screw bracket: I don't have the biggest selection of material sizes, milling it out of one piece would've worked, I just
didn't have the size on hand.
didn't have the size on hand.
Oh outstepper, unlucky not getting a ex mould tool clamp plate or alike. I used to work at a company where we did about 200-300 new tools a year. Every year we went through a big list of tools that were never going to run again. So many plates were scrapped.
Anyway sounds like you got some nice bits and bobs from your travels.
Oh BTW the cheapest place I would guess you could get a ground plate from if it came to having to order a new piece is Bruy Rubio. They are a Spanish mould part supplier and usually come out cheaper than the other European suppliers. They supply in Italy.
Anyway sounds like you got some nice bits and bobs from your travels.
Oh BTW the cheapest place I would guess you could get a ground plate from if it came to having to order a new piece is Bruy Rubio. They are a Spanish mould part supplier and usually come out cheaper than the other European suppliers. They supply in Italy.
Wedg1e
They call me Mr. Bodge-angles
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Like it. The only criticism I would have is the way you've positioned the two prox sensors in line with the block that triggers them... if the proxy fails or some other issue causes the axis to over-run it'll crash into the sensors!
I always use a 'passing edge' to trigger them... and usually the trigger's just a small bolt threaded in with a locknut. Yours is a bit more macho
The last CNC I was involved with used NEMA 34s (I think) with 20:1 reduction gearboxes on them; that gantry would do you a mischief if you got in the way!
As an aside, does nobody use encoders for positional feedback? Every machine I see seems to rely on the axes being homed at the start and then not being stalled when in motion (which would throw the measurements out).
I always use a 'passing edge' to trigger them... and usually the trigger's just a small bolt threaded in with a locknut. Yours is a bit more macho
The last CNC I was involved with used NEMA 34s (I think) with 20:1 reduction gearboxes on them; that gantry would do you a mischief if you got in the way!
As an aside, does nobody use encoders for positional feedback? Every machine I see seems to rely on the axes being homed at the start and then not being stalled when in motion (which would throw the measurements out).
I think the problem with encoders is that as far as I know the open source software alternatives doesn't support them.
"Real" machines use servos, as you of course know, but yes, encoders would be a good thing, however what do you do once you missed a step on e.g. a curve? The part is potentially already ruined (although you could argue that a step "wrong & corrected" is better than just a step wrong, of course
Wedg1e
They call me Mr. Bodge-angles
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I think the problem with encoders is that as far as I know the open source software alternatives doesn't support them.
"Real" machines use servos, as you of course know, but yes, encoders would be a good thing, however what do you do once you missed a step on e.g. a curve? The part is potentially already ruined (although you could argue that a step "wrong & corrected" is better than just a step wrong, of course
Ah good point. The 7m beast of an inspection rig that we built uses steppers but I fitted encoders assuming our software guru/geek/git
would be able to read them into the PLC and tell the axes where they'd gone wrong.He couldn't
so despite my best efforts to make a super-duper machine it is compromised by relying on the number of pulses sent to the steppers being correct.Mind you, the reduction gearboxes do a bloody good job of making sure that nothing much stalls it
One of the guys at work is building a CNC in his garage for woodworking, trouble is that he's designed in so much adjustment to everything it's in danger of being more flexible than a Russian gymnast!
MattH
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Ah good point. The 7m beast of an inspection rig that we built uses steppers but I fitted encoders assuming our software guru/geek/git
He couldn't
Mind you, the reduction gearboxes do a bloody good job of making sure that nothing much stalls it
One of the guys at work is building a CNC in his garage for woodworking, trouble is that he's designed in so much adjustment to everything it's in danger of being more flexible than a Russian gymnast!
There's a couple of hardware solutions that support encoder feedback to close the loop. The KFLOP can do it and the CS Labs controller can do it. EMC (AKA LinuxCNC) can also do it in software.
Wedg1e
They call me Mr. Bodge-angles
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Ah cheers, I'll look into that.
outofstepper
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third and final video in the CNC build saga.
i do a 'senior project' at the end, a multishot rubberband gun for the boy.. starts at 26minutes
if you'd rather just see what the machine does instead of hear me yammer on.
let me know what you think. Thanks!
i do a 'senior project' at the end, a multishot rubberband gun for the boy.. starts at 26minutes
if you'd rather just see what the machine does instead of hear me yammer on.
let me know what you think. Thanks!
