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Some of that Z80 stuff is before my time, but I want one of those kits just because retro tech fascinates me.
I mean, I just got an original C64...and even that is a few years before me.
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I had a C64, was my first store bought computer and I loved it. The Z80 will be different but if you like to tinker it will be a lot of fun. If you're on Facebook there's a Z80 MBC2 users group.
Did a little mechanic work today.
Put a rear end in a recliner!
JaxCoder.com
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That takes me back...
One of my first pieces of professional (i.e. for pay) programming was writing a floating-point package (7-bit exponent, 16-bit mantissa) on the Z80 for use in a spectrum acquisition program. The standard Basic floating-point (Microsoft format - 8-bit exponent, 23-bit mantissa) was at least an order of magnitude too slow for what we wanted, but we didn't need high precision.
Fun times!
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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Cool beans 
Did a little mechanic work today.
Put a rear end in a recliner!
JaxCoder.com
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That's cool, I've see it before somewhere, but yes, maybe I will print that out! I'm still waiting for my larger Predator printer to arrive, they are waiting stock, so might supersize it!
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DaveAuld wrote: so might supersize it
I thought so. 
This is definitely one of those things that get better with size.
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I downloaded the files and trying different slicing settings, when I first managed to squeeze all the parts on to the build plate, the original print time was 2 Days!
Think I will do the parts individually, just in case something goes wrong!
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Keep in mind that the original drawing is meant to be screwed onto a jar.
There might not be any fitting jars around if you supersize it.
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But is it alexa ready?
I wanna be a eunuchs developer! Pass me a bread knife!
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That's sweet!
But ... as you say, we don't see the sun much here, and I'm in the middle of switching my printer from PLA to ABS and it's being a PITA.
PLA was fine - every print was perfect - but I've got real adhesion problems with ABS (as in everything I print warps and then lifts off the base plate) so I need to fix that before I try anything complex ... or indeed simple! 
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Do you have a heated bed for the printer?
If you do, try different temperatures of the bed.
I also wonder how much your casing affects the warping?
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Yes, and I'm up to 110C on the bed. The "adhesion pattern" looks excellent, it just warps as it "grows" then lifts and forms spaghetti instead of a print. I'm down to 50% speed, and am re-doing the bed leveling because there is a slight "crown" in the middle of the bed which may be related to not-quite-straight X rods - according to my DTI, there's about 0.2mm between the center and edge of the bed, which isn't far off the print filament thickness ...
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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What material is the bed?
This "crown", is it there also when the bed is cold?
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Glass bed - they call it an "Ultrabase" - and yes, it's there cold which is why I suspect the rails rather than the bed itself. It's a glass bed mounted to an aluminium heating plate which is held up from the linear bearings by four corner-mounted screws - so an upward deflection in the center is more likely to be the result of an bend in the rails than the bed itself, particularly since it's at its worst at or near the bed center. I'd guess that the "right most" rail is slightly more deflected than the left.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Are those rails symmetric? So that they can be "inverted"?
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Yes, they are just 8mm stainless round bar. But at a guess the mountings - one at each end - are misaligned, which would "push the middle up" so as the trolley moves on it's linear bearings it physically lifts and then drops down again.
Just loosening both ends of each rod should show that, if that's the case, and a little BF'n'I* to the end mounts may fix it.
You'd be surprised how much solid metal flexes: Lathe Leveling - YouTube[^] what from about 13 minutes to see the effect of raising one foot on a 2 ton lump of cast iron by 1/4 inch!
* Brute Force 'n' Ignorance
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Best part was the comment in the end: "Machinery maintenance isn't that exciting"
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I like ThisOldTony - I own no metalworking stuff, and I'm not about to buy any, but he just knows what he is doing, and explains it both well, and entertainingly. Not something you can say about 99% of all YouTube software videos ... 
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Oh, and the casing should help with warping, as it makes the internal temperature more uniform.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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I've just repeated my "bed map" with the DTI:
-3 18 22 0
14 37 40 12
18
0 12 28 4 (all in 1/100th mm)
(where there are more than 3 measurements in a line, that's the approx location of the max value)
Which implies I have roughly 0.2mm in the X rails, and 0.2mm / 0.3mm in the Y
It's quite possible that I can easily sort the X rails by loosening the rail mounts and seeing if the rails themselves deflect upwards when not held down (which would imply a bend in the right direction when tight). That I can fix by mending the mounts gently to eliminate nearly all the deflection. The Y rails are mounted differently, so I may leave them alone unless I have to.
But that's a job for tomorrow!
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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So I thought about this, first, there's how flat is the bed? Then, does it move, ( yes, it's heated, it moves, but likely not "that much" ) then how straight are your rails and ...
Then I thought "this is what software compensation is for". You should be repeatable, the loads don't change that much, ( and the measurements are the same coming from either direction? your Z axis acts nice? - Hmm, another potential can of worms, there's likely some "shimmy" with Z motion that affects all 3 dimensions. )
Have fun,
Oh, occurs to me, if the bed isn't flat, a 4mm sheet of AL. would be easy to scrape in. ( But that's the machinist cutting back in. )
dave
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Wow, that is really neat!
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After the holidays it feels extremely difficult to get back to work.  How do you motivate yourself to get back in?
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