Jump to content

G_T's build log - trials of an insulated hotter printer


G_T

Recommended Posts

 

I need to provide a real build log here when I get the chance (have plenty of pics), but continuing from

I printed a part in PC-CF with 120C bed 300C extrusion and chamber hovering a hair under 70C. It was a nozzle scrubber to take a little more heat. The part came out perfect. But, the part wouldn't quite fit due to kinematic mount, so I modified the part to print it again.

This is getting into the lower end of the range of materials I want to be printing. So I was quite pleased. I also guessed the numbers rather than making any calibration prints. Sometimes it's better to be lucky than to be good! I gave the part a good stress test. It is quite stiff and solid.

The second print showed intermittent layers where underextrusion appeared to be happening in short stretches every few layers, and then the printer went into air printing. I cleared the clog and went at it again, this time increasing to 305C and slightly decreasing the already slow max print speed. It went into air printing without warning after the first few layers.

What I think is happening is the hot end cooling fan is not handling these temperatures very well and starts to slow down, and then heat creep progresses past the heat break terminating the print. The slow printing speed is helping the filament transfer heat. Although it is also possible it is the extruder motor which is having the issue. Or both. I don't think it is filament slipping. It doesn't take much force to push the filament at these speeds and temps (hand push test) and the extruder seems to be gripping it just fine.

Of course I tried to clear the filament path by running the temp higher and manually pushing filament with more force... That has worked before, but not this time. Now it is seriously clogged! I might have to replace that heat break and I don't have a spare.

It was funny - I could manage to slowly ooze mostly clear PC out the nozzle, but the carbon fiber was left in the heat break and nozzle! I'm guessing it is at least 40%CF up there now, probably quite a bit higher. I'm resisting the temptation to reassemble without the nozzle or cooling fan, (actually just dangle the mosquito) and run the temp up higher to see if I can drip the massive clog out.

Gerald

 

Link to comment
Share on other sites

I began this project in November. It's hard to believe it has taken this long and I still have a ways to go. It started life as an LDO 300 cube, but with corner braces added (a bit of remachining of braces available off Amazon), a 6mm polycarbonate front door, and https://www.amazon.com/dp/B0CFW3NZ84?psc=1 for most all the other panels.

This is what can happen to the standard POM Z nuts when running at somewhat elevated temperature when grease is present. The plastic was essentially slowly dissolving, and Z moves were getting very squealy. Z artifacts were increasing. This didn't start until the chamber temp was over 60C roughly, perhaps 65C. Above 65C the parts deteriorated very rapidly. Bed leveling would sometimes fail. So I machined drop-in replacements out of PEEK. These work better.

Delrin (POM) is softer so it absorbs vibration better. So I did have to reduce Z rapids or the rods would go into resonance. I should just clog them up with POM dust and grease to dampen the resonance! It won't hurt the PEEK. Anyway having slower Z rapids is a non-issue from my perspective. So little of the print time is spent doing Z rapids...

The printer picture is not current but it will give an idea of the beast. Mostly I've just been upgrading parts to higher temperature parts as I've found or anticipated the need. There are lots of updates to come, but I need to print some of the parts first. I'm intending to replace ABS anywhere it might get any load or be close to the bed, with PC-CF or aluminum. Some parts are already replaced with PC-ABS as an intermediate material. I may have to go back to that approach rather than jumping straight to PC-CF.

I attached a pic of one of the sides before I drilled the mounting holes. You can see I had to contour the thickness of the insulation to provide room for the belts and the Z motion. The panels are working well, but I should have probably used a little more insulation. But if I had, then I'd be having more thermal issues at this point. I can always improve the insulation later once the thermal issues are all worked out. That's if I even need to.

The front door is funny. Polycarbonate has a decent coefficient of thermal expansion. Just having the view port in the front door means that part tries to warp when hot, causing the door to hold itself somewhat open. I added a miniature bungee-like strap to hold the door closed. I'll probably end up adding another layer of insulation to the door and reducing the viewport size.

Insulation is pretty simple in this one. I tiled the panels on the inside with 4" x 1mm self-adhesive cork squares, and then added thin metalized fiberglass on top. Amazon again - https://www.amazon.com/gp/product/B08M6BQ1HT and https://www.amazon.com/gp/product/B08M6BQ1HT I should perhaps have used slightly thicker insulation. TBD. I can fix that later if I have to.

Bootstrapping a printer...

While I'm getting the hot end working again, I'm also going to be replacing the lights. Those stick-on LED strips don't stick when you get up around 70C. I'm replacing them with light bars. We'll see how those handle the heat.

Lots of other changes are in store for this one. Unless I give up!

Gerald

IMG_1645.JPG

IMG_1643.JPG

IMG_1600_crop.jpg

IMG_1581.JPG

  • Like 2
Link to comment
Share on other sites

Hmm, now you got me thinking. My Trident is getting squealing Z on large Z movements (like when parking). I'm on my original POM nuts, which are now at (<checks history>) a bit over 3000 hours. I wonder if they are wearing out. 

  • Like 2
Link to comment
Share on other sites

It is possible. The squealing can be accompanied by resonance in the threaded rods. You can see them vibrate rather than just rotate on axis. So it can also be wear in the stepper bearings, or lead to premature wear of the bearings.

What you can do is grab each Z mount and see if you think the slop is excessive in any of them. Replacing the nuts is a minor pain. If you are not having trouble getting consistent Z motion you may still be ok. You can test that directly with TAP, or set a paper's width off a nozzle, move down some distance then move back. Check fit of paper... Try different distances... If it isn't consistent, it's time for some maintenance IMHO! If it is consistent, you could just slow down your max Z speed until the sound disappears.

Having spares on hand though might be a good thing.

Looks like I might have trashed my Mosquito. I cannot get the heat break out of the heater block. It is fused. And to add to the fun, my order of EPDM 6mm Gates belts seems to have been stolen before I got home from work. Just not my day.

Gerald

Link to comment
Share on other sites

Well, for one I have WobbleX so the lead screws are free to wobble around as they need. I'm also playing with Orca 2.0 and running the 0.25 nozzle & 0.1 layers; I'm currently getting absolutely gorgeous first layers on print jobs. The squealing is occasional during big, fast Z moves, never during a print. I did find I have a full set of POM (and brass) nuts in my parts bins, so I'm all set if an when they are actually a problem. I'll leave it for now--I have two working printers again after a couple of weeks of struggle so I just want to print for a bit.

Link to comment
Share on other sites

FWIW, I have a small collection of brass and pom nuts as well. The quality varies. One set of the brass nuts has the thread tilted off axis. Those would be unusable. So check quality before use!

I hit another interesting issue. I've been working towards a rebuild step, replacing more of the ABS parts with higher temp parts - aluminum, polycarbonate, high temp nylon... Along with the update I intended to replace the Gates belts with Gates EPDM higher temp belts.

I've bought these belts now three times, from different suppliers. I have reason to think they are genuine. They are also IMHO not suitable for our use. They appear to be good quality, but here's a test to perform on any belts you want to use:

Take two lengths of belt, and intermesh the teeth. Keep hold of one place or clamp them together at a spot. Then run your fingers down the pair of belts keeping them meshed. Once you get to moderate length I'm finding large error.

This is going to result in oddities of the motion, since a given rotation of a stepper will result in inconsistent length being moved, courtesy of the pinion being splined. We rely on belt consistency and the Gates EPDM belts don't seem to have it. That's why I have the regular belts in the printer at present. It may be luck of the draw. The first batch of regular belts was quite a bit more consistent so that's what's in there. None of the EPDM Gates have been usable.

Now if the glass filled high temp nylon will arrive, and the replacement heat break for my mosquito, I can get back to printing parts.

I did repace the lights, but haven't really tested it much yet.

I also splurged and picked up a UHT Revo (the 400C High Precision model not the 500C version). I doubt I'll have real use for going above 400C. I'll never get the chamber hot enough to warrent using such filament!

I can't use this hot end yet since I only have an ABS mount for the Revo Voron. That's something I plan to print out of the GF high temp nylon. I don't want PC there since PC burns too well once lit.

But I'm not really sure I want to stay with Stealthburner anyway. For me it's too much form over function. I don't need a decorative faceplate. I don't need voron pattern lights in the front. I don't need parts lights - my chamber lighting is plenty bright if I want it to be. I'd prefer smaller printed parts, and less weight.

I'd like something like a WristWatch or G2SA (printed in CF PEKK or other) or LDO Orbiter 2 bolted on top an aluminum combo fan mount and heatsink for the heat break. Put a fan on the heatsink. Add a second fan with duct for parts cooling, but perhaps make that assembly easily removable. Generally I won't be needing as much parts cooling, as I don't plan to be running all that much PLA and the higher temp filaments don't seem to need much if any cooling for engineering parts (avoiding bridges and overhangs). Then I want this assembly bolted onto a Vitali Tap. I'm running that tap version now and it is rock solid and reliable. There's no play when it is down.

If I still had my Bridgeport vertical mill I'd have already made it.

Gerald

Link to comment
Share on other sites

New record for chamber temperature, peaked at 76.5C and stayed close for a few hours printing. Unfortunately I had another nozzle clog at about 4 1/2 hours in. It seems the 0.4 nozzles clog about every 16 hours so far when printing 3DXTech PC+CF. Hot end 305C, bed 120C.

It's being a race at the moment. I'm printing hot enough that ABS fumes are coming out of the printer, in spite of it being pretty well sealed, and in spite of not printing ABS. The ABS parts in there are outgassing. I'm pushing it really near the limit, printing some parts that will allow me to take it hotter.

The batch I'm working on is A/B motor mounts with pin mod and upper bearing mod. I have some long shaft steppers that I'll be switching to. The bearing mod puts a support bearing in the upper parts so the shaft is fully supported.

These PC+CF parts aren't going to win any beauty contest, but they are strong. I couldn't break a flow test tab in my hands. Layer adhesion is quite good, probably due to printing slowly at good temps.

When I swap these in I'll also be swapping in an all metal gantry. That leaves the tensioners. As much as I'd like to print them in PC-CF that would be no good for sliding parts. I'll see what I can do with PA12-GF but I expect the same result. I'll probably end up reprinting the RamaLama-II in 3DXMax PC.

Sorry the short video is upside-down. I've done very little video editing before.

There is a temperature gradient in the printer, the top being hotter than the bottom. So I'm replacing parts top-down at this point.

I think I mentioned it before, but the first thing I had to replace was the POM nuts with ones I machined out of PEEK. The POM nuts were sort of dissolving away when I went above 70C. The holder for the Mosquito is high temp nylon. I have the hatch removed from the Stealthburner for a bit better cooling. The bed mounts are kinematic which helps given the wide temperature range involved.

The magnet sheet is down to at best half its original strength. When I get all the ABS parts replaced then ramp up the temps, that magnet is dead. I'm planning on seeing if things will be stable at 90C chamber temp. I'm not really planning on going above that.

The last pic was during construction.

Gerald

IMG_1706_mod.JPG

IMG_1700_mod.JPG

IMG_1676_mod.JPG

IMG_1582_mod.JPG

Edited by G_T
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...