@theruttmeister said in Compensation for lost motion:
Pick one, 80-90C is a very different challenge than 150C. You can use regular neoprene belts etc.
I set the target at 150C. If that ends up being too costly or too much hassle I might scale down.
You can't buy them online, you need to talk directly to either a manufacturer or a specialist supplier.
https://www.belttechnologies.com/timing-belts/
As an example.
I found those ones. Oh well, might give it a shot.
Never tell people you are building a single machine for your own use! Its an R&D project!
It sure is, I'm not lying when I say that 😁
But still, I have issues with lying too much and I hate having those sales reps calling me every few weeks.
Talk to your local Igus rep. Yes they prefer to sell lots of stuff at a time to companies, but its not hard to get them to sell you (or even just give you) small quantities for R&D purposes. (I have drawers full of slides and bearings from them, they have always been very generous with samples).
My experience is different. Getting dispatched to a distributor that handles linear systems, taking ages to talk to someone, note reacting to E-mail, and when you finally have an answer it is 'no, cannot do sir'..
I have a request for quote out on the 12x25 J350 threaded nuts and matching screws. We shall see if it is a viable option or one of those unobtainium ones.
Run the wire outside of the envelope, then you can just use a a belt reduction stage.
That is another option I was thinking about. Would need a thicker cable though since the printheads are going to be fairly heavy and therefore the pulley even larger in diameter, but it also makes the 'triangle problem' causing position deviations quite insignificant.
Not using steel to obtain a suitable bending radius is another option. Why not carbon or kevlar, for example?
I also ordered a piece of simple unhardened rack and a few pinions to play with. It is cheap, I still see that as a viable option, and if it doesn't work out there are plenty of other uses for that around the workshop.
If you don't need to worry about the IP side, moving as much outside the heated envelope as possible makes life a lot easier.
I am still not convinced. Having those folded fiberglass curtains behave nicely, enough ventilation and associated heat loss above the curtains, dealing with drafts because the insulation differs, etcetera.
Don't forget, you need to match the co-efficient of thermal expansion on your frame and rails. And then thermally isolate the frame so its not just a big heatsink.
That one is easy. Just use steel for everything, and don't overconstrain. Shafts need to be fixed in one location only, allow axial movement at the other side, for example.
With everything in the chamber it is also easy to dress that chamber in a nice and thick layer of rock wool with only the various wires and hoses poking through.
You can also get stepper motors rated to 150C. You'll need to talk directly to a manufacturer, but they can be sourced.
Sure. But they are still specialty items with specialty prices and I expect them to perform less due to increased winding resistance and possibly lower strength hightemp magnets.
The moment you decide you want to liquid cool stuff you can use it to cool many more things like the steppers.
This might work:
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Steppers shed most of their heat through the flange. A small piece of tooling plate, a couple of minutes on the milling machine, and done. The sintered bronze bearing can sink some heat from the shaft.
I would have to test, but I expect that a cooling block at the flange and a thin layer of Armaflex HT on the body to prevent heat ingress is sufficient to keep stepper temperature below 80 degrees in a 150 degree environment.
Use a stepper with connector, escape the stepper with some silicone wire, and that part is covered too.
Everything that will get hot will have a limited service life, it takes an age to heat up and cool down, you need to do additional things like anneal your prints. Drying the filament and keeping it dry is critical (I found a toaster oven very effective for drying Ultem1000, but you do need a steel spool!).
The steel spool is not a big drama; I have friends with CNC plasmacutters, and even ordering the metal from 24/7 tailorsteel is not that expensive.
Drying, well, I do have an oven in the garage which is mainly used for curing epoxy and silicones (both love a high-temp post cure), and vacuum pump too when needed. Those two don't work together yet, but that can be done also.
Unless you actually need the non-strength properties of things like PEI, PPSU, PEEK etc, milling aluminium is often less work and faster.
It is mainly the absense of electrical conductivity, heat deflection temperature, fairly low thermal conductivity and freedom of form I am after.
I won't be printing much of it; 99% of the print jobs are handled fine with ASA, TPU, PETG or PACF, but I would like to be able to do it.
And I am not too sure about the 'less work and faster' (but I have no experience printing engineering plastics higher up the ladder than polycarbonate, which also is not easy without heated chamber).
3D-printing means slicing, sending it to the printer, preparing the build plate, heat things up and let it soak for a while, hit the start-job button, and wait for it to finish. Takes a while, but I can do other stuff while the machine is busy. That has proven to be quite valuable.
Milling means adding reference features when needed for multi-side milling and generally dressing up the design for milling, 10-120 minutes of CAM work, prepare tools, prepare stock, create a fixture if it cannot be held in a vice, juggle the touch probe to set up WCS, do the milling, cleanup the mill, cleanup the part. There is no such thing as 'let's quickly mill something'.
I am not doing that much commercial work, just enough to somewhat compensate the steady flow of money into boys toys and keep the round-breasted head of finance happy, but when I do the price I have to quote for printed parts are way, way lower than milled parts, especially when it is only one or two.
Threads like this make me reconsider building a high-temp printer... I have that spool of Ultem somewhere, that will never get used up unless...
Dammit.
Hah, gotcha! 😁
Also... is it a crazy idea to think that using the hangprinter kinematics to eliminate the need for any kind of linear rails inside the heated chamber might be an interesting solution?
Would be interesting to see how that handles small zig-zag moves 😀
