More issues with the Mono Price Select

[Moccasin]

I must not be asking the right questions as I have received almost no responses other than from one Moderator. Never the less, I’ve fought my way through most of the issues, replacing the hotend with a micro swiss all metal hotend, added the glass bed, added braces to the Z axes, several adjustments to settings along with elongating the slots on the Z axes and moving the limit switch down. All have had positive effects but it seems when I solve one problem, others crop up. I need to print parts from ASA for the UV resistance and managed to get one part printed. I removed the part and selected print for the next identical part and the extruder stops a few rounds into the skirt. It did this on the first part so I removed the gear motor and cleaned out the drive gear that did have partials embedded in the teeth. Once reassembled, all went well till I called for the next part. I am waiting for the hotend to cool down to clean it again as it is again refusing to extrude. The odd thing is that I can manually run the extruder and the filament flows fine. It only stops after it starts to print. I can only make a WAG as to what may be happening. Could it be that there is just enough trash in the drive gear to allow it to slip once the filament has a slight back pressure when extruding onto the bed? It will not extrude again if I lift the head up and run the extruder until I release the lever and push down on the filament. It will then again work OK till the head goes down onto the bed. It may extrude a small amount or may not, once it starts the brim. Any ideas are welcome.

BTW: I placed an order for the original Prusa MK2 but it’s weeks out.

[curious aardvark]

pla also has great uv resistance.

Also any time you strip an extruder, get a craft knife and clean the hobbed bolt. It's not often the issue but getting the crap out never hurts.

Sometimes you just need to increase the extruder temperature.
The max temps on most filament are 'guides' sometimes printing hotter will work better on your machine.

Also sounds like you might have your nozzle too close to the bed.

From what i've heard asa is similiar to abs as far as shrinkage and warped prints goes - so not the easiest of filaments to print with.

[Moccasin]

This extruder is not so simple to clean. 2 screws hold the gear motor to the cooling fan through the cooling block and must be removed to get to it.
It is turning out to be a fine line between too close and too high with the print head. The original plate that came on the printer is a bit warped so impossible to get right. Adding the glass helped considerably but the 4-bolt leveling system could be better. I am going to try a 3-screw approach to see if that make it any easier. I’ll remove the 2 in the back and move one to the middle of the bed in the back. That should allow me to level the bed left to right then raise or lower the back. If the front is then off, either way, it’s just a matter of turning both front screws the same amount.
From what I’ve read, ASA is 10 times stronger and less likely to warp than ABS. The prints look great once I ever get one to finish.
Thanks for the reply.

[curious aardvark]

You can get those extruders apart and back together in about 10 minutes. I've done it more than a few times :-)

As far as levelling systems go. I massively prefer a 4 screw - one at each corner - approach than the totally non-logical three point levelling system.
How do you just lower the right or left hand edge with 3 screws ?

Something that might help - what you actually have is a re-badged wanhao i3 duplicator.
So using that in your searches should brig up a lot more results :-)

[Moccasin]

That is a great question and here is how it works for me. Hope this is not too wordy.

Ever tried to level a table or stool with four legs? I know everybody has been in a restaurant where the table rocks where the floor is not level. On the other hand, there is no such issue with a three-legged table or stool. Think of it like this. You have a three-sided pyramid. Assuming you are on a level surface, all you will need to do is shim one of the three bottom points to make it level. If we had a lot of weight out on the two back corners then they may droop but that is not an issue here, at least not with my small bedplate. If you cut the two back corners of the bed off so that you had a triangle, it’s the same thing – you don’t need the fourth point.

I have built towers all my life and nearly every tower has three legs so we use transits and set one up 90 degrees to a flat face looking through the tower to the back leg. That puts us halfway between two guy points, one to the right and the second to the left. We adjust the tension on these two points only, till the tower is plum left to right. The second transit is 90 degrees to the first one. If the tower is leaning towards to away from the first transit, it a simple matter of adjusting the tension on the third guy point until the tower is plum in that direction. The first two points are only adjusted together or the same amount if the tension on guy cables needs to change, so the tower never get out of plum.

That’s is the same thing I am doing here with the bed plate. I had to make a couple of mods to allow the knurled nut to pass over the back edge of the frame when the bed goes to the back. I also added a short offset tab to the center of the bed on the back to allow for the adjustment screw. I have not got it completely back together but will report how well it works or doesn’t work once it’s up and running.

See if the attached illustration makes sense?
bed leveling.jpg

[curious aardvark]

the thing is a build plate is not a structure.

So when you adjust one point it also effect the other 2.
Whe you adjust an edge on a four point plate, you adjust the bolts for just that side.
were you dealing with a tringular plate or a round one as on a delta. it makes sense. Because essentially you are adjusting a trinagle.

But 3 point levelling on a four corner bed is just stupid and almost impossible to visualise and adjust correctly.

[Moccasin]

I sometimes have difficulty explaining a concept so it may be clearly understood and that is why I included the previous illustration. If you look closely at the drawing, you'll notice the similarities between a triangle bed and the four-corner bed I’m dealing with. As I stated, remove two right angle triangles from the two back corners and you have a triangle bed. The dotted lines represent where you would remove part of the bed to make it the same as a triangle bed. Tell me why the extra corners matter anymore in my case that if you added two corners to a triangle bed that is leveled with three points. Meanwhile, back at the ranch, the printer has been running all afternoon and has not missed a beat. The three-point system is working fine. I adjusted the two points at the front of the bed for the right clearance then moved the bed forward and adjusted the back point. I did have to return the bed back to the front a couple of times until it was level but it took far less time than usual. The proof is in the pudding, as they say. Maybe I have a case of the bumblebee syndrome, I didn’t know I couldn’t do it so it works.
3_point.jpg