snowygrouch
-
Posts
348 -
Joined
-
Last visited
Never
Content Type
Forums
Events
3D Prints
Posts posted by snowygrouch
-
-
Looks good, I think the idea about spherical bearings on the ends of the XY rods in the blocks is a very good idea.
Only difficulty could be the tolerance, if they were even a bit rattley it would be a disaster. But in principle its
a very good idea I think.
I dont think there is much hope to control the heat actively, as unless you make some sort of really custom coaxial
heater unit the distribution will be awful, and heatflux will never be high enough to change fast enough, so really you just need a block there as thermal mass. However, just because you want some mass there doesnt mean it has to be a tall block....a thin one will work fine too - to keep the short melt zone.
I have done a re-design of the mooncactus blocks, but I think that now I need to do a "rev_2" with spherical bearings for the XY rods...I have also had some resonance problems with the mooncactus blocks. Some of which was due to
one end of the 6mm steel rod being shoved directly up against the bronze bush, some of which was due to all the
bolts being loose (as otherwise it totally locks up the bushes onto the 8mm rods). We will see if it dissapears
completely with a new block design and fully tightened bolts (or even perhaps just no bolts !).
Joergen, what is the specific link for you between Cura and the bad perimeters ? With which slicer have you
found it to be better ?
C.
-
For me, modelling that engine in AutoCAD is probably just as impressive as the print itself.....
I would be interested to know how you got the cooling fins to print without spending 1 week removing
support in between them...or are the cylinders split vertically and glued in two halves ?
C.
-
I found that initially I had horrible friction with the "mooncactus" XY blocks. Which drove me nuts,
which was eventually traced to there being too much clamping on the XY bushes. Such that even three
little M3 screws were able to squash it enough to deform the bronze to clamp right onto the 8mm steel rods.
So had to spend some time reworking the 11mm bore on the XY blocks. Its much better now, but I think
that a clamp design is not ideal for these bushes. So will probably redesign the XY blocks to reuse
excellent belt tension concept but have original push fit design for bronze bushes.
I think we are wandering somewhat off track on this thread now...I suppose we ought to start a "New XY blocks" thread
in modifications and hacks...
C.
-
I just bought a big box of flexible 5to8mm couplers.
They are not quite as good as the last ones I got, but I will replace the Z coupler
with one and see what happens.
I think also stiffer Bedplate springs will help. My table just flies around like those play toys in the park
which consist of a seat and handes on a big spring...
But I have a horrible suspicion that this will all lead to the inevitable...complete replacement of the Z stage.
-
Im not very convinced that a valuation of 500,000,000 is a very representative amount...for what in the end
is basically a website, and a company making a product that is (compared to the kind of tech that
Stratasys already has) pretty obsolete in a commercial printer product context.
Which suggests to me, that either its just another "buy-it-out-and-let-it-wither-on-the-vine" story, or perhaps
that we will see both being fully commercialised in the near future.
Either way, I very much doubt that its something that will make any contribution to the open source maker community.
However, it can be seen as good news - in a way - because its one less competitor for UMaker. Im quite certain
that after the Makerbot has been put through the full commercial treatment it will be less attractive to buy.
Probably we can expect to see the filament "cartridge" prices hiking up soon I reckon.
C
-
Will post pics later, but result for me is postitve.
Good points = vertical lines in print corresponding to pulley tooth pitch are almost gone now
Bad points = improved accuracy reveals even more the negatives from the Z carrige wobble and vibration.
-
The price is paid for by the customer...what has it to do with the company how much a PSU costs ?
If you want a self levelling bed - you will need a sensor.....
-
By "same place", do you mean just "the back"...or its the same Z height level as well ?
-
Pulleys received with thanks, currently installing - and taking opportunity to replace XY blocks
with MoonCactus`s printed ones...I hope they work ok.
Will post results late tonight, have to pause in installation to go outside* to get food.
(* A desolate barren place with no printers)
Ughhh I really really need to get a proper camera...these pics are useless
-
The reason I put the fan on the back, is that the metal there is one nice big flat surface, but in the
middle its three things sandwiched...so not quite so good for the thermal conductivity. But honestly
on the top is probably completely fine.
I would be concerned if the tension is now so much that its harder to move than before !
If its that high, your bearings will be suffering alot and you are in danger of skipping steps (esp when the head
nozzle tip rubs across a bit of raised print).
I would recommend considering a new slider block arrangement like this one, which decouples the clamping
of the Ø6mm rods and the belt tensioning functions. So will probably make it easier to tune your belts a bit.
http://www.thingiverse.com/thing:45236
Looks nice though !
-
Just be very sure to get "pinch clamp" couplers and not with grub screws.... or you can end up with the same thing
happening again....
-
Agreed..... (90%
) -
There are so many clever people on the forums, who are all probably happy to share their own developments
to their own machines. I dont think it would be that hard to arrange a "european ulti-weekend" or something
where people could be invited to bring their modified machines, all get together and help out.
If the problem is that UMaker is flat out just building the machines, then there are 3 choices:
1) dont make new developments and eventually "do a Commodore"
2) hire a mechanical engineer for R&D
3) Use the engineers/inventors/hobby engineers/and so on, who are already on your forum !
For me #3 is the winning choice....look how well it worked out with the Umaker/Bertho extruder mod !
-
There is no reason to panic, and I am not trying to be a pain.
Just a good example, is this one. Which is I think a really better way to do the bed adjustment.
http://www.thingiverse.com/thing:8550
Im not saying do THIS design. Just that its a good concept that can be surely applied to the machine at very
minimal cost without any super high cost parts.
Most of the stuff on the "wanted" list is similar. Its just that someone needs to sit down for a few months and
make all the changes.
I hope they will !
-
Well sorry but I disagee almost completey with the validity of any of that.
The things I am suggesting are NOWHERE NEAR, reaching the standards that commercial printers are using.
Neither are they even getting in the same ballpark, as the kinds of things that can be produced in terms of
presicion or expense.
3D Printing is not some kind of huge playpen full of happy tinkerers....it looks like that now beause we are right at
the base of the "technology curve". When everything is new and interesting and things are still at a level where
"a guy in a shed" can produce results that are still at least vaguely comparable to a commercially produced part.
However this is not a static situation !!!
Things are moving at an incredible rate, and quite simply you must be running at full speed - to have even a
chance of standing still in relation to the competition. To be actually standing still, and admitting you have no
interest in any particular development is utter and total madness, because you are then moving backwards
at a tremendous rate of knots relative to everyone else.
Quite simply what will happen is that at some point (I dont have a time-machine so I cannot say exactly), someone
will release a machine that has ALL the things in the list above, for the same price as your machine. Or also
possibly the price of the UV resin will continue dropping (now $60 USD for 1 Litre from SOLAREZ) and someone
will make a printer than can make net shapes bigger, cheaper, faster and better than you can......then one day
you will notice a few less orders than usual....which will quickly become just your mates and a few die-hards
buying it and you will be left high and dry.
Its not my company ! Just saying that thats exactly what will happen....take it or leave it. But any amateur
historian of tech will have books filled to the brim with idential stories. (Eg, Commodore Amiga - came out and blew everything away, but they were so pleased with themselves that they never bothered upgrading the hardware significantly and eventually someone went into a computer shop and saw the same games being played on an IBM PC for less money...then sales simply stopped).
The "hobby market" you are referring to will simply not exist in its current form in a very short period of time. Its going to move forward too....move with it...or be prepared to end up on the street at some point.
If UMaker have no interest in improving significantly, did they send the same memo out to every other garage maker on earth ? Will they also stop because UMaker doesnt want to ?
I dont know......but I can make a pretty good guess.
C.
-
Well its probably "ok", but its certainly not classed as an insulator either...
However the issue with all these things is "what do you DO with it".
If you suspend it in grease, its just moly grease. Which due to the soap suspension gives you the same
problems as all other greases which is to say massive friction drag.
Or you can "apply" it as powder...which will then be very effectivley wiped off by the runner blocks. I couldnt
say how many hours it would take it wipe it all off or at least wipe the stuck bits all down to the ends of the rods..where
they dont do anything useful.
The best things to do, are either apply something like moly as a baked on coating to the rods (expensive), which
keeps it where you want it. Or you can just buy the dry-lube bushes I already posted a link for.
You dont have to get THOSE ones, its just an example of the kind of things you can get off the shelf.
But its a very good idea to get the lubricant as part of whatever bit is moving, because otherwise it just gets
wiped off.
So if you run plain steel rods, with dry-lube purpose make bushes it will probably work very well.
Lubrication is an extremely complex science, and there are so many coatings and so on available that the best
is to find a supplier of dry-lube bushes and telephone them and explain the exact application you need.
The speeds, loads, duty cycle, mating material, surface finish are all critical bits of info to make a good system.
If that all sounds like a pain in the arse, then just go old-school and buy some properly oil impregnated
phosphor bronze bushes and be done with it. I cannot comment on what the UMaker has because its
only "semi-open source". So I dont know what materials specs or suppliers they use for any of this stuff.
Perhaps the standard ones ARE as above...who knows.
Regards
C.
-
Yes you are correct about the heated chamber Daid, my mistake on that.
However there are alot of people on the forum who just paid out their own pockets to
upgrade the pulleys.
So depends what you mean by "fine". Do they turn round, and not melt ? Yes.
Are the well made, concentric, with properly toleranced bore, acurate toothform and deburred ? No, no, no, no and no.
Depends what you want. My wishes are now extended beyond function, to functioning well. So thats where all
this comes from.
C.
-
Especially as pretty much every single thing above has been invented and developed by people
on this forum on their own machines....but there comes a point when the number of add-ons and widgets outnumber the original parts...that to work properly, all the new stuff should be consolidated into the official design.
I vote its time that happens. Its no good just waiting until things start breaking, we need performance upgrades
not just failure fixes.
C.
-
Good packaged slicer software = yes
Good website and forum = yes
Good sales = yes
Good reputation = yes
Dual extrusion = no
Heated bed = no
Heated chamber = no
Belt tensioners = no
Direct drive = no
Bed height sensor = no
Filament thickness sensor = no
ABS proven hotend = no
Decent pulleys = no
Proper 3 point bedheight adjustment = no
When do I get to put a "yes" after something mechanical ?
C.
-
Graphite is just about the worst possible thing you can do, its electrically conductive....
The fans will blow it around and the electronics fan will (at some point), suck it into the electronics main board area.
The point about the oil imprgnated bushing is that it does not require anything else to be applied.
-
Grease is a definite disaster, light oil is pretty good (much better than dry) but as mentioned needs to be
re-oiled reguarly.
I dont know exactly what the slider sleeves in the XY blocks are made of, but for it to work it needs to be
sintered phosphor bronze (which is highly porous, like a sponge). These then need to be impregnated in oil
preferable under pressure.
http://www.use-enco.com/1/1/86630-sae-841-oil-impregnated-bronze-round-rods.html
People used to just drop them in a bucket of oil for a week and call it done, but
that will never force the oil into the structure very deep so they stop working quickly. The whole idea of
self lubricating phosphor bronze is that its sponge structure is filled with oil, which slowly leaches out over
months and years keeping it running well.
Many people dont really understand how it works, and just buy a bar of "stuff that looks like bronze" and lathe
sleeves out of it. Of course it doesnt work very well at all....it has to be sintered phosphor bronze which has been
properly oil impregnated. The phosphor helps a bit, because its so soft and has some self lubricating properties. Which
is much better than just steel on steel, but not really good enough for constant high speed friction.
http://www.bearingbush.com/sintered.html
Possibly a good thing is to try properly engineered dry lubrication bushes, like these. They will only work with low loads.
http://www.igus.eu/wpck/default.aspx?Pagename=RJUM_01_ES&C=DE&L=en
At the moment I am still just using light oil every 20hours of printing, and it works very well. But its not really a great
solution.
Either that or put linear ball bearing races in everything. But honestly the loads probably dont warrant it and
might even result in more play - given the pretty wide tolerances on the standard steel axes.
C.
-
Just some clamps to hold on the brake cables, the normal adhesive pads dont stick to the carbon frame...
-
I dont think Calcium Silicate has useful mechanical properties, and I would be very surprise if you could clamp into lathe jaws without crushing it like chalk (EDIT, yes Calcium Silicate has a compressive strength of about 600kPa....so thats about 100x less than ABS plastic and in fact slightly LOWER than chalk)
MACOR (developed as a machinable ceramic) is a much better material if you want a high temp insulator, its a little more conductive - but
its not really expensive, its machinable and quite strong. Its also stable to extreme temperatures
far higher than you would ever need to print any thermoplastic.
C.
-
I run all fans on a separate PSU, so I can control exactly what happens without relying on the printer to control it.
The steppers get very hot, and mine would reguarly be hot enough to be painful to touch (before direct drive).
I dont think there is any issue, and am 99% sure you only notice because the motors are now sticking out so you can touch them.
C.
)
Complete Hot-end and Print Head Redesign
in Third party products & modifications
Posted
The clerance I was thinking of was between the 6mm rod, and the inside bore of the spherical bearing. However
worse case, probably some loctite would sort that out...or even perhaps a sliver of ptfe tape.
The bronze bushes are Ø11mm nominal size. I didnt take the opportunity to measure one properly
while I had it all dissasembled....
C.